BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:A simple model for the transmission of malaria
DTSTART;VALUE=DATE-TIME:20091119T090000Z
DTEND;VALUE=DATE-TIME:20091119T103000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-242@cern.ch
DESCRIPTION:We study a simple lattice model describing the transmission of
\nmalaria. The transmission of the disease to humans occurs through conta
ct with an infected mosquito\, while a healthy mosquito can become infecte
d through contact with an infected human. Recovered individuals are susce
ptible to re-infection. The mosquitoes diffuse through the lattice\, spre
ading the disease. We show preliminary results for the model obtained via
site approximation (mean-field theory).\n\nhttps://indico.tifr.res.in/ind
ico/conferenceDisplay.py?confId=242
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=242
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Origin of Life: from geophysics to biology
DTSTART;VALUE=DATE-TIME:20091219T090000Z
DTEND;VALUE=DATE-TIME:20091219T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-304@cern.ch
DESCRIPTION:One of the deepest and most controversial questions is that of
the\nOrigin of Life. In this lecture\, a hypothesis is presented accordi
ng\nto which the temperature gradients existing in the earth - which led t
o plate tectonics and the formation of undersea thermal vents - also led t
o the evolution of life around these vents. Movies will be shown of exper
iments\, in which all stages of this scenario are presented: how thermal g
radients led to plate tectonics\, to DNA amplification\, to polymerization
of peptides at high pressure and to the organization of bacteria. This m
ixture of physics\, chemistry and biology illustrates how life could origi
nate without the intervention of the sun\, driven only by geophysical ther
mal gradients.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?c
onfId=304
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=304
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collective excitations of composite fermions across multiple effec
tive Landau levels
DTSTART;VALUE=DATE-TIME:20100113T210000Z
DTEND;VALUE=DATE-TIME:20100113T220000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-396@cern.ch
DESCRIPTION:The paradigm of density-wave modulation over the ground state\
nas collective excitations\, pioneered by Feynman\, works very well\nfor f
undamentally important excitations from the roton in superfluid Helium-4 t
o the plasmon in electron gas. This approximation which is basically a sin
gle mode approximation predicts experimentally observed rotons in the coll
ective\nexcitations of fractional quantum Hall states as well. However\, t
his theory fails to explain the recent observation of merging of modes in
the long wave length limit at fractional quantum Hall state 1/3 by inelast
ic light scattering experiments. In this talk\, I will present our theory
which solves this puzzle and predicts several other experimentally verifia
ble features some of which are already observed.\n\nhttps://indico.tifr.re
s.in/indico/conferenceDisplay.py?confId=396
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=396
END:VEVENT
BEGIN:VEVENT
SUMMARY:Grand-canonical and canonical solution of self-avoiding walks with
up to 3 monomers per site on the Bethe lattice
DTSTART;VALUE=DATE-TIME:20100121T090000Z
DTEND;VALUE=DATE-TIME:20100121T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-430@cern.ch
DESCRIPTION:We solve a model of polymers represented by self-avoiding walk
s on a lattice which may visit the same site up to three times in the gra
nd-canonical formalism on the Bethe lattice. This may be a model for the c
ollapse transition of polymers where only interactions between monomers at
the same site are considered. The phase diagram of the model is very rich
\, displaying coexistence and critical surfaces\, critical\, critical endp
oint and tricritical lines\, as well as a multicritical point. From the gr
and-canonical results\, we present an argument to obtain the properties of
the model in the canonical ensemble\, and compare our results with simula
tions in the literature. We do actually find extended and collapsed phases
\, but the transition between them\, composed by a line of critical endpoi
nts and a line of tricritical points\, separated by the multicritical poin
t\, is always continuous. This result is at variance with the simulations
for the model\, which suggest that part of the line should be a discontinu
ous transition. Finally\, we discuss the connection of the present model w
ith the standard model for the collapse of polymers (self-avoiding self-at
tracting walks)\, where the transition between the extended and collapsed
phases is a tricritical point.\n\nhttps://indico.tifr.res.in/indico/confer
enceDisplay.py?confId=430
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=430
END:VEVENT
BEGIN:VEVENT
SUMMARY:How proteins find and recognize targets on DNA
DTSTART;VALUE=DATE-TIME:20100211T090000Z
DTEND;VALUE=DATE-TIME:20100211T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-482@cern.ch
DESCRIPTION:Protein searching and recognizing the targets on DNA is an imp
ortant initial step in many biological processes. It is often argued that
some proteins are capable of finding their targets 10-100 times faster tha
n predicted by the three-dimensional diffusion rate. Current theoretical v
iew of this phenomenon is based on the idea of lowering dimensionality\, i
.e.\, the overall search process is viewed as a combination of uncorrelate
d 3D excursions in the solution and 1D hopping on DNA. However\, some pred
ictions of this theoretical picture contradict recent single-molecule meas
urements of protein diffusion along the DNA molecule. We present an altern
ative theoretical approach that points out into importance of correlations
during the search process. That correlations appear due to non-specific i
nteractions between proteins and DNA molecules. Our theoretical prediction
s agree with all available experimental observations\, as well as with ext
ensive lattice Monte Carlo simulations. It is argued that the acceleration
in the search could only be achieved at some intermediate non-specific bi
nding energies and proteins concentrations.\n\nhttps://indico.tifr.res.in/
indico/conferenceDisplay.py?confId=482
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=482
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamical Phases and Noise in Transcription Process
DTSTART;VALUE=DATE-TIME:20100318T090000Z
DTEND;VALUE=DATE-TIME:20100318T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-548@cern.ch
DESCRIPTION:Transcription\, the process of polymerization of mRNA is catal
yzed by a molecular machine\, RNA polymerase. It uses DNA template as a tr
ack on which it moves like a motor utilizing chemical energy supplied by N
TP hydrolysis. It has been observed experimentally that many RNAPs simult
aneously move on the same track (very similar to one way traffic on the ro
ad). We give a model which takes into account steric interactions among t
he RNAPs as well as the mechanochemical cycle of the RNAPs. We plot three
dimensional phase diagrams of the RNAP traffic using extremum current hypo
thesis for our model. Recent in-vivo experiments with single cells show t
hat the transcription process takes place into bursts. In another model we
include switching of the gene between on and off state\, together with me
chanochemical cycle and steric interactions. This model accounts for stati
stical properties of transcriptional bursts.\n\nhttps://indico.tifr.res.in
/indico/conferenceDisplay.py?confId=548
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=548
END:VEVENT
BEGIN:VEVENT
SUMMARY:Unconventional Superconductivity in Noncentrosymmetric Superconduc
tor(NCS)
DTSTART;VALUE=DATE-TIME:20100603T090000Z
DTEND;VALUE=DATE-TIME:20100603T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-653@cern.ch
DESCRIPTION:The discovery of superconductivity in crystals which lack spat
ial inversion symmetry is an active field of research over the past few ye
ars. The spatial symmetry breaking in these materials gives rise to some s
pin-orbit interaction which lifts the degeneracy of the electronic band an
d splits it into two. As a result the superconducting order-parameter beco
mes a combination of singlet and triplet components\, which is responsible
for many peculiar properties of this system. In this talk we will focus o
n this system in general with special attention to (1)the Ginzburg-Landau
theory of this superconductor and (2) the consequence of the predicted edg
e states in this system on the tunneling process.\n\nhttps://indico.tifr.r
es.in/indico/conferenceDisplay.py?confId=653
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=653
END:VEVENT
BEGIN:VEVENT
SUMMARY:Superfluid Insulator Transition
DTSTART;VALUE=DATE-TIME:20100701T090000Z
DTEND;VALUE=DATE-TIME:20100701T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-687@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
687
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=687
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quenching across a quantum critical point: non-trivial power laws
in different topological sectors
DTSTART;VALUE=DATE-TIME:20100708T090000Z
DTEND;VALUE=DATE-TIME:20100708T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-699@cern.ch
DESCRIPTION:We study what happens when the Hamiltonian of a system with di
fferent topological sectors is quenched at a finite rate across a quantum
critical point. We show that the quenching leads to a residual energy whic
h scales as a power of the quenching rate\, where the power depends on the
topological sector in a non-trivial way. This generalises the idea of a L
andau-Zener transition in two important ways: depending on the sector\, th
e analysis may involve more than two states\, and the effective Hamiltonia
n in the low-energy subspace may involve non-linear quenching even when th
e quenching of the original Hamiltonian is linear in time. As a specific e
xample\, we discuss all these ideas in the context of the Kitaev model def
ined on a two-leg ladder which can be studied by mapping it to a system of
non-interacting fermions.\n\nReference:\nSen and Vishveshwara\, arXiv:100
3.0058\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=69
9
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=699
END:VEVENT
BEGIN:VEVENT
SUMMARY:3He in Aerogel: a Dirty Superfluid
DTSTART;VALUE=DATE-TIME:20101028T090000Z
DTEND;VALUE=DATE-TIME:20101028T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-892@cern.ch
DESCRIPTION:Liquid $^3$He undergoes a superfluid transition to a p-wave pa
iring state at millikelvin temperatures. When $^3$He is filled into highly
porous silica aerogel\, a system of impure unconventional superfluid is r
ealised. The effect of the aerogel on $^3$He has been studied extensively
both experimentally and theoretically. I will give a historical review of
the major developments in the study of this system. The order parameter of
superfluid $^3$He is considered a paradigm for unconventional pairing due
to its rich symmetry structure. The effects of disorder on this order par
ameter are drastic and significant. On the other hand\, the effect of the
aerogel structure on the Landau Fermi liquid state of normal $^3$He is als
o very interesting. I will talk about my calculations of magnetisation and
transport in the normal and superfluid states.\n\nhttps://indico.tifr.res
.in/indico/conferenceDisplay.py?confId=892
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=892
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collective relaxation of magnetization in magnetic molecular solid
s
DTSTART;VALUE=DATE-TIME:20101029T090000Z
DTEND;VALUE=DATE-TIME:20101029T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-914@cern.ch
DESCRIPTION:The quantum mechanical magnetization dynamics of magnetic mole
cular solids are very well understood at the single molecule level. This i
s not so for the dynamics of the full solid. The talk will discuss how the
dynamics changes from coherent tunneling to incoherent relaxation when en
vironmental interactions are included\, and how intermolecular dipole fiel
ds affect the collective relaxation. Results of preliminary Monte Carlo si
mulations will be presented\, and interpreted via a set of rate equations.
\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=914
LOCATION:Colaba Campus AG-69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=914
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Next Revolution in Biology after Genomics can be Delivered if
only Biology is Integrated with Physical\, Engineering and Computational S
ciences
DTSTART;VALUE=DATE-TIME:20101112T110000Z
DTEND;VALUE=DATE-TIME:20101112T120000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-923@cern.ch
DESCRIPTION:In this broad overview I discuss the influence of physical\, e
ngineering and computational sciences in biology. I argue that\, to achiev
e breakthroughs in modern biology and medicine\, it will be essential for
biology to be integrated. I trace the history of such developments and go
beyond what the historians of science have so far dealt with\, namely scie
ntists such as Crick\, Wilkins\, Perutz\, Delbruck etc. The conventional a
rguments have hinged around which organization saw the need to bring physi
cal sciences to solve molecular biology problems. I discuss how Schrodinge
r's book\, ``What is life?'' influenced physicists to move to iology. I w
ill discuss my interviews with leading scientists such as Walter Gilbert (
QFT)\, who got the Nobel Prize for developing a technique to sequence DNA
\; Howard Berg (Ph.D. in Maser Physics) who studies bacterial chemotaxis\;
Benzer (p-njunction) who is considered a world authority on {\\em Drosoph
ila} genetics and many others\, scientists that have not been interviewed
before\, who gave reasons for their switch to biology. Among them were the
influence Delbruck exerted by his courses at the CSHL\, Schrodinger's boo
k\, war and a host of other reasons. I discuss some examples how genomics
has created a true revolution from medicine to evolution and helped closin
g the gap in understanding Darwin's volution\, especially in the light of
a new branch in biology\, Evo-Devo. I also draw attention to the current
effort by some biologists to ``overcome'' the central dogma of molecular b
iology and discuss whether systems biology is reductionist or holistic.\n\
nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=923
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=923
END:VEVENT
BEGIN:VEVENT
SUMMARY:Early warning signals of discontinuous ecological transitions
DTSTART;VALUE=DATE-TIME:20101112T090000Z
DTEND;VALUE=DATE-TIME:20101112T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-931@cern.ch
DESCRIPTION:Diverse ecological systems\, from swarms of locusts to forests
\, can show drastic (discontinuous) response in their states even for the
smallest changes in external conditions. In this talk\, I will present how
principles of nonequilibrium phase transitions from physics can be employ
ed to devise early warning signals of such ecological transitions. It will
be shown that simple measurable quantities such as changing skewness in t
imeseries data\, and rising trends in variance and skewness of spatial dat
a can act as leading indicators of abrupt transitions. I will present empi
rical evidence for the utility of these techniques.\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=931
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=931
END:VEVENT
BEGIN:VEVENT
SUMMARY:How solvable is Burgers-KPZ turbulence?
DTSTART;VALUE=DATE-TIME:20101223T090000Z
DTEND;VALUE=DATE-TIME:20101223T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1036@cern.ch
DESCRIPTION:We show that the evolution of Burgers turbulence is given by a
completely integrable Hamiltonian system. This seems related in some as y
et unexplained way to some surprising exact solutions to KPZ. The point he
re is that Burgers-KPZ admits not just computable exponents as originally
expected\, but a great deal more.\n\nhttps://indico.tifr.res.in/indico/con
ferenceDisplay.py?confId=1036
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1036
END:VEVENT
BEGIN:VEVENT
SUMMARY:Top Eigenvalue of a Random Matrix: Tracy-Widom distribution
DTSTART;VALUE=DATE-TIME:20110112T090000Z
DTEND;VALUE=DATE-TIME:20110112T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1077@cern.ch
DESCRIPTION:In this blackboard talk I'll try to provide some general backg
rounds on the theory of random matrices with an emphasis on the distributi
on of the top eigenvalue. I'll describe the Tracy-Widom distribution: how
does it look like and why is it interesting? I'll also show that this dis
tribution appears in a number of different problems\, from Brownian motion
s to gauge theory.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=1077
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1077
END:VEVENT
BEGIN:VEVENT
SUMMARY:Statics and Dynamics of Exclusion Processes
DTSTART;VALUE=DATE-TIME:20110125T090000Z
DTEND;VALUE=DATE-TIME:20110125T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1112@cern.ch
DESCRIPTION:A series of 4 lectures (on January 25\, January 27\, February
3 and February 4).\n\nThe lectures will be at the level of a graduate stud
ent.\n\nExclusion processes are very simple lattice gas models which are f
undamental models of many-particle stochastic dynamics and nonequilibrium
phenomena. In these lectures I will describe an important an important exa
mple\, the asymmetric exclusion process with\nopen boundaries\, and show h
ow nonequilibrium phase transitions come about in this one-dimensional sys
tem. I will show how the nonequilibrium stationary state may be solved exa
ctly as a matrix product state. Generalisations to multi species processes
which give rise to tensor product states will also be discussed.\n\nProvi
sional Plan:\n\nI Asymmetric Exclusion Process with open boundaries:phas
e diagram and mean field theory\n\nII Exact solution : matrix product stat
ionary state\n\nIII Nonequilibrium partition function: Yang-Lee zeros\;
static and dynamic phase transitions\n\nIV Multispecies generalisations:
tensor product States and relation to queueing theory\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=1112
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1112
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collective vesicle transport on biofilaments carried by competing
molecular motors
DTSTART;VALUE=DATE-TIME:20110203T090000Z
DTEND;VALUE=DATE-TIME:20110203T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1111@cern.ch
DESCRIPTION:We study a minimal model for bidirectional collective transpor
t of cargo vesicles on a biofilament where the competing motion is charact
erized by the cargo densities moving toward the opposite filament ends. Th
e model incorporates inter-vesicle interaction (through excluded volume) a
nd active transport as well as motor regulation and environment interactio
ns. From the current profiles we derive the non-equilibrium phase diagram.
In terms of the filament end cargo fluxes\, the phase diagram allows for
re-emergent density shocks. This approach captures qualitatively a number
of features of the collective state of the cargoes associated with bidirec
tional transport: current reversals due to internal regulation\, boundary
induced phase transitions and domain wall localization in the bulk. Vesicl
e polarization emerges naturally within the proposed framework.\n\nhttps:/
/indico.tifr.res.in/indico/conferenceDisplay.py?confId=1111
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1111
END:VEVENT
BEGIN:VEVENT
SUMMARY:Deconfined spinons in a quantum-critical 2D antiferromagnet
DTSTART;VALUE=DATE-TIME:20110210T090000Z
DTEND;VALUE=DATE-TIME:20110210T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1175@cern.ch
DESCRIPTION:Adding certain multi-spin interactions of strength Q to the st
andard 2D Heisenberg model with exchange J (the J-Q model) leads to the de
struction of Neel order and a transition into a valence-bond-solid (VBS) s
tate [1]. Large-scale quantum Monte Carlo simulations of this system revea
ls scaling behavior at the Neel-VBS transition consistent with a continuou
s quantum critical point\, in agreement with the theory of "deconfined" qu
antum criticality [2]. There are\, however\, significant scaling correctio
ns\, possibly logarithmic [3\,4]\, that had not been anticipated. These co
rrections may actually be a fingerprint of deconfined spinons [5]. I will
discuss the latest QMC evidence for a continuous ground state transition a
s well as signatures of spinon deconfinement in thermodynamic properties.
\n[1] A. W. Sandvik\, Phys. Rev. Lett. 98\, 227202 (2007).\n[2] T. Senthil
et al.\, Science 303\, 1490 (2004).\n[3] A. W. Sandvik\, Phys. Rev. Lett.
104 177201 (2010).\n[4] A Banerjee\, K. Damle\, and F. Alet\, Phys. Rev.
B 82\, 155139 (2010).\n[5] A. W. Sandvik\, V. N. Kotov\, and O. P. Sushkov
(arXiv:1010.2522).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay
.py?confId=1175
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1175
END:VEVENT
BEGIN:VEVENT
SUMMARY:Analytical solution for a genetic switch
DTSTART;VALUE=DATE-TIME:20110225T043000Z
DTEND;VALUE=DATE-TIME:20110225T053000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1209@cern.ch
DESCRIPTION:Genetic circuits are systems composed of genes and proteins\,
where interactions between the components exist. A prime example of them i
s a genetic switch\, where the produced proteins affect the state of other
genes. That way\, a self-regulation appears between the different compone
nts. I will present the model for a genetic switch and how an analytical a
pproach can be developed to compute the number of proteins.\n\nhttps://ind
ico.tifr.res.in/indico/conferenceDisplay.py?confId=1209
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1209
END:VEVENT
BEGIN:VEVENT
SUMMARY:A new route to Explosive Percolation
DTSTART;VALUE=DATE-TIME:20110411T090000Z
DTEND;VALUE=DATE-TIME:20110411T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1293@cern.ch
DESCRIPTION:The biased link occupation rule in the Achlioptas process (AP)
discourages the large clusters to grow much ahead of others and encourage
s faster growth of clusters which lag behind. In this paper we propose a m
odel where this tendency is sharply reflected in the Gamma distribution of
the cluster sizes\, unlike the power law distribution in AP. In this mode
l single edges between pairs of clusters of sizes $s_i$ and $s_j$ are occu
pied with a probability $\\propto (s_is_j)^{\\alpha}$. The parameter $\\al
pha$ is continuously tunable over the entire real axis. Numerical studies
indicate that for $\\alpha \n\nhttps://indico.tifr.res.in/indico/conferenc
eDisplay.py?confId=1293
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1293
END:VEVENT
BEGIN:VEVENT
SUMMARY:Universality in complexity: a random matrix view-point
DTSTART;VALUE=DATE-TIME:20110428T090000Z
DTEND;VALUE=DATE-TIME:20110428T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1330@cern.ch
DESCRIPTION:For systems that can be described mathematically\, physical in
formation can be derived\, in principle\, from detailed knowledge of the o
perators that govern their evolution. Physical systems can however be comp
lex in nature and it is not always possible to determine the operator exac
tly or\, even if they are known\, to solve the equations they determine.
This paper aims to model the statistical behaviour of those complex system
s where a matrix representation of the operators is meaningful.\n\nThe com
plexity of a system\, in general\, makes it difficult to determine some or
almost all matrix elements of its operators. The lack of accuracy acts as
a source of randomness for the matrix elements which are also subjected t
o an external potential due to existing system conditions. The fluctuatio
n of accuracy due to varying system conditions leads to a diffusion of the
matrix elements. We show that\, for single-well potentials\, the diffusio
n can be described by a common mathematical formulation where system infor
mation enters through a single parameter. This suggests a possible classif
ication of complex systems in an infinite range of universality classes ch
aracterized just by a single parameter and the nature of global physical c
onstraints. It seems to indicate a web of connection hidden underneath com
plex systems.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?co
nfId=1330
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1330
END:VEVENT
BEGIN:VEVENT
SUMMARY:Electron doped CrO_{2} : An unsual example of a charge ord
ered ferromagnet
DTSTART;VALUE=DATE-TIME:20110526T090000Z
DTEND;VALUE=DATE-TIME:20110526T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1384@cern.ch
DESCRIPTION:Usually metallicity accompanies ferromagnetism. K2Cr8O16 is on
e of the less common examples of magnetic materials\, exhibiting ferromagn
etism in the insulating state [1]. Analyzing the electronic and magnetic p
roperties within first principle electronic structure calculations\, we fi
nd [2] that K acts like a donor. The doped electrons associated with the i
ntroduction of K in the lattice\, induces a charge ordered and insulating
ground state and interestingly also introduces a ferromagnetic coupling be
tween the Cr ions. The primary considerations driving the charge ordering
are found to be electrostatic ones with the charge being localized on two
Cr atoms that minimize the electrostatic energy. The structural distortion
that accompanies the ordering\, generates a pathway for the electron loca
lized on one site to hop on to the neighboring sites\, a process more favo
rable in the ferromagnetic case\, thus\, giving rise to a rare example of
a charge-order driven ferromagnetic insulator\n\n \n Kunihiro Hasegawa et
al.\, Phys. Rev. Lett. 103\, 146403(2009). \n \n Priya Mahadevan\, Abhi
nav Kumar\, Debraj Choudhury and D.D. Sarma\, Phys. Rev. Lett 104\, 256401
(2010)\n\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId
=1384
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1384
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamo Transition and Reversals
DTSTART;VALUE=DATE-TIME:20110629T090000Z
DTEND;VALUE=DATE-TIME:20110629T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1463@cern.ch
DESCRIPTION:Generation of magnetic fields in planets\, stars\, and galaxie
s\, also\nknown as the dynamo\, is an outstanding problem. Recent experi
ments\nand simulations explore the conditions of the dynamo transition\, a
s well\nbehaviour near the transition. Various periodic\, quasiperiodic\,\
nchaotic dynamo states have been observed near the transition in dynamo \n
experiments and simulations. Another intriguing feature of the dynamo\nis
reversal of the magnetic field. Both the solar- and geo-magnetic\nfield
s are known to reverse. In the present talk we will present some\nof the
recent results related to the above issues. We will also\npresent certain
similarities of the dynamo reversal with \nreversals observed in convecti
on.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1463
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1463
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum phase transitions studies of some low-dimensional exactly
solvable dimerized quantum antiferromagnets
DTSTART;VALUE=DATE-TIME:20110803T090000Z
DTEND;VALUE=DATE-TIME:20110803T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1550@cern.ch
DESCRIPTION:Quantum fluctuations play very crucial role in low-dimensional
\nfrustrated antiferromagnets. As a result\, the magnetic ordered ground\n
state of a system becomes unstable and a quantum paramagnetic state\nemerg
es as the ground state. An ordered state is also influenced by\nthe frustr
ation which arises from the competing interactions present\non the lattice
geometry. Quantum fluctuations and frustration together\ngive many novel
quantum paramagnetic phases such as valence bond\ncrystal\, spin-liquid ph
ases. In this talk\, I will present quantum\nphase transitions studies of
certain quantum antiferromagnetic spin\nmodels in 2D which show spontaneou
sly dimerized valence bond crystal\nground states. An important feature of
these models is that these are\nexactly solvable at some special limits.\
n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1550
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1550
END:VEVENT
BEGIN:VEVENT
SUMMARY:Majorana fermions and topological superconducting quantum phase tr
ansitions in semiconductors
DTSTART;VALUE=DATE-TIME:20110818T083000Z
DTEND;VALUE=DATE-TIME:20110818T093000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1606@cern.ch
DESCRIPTION:I will describe our recent work on constructing new topologica
l\nsuperconducting mediums which carry Majorana fermions as lowest energy\
nexcitations and which can therefore be used as platforms for\ntopological
quantum computation. I will also describe topological\nquantum phase tran
stions in and out of these interesting phases.\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=1606
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1606
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spin-orbit induced effects in quantum wire and quantum dot
DTSTART;VALUE=DATE-TIME:20111027T090000Z
DTEND;VALUE=DATE-TIME:20111027T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1746@cern.ch
DESCRIPTION:We consider interactions in a quantum wire and a quantum dot i
n the\npresence of a magnetic field and spin-orbit interaction. An interpl
ay\nof Zeeman and spin-orbit terms in the quantum wire opens up a new\nsca
ttering channel when the magnetic field and the spin-orbit axes are\northo
gonal: two electrons with opposite momentum and in the same\nspin-subband
scatter into a different spin-subband while conserving\nmomentum. This sca
ttering process is relevant and results in a\nspin-density wave (SDW) stat
e. We will discuss the role of this state\nfor transport in the presence o
f single impurity.\n\nIn the second part of this talk I will consider a do
uble quantum dot\nset-up and show that spin-orbit induces a novel spin-spi
n\ncoupling. This coupling is of the van der Waals type and\, unlike the\n
standard exchange coupling\, is present even in the absence of wave\nfunct
ion overlap between the two electrons in quantum dots.\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=1746
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1746
END:VEVENT
BEGIN:VEVENT
SUMMARY: Electron-Electron Interactions in Bilayer Graphene
DTSTART;VALUE=DATE-TIME:20111109T060000Z
DTEND;VALUE=DATE-TIME:20111109T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1763@cern.ch
DESCRIPTION:Bilayer graphene has emerged as novel chiral gapless electron-
hole\nsystems with potential technological applications. In this talk\, I\
nwill discuss the effects of electron-electron interactions in this\nsyste
m. I will present the dynamic screening properties and the\nplasmon collec
tive modes in bilayer graphene\, comparing it with\nmonolayer graphene and
2D electron gas\, and show the effects of\nplasmon-phonon coupling in bot
h monolayer and bilayer graphene. I\nwill also present the effects of ele
ctron-electron interactions on the\nsingle particle spectral function of b
ilayer graphene\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?
confId=1763
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1763
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thermodynamic structure for nonequilibrium steady-state systems in
contact
DTSTART;VALUE=DATE-TIME:20111215T090000Z
DTEND;VALUE=DATE-TIME:20111215T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1869@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
1869
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1869
END:VEVENT
BEGIN:VEVENT
SUMMARY:The impact of antisite disorder on the double perovskites
DTSTART;VALUE=DATE-TIME:20111223T090000Z
DTEND;VALUE=DATE-TIME:20111223T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1881@cern.ch
DESCRIPTION:Several double perovskite materials exhibit high ferromagnetic
Tc\,\nhalf-metallicity and significant low-field magnetoresistance. The\n
potential usefulness of these materials is\, however\, frustrated by the\n
inevitable antisite disorder. The result is a strong dependence of\nphysic
al properties on preparative conditions. We have studied the\nimpact of sp
atially correlated antisite disorder\, as observed\nexperimentally\, on th
e double perovskites. In the ferromagnetic phase\,\nantisite disorder supp
resses the saturation magnetisation\, leaves the\nTc mostly unaffected\, b
ut leads to a metal-insulator transition in the\nelectronic ground state.
The insulating samples shows huge low-field\nnegative magnetoresistance a
t low temperature.\n\nOn the other hand antiferromagnetic phases (A and G
type)\, that are\npredicted in the clean limit are actually suppressed les
s strongly\nthan the ferromagnetic phase by the antisite disorder. The\nan
tiferromagnetic phases are metallic\, and\, remarkably\, more\nconducting
than the ferromagnetic phase for similar antisite\ndisorder. Beyond the mo
dest field needed for the suppression of long\nrange antiferromagnetic (A
type) order\, the system shows almost\ntenfold increase in resistivity nea
r Tc. The large positive\nmagnetoresistance\, though suppressed gradually\
, survives the presence\nof significant antisite disorder. The principle t
hat we uncover behind\nthis 'colossal positive magnetoresistance' should b
e applicable to\nother local moment metals that show field driven suppress
ion of\nnon-ferromagnetic order.\n\nhttps://indico.tifr.res.in/indico/conf
erenceDisplay.py?confId=1881
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1881
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topological qubits in quantum spin chain
DTSTART;VALUE=DATE-TIME:20111223T103000Z
DTEND;VALUE=DATE-TIME:20111223T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1885@cern.ch
DESCRIPTION:For Topological Quantum Computation non abelian anyons can be
made up\nof unpaired Majorana fermions. We study a simple one dimensional
model\nXY-Ising model where unpaired Majorana modes can be created and\nma
nipulated. Further\, we showed that a Qubit made up of degenerate\nunpaire
d Majorana modes of the model are protected from decoherence by\nenvironme
ntal perturbations. Physical realization of the model using\nJosephson jun
ction quantum circuit has also been achieved.\n\nhttps://indico.tifr.res.i
n/indico/conferenceDisplay.py?confId=1885
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1885
END:VEVENT
BEGIN:VEVENT
SUMMARY: Direct Estimate of the Static Length-Scale Accompanying the Glass
Transition
DTSTART;VALUE=DATE-TIME:20111228T053000Z
DTEND;VALUE=DATE-TIME:20111228T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1889@cern.ch
DESCRIPTION:Glasses are liquids whose viscosity has increased so much that
they\ncannot flow. Accordingly there have been many attempts to define a\
nstatic length-scale associated with the dramatic slowing down of\nsuper-c
ooled liquid with decreasing temperature. In this talk\, I will\npresent a
simple method to extract the desired length-scale which is\nhighly access
ible both for experiments and for numerical\nsimulations. The fundamental
new idea is that low lying vibrational\nfrequencies come in two types\, th
ose related to elastic response and\nthose determined by plastic instabili
ties. The minimal observed\nfrequency is determined by one or the other\,
crossing at a typical\nlength-scale which is growing with the approach of
the glass\ntransition. This length-scale characterizes the correlated diso
rder in\nthe system: on longer length-scales the details of the disorder b
ecome\nirrelevant\, dominated by the Debye model of elastic modes. After\n
introducing the length-scale I will show how this scale completely\ndeterm
ines the dynamics of the super-cooled liquid under external\nconstraints\,
thereby proving beyond doubt the static nature of the\nproposed length-sc
ale. Finally I talk about consequence of this scale\non the mechanical pro
perties of the amorphous solids.\n\nhttps://indico.tifr.res.in/indico/conf
erenceDisplay.py?confId=1889
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1889
END:VEVENT
BEGIN:VEVENT
SUMMARY:Solitonic Excitations in an inhomogenous DNA with flexible strands
DTSTART;VALUE=DATE-TIME:20120104T100000Z
DTEND;VALUE=DATE-TIME:20120104T110000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1911@cern.ch
DESCRIPTION:Base pair opening in an inhomogenous double helical molecular
chain\nwith flexible strands is studied by solving the governing dynamical
\nequations analytically and numerically. The results show that\ninhomogen
eity in stacking and hydrogen bonds in localized and periodic\nforms and t
he helicity do not alter the amplitude of the bubble\nsoliton. However the
flexibility of the strands makes the amplitude to\ndamp. On the otherhand
the velocity of the bubble soliton is\nunaltered. Further the above effec
ts introduce small fluctuation in\nthe tail of the bubble soliton without
affecting the robust nature of\nthe soliton during propagation.\n\nhttps:/
/indico.tifr.res.in/indico/conferenceDisplay.py?confId=1911
LOCATION:Colaba Campus 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1911
END:VEVENT
BEGIN:VEVENT
SUMMARY:Field-Theoretic Modeling of Supramolecular Polymer Networks and Ge
ls
DTSTART;VALUE=DATE-TIME:20120111T090000Z
DTEND;VALUE=DATE-TIME:20120111T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1929@cern.ch
DESCRIPTION:Multifunctional supramolecular polymer networks and gels are e
mployed in several areas including biotechnology\, nanotechnology and micr
oelectronics. For example\, self-healing polymers composed of di- and tri-
functional groups (Cordier et al.\, 2008) find applications in constructio
n\, cosmetics\, electronics and medicine. Furthermore\, block copolymer li
thography has applications in semiconductor design (Tang et al.\, 2008).\n
\nThis talk will present a field-theoretic model of polymer networks and g
els composed of reactive multifunctional monomeric units. Two examples are
presented to illustrate the application of self-consistent field theory i
n determining equilibrium structures arising from reactions among multifun
ctional monomers. In the first case\, network formation and gelation in a
confined system of single-component multifunctional monomers is considered
. In the second case\, microstructures arising from copolymerization react
ions in a binary system of multifunctional monomers are investigated. Morp
hologies arising from copolymerization may range from homogeneous disorder
ed morphologies to ordered microstructures such as lamellae\, wherein the
distinct constituents assemble into alternating layers. The goal of this w
ork is to enable the rational design of polymer materials with desirable p
roperties\, based the a priori prediction of microstructures resulting fro
m selected monomeric constituents.\n\nhttps://indico.tifr.res.in/indico/co
nferenceDisplay.py?confId=1929
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1929
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rare beneficial mutations can halt Muller's ratchet
DTSTART;VALUE=DATE-TIME:20120112T090000Z
DTEND;VALUE=DATE-TIME:20120112T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1935@cern.ch
DESCRIPTION:The vast majority of mutations are deleterious\, and are elimi
nated by\npurifying selection. Yet in finite asexual populations\, purifyi
ng\nselection cannot completely prevent the accumulation of deleterious\nm
utations due to Muller's ratchet: once lost by stochastic drift\, the\nmos
t-fit class of genotypes is lost forever. If deleterious mutations\nare we
akly selected\, Muller's ratchet turns into a mutational\n``meltdown'' lea
ding to a rapid degradation of population\nfitness. Evidently\, the long t
erm stability of an asexual population\nrequires an influx of beneficial m
utations that continuously\ncompensate for the accumulation of the weakly
deleterious ones. Here\nwe propose that the stable evolutionary state of a
population in a\nstatic environment is a dynamic mutation-selection balan
ce\, where\naccumulation of deleterious mutations is on average offset by
the\ninflux of beneficial mutations. We argue that this state exists for\n
any population size /N/ and mutation rate /U/. Assuming that\nbeneficial a
nd deleterious mutations have the same fitness effect s\,\nwe calculate th
e fraction of beneficial mutations\, $\\epsilon$\, that\nmaintains the bal
anced state. We find that a surprisingly low\n$\\epsilon$ suffices to main
tain stability\, even in small populations\nin the face of high mutation r
ates and weak selection. This may\nexplain the maintenance of mitochondria
and other asexual genomes\, and\nhas implications for the expected statis
tics of genetic diversity in\nthese populations.\n\nhttps://indico.tifr.re
s.in/indico/conferenceDisplay.py?confId=1935
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1935
END:VEVENT
BEGIN:VEVENT
SUMMARY:The onset of antiferromagnetism in metals: from the cuprates to t
he heavy-fermion compounds
DTSTART;VALUE=DATE-TIME:20120118T090000Z
DTEND;VALUE=DATE-TIME:20120118T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1957@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
1957
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1957
END:VEVENT
BEGIN:VEVENT
SUMMARY:Density wave super solid and Mott insulator-superfluid transition
in presence of an artificial gauge field : Mean field and Strong Coupling
results
DTSTART;VALUE=DATE-TIME:20120120T103000Z
DTEND;VALUE=DATE-TIME:20120120T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1973@cern.ch
DESCRIPTION:We study the effect of an artificial gauge field on the zero\n
temperature phase diagram of extended Bose Hubbard model\, that\ndescribes
ultra cold atoms in optical lattices with long range\ninteraction using m
ean field and strong coupling perturbation\ntheory. We determine analytica
lly the effect of the artificial gauge\nfield on the density wave - supers
olid (DW-SS) and the the Mott\ninsulator-superfluid (MI -SF) transition bo
undary. The momentum\ndistribution at these two transition boundaries is a
lso calculated in\nthis approach. It is shown that such momentum distribut
ion which can\nbe observed in time of flight measurement\, reveals the sym
metry of the\ngauge potential through the formation of magnetic Brillouin
zone and\nclearly distinguishes between the DW-SS and MI-SF boundary. We a
lso\npoint out that in symmetric gauge the momentum distribution structure
\nat these transition boundaries bears distinctive signatures of\nvortices
in supersolid and superfluid phases.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=1973
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1973
END:VEVENT
BEGIN:VEVENT
SUMMARY:Is Brain in a Coherent State?
DTSTART;VALUE=DATE-TIME:20120209T090000Z
DTEND;VALUE=DATE-TIME:20120209T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-1999@cern.ch
DESCRIPTION:Bose Condensation occurs in a variety of physical systems\; fr
om dense neutron stars where it happens supposedly at million degrees Kelv
in to atomic traps with dilute condensed alkali gases at nanokelvin temper
atures passing through liquid He4 and High temperature Superconductors. It
has been suggested that this also happens in human brain. I would like to
point out that our brain may well be in a coherent superfluid state\, not
necessarily Bose condensed.\n\nI will treat our mind that neurons encompa
ss as an abstract Hilbert space -- it is an information space whose centra
l function is gathering meaningful information and asking the organism to
act on it. We postulate that a quantum of information is a bosonic quasipa
rticle that is created each time a neuron fires. Like any fundamental part
icle\, the thought quanta must carry energy and momentum (a short video wi
ll be projected) . An operator S+\, called self-operator will be defined t
o create such a quasiparticle. This S operator is nothing but our genetic
identity. A phase coherent state of mind occurs whenever a macroscopic ave
rage ~~ ≠ 0 appears. At this point a phase transition occurs from an in
coherent to a coherent state. The driving force behind this phase transiti
on is not temperature but neural connectivity. This is precisely the point
where an I am emerges for each one of us! I is the Ginzburg- Landau ord
er parameter of the cognitive field.\n\nBrain is an open system. Its basic
physics and chemistry is characterised by dissipation and nonreversibilit
y. This is why the sense of time present or passing is built into our cons
ciousness. The Hamiltonian governing the dynamics can only be non-Hermitia
n. I will show the fundamental significance of such a Hamiltonian as far a
s our mind is concerned. I will also show how consciousness can be precise
ly defined as a response function\, of the S -- operator to the world.\n\n
What I am trying to develop is a simple language that would mean something
to both physicists and neuroscientists. Introducing the concept of self a
t the very basement level (bottom up) seems to me unavoidable if we are to
understand self-organisation behind the cognition phenomenon.\n\nhttps://
indico.tifr.res.in/indico/conferenceDisplay.py?confId=1999
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1999
END:VEVENT
BEGIN:VEVENT
SUMMARY:Frustration Induced Exotic Phases in Axial Anisotropic Spin-1/2 Ch
ain
DTSTART;VALUE=DATE-TIME:20120222T090000Z
DTEND;VALUE=DATE-TIME:20120222T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2026@cern.ch
DESCRIPTION:Recent experimental realizations of axial anisotropic spin-1/2
chains\nhave intensified the research in one-dimensional spin-1/2 systems
. The\ncombination of anisotropy and frustration induced by competition\nb
etween the nearest and next nearest neighbor exchanges in these\nsystems g
ives rise to many interesting exotic phases like bond order\nwave\, Neel a
nd chiral vector wave phases in the ground state. In\nthis talk\, scaling
of the order parameters and the Quantum phase\ndiagram of a model Hamilton
ian with axial anisotropic nearest and next\nnearest neighbor spin exchang
e interactions are discussed. A new\nQuantum phase diagram of this model H
amiltonian is constructed using a\ncombination of the exact results of fin
ite system sizes and density\nmatrix renormalization group method.\n\nhttp
s://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2026
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2026
END:VEVENT
BEGIN:VEVENT
SUMMARY:Revisiting the case for negative Nernst signals in extreme type-II
superconductors
DTSTART;VALUE=DATE-TIME:20120229T090000Z
DTEND;VALUE=DATE-TIME:20120229T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2057@cern.ch
DESCRIPTION:Different transport coefficients have been measured in High-Tc
superconductors to pinpoint the nature of the pseudogap phase. In particu
lar\, the thermoelectric coefficients received considerable attention both
theoretically and experimentally. We numerically simulate the Nernst effe
ct in extreme type-II superconductors using time-dependent Ginzburg-Landau
equations. We report a sign reversal of the thermoelectric coefficient\,
αxy\, at temperatures close to the mean-field transition temperature TcMF
(H)\, which qualitatively agrees with recent experiments on high-Tc materi
als. We also discuss the noise power spectrum of αxy\, which shows 1/fβ
behavior. Based on this observation\, we propose an experiment to determin
e different regimes of vortex dynamics by measuring the noise correlations
of the Nernst signal.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=2057
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2057
END:VEVENT
BEGIN:VEVENT
SUMMARY:Algebraic and arithmetic area for m planar Brownian paths
DTSTART;VALUE=DATE-TIME:20120416T090000Z
DTEND;VALUE=DATE-TIME:20120416T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2136@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
2136
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2136
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase transitions in continuous opinion dynamics models
DTSTART;VALUE=DATE-TIME:20120417T090000Z
DTEND;VALUE=DATE-TIME:20120417T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2129@cern.ch
DESCRIPTION:Quite a few models for continuous opinion dynamics have been p
roposed\nrecently. The phase transitions driven by the parameters in thes
e\nmodels will be discussed and compared.\n\nhttps://indico.tifr.res.in/in
dico/conferenceDisplay.py?confId=2129
LOCATION:Colaba Campus AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2129
END:VEVENT
BEGIN:VEVENT
SUMMARY:Active gels\, cells and information processing
DTSTART;VALUE=DATE-TIME:20120510T090000Z
DTEND;VALUE=DATE-TIME:20120510T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2208@cern.ch
DESCRIPTION:The material of the living cell is driven out of equilibrium b
y energy\nconsuming processes. The collective behaviour of such systems i
s\ndescribed by active hydrodynamics. We will use this to study the\nstea
dy state organization and dynamics of molecules on the two\ndimensional ce
ll surface. We will use ideas from information theory to\nshow that this d
ynamic organization is a solution of an error\noptimization problem.\n\nht
tps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2208
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2208
END:VEVENT
BEGIN:VEVENT
SUMMARY:Defects in Solids
DTSTART;VALUE=DATE-TIME:20120517T090000Z
DTEND;VALUE=DATE-TIME:20120517T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2214@cern.ch
DESCRIPTION:In this talk\, I will discuss first principles methods for\nun
derstanding and predicting ground and excited-state phenomenon in\nmateria
ls. In particular\, I will talk about the physics of defects in\nsolids an
d discuss in detail two different kind of defects. The first\ndefect I wil
l discuss are oxygen-related point defects in\nhafnia. Hafnia is a high-k
dielectric material used as a gate\ndielectric in todays MOSFETs. Oxygen-r
elated point defects are\nbelieved to responsible for device performance i
ssues in modern\nMOSFETs. I will present our results on the stability of v
arious\noxygen-related point defects in hafnia. The second defect I will\n
discuss is the negatively charged nitrogen vacancy center in\ndiamond. Thi
s defect is the leading candidate for realization of\nindividually address
able spins in the solid state for quantum\ncomputing under ambient conditi
ons. This is because\, this defect can\nbe optically initialized from its
ground state into an un-entangled\nspin state. I will discuss our results
on the electronic structure of\nthe negatively charged nitrogen vacancy ce
nter and put forward a\nconcrete optical initialization mechanism.\n\nhttp
s://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2214
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2214
END:VEVENT
BEGIN:VEVENT
SUMMARY:The emergence of patterns in liquids
DTSTART;VALUE=DATE-TIME:20120628T090000Z
DTEND;VALUE=DATE-TIME:20120628T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2303@cern.ch
DESCRIPTION:Pattern formation in nature has interested humankind for centu
ries\,\nwith the first descriptions of intricate patterns in snowflakes\no
ccurring in Chinese texts dating back to 150 BCE. I shall describe a\nrec
ent series of recent experiments conducted in my laboratory in\nwhich patt
erns are generated in a variety of liquids\, with a little\nhelp from an i
nfrared laser and some carbon nanotubes. The patterns\nthat we obtain are
dendritic\, and are produced on unprecedentedly fast\n(millisecond) timesc
ales. The results will be discussed in relation to\nmicroscopic solvabilit
y theory. Unresolved issues\, both experimental\nand theoretical\, will be
highlighted.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?co
nfId=2303
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2303
END:VEVENT
BEGIN:VEVENT
SUMMARY:Superconducting gap structure and symmetry in hole doped BaFe2As2
DTSTART;VALUE=DATE-TIME:20120906T083000Z
DTEND;VALUE=DATE-TIME:20120906T093000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2435@cern.ch
DESCRIPTION:BaFe2As2 is one of the heavily investigated compounds in the\n
Fe-pnictide family. Hole doping is achieved by doping in K on Ba\nsites.
The parent compound is known to be an antiferromagnetic(AFM)\nmetal with a
Spin Density Wave order. As one dopes the system the AFM\ngives way to th
e coexistence region where AFM and\nsuperconductivity(SC) coexist. Doping
further leads to exclusively SC\nbehavior which remains all the way up to
100% K-doping. The character\nof the SC varies from one end to other and t
here are several\ninteresting features across the phase diagram. In this
talk I shall\npresent our approach towards understanding the physics behin
d the hole\ndoped pnictides. I shall present how a simple technique can be
used to\nunderstand this doping dependence in terms of fermi-surface topo
logy\nand also show how dramatic changes can occur in the coexistence regi
on\nwhich involves reconstruction of the electron and hole pockets.\n\nhtt
ps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2435
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2435
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theory of the t-J model
DTSTART;VALUE=DATE-TIME:20120907T090000Z
DTEND;VALUE=DATE-TIME:20120907T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2451@cern.ch
DESCRIPTION:A new systematic theory of the t-J model is described\, releva
nt to the\nHigh Temperature Superconductors\, based on the Schwinger appro
ach to\nfield theory. Remarkably close agreement with experimental data is
\nfound for the simplest version of the theory\, and detailed predictions\
nfor asymmetry of lines are given\, which should be amenable to\nexperimen
tal check in the near future.\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=2451
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2451
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shock Propagation in Loosley Packed Granular Systems
DTSTART;VALUE=DATE-TIME:20121004T090000Z
DTEND;VALUE=DATE-TIME:20121004T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2501@cern.ch
DESCRIPTION:Consider a collection of particles evolving in time through ba
llistic\nmotion and inelastic collisions. What is the response of this sys
tem\nto an instantaneous input of energy in a localised region? This\nprob
lem is the generalisation of the classic Taylor-Sedov problem of\nthe spre
ading of energy following a nuclear explosion. In this talk\,\nthe exponen
ts characterizing the long time behaviour of the above\nproblem will be ob
tained using scaling arguments. The results will be\ncompared with three r
ecent experiments.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=2501
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2501
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chemotaxis when bacteria remember: drift vs diffusion
DTSTART;VALUE=DATE-TIME:20121018T090000Z
DTEND;VALUE=DATE-TIME:20121018T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2525@cern.ch
DESCRIPTION:Escherichia coli (E. coli) bacteria govern their trajectories
by\nswitching between running and tumbling modes as a function of the\nnut
rient concentration they experienced in the past. In a recent\nstudy\, it
has been argued\, using approximate analytical treatments in\none dimensio
n\, that there is a conflict between the ability of the\nbacterium to reac
h regions of high nutrient concentration quickly and\nremaining there at l
ong times. Here we perform numerical simulation in\none-dimension and show
that there is no such conflict. To understand\nthese results we propose a
coarse grained model which is shown to\nagree well with the numerics. Imp
ortantly\, the model is significantly\ndifferent from the common one used
in many earlier works and which\ndoes not capture the behavior found in ou
r numerics. The origin of the\ndiscrepancy is discussed.\n\nhttps://indico
.tifr.res.in/indico/conferenceDisplay.py?confId=2525
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2525
END:VEVENT
BEGIN:VEVENT
SUMMARY:Agglomerative percolation and network renormalization
DTSTART;VALUE=DATE-TIME:20121031T090000Z
DTEND;VALUE=DATE-TIME:20121031T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2542@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
2542
LOCATION:Colaba Campus 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2542
END:VEVENT
BEGIN:VEVENT
SUMMARY:From standard percolation to rough pinned surfaces: a tricritical
point induced by cooperativity
DTSTART;VALUE=DATE-TIME:20121101T090000Z
DTEND;VALUE=DATE-TIME:20121101T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2543@cern.ch
DESCRIPTION:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
2543
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2543
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fractal dimentions of watersheds
DTSTART;VALUE=DATE-TIME:20121107T090000Z
DTEND;VALUE=DATE-TIME:20121107T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2559@cern.ch
DESCRIPTION:The statistical properties of watersheds (e.g. in the Himalaya
ns) have\nbeen studied by geograpers since several decades\, and it was re
alized\nquite early that they are fractal with dimensions roughly between
1.1\nand 1.2. In the talk I will discuss the case of random landscapes\nbo
unded between two drainage sinks. I will present three different\nmicrosc
opic definitions of the watershed\, that all have the same\ndimension but
have vastly different corrections to scaling\, and need\ndifferent algorit
hms for efficient simulations. The numerically\nobtained fractal dimension
s (both in 2 dimensions and in a\ngeneralization to 3-d) seem to fall into
no known universality class.\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=2559
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2559
END:VEVENT
BEGIN:VEVENT
SUMMARY:Practical Applications of Mutual Information: Phylogenetic Trees\,
Independent Component Analysis\, and Network Inferences
DTSTART;VALUE=DATE-TIME:20121108T090000Z
DTEND;VALUE=DATE-TIME:20121108T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2558@cern.ch
DESCRIPTION:The mutual information (MI) between X an Y is the amount by wh
ich \nthe information (either in Shannon or Kolmogorove sense) needed \nto
specify one is decreased when the other is known. It is \nnon-negative an
d symmetric\, and vanishes only when X and Y are \nindependent\, therefore
it is a very natural candidate for a \nuniversal similarity measure. I wi
ll first review the general \nconcepts and practical methods for estimatin
g MI. The I will \npresent three applications: (a) Independent component a
nalysis\, \nillustrated by the problem of disentangling the EEG of a \npre
gnant woman into the one of the mother and the one of the \nfetus\; (b) Cl
assifying "texts"\, either of natural languages \nor of DNA. In the latter
case\, I will discuss MI-based\nmethods to construct phylogenetic trees f
rom mitochondrial \nDNA\; and (c) Attempts to reconstruct gene regulation
networks\nfrom gene expression data obtained by microarrays.\n\nhttps://in
dico.tifr.res.in/indico/conferenceDisplay.py?confId=2558
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2558
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emerging patches and strings in the Abelian Sandpile Model
DTSTART;VALUE=DATE-TIME:20121122T090000Z
DTEND;VALUE=DATE-TIME:20121122T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2595@cern.ch
DESCRIPTION:The Abelian Sandpile Model is a simple cellular automaton desc
ribing\nthe dynamics of a pile of sand under particle addition. It present
s\nSelf-Organized Criticality and seems to display allometry. I will\npres
ent a number of deterministic protocols where patches emerge\,\nplaying a
crucial role in the description of the final\nconfiguration. I will then p
ropose a classification of these patches\nby means of new\, unidimensional
\, objects\, the strings. The interplay\nof these two classes of object wi
ll be investigated.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay
.py?confId=2595
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2595
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jamming and Clogging Transitions for Systems with Quenched Disorde
r
DTSTART;VALUE=DATE-TIME:20121206T090000Z
DTEND;VALUE=DATE-TIME:20121206T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2632@cern.ch
DESCRIPTION:Jamming can occur in systems consisting of collections of\npar
ticles. It appears as a transition from a fluid like state that can\neasil
y flow to a state that acts like a solid. For example\, a loose\ncollectio
n of grains flows readily at low densities\, but as the\ndensity increases
there is a transition to a jammed state at a density\ntermed Point J. Liu
and Nagel have proposed that there may be a\nuniversal jamming phase diag
ram as a function of density\, load\, or\ntemperature [1]. Here we propose
adding a new axis to the jamming\nphase diagram in the form of the densit
y of fixed obstacles or\nquenched disorder that can cause the system to ja
m at densities below\nPoint J and can strongly influence the dynamics. We
find that as the\nobstacle density increases\, there is a crossover to a b
ehavior which\nwe term clogging rather than jamming. The clogged states ar
e highly\nheterogeneous and fragile\, and they exhibit memory effects. The
se\nresults are relevant to particle flow in porous media as well as\nde-p
inning transitions in systems such as vortices in type-II\nsuperconductors
. I will describe other systems we have been studying\nbeyond granular mat
ter that exhibit jamming or clogging behaviors\,\nincluding vortices in ty
pe-II superconductors with funnel geometries\,\nactive matter such as swar
ming bacteria\, and dislocation pileup\nformation in materials.\n\n[1] A.J
. Liu and S.R. Nagel\, Nature 396\, 21 (1998)\n\nhttps://indico.tifr.res.i
n/indico/conferenceDisplay.py?confId=2632
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2632
END:VEVENT
BEGIN:VEVENT
SUMMARY:The search for topologically degenerate Majorana modes in semicond
uctor/superconductor interfaces
DTSTART;VALUE=DATE-TIME:20121217T060000Z
DTEND;VALUE=DATE-TIME:20121217T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2650@cern.ch
DESCRIPTION:Majorana fermions are fermion-like excitations that were origi
nally\nproposed in particle physics by Ettore Majorana and are characteriz
ed as\nbeing their own anti-particles. The possibility of discovering Majo
rana\nfermions as emergent fractionalized excitations in condensed matter\
nsystems has lead to a lot of excitement because of the topologically\npro
tected degeneracy associated with such excitations. In this talk\, I\nwill
discuss a recent set of proposals for realizing Majorana modes in a\nlarg
e class of spin-orbit coupled\, time-reversal symmetry broken\nsuperconduc
ting systems. The simplicity of this class of systems has\nresulted in sev
eral experimental attempts\, which have successfully\nobserved preliminary
evidence for the Majorana modes in the form of\nzero-bias conductance pea
ks and doubled Shapiro steps. Following this I\nwill then discuss future p
ossibilities in terms of modifications to the\nexperiments to help confirm
the presence of Majorana modes. Possible ways\nof manipulating the Majora
na modes and probing their non-local properties\nwill also be discussed.\n
\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2650
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2650
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emergent spins on a randomly diluted antiferromagnet at the percol
ation threshold
DTSTART;VALUE=DATE-TIME:20130104T060000Z
DTEND;VALUE=DATE-TIME:20130104T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2673@cern.ch
DESCRIPTION:We study the spin 1/2 quantum Heisenberg antiferromagnet on a
Bethe\nlattice diluted to the percolation threshold. Dilution creates area
s\nof even/odd sublattice imbalance resulting in "dangling spins'' :\nspin
s which can not be paired up into dimers with their nearest\nneighbors (L.
Wang and A. W. Sandvik\, Phys. Rev. Lett. 97\, 117204\n(2006)\; Phys. Rev
. B 81\, 054417 (2010)). These spins are found to\nsignificantly affect th
e low energy spectrum: the lowest energy gaps\nare found to scale â€œa
nomalouslyâ€ with system size (N)\, being much\nsmaller than the expe
cted 1/N scaling. By computing multiple excited\nstates in the low energy
spectrum (using a version of the Density\nMatrix Renormalization Group (DM
RG) algorithm for generic tree\ngraphs)\, and studying their correspondenc
e with the geometry of the\npercolation cluster\, we provide evidence that
the dangling spins\ncollectively act as "emergent'' spin 1/2 (or in some
cases spin-1)\ndegrees of freedom. By evaluating inter-site correlation an
d\nsusceptibility matrices\, we detect the presence and location of these\
nemergent spins. We process our numerical data to compute an effective\nHa
miltonian in terms of the emergent spins\, and find them to have\npairwise
Heisenberg interactions that decay exponentially with\ndistance.\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2673
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2673
END:VEVENT
BEGIN:VEVENT
SUMMARY:An Inhomogeneous Directed Ising Model
DTSTART;VALUE=DATE-TIME:20130107T103000Z
DTEND;VALUE=DATE-TIME:20130107T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2675@cern.ch
DESCRIPTION:Motivated by Glauber dynamics of the Ising model\, I will desc
ribe a\ndynamical model of spins in one dimension at zero temperature with
\nbond disorder. I will prove exact formulas for the spectrum and\ndensity
for any size. I will then specialize the model to two natural\ncases\, wh
ere explicit formulas for the partition function can be\nproved.\n\nhttps:
//indico.tifr.res.in/indico/conferenceDisplay.py?confId=2675
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2675
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edge states and fractionalization in condensed matter
DTSTART;VALUE=DATE-TIME:20130110T090000Z
DTEND;VALUE=DATE-TIME:20130110T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2707@cern.ch
DESCRIPTION:In this talk\, I would like to review the physics of\nfraction
alization of fermion numbers in localized states in\nseveral condensed mat
ter systems. The main focus of the\ntalk would be on realization of these
states at the edges of\nsuperconductors with non-s-wave pairing symmetry a
nd\ntheir possible signature in tunneling conductance and\nJosephson effec
t. Time permitting\, I would like to discuss\nthe fate of these states in
time-reversal broken systems.\n\nhttps://indico.tifr.res.in/indico/confer
enceDisplay.py?confId=2707
LOCATION:Colaba Campus AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2707
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Nodal Count {0\, 1\, 2\, 3\,...} Implies the Graph is a Tree
DTSTART;VALUE=DATE-TIME:20130220T090000Z
DTEND;VALUE=DATE-TIME:20130220T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2774@cern.ch
DESCRIPTION:This talk answers the question "Can one count a tree?" which a
ppears\nin the following context: It is known that for all n\, the n-th\ne
igenfunction on a tree graph has n-1 sign changes. Is the reverse\ntrue? I
f yes\, one can tell a tree just by counting the number of its\nsign chang
es. We treat this question for both metric and combinatorial\ngraphs. For
the proof we introduce an auxiliary magnetic field and\nuse a very recent
result initiated by Berkolaiko (with follow-up works\nby Colin de-Verdier
e and by Berkolaiko and Weyand) to connect the\nspectrum and the number of
sign changes. The proof also shows that\nwhen the graph is supplied with
a magnetic field it is not possible\nfor all (or even almost all\, in the
metric case) the eigenvalues to\nexhibit a diamagnetic behaviour.\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2774
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2774
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quadratic algebras\, combinatorial physics and planar automata
DTSTART;VALUE=DATE-TIME:20130228T090000Z
DTEND;VALUE=DATE-TIME:20130228T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2809@cern.ch
DESCRIPTION:For certain quadratic algebras Q\, we introduce the concept of
\nQ-tableaux\, which are certain combinatorial objects drawn on the\nsquar
e lattice. These tableaux are equivalent to the notion of a\nplanar automa
ton. Planar automata is a new concept (not to be confused\nwith cellular a
utomata) which formalizes the idea of recognizing\ncertain "planar figures
" drawn on a 2D lattice. Two quadratic algebras\nwell known in physics are
good examples of planar automata: the most\nsimple Weyl-Heisenberg algebr
a defined by the commutation relation\nUD=DU+Id (creation-annihilation ope
rators in quantum mechanics) and\nthe so-called PASEP algebra defined by t
he relation DE=ED+E+D\, in the\nphysics of dynamical systems far from equi
librium. The associated\nQ-tableaux are respectively rook placements\, per
mutations and the\nso-called alternating\, tree-like and permutation table
aux. Other\nexamples include non-crossing configurations of paths\, tiling
\, plane\npartitions and alternating sign matrices.\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=2809
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2809
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fermions in synthetic non-Abelian gauge fields
DTSTART;VALUE=DATE-TIME:20130411T090000Z
DTEND;VALUE=DATE-TIME:20130411T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2902@cern.ch
DESCRIPTION:The ability of cold atoms to simulate condensed-matter systems
has\nbeen bolstered by the recent spectacular experimental advances in th
e\ngeneration of synthetic gauge fields. After a brief review of ideas\nf
or the generation of synthetic non-Abelian gauge fields\, I shall\ndiscuss
the physics of interacting fermions in their presence. Such\ngauge fields
induce a generalized spin-orbit interaction for the two\ncomponent fermio
ns. I shall demonstrate that on increasing the\nstrength of the spin-orbit
coupling\, a BCS superfluid that is realized\nin the presence of weak att
raction in the absence of the gauge field\,\nis driven to BEC state. The B
EC state is a condensate of a new kind of\nnematic bosons\, which we call
"rashbons"\, whose properties are\ndetermined solely by the gauge field an
d not by the strength of the\nattraction between the fermions. The rashbon
-BEC is shown to have a\ntransition temperature of the order of the Fermi
temperature\nsuggesting a route to enhancing the transition temperature in
weakly\nattracting systems using spin-orbit interaction. I shall then sho
w\nthat the rashbon-BEC is described by a Bogoliubov theory and estimate\n
that the rashbon-rashbon scattering length which is shown to be\n*independ
ent* of the scattering length between the constituent\nfermions. Finally\,
I will make a proposal of using a non-Abelian gauge\nfield in a conjuncti
on with another potential for the realization of\ninteresting condensed ma
tter Hamiltonians such as that due to a\nmagnetic monopole.\n\nhttps://ind
ico.tifr.res.in/indico/conferenceDisplay.py?confId=2902
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2902
END:VEVENT
BEGIN:VEVENT
SUMMARY:Junctions of Dirac materials (Live Video Talk)
DTSTART;VALUE=DATE-TIME:20130417T103000Z
DTEND;VALUE=DATE-TIME:20130417T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2892@cern.ch
DESCRIPTION:In this talk\, I would provide a pedagogical introduction to D
irac\nmaterials such as graphene and topological insulators. This will be\
nfollowed by a discussion of transport properties of their junction\nwith
emphasis on unconventional nature of such transport due to Dirac\nnature o
f these quasiparticles.\n\nhttps://indico.tifr.res.in/indico/conferenceDis
play.py?confId=2892
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2892
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics of ultracold bosons in optical lattices
DTSTART;VALUE=DATE-TIME:20130418T103000Z
DTEND;VALUE=DATE-TIME:20130418T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2893@cern.ch
DESCRIPTION:In this talk\, we shall discuss the non-equilibrium dynamics o
f the\nBose Hubbard model for both ramp periodic protocols using a project
ion\noperator method which allows us to track the dynamics of the model\nb
eyond mean-field theory. Our analysis shows that for periodic\ndynamics\,
there exists special frequencies at which the system\nwavefunction comes b
ack to itself after a period. We connect to recent\nexperiments on these m
odels using cold atoms and suggest further\nexperiments to test our theory
. We also study the dynamics of these\nbosons in the presence of an ``elec
tric field'' in the Mott phase and\nshow that it provides an ideal test be
d for Kibble-Zureck laws for\nfinite size systems.\n\nhttps://indico.tifr.
res.in/indico/conferenceDisplay.py?confId=2893
LOCATION:Colaba Campus A414
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2893
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thermodynamics of bits and batteries
DTSTART;VALUE=DATE-TIME:20130425T090000Z
DTEND;VALUE=DATE-TIME:20130425T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-2939@cern.ch
DESCRIPTION:It is not uncommon in nonequilibrium statistical mechanics to
describe\na system by a Fokker-Planck equation obeying the\nfluctuation-di
ssipation theorem. If one treats the theory of such\nFokker-Planck equatio
ns axiomatically\, one finds that the finite\nmodels of this theory are pr
ecisely the detailed-balanced\, finite\nMarkov chains. In this setting\, g
iven a pair of systems each described\nby a Markov chain\, we present an a
xiom that describes which\ndetailed-balanced Markov chains on the product
space are\nphysically-valid interactions. To every system\, we associate a
\nreal-valued function we call "internal action" on its probability\nsimpl
ex. This function captures not only how much free energy a system\nholds\,
but also how slowly this free energy relaxes to the equilibrium\nvalue. F
or triples consisting of two systems and an interaction\nbetween them\, we
conjecture an action processing inequality that\ninteractions reduce inte
rnal action. Together with the\nSzilard-Landauer correspondence between en
ergy and information\, this\nimplies the impossibility of spontaneous copy
ing of information from a\nbit of low robustness to a bit of high robustne
ss\, i.e.\, a\nthermodynamic no-cloning. We are able to prove this conject
ure for the\nsimplest non-trivial case --- Markov chains with two states -
--\nthrough case enumeration and explicit calculation.\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=2939
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2939
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-fermi liquids and the Wiedemann-Franz law
DTSTART;VALUE=DATE-TIME:20130703T090000Z
DTEND;VALUE=DATE-TIME:20130703T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3057@cern.ch
DESCRIPTION:This talk will present a general discussion of the ratio of th
ermal\nand electrical conductivities in non-Fermi liquid metals. The\ncond
uctivities of non-Fermi liquids are obtained within a\nfundamentally diffe
rent kinematics to Fermi liquids. Among these\nstrongly interacting non-Fe
rmi liquids we distinguish cases with only\none almost-conserved momentum\
, and with many patchwise\nalmost-conserved momenta. We obtain universal e
xpressions for the\nratio of conductivities that violate the Wiedemann-Fra
nz law. We\nfurther discuss the case in which long-lived `cold' quasiparti
cles\, in\ngeneral with unconventional scattering rates\, coexist with str
ongly\ninteracting hot spots\, lines or bands. For these cases\, we\nchara
cterize circumstances under which a linear in temperature\nresistivity is
and is not compatible with the Wiedemann-Franz law. We\nsuggest the likely
outcome of future transport experiments on CeCoIn5\,\nYbRh2Si2 and Sr3Ru2
O7 at their critical magnetic fields.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=3057
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3057
END:VEVENT
BEGIN:VEVENT
SUMMARY:Population imbalanced superfluidity in ultracold atomic Fermi syst
ems in the BEC limit (Skype Talk)
DTSTART;VALUE=DATE-TIME:20130711T060000Z
DTEND;VALUE=DATE-TIME:20130711T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3078@cern.ch
DESCRIPTION:Ultracold atomic Fermi systems present unique opportunity to e
xplore\nexotic superfluid states.One such scenario is survival of\nsuperfl
uidity under population imbalance of its pairing\nconstituents. In this ta
lk\, population imbalanced two-component Fermi\nsystem under harmonic conf
inement (trap) in the BEC regime of\ninteraction is discussed. In this reg
ime Sarma phase or polarized\nsuperfluid is stable where excess fermions o
ccupy negative\nquisiparticle energy states. The system exhibit shell stru
cture:\nunpolarized superfluid -> polarized superfluid ->normal\nstate. Fu
rthermore it is shown that using two different trap\nfrequencies\, shell r
adii can be tuned eventually forming polarized\nsuperfluid core at experim
entally feasible polarization.\n\nReference: PRA 81\, 013623 (2010)\n\nhtt
ps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3078
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3078
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tunneling Dynamics of Ultracold Atoms in Traps (Skype Talk)
DTSTART;VALUE=DATE-TIME:20130711T080000Z
DTEND;VALUE=DATE-TIME:20130711T090000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3079@cern.ch
DESCRIPTION:The tunneling dynamics of a few boson system in a double-well
is\ninvestigated from an ab-initio perspective using the numerically exact
\nMulti-Configuration Time-Dependent Hartree method.\n\nWe first study a s
ystem consisting of single species of bosons with a\nspatially modulated i
nteraction. The main emphasis is on the role of\ninhomogeneity and its eff
ect on the tunneling. The dynamics changes\nfrom Rabi oscillations in the
non-interacting case to a highly\nsuppressed tunneling for intermediate in
teraction strengths followed\nby a reappearance of tunneling near the ferm
ionization limit. With\nextreme interaction inhomogeneity in the regime of
strong correlations\nwe observe tunneling between the higher bands. A ric
her behavior is\nfound for systems with higher particle number. For system
s with more\nthan two bosons\, the inhomogeneity of the interaction can be
tuned to\ngenerate tunneling resonances. These observations are explained
on the\nbasis of the few-body spectrum and stationary eigenstates. A tilt
ed\ndouble-well and its interplay with the interaction asymmetry is\ndiscu
ssed next.\n\nWe then explore tunneling dynamics of binary bosonic mixture
s. The\nfocus is on the role of the inter- and intra-species interactions
and\ntheir interplay. The dynamics is studied for three initial\nconfigura
tions: complete and partial population imbalance and a phase\nseparated st
ate. Increasing the inter-species interaction leads to a\nstrong increase
of the tunneling time period analogous to the quantum\nself-trapping for c
ondensates. The intra-species repulsion can\nsuppress or enhance the tunne
ling period depending on the strength of\nthe inter-species correlations a
s well as the initial\nconfiguration. Completely correlated tunneling betw
een the two species\nand within the same species as well as mechanisms of
species\nseparation and counterflow are revealed. These effects are explai
ned\nby studying the many-body energy spectra as well as the properties of
\nthe contributing stationary states.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=3079
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3079
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantifying the Cosmic web using the Shapefinder diagnostic ( Cosm
ology Seminar)
DTSTART;VALUE=DATE-TIME:20130711T103000Z
DTEND;VALUE=DATE-TIME:20130711T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3080@cern.ch
DESCRIPTION:One of the most successful method to quantify the structures i
n the\nCosmic Web is the Minkowski Functionals. We have developed a powerf
ul\ndiagnostic SURFGEN\, a method to calculate the Minkowski Functionals\n
and shapefinders (ratio of Minkowski Functionals) using triangulated\npoly
hedral surface (contours). The triangulated polyhedral surface\n(contour)
is generated from a discrete data set using Marching cube\n(Marching squar
e) algorithm. Applying SURFGEN to different data sets\nwe obtain interesti
ng results related to the geometry\, morphology and\ntopology of the large
scale structure.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.p
y?confId=3080
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3080
END:VEVENT
BEGIN:VEVENT
SUMMARY:Transport and optical properties across the Mott transition (Throu
gh Skype)
DTSTART;VALUE=DATE-TIME:20130711T090000Z
DTEND;VALUE=DATE-TIME:20130711T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3082@cern.ch
DESCRIPTION:Strong Coulomb repulsion between electrons in a crystal lattic
e can\ncause localization of electrons and results in a metal-to-insulator
\ntransition. Such a transition is known as the Mott transition and the\ni
nsulating phase is called the Mott insulator.\n\nAfter the discovery of cu
prate superconductors in 1986\, physics around\nthe Mott transition has re
ceived immense attention as they originate\nfrom a doped Mott insulator.
We have attempted to capture some of the\nessential features of the transp
ort and optical properties in the\n'normal' phase of the cuprate phase dia
gram\, using the dynamical\nmean-field theory (DMFT) applied to the partic
le-hole asymmetric\nsingle-band Hubbard model. We have employed the local
moment approach\n(LMA) to solve the impurity problem in the context of DMF
T. I shall\ndiscuss our results and physical implication of our approach a
nd make\ncomparison to recent experiments on several cuprate compounds.\n\
nIn the second part of my talk\, I shall discuss another interesting\nphen
omenon\, namely the occurrence of steps or avalanches in the\nresistance h
ysteresis in the Mott transition systems. We formulate a\nresistor-network
based model mapped from a random-field Ising model\n(RFIM) in order to in
vestigate the stochastic behavior of the\nresistance avalanches. Our work
has been motivated by a recent\nexperiment on the vanadium dioxide materia
l\, a prototype that\nencounters Mott transition due to change in temperat
ure.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3082
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3082
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fractionalization from Crystallography
DTSTART;VALUE=DATE-TIME:20130911T090000Z
DTEND;VALUE=DATE-TIME:20130911T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3186@cern.ch
DESCRIPTION:A standard tenet of condensed matter physics is that when a cr
ystal\nwith a partially filled energy band is forced to insulate\, interes
ting\nphysics must arise. As band insulators appear only when the filling
--\nthe number of electrons per unit cell and spin projection -- is an\ni
nteger\, at fractional filling an insulating phase that preserves all\nsym
metries is a Mott insulator\, i.e. it is either gapless or\, if\ngapped\,
displays fractionalized excitations and topological order.\nRemarkably\, t
he little-studied inverse question -- whether a 'trivial'\nband insulator
is always possible at integer filling -- has a rich\nanswer involving basi
c ideas of crystallography. In my talk\, I will\nshow that lattice symmetr
ies may forbid a band insulator even at\ncertain integer fillings\, if the
crystal is *non-symmorphic* -- a\nproperty of the majority of three-dimen
sional crystal structures. In\nthese cases\, one may infer the existence o
f topological order and the\npresence of fractionalized excitations\, if t
he ground state is gapped\nand fully symmetric -- in other words\, these a
re Mott insulators\, but\nwith fully filled bands! This is demonstrated us
ing a non-perturbative\nflux threading argument\, and has immediate applic
ations to quantum spin\nsystems and bosonic insulators in addition to elec
tronic band\nstructures in the absence of spin-orbit interactions [1]. Alo
ng the\nway\, we will naturally be led to systematic methods for construct
ing\nsymmetric gapped ground states for interacting boson and spin models\
non generic symmorphic lattices [2\, 3].\n\nReferences: \n1. S.A. Paramesw
aran\, A. M. Turner\, D.P. Arovas & A. Vishwanath\,\n Nature Physics 9\,
299 (2013) \n2. I. Kimchi\, S.A. Parameswaran\, A. M. Turner\, F. Wang &\
n A. Vishwanath\, arXiv:1207.0498\, in press\, PNAS. \n3. S.A. Parameswa
ran\, I. Kimchi\, A. M. Turner\, D. M. Stamper-Kurn &\n A. Vishwanath\,
Phys. Rev. Lett. 110\, 125301.\n\nhttps://indico.tifr.res.in/indico/confer
enceDisplay.py?confId=3186
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3186
END:VEVENT
BEGIN:VEVENT
SUMMARY:An assortment of three stories
DTSTART;VALUE=DATE-TIME:20131003T090000Z
DTEND;VALUE=DATE-TIME:20131003T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3239@cern.ch
DESCRIPTION:I will hope to present the following three independent works:\
n\n\nMicroscopic origin of thermodynamic entropy in isolated systems: The
quantum entropy is usually defined using von Neumann's formula\, which mea
sures lack of information and vanishes for pure states. In contrast\, we o
btain a formula for the entropy of a pure state as it is measured from the
rmodynamic experiments\, solely from the self-entanglement of the wave fun
ction\, and find strong numerical evidence that the two are in agreement f
or nonintegrable systems\, both for energy eigenstates and for states that
are obtained at long times under the evolution of more general initial co
nditions. This is an extension of Boltzmann's hypothesis for classical sys
tems\, relating microscopic motion to thermodynamics [1].\n\nFine structur
es in the spectrum of the open-boundary Heisenberg XXZ chain at large anis
otropies: At large anisotropies\, the spectrum of the Heisenberg XXZ spin
chain separates into `bands' with energies largely determined by the numbe
r of domain walls. The band structure is richer with open boundary conditi
ons: there are more bands and the bands develop intricate fine structures.
We characterize and explain these structures and substructures in the ope
n-boundary chain. The fine structures are explained using degenerate pertu
rbation theory. We also present some dynamical consequences of these sub-b
and structures\, through explicit time evolution of the wavefunction from
initial states motivated by the fine structure analysis [2].\n\nHysteresis
in a fully-connected XY spin glass: We study the avalanches along the mag
netization hysteresis curve of a long-range interacting spinglass with con
tinuous XY symmetry. We numerically identify sudden jumps of magnetization
in the T = 0 configurations of spins as the external field is increased.
Jumps are initiated by the softest mode of an inverse susceptibility matri
x\, that becomes unstable and leads to an avalanche. We analyze the statis
tics of these events\, and nd that the density of jumps is scale-free\, si
milarly as in the Ising spin-glass (Sherrington-Kirkpatrick) that were stu
died previously\, however with the absence of a clear powerlaw\, thus disp
laying a novel type of `self-organized criticality' [3].\n\n\nReferences:\
n\n1. Deutsch\, J. M.\, Haibin Li\, and Auditya Sharma\, ``Microscopic ori
gin of thermodynamic entropy in isolated systems.'' Physical Review E 87 (
2013)\, 042135.\n\n2. Auditya Sharma\, and Masudul Haque\, ``Fine structur
es in the spectrum of the open-boundary Heisenberg XXZ chain at large anis
otropies.'' arXiv preprint arXiv:1309.1471 (2013).\n\n3. Auditya Sharma\,
Alexei Andreanov\, and Markus uller. In preparation.\n\nhttps://indico.tif
r.res.in/indico/conferenceDisplay.py?confId=3239
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3239
END:VEVENT
BEGIN:VEVENT
SUMMARY:DC Conductivity as a Geometric Phase
DTSTART;VALUE=DATE-TIME:20131113T090000Z
DTEND;VALUE=DATE-TIME:20131113T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3294@cern.ch
DESCRIPTION:The notion of a topological invariant is at the heart of a num
ber of\nphysical phenomena of recent interest\, for example the integer an
d\nfractional quantum Hall effects or topological insulators. The first\ns
uch invariant was introduced into physics by Thouless\, Kohmoto\,\nNightin
gale\, and den Nijs (TKNN) to describe quantization of the Hall\nconductan
ce. In this talk I will show that the Drude weight\, the\nstrength of the
zero frequency conductivity\, is also a topological\ninvariant whose form
is similar to the TKNN invariant. The many-body\nterm of the Drude weight
turns out to be a line-integral around a\nrectangle\, one side of which is
the total momentum\, the other the\ntotal position. The conjecture of Koh
n\, according to which an\ninsulator is a system in which the wavefunction
is localized in the\nmany-body space\, is explicitly demonstrated and ref
ined as follows: if\na wavefunction is an eigenstate of the total current\
, the\ncorresponding system is delocalized\, the Drude weight is finite\,\
ntherefore the system is conducting. Wavefunctions which have\ncontinuous
distributions of total momentum give rise to insulation.\nThese results ca
n also be understood in terms of a generalization of\noff-diagonal long ra
nge order.\n\nReferences: \n1. arXiv:1309.2962 \n2. Phys. Rev. B 87 235123
(2013) \n3. J. Phys. Soc. Japan 81 124711 (2012) \n4. J. Phys. Soc. Japan
81 023701 (2012).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=3294
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3294
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Magnetism with Ultra cold Rydberg atoms/ions
DTSTART;VALUE=DATE-TIME:20131120T090000Z
DTEND;VALUE=DATE-TIME:20131120T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3304@cern.ch
DESCRIPTION:We discuss the possible realizations of frustrated magnetic sy
stems by\nexploiting the properties of Rydberg excitations in an ultra col
d\natomic setups. In particular\, we focus on designing interactions\nbetw
een atoms which gives us a toy model for quantum spin ice on a two\ndimens
ional checkerboard lattice. In addition\, the implementation of\nBalents-F
isher-Girvin model in a Kagome lattice using trapped ion\nsetup will be co
nsidered.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId
=3304
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3304
END:VEVENT
BEGIN:VEVENT
SUMMARY:Many Body Physics in atomic dipolar Bose Condensates\, near and fa
r from equilibrium
DTSTART;VALUE=DATE-TIME:20131212T090000Z
DTEND;VALUE=DATE-TIME:20131212T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3339@cern.ch
DESCRIPTION:In this talk\, I will discuss recent experimental progress in
cooling\nof atomic dipolar Bose gases and give an overview of their basic\
nphenomenology. I will then discuss some recent work on the damping of\nlo
w energy quasi-particles in a weakly interacting dipolar Bose\ncondensates
\, at zero and finite temperature. In particular\, I will\nshow that dampi
ng processes which are typically active in Bose\ncondensates with short-ra
nge interactions\, are absent\, or highly\nsuppressed in the dipolar gas\,
owing to the peculiar nature of its low\nenergy excitation spectrum. I wi
ll then discuss the\nfar-from-equilibrium dynamics of dipolar Bose gases a
nd show how\nquantum quenches can be used to probe the underlying excitati
on\nspectrum of a dipolar gas.\n\nhttps://indico.tifr.res.in/indico/confer
enceDisplay.py?confId=3339
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3339
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase Transitions in Liquid Crystals: Ordering kinetics in nematic
s and properties of ferroic mesogens
DTSTART;VALUE=DATE-TIME:20131219T090000Z
DTEND;VALUE=DATE-TIME:20131219T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3356@cern.ch
DESCRIPTION:In this talk\, I shall address some of the questions related w
ith two fascinating problems: (i) Monte-Carlo simulations for the kinetics
of phase ordering in nematic liquid crystals and (ii) Description of phas
e transition properties of ferroic mesogens.\n\nThe theory of phase orderi
ng kinetics\, that is the growth of order via domain coarsening when a sys
tem is quenched from a homogeneous phase to a broken symmetry phase\, has
been the subject of much active investigation for some time. The problem o
f ordering dynamics in liquid crystals is almost unexplored and is one of
the most challenging fields of soft condensed state and statistical physic
s. We shall discuss some of the questions related with the morphology of n
ematic domains and the growth law which they will follow. We have performe
d comprehensive Monte-Carlo (MC) simulations for the phase ordering kineti
cs of nematic liquid crystals in d=2 and report the results for three LC H
amiltonians: LL model\, LL model with long-ranged interactions (V(r) ∼ r
n) and GLL model. We have obtained an analytic form for the correlation fu
nction of LC order parameter and found that the simulation and analytic re
sults are in excellent agreement. We have examined the time dependence of
domains morphology\, structure factor\, and order parameter correlation fu
nction and domain length scale. We find that the domain morphology and its
scaling behavior are significantly influenced by the range and form of in
teraction Hamiltonians and that the growth law is consistent with the Alle
n-Cahn law with logarithmic correction: L(t) ∼(t/ln r)1/2. For the case
of long-ranged interactions\, we observe no evidence in the dynamical univ
ersality class for n=4\, as predicted theoretically on the basis of renorm
alization- group argument. Our work shows that a large class of systems li
es in the same universality class as the system with nearest-neighbor (LL)
interactions. This finding provides a firm basis for the robustness and u
niversality of experimental results for ordering kinetics in liquid crysta
ls.\n\nThe understanding about the phase transition behaviour of ferroic l
iquid crystals is still at the primitive level. We have developed a thermo
dynamic model for the description of characteristic features of Sm C* and
Sm A- Sm C* transition exhibited by several mesogens. We have extended the
theory to analyze the influence of external perturbations on the phase tr
ansition properties of calamitic as well as bent-core ferroic liquid cryst
als. In conclusion\, we would like to emphasise that the thermodynamic mod
el developed by us is conceptually correct and incorporates the physical r
eality and are capable of explaining the phase transition properties of fe
rroelectric and antiferroelectric liquid crystals.\n\nhttps://indico.tifr.
res.in/indico/conferenceDisplay.py?confId=3356
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3356
END:VEVENT
BEGIN:VEVENT
SUMMARY:Moving from Physics to Biology: the Upsides\, Downsides & Unexpect
ed Sides
DTSTART;VALUE=DATE-TIME:20131223T090000Z
DTEND;VALUE=DATE-TIME:20131223T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3358@cern.ch
DESCRIPTION:My move from Theoretical Physics to Biology has exposed me to
quite a\nfew significant differences between the disciplines. I try to des
cribe\nsome of these and to point out the aspects of this momentous move t
hat\nwere gratifying and those which I found frustrating. I assume basic\n
knowledge of Biology\, but will try to explain things in a way that\nwill
be understandable to a Physics audience as well. While the talk\nmay be pe
rceived as provocative by some\, I do promise that it will not\nbe boring!
\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3358
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3358
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics of a two-dimensional quantum spin liquid: signatures of e
mergent Majorana fermions and fluxes
DTSTART;VALUE=DATE-TIME:20140108T090000Z
DTEND;VALUE=DATE-TIME:20140108T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3392@cern.ch
DESCRIPTION:Topological states of matter present a wide variety of strikin
g new\nphenomena. Prominent among these is the fractionalisation of electr
ons\ninto unusual particles: Majorana fermions\, Laughlin quasiparticles o
r\nmagnetic monopoles. Their detection\, however\, is fundamentally\ncompl
icated by the lack of any local order\, such as\, for example\, the\nmagne
tisation in a ferromagnet. While there are now several instances\nof candi
date topological spin liquids\, their identification remains\nchallenging.
Here\, we provide a complete and exact theoretical study\nof the dynamica
l structure factor of a two-dimensional quantum spin\nliquid in gapless an
d gapped phases. We show that there are direct\nsignatures - qualitative a
nd quantitative - of the Majorana fermions\nand gauge fluxes emerging in K
itaev's honeycomb model. These include\ncounterintuitive manifestations of
quantum number fractionalisation\,\nsuch as a neutron scattering response
with a gap even in the presence\nof gapless excitations\, and a sharp com
ponent despite the\nfractionalisation of electron spin. Our analysis ident
ifies new\nvarieties of the venerable X-ray edge problem and explores conn
ections\nto the physics of quantum quenches.\n\nhttps://indico.tifr.res.in
/indico/conferenceDisplay.py?confId=3392
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3392
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the growth and form of the gut
DTSTART;VALUE=DATE-TIME:20140109T060000Z
DTEND;VALUE=DATE-TIME:20140109T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3393@cern.ch
DESCRIPTION:During development\, the vertebrate gut starts out as a simple
tube\nthat lengthens\, coils and gets patterned internally with absorptiv
e\nvilli. I will show how a minimal physical picture based on\ndifferentia
l growth systematically breaks various spatial symmetries\nand allows us t
o quantify this process\, with testable experimental\npredictions borne ou
t in an organism (the chick) over developmental\ntime\, and across species
such as birds\, reptiles\, amphibians and\nmammals. The theoretical model
s that characterize these patterns raise\ndeep mathematical and geometrica
l questions that I hope to end with.\n\nhttps://indico.tifr.res.in/indico/
conferenceDisplay.py?confId=3393
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3393
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monogamy in Quantum Information
DTSTART;VALUE=DATE-TIME:20140410T090000Z
DTEND;VALUE=DATE-TIME:20140410T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3583@cern.ch
DESCRIPTION:Monogamy is a non-classical property that restricts the sharab
ility of\nquantum correlation and ability to perform quantum information\n
processing tasks among the constituents of a multipartite quantum\nsystem.
I will discuss how classical information transmission via\nmultipartite q
uantum states\, known as quantum dense coding\, respects\nan exclusion pri
nciple. I will also show that quantum correlations may\nsatisfy or violate
monogamy for quantum states and that the monogamy\nconstraint can be a us
eful tool to estimate two-site entanglement in\nresonating valence bond st
ates.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=358
3
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3583
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fate of disorder-induced inhomogeneities in strongly correlated d-
wave superconductors
DTSTART;VALUE=DATE-TIME:20140416T090000Z
DTEND;VALUE=DATE-TIME:20140416T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3582@cern.ch
DESCRIPTION:We analyze the complex interplay of the strong correlations an
d\nimpurities in a high temperature superconductor and show that both the\
nnature and degree of the inhomogeneities change drastically due to\nstron
g correlations. While both the strong electronic repulsions and\ndisorder
contribute to the nanoscale inhomogeneity in the population\nof charge-car
riers\, we find them to compete with each other leading to\na relatively s
mooth variation of the local density. Our\nself-consistent calculations pr
ohibit the formation of distinct\nsuperconducting-`islands'. The reorganiz
ation of the spatial\nstructures makes these superconductors surprisingly
insensitive to the\nimpurities. We also conclude that the underlying one-p
article normal\nstates reshape in a rich manner\, such that the supercondu
ctor formed\nby pairing these states experiences a weaker but spatially co
rrelated\neffective disorder. Such a route to superconductivity makes it\n
tempting to extend Anderson's theorem to the correlated d-wave\nsupercondu
ctors.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=35
82
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3582
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Hilbert-glass transition: new universality of temperature-tune
d many-body dynamical quantum criticality
DTSTART;VALUE=DATE-TIME:20140430T090000Z
DTEND;VALUE=DATE-TIME:20140430T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3648@cern.ch
DESCRIPTION:We study a new class of unconventional critical phenomena that
is\ncharacterized by singularities only in dynamical quantities and has n
o\nthermodynamic signatures. Describing this purely dynamical quantum\ncri
ticality is technically challenging as understanding the\nfinite-temperatu
re dynamics necessarily requires averaging over a\nlarge number of matrix
elements between many-body eigenstates. Here we\ndevelop a real-space reno
rmalization group method for excited state\n(RSRG-X) that allows us to ove
rcome this challenge in a large class of\nmodels. We characterize a specif
ic example: the 1D disordered\ntransverse field Ising model with generic i
nteractions. While\nthermodynamic phase transitions are generally forbidde
n in this model\,\nusing RSRG-X we find a finite-temperature dynamical tra
nsition between\ntwo localized phases. The transition is characterized by\
nnon-analyticities in the low frequency heat conductivity and in the\nlong
-time (dynamic) spin correlation function. The latter is a\nconsequence of
an up-down spin symmetry that results in the appearance\nof an Edwards-An
derson-like order parameter in one of the localized\nphases.\n\nhttps://in
dico.tifr.res.in/indico/conferenceDisplay.py?confId=3648
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3648
END:VEVENT
BEGIN:VEVENT
SUMMARY:Probing low-energy excitations of ordered and critical antiferroma
gnets via Quantum Monte-Carlo
DTSTART;VALUE=DATE-TIME:20140501T090000Z
DTEND;VALUE=DATE-TIME:20140501T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3649@cern.ch
DESCRIPTION:The low-energy spectrum of antiferromagnets reveal a lot about
the\nnature of the phase (or\, phase transition) in such systems. We disc
uss\nhow to probe the dispersion of the excitations in a variety of SU(2)\
nsymmetric S=1/2 spin systems using Quantum Monte-Carlo (QMC) methods.\nVa
rious applications of the method will be presented in one and two\ndimensi
ons\, which include studying the critical excitations in 2D\,\nboth for co
nventional and unconventional quantum critical points. In\nthe latter case
\, the excitation spectrum is highly unusual and has\nadditional gapless m
odes which are not present otherwise.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=3649
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3649
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spin noise spectroscopy of atomic vapors and semiconductors
DTSTART;VALUE=DATE-TIME:20140709T090000Z
DTEND;VALUE=DATE-TIME:20140709T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3754@cern.ch
DESCRIPTION:Spin noise spectroscopy (SNS) is a powerful technique to passi
vely\nprobe spin dynamics in atomic vapors and semiconductors by detecting
\nFaraday rotation fluctuations of a linearly polarized off-resonant\nlase
r beam passing through the sample. The SNS has been useful to\nmeasure var
ious spin properties including hyperfine coupling in atomic\nvapors\, elec
tron spin life-time in semiconductors and anisotropic hole\ng-factor of se
lf-assembled quantum dots. I will start my talk by\nintroducing physics of
SNS. Next I will show our results on detection\nof correlations between t
wo spin-resonances using a double-frequency\nSNS with an additional radio-
frequency magnetic field along with the\nprobe laser beam. Finally I will
discuss our recent proposal to\nmeasure spin-spin correlations between two
interacting spin subsystems\nusing a two-color SNS with two linearly pola
rized laser beams of\ndifferent wavelength. The spin-spin correlations hav
e been probed\nexperimentally following our proposal.\n\nhttps://indico.ti
fr.res.in/indico/conferenceDisplay.py?confId=3754
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3754
END:VEVENT
BEGIN:VEVENT
SUMMARY:RG Analysis of a Non-Fermi Liquid System
DTSTART;VALUE=DATE-TIME:20140724T060000Z
DTEND;VALUE=DATE-TIME:20140724T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3792@cern.ch
DESCRIPTION:We devise a renormalization group analysis for quantum field t
heories with Fermi surface to study scaling behaviour of non-Fermi liquid
states in a controlled approximation. The non-Fermi liquid fixed points ar
e identified from a Fermi surface in (m+1) spatial dimensions\, while the
co-dimension of Fermi surface is also extended to a generic value. We also
study superconducting instability in such systems as a function of dimens
ion and co-dimension of the Fermi surface. The key point in this whole ana
lysis is that unlike in relativistic QFT\, the Fermi momentum kF enters as
a dimensionful parameter\, thus modifying the naive scaling arguments. Th
e effective coupling constants are found to be combinations of the origina
l coupling constants and kF.\n\nhttps://indico.tifr.res.in/indico/conferen
ceDisplay.py?confId=3792
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3792
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonequilibrium dynamics of extended systems
DTSTART;VALUE=DATE-TIME:20140806T090000Z
DTEND;VALUE=DATE-TIME:20140806T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3809@cern.ch
DESCRIPTION:A spatially extended system often involves a large number of d
egrees\nof freedom that are strongly interacting with one another. Here\,
we\nanalyze the dynamics of a tagged monomer of an elastic chain of\npolym
ers. In the case of free evolution\, the monomer displays\nsubdiffusive be
havior. In presence of a quench/resetting protocol\, our\nexact solution s
hows that the system displays strong memory-dependent\nrelaxation and nont
rivial out-of-equilibrium steady states.\n\nRefs: \n[1] S G\, A Rosso and
C Texier\, Phys. Rev. Lett. 111\, 210601\n(2013)\, \n[2] S G\, S N Majumda
r and G Schehr\, Phys. Rev. Lett. 112\,\n220601 (2014).\n\nhttps://indico.
tifr.res.in/indico/conferenceDisplay.py?confId=3809
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3809
END:VEVENT
BEGIN:VEVENT
SUMMARY:Interacting electronic topological insulators in three dimensions
DTSTART;VALUE=DATE-TIME:20140806T060000Z
DTEND;VALUE=DATE-TIME:20140806T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3821@cern.ch
DESCRIPTION:I will review recent progress in describing interacting electr
onic topological insulators/superconductors in three dimensions. The focus
will be on Symmetry Protected Topological (SPT) phases of electronic syst
ems with charge conservation and time reversal. I will argue that the well
known Z2 classification of free fermion insulators generalizes to a Z23 c
lassification in the presence of interactions. I will describe the experim
ental fingerprints and other physical properties of these states. If time
permits\, I will describe results on the classification and properties of
3d electronic SPT states with various other physically relevant symmetries
.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3821
LOCATION:Colaba Campus
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3821
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collective far-from-equilibrium behavior in quantum gases: Open
and Closed Systems
DTSTART;VALUE=DATE-TIME:20140820T090000Z
DTEND;VALUE=DATE-TIME:20140820T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3854@cern.ch
DESCRIPTION:In this presentation\, I will discuss non-equilibrium aspects
of\nBosonic atoms in two different scenarios\, (i) when it behaves as an\n
isolated quantum system out-of equilibrium and (ii) when it is an open\nqu
antum system in which the Bose gas is driven and coupled to photons\ninsid
e a leaky cavity.\n\nI will first discuss the nonlinear dynamics of an iso
lated Bose\ngas. In particular\, I will discuss the physics and universali
ty\narising upon quenching an excited state corresponding to a collective\
nsolitonic excitation. I will show that\, in this case\, the Bose gas\nfal
ls into the universality class described by the Korteweg-de Vries\nequatio
n [1]. I will also discuss results on dynamical critical\nphenomenon of a
1D Bose gas and show its strong connection to the\nKardar-Parisi-Zhang uni
versality class [2\,3].\n\nI will then discuss an open quantum system cons
isting of a Bose gas\nplaced in an optical cavity and pumped by a laser [4
]. This can be\nmapped to a non-local Gross-Pitaeveski equation and also t
o the\nCaldeira-Leggett model of quantum dissipation. I will describe the\
nnon-trivial dissipative properties near the critical point of an open\nqu
antum phase transition [5]\, which explained recent surprising\nexperiment
al findings. I will also describe the rich dynamics of this\ndriven-dissip
ative quantum gas and show this to be deeply rooted in\nthe theory of non-
Hermitian physics and the pseudo-spectrum of this\nopen quantum system [6]
.\n\n(1) M. Kulkarni\, A. G. Abanov\, Phys. Rev. A\, 86\, 033614\; F. Fran
chini\,\nA. Gromov \, M. Kulkarni\, A. Trombettoni\, (2014) \n(2) M. Kulka
rni\, D. A. Huse\, H. Spohn (2014)\; M. Kulkarni\,\nA. Lamacraft\, Phys. R
ev. A 88\, 021603\, Rapid Communication \n(3) M. Kulkarni\, Journal of St
atistical Physics (invited article\,\n2014) \n(4) R. Mottl et al\, Scienc
e 336\, 1570 (2012)\; K. Baumann et al\, Nature\n464\, 1301 (2010)\n(5) M.
Kulkarni\, B. Oztop and H. E. Tureci\, Phys. Rev. Lett\, 111\,\n220408 \n
(6) M. Kulkarni\, K. G. Makris\, H. E. Tureci (2014)\n\nhttps://indico.tif
r.res.in/indico/conferenceDisplay.py?confId=3854
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3854
END:VEVENT
BEGIN:VEVENT
SUMMARY:Interplay of spin-orbit coupling and electron-electron correlation
s in Iridates
DTSTART;VALUE=DATE-TIME:20140827T090000Z
DTEND;VALUE=DATE-TIME:20140827T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3869@cern.ch
DESCRIPTION:Quantum spin liquids and Topological insulators are prototypes
of phases whose properties are not captured within the framework of spont
aneous symmetry breaking. Recent parallel developments in material science
s and theory have led to exciting possibilities of realizing these and oth
er phases in a class of Iridium based compounds. This is primarily due to
the interplay of strong spin-orbit coupling and electron-electron interact
ions in Iridates. In this talk\, I shall discuss such phases in context of
two families of Iridatesâ€” the honeycomb and the Hyper-honeycomb\,
which have been synthesized. In particular\, I shall focus on the a Topolo
gical Band insulator and a three dimensional Z2 spin liquid that may be st
abilized in hyper-honeycomb iridates.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=3869
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3869
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topology and Correlations driving new materials\, phases and pheno
mena
DTSTART;VALUE=DATE-TIME:20140912T090000Z
DTEND;VALUE=DATE-TIME:20140912T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3894@cern.ch
DESCRIPTION:Quantum materials today can be classified as a function of the
strength of Coulomb interactions U and spin orbit coupling λ\, in units
of the bandwidth W. At large U lie the 3d transition metal oxides that sho
w phenomena such as colossal magneto-resistance and high Tc superconductiv
ity. In the opposite quadrant we encounter topological band insulators wit
h large &\\lambda\; but in weakly correlated s- and p- band materials. I w
ill discuss the next frontier of 4d and 5d oxide materials in the central
region of such a phase diagram and show how novel phases and phenomena ari
se from the close interplay of all three scales -- λ\, U and W. I will cr
itically review the combination of computational methods that are necessar
y to address the richness of the 4d and 5d materials. The role of advanced
spectroscopies such as angle resolved photoemission\, inelastic neutron s
cattering\, THz spectroscopy\, and resonant x-ray scattering using circula
rly polarized photons\, to identify different response functions of comple
x oxides will also be discussed.\n\nhttps://indico.tifr.res.in/indico/conf
erenceDisplay.py?confId=3894
LOCATION:Colaba Campus AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3894
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towards quantum simulations of chemical and biological processes u
sing ultra-cold Rydberg atoms
DTSTART;VALUE=DATE-TIME:20140917T090000Z
DTEND;VALUE=DATE-TIME:20140917T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3905@cern.ch
DESCRIPTION:Ultracold Rydberg atoms constituting a ``frozen gas'' have bec
ome a\nversatile tool well beyond atomic physics and serve as experimental
ly\naccessible interacting many-body systems for quantum information and\n
in condensed matter physics. While for those applications the\nresidual a
tomic motion is usually an unavoidable perturbation and\nsource of noise\,
we will use this motion for preserving coherent\nelectronic transport\, v
ery much like in molecules.\n\nDuring acceleration of several Rydberg atom
s due to resonant\ndipole-dipole interactions\, the responsible Born-Oppen
heimer surfaces\nof the atomic system provide an intricate link between at
omic motion\nand excitation transport. This link allows the engineering o
f\nadiabatic exciton transport schemes\, laboratory accessible conical\nin
tersections or mesoscopic entangled atom clouds. These conical\nintersecti
ons among dipole Born-Oppenheimer surfaces allow the\ndetailed monitoring
of many-body dynamics near the intersection and\ncan further be functional
ised as switches for exciton transport.\n\nOn shorter time scales where mo
tion is no longer crucial\, the system\nshows parallels to energy transpor
t in light harvesting\ncomplexes. Consequently Rydberg atoms can provide a
clean analog\nsystem for the quantum simulation of photosynthetic energy
transport\,\ninto which crucial complex features like disorder and decoher
ence can\nbe introduced in a controlled manner. This control can be achie
ved by\nembedding the assembly of Rydberg atoms into a background atomic g
as.\n\nAfter a brief overview of the concept of quantum simulation and\nan
alogies to ultra cold atom systems recently exploited by a number of\ndisc
iplines\, I will focus on the above studies related to chemical\nproblems
and the prospects to describe biological processes.\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=3905
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3905
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum oscillations in high-temperature superconductors
DTSTART;VALUE=DATE-TIME:20140918T090000Z
DTEND;VALUE=DATE-TIME:20140918T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3906@cern.ch
DESCRIPTION:The observation of quantum oscillations in underdoped cuprates
\nhas generated intense debate about the nature of the field-induced\nresi
stive state and its implications for the enigmatic `normal\nstate' of high
-temperature superconductors. Quantum oscillations\nsuggest an underlying
Fermi liquid at high magnetic fields H and low\ntemperatures\, in contrast
with the `pseudogap' seen in zero-field\,\nhigh-temperature spectroscopic
experiments. Recent specific heat\nmeasurements show quantum oscillations
in addition to a large\nfield-dependent suppression of the electronic den
sity of states. I\nwill present a theoretical analysis [1] that reconciles
these\nseemingly contradictory observations. I will give a general\nintro
duction to `fermiology' of cuprate superconductors\, namely\nquantum oscil
lations\, electronic spectra and Fermi surface\nreconstruction. Then I wil
l discuss our approach that models the\nfield-induced resistive state as a
vortex liquid with short-range\nd-wave pairing correlations. We show that
this state exhibits\nquantum oscillations\, with a period determined by a
Fermi surface\nreconstructed by a possible translational symmetry-breakin
g order\nparameter\, in addition to a large suppression of the density of\
nstates that goes like square root of H at low fields. \n\n1. S. Banerjee\
, S. Zhang and M. Randeria\, Nature Comm. 4:1700 (2013).\n\nhttps://indico
.tifr.res.in/indico/conferenceDisplay.py?confId=3906
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3906
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spatial extent of N Brownian walkers
DTSTART;VALUE=DATE-TIME:20140924T090000Z
DTEND;VALUE=DATE-TIME:20140924T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3907@cern.ch
DESCRIPTION:Statistical properties of the spatial extent of N Brownian wal
kers is\nrelevant to various physical situations like estimation of habita
t\nsizes of animal populations\, disease spread in crop fields and river\n
pollution amongst others.\n\nIn the first part of my talk\, I will focus o
n the distribution of the\nsize of the region visited and of the region ov
erlapped by N\nindependent and identical one-dimensional Brownian walkers.
Using a\nconnection between the spatial extent and extreme displacements
I will\nshow\, in the large N limit\, that these distributions have intere
sting\nlimiting forms. These limiting forms are different from the standar
d\nextreme value distributions of independent and identical random\nvariab
les. In the second part of my talk\, I will discuss possible\ngeneralizati
ons to situations where the walkers are interacting.\n\nhttps://indico.tif
r.res.in/indico/conferenceDisplay.py?confId=3907
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3907
END:VEVENT
BEGIN:VEVENT
SUMMARY:Long-range correlation in driven diffusive systems
DTSTART;VALUE=DATE-TIME:20141029T090000Z
DTEND;VALUE=DATE-TIME:20141029T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-3981@cern.ch
DESCRIPTION:Systems driven out of equilibrium often reach a stationary sta
te which\nunder generic conditions exhibit long-range correlation. As a re
sult\nthese systems sometimes exhibit properties which are in striking\nco
ntrast with equilibrium\, such as non-local response to local\nperturbatio
n\, existence of long-range order and spontaneous symmetry\nbreaking in on
e dimension\, etc. I shall present two examples from my\nwork emphasising
this aspect of non-equilibrium.\n\nIn the first example\, I shall discuss
the effect of a spatially\nlocalized perturbation which breaks detailed ba
lance\, in an otherwise\ndiffusive system. Such perturbation often leads t
o long-range\ncorrelation and non-local changes in the stationary state. O
ur study\nis based on a microscopic model where particles on a d-dimension
al\nlattice interact with symmetric simple exclusion. The system is\nbroug
ht out of equilibrium by a drive across a single bond in the\nbulk. Using
an electrostatic analogy I show that the average density\nprofile and the
density-density correlation has a power-law tail.\n\nIn the second example
\, I shall discuss the effect of a localized drive\non the nonequilibrium
stationary state of an interface separating two\nphases in coexistence. Th
is is done using a spin conserving kinetic\nIsing model on a two dimension
al lattice with cylindrical boundary\ncondition\, where a drive is applied
along a single ring on which the\ninterface separating the two phases is
centered. Unlike the\nequilibrium case of a localizing potential\, the dri
ve is found to\ninduce an interface spontaneous symmetry breaking whereby
the\nmagnetization of the driven ring becomes non-zero. The width of the\n
interface becomes finite and its fluctuation around the driven ring\nare n
on-symmetric. I shall analyze the dynamical origin of these\nproperties in
an adiabatic limit which allows the evaluation of the\nlarge deviation fu
nction of the driven-ring magnetization.\n\nRef: \n\n[1] Tridib Sadhu\,
Satya N. Majumdar and David Mukamel\, Phys. Rev. E\n 84\, 051136 (2011)
\n\n[2] Tridib Sadhu\, Zvi Shapira and David Mukamel\,\n Phys. Rev. Let
t. 109\, 130601 (2012)\n\n[3] Tridib Sadhu\, Satya N. Majumdar and David M
ukamel\, Phys. Rev. E\n 90\, 012109 (2014)\n\n[4] Tridib Sadhu\, Satya
N. Majumdar and David Mukamel\, J. Phys. A:\n math theo (accepted for p
ublication\, 2014)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=3981
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3981
END:VEVENT
BEGIN:VEVENT
SUMMARY:Correlated Extreme Values in Branching Brownian Motion
DTSTART;VALUE=DATE-TIME:20141105T090000Z
DTEND;VALUE=DATE-TIME:20141105T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4001@cern.ch
DESCRIPTION:We investigate one dimensional branching Brownian motion in wh
ich at each time step particles either diffuse (with diffusion constant D)
\, die (with rate d)\, or split into two particles (with rate b). When the
birth rate exceeds the death rate (b > d)\, there is an exponential proli
feration of particles and the process is explosive. When b < d\, the proce
ss eventually dies. At the critical point (b = d) this system is character
ized by a fluctuating number of particles with a constant average. Quite r
emarkably\, although the individual positions of these particles have a no
n-trivial finite time behaviour\, the average distances between successive
particles (the gaps) become stationary at large times\, implying strong c
orrelations between them. We compute the probability distribution function
s (PDFs) of these gaps\, by conditioning the system to have a fixed number
of particles at a given time t. At large times we show that these PDFs ar
e characterized by a power law tail &sim\; 1/g3 (for large gaps g) at the
critical point and ~ exp (- g/c) otherwise\, with a correlation length c ~
\\sqrt{{(D/|b - d|)}. We discuss the emergence of these two length scales
\, the dominant overall length scale of the individual positions\, and the
sub-dominant gap length scale in this system. Direct Monte Carlo simulati
ons confirm our predictions.\n\nhttps://indico.tifr.res.in/indico/conferen
ceDisplay.py?confId=4001
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4001
END:VEVENT
BEGIN:VEVENT
SUMMARY:Large Deviations for the Tagged Particle in Single File Motion
DTSTART;VALUE=DATE-TIME:20141230T090000Z
DTEND;VALUE=DATE-TIME:20141230T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4114@cern.ch
DESCRIPTION:Consider a gas of point particles moving in a one-dimensional
channel\nwith a hard-core inter-particle interaction that prevents particl
e\ncrossings --- this is called single-file motion. Starting from\nequilib
rium initial conditions the motion of a tagged particle is\nobserved. It i
s well known that if the individual particle dynamics is\ndiffusive\, then
the tagged particle motion is sub-diffusive\, while for\nballistic partic
le dynamics\, the tagged particle motion is\ndiffusive. The large deviatio
n function for the tagged particle\ndisplacement has been obtained exactly
\, which is shown to be quite\ngeneral\, independent of the individual dyn
amics.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=41
14
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4114
END:VEVENT
BEGIN:VEVENT
SUMMARY: Quantum and classical annealing in spin glasses and quantum compu
ting
DTSTART;VALUE=DATE-TIME:20150121T090000Z
DTEND;VALUE=DATE-TIME:20150121T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4150@cern.ch
DESCRIPTION:The simulated annealing method for was first proposed in the\n
context of classical spin glasses and has become one of the most\nsuccessf
ul global optimization methods. The basic idea is that a\nMonte Carlo simu
lation with slowly decreasing temperature can\nexplore the energy (cost-fu
nction) landscape of a complex system\nwithout getting trapped in local mi
nimums. It is then natural to\nconsider similar schemes based on slow redu
ction of quantum\nfluctuations in quantum annealing processes. Such scheme
s have been\nexplored for some time\, in theoretical model studies as well
as in\nexperiments on frustrated Ising spin systems. Quantum annealing h
as\nrisen to particular prominence in the context of quantum\ncomputation\
, where there are now serious efforts to implement the\nmethod in actual d
evices\, such as the D-wave quantum annealer. It\nis not yet clear whethe
r true quantum annealing has been realized\,\nhowever. Beyond this practic
al issue\, a fundamental question is\nwhether quantum annealing really is
more efficient than classical\nsimulated annealing for solving important o
ptimization problems. I\nwill discuss recent numerical work on this issue
based on\nnon-equilibrium quantum Monte Carlo simulations in imaginary tim
e\,\nin which a quantum Ising spin glass is brought toward a\nquantum-crit
ical point on its way to reaching the classical optimum\nground state ener
gy.}\n\nReference: C.-W. Liu\, A. Polkovnikov\, A. W. Sandvik\, arXiv:1409
.7192.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=41
50
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4150
END:VEVENT
BEGIN:VEVENT
SUMMARY:Free Fermions in a one dimensional harmonic trap and Gaussian rand
om matrices
DTSTART;VALUE=DATE-TIME:20150209T043000Z
DTEND;VALUE=DATE-TIME:20150209T053000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4182@cern.ch
DESCRIPTION:Consider N free Fermions in a one dimensional harmonic trap. H
ow many Fermions are there at zero temperature in an interval [-L\,L]? The
ground state quantum fluctuations of the number of Fermions in [-L\,L] ca
n be mapped to the classical fluctuations of the number of eigenvalues in
[-L\,L] of a Gaussian random Hermitian matrix with complex entries. This m
apping allows us to compute exactly for large N\, using a Coulomb gas appr
oach\, the variance of number of Fermions in the quantum system at T=0\, a
s a function of L. The variance exhibits\, as a function of L\, a very int
eresting non-monotonic behaviour. These results can then be used to comput
e also the ground state entanglement entropy of the interval [-L\,L] with
the rest of the system.\n\nhttps://indico.tifr.res.in/indico/conferenceDis
play.py?confId=4182
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4182
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adaptation dynamics of asexual populations
DTSTART;VALUE=DATE-TIME:20150318T090000Z
DTEND;VALUE=DATE-TIME:20150318T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4276@cern.ch
DESCRIPTION:Adaptation in asexual populations happens only by means of rar
e\,\nbeneficial mutations. These mutations occur in the tails of fitness\n
distributions and hence can belong to only one of the three extreme\nvalue
domains. In my talk\, I shall discuss an experimentally\nmeasurable quant
ity that shows a qualitatively different behavior in\neach extreme value d
omain and thus\, can be used to distinguish between\nthem.\n\nhttps://indi
co.tifr.res.in/indico/conferenceDisplay.py?confId=4276
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4276
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Birth of a New Domain: Combinatorial Physics
DTSTART;VALUE=DATE-TIME:20150323T060000Z
DTEND;VALUE=DATE-TIME:20150323T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4286@cern.ch
DESCRIPTION:The interaction between Combinatorics and Physics is not new:
the classical combinatorial solution of the Ising model for ferromagnetism
goes back to the s. In the last 30 years\, there have been a renaissance
of combinatorics\, especially what is called enumerative\, algebraic and b
ijective combinatorics. Powerful combinatorial tools have been discovered\
, in relation with other domains of pure mathematics\, and such tools appe
ar to be useful for theoretical physics.\n\nWith some examples I will illu
strate this fruitful interaction between combinatorics and physics\, givin
g rise to a domain which can be called Combinatorial Physics. A new journa
l is born\, Combinatorics\, Physics and their Interactions\, in the presti
gious series of the Annales of Poincarre Institute in Paris. In the front
page one can read:\n\n``The unfolding of new ideas in physics is often tie
d to the development of new combinatorial methods\, and conversely some pr
oblems in combinatorics have been successfully attacked using methods insp
ired by statistical physics or quantum field theory.''\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=4286
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4286
END:VEVENT
BEGIN:VEVENT
SUMMARY:Critical dynamics of anisotropic N-vector models
DTSTART;VALUE=DATE-TIME:20150813T043000Z
DTEND;VALUE=DATE-TIME:20150813T060000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4511@cern.ch
DESCRIPTION:To identify and classify universality classes has been a major
pursuit\nsince the advent of Renormalization Group. This pursuit is not
just\nrestricted to equilibrium statistical mechanics. I will introduce a\
nclass of non-equilibrium non-conserved N-vector models described by\ntime
-dependent Landau-Ginzburg theory. I will then discuss about the\ninteract
ions that are consistent with a single length-scale. The RG\nanalysis reve
al genuine non-equilibrium fixed-points.\n\nhttps://indico.tifr.res.in/ind
ico/conferenceDisplay.py?confId=4511
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4511
END:VEVENT
BEGIN:VEVENT
SUMMARY: Particle dynamics in time-periodic systems
DTSTART;VALUE=DATE-TIME:20150813T090000Z
DTEND;VALUE=DATE-TIME:20150813T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4512@cern.ch
DESCRIPTION:Theoretical analysis of particle dynamics in time-periodic sys
tems is\nof great interest in plasma physics. We have analysed this proble
m for\nthe case of both continuous and discrete systems. For the continuou
s\ncase\, we have derived analytic expressions of the plasma distribution\
nfunction in Paul traps and have shown that the time averaged plasma\ndens
ity is very different from that predicted by conventional\ntheory. For the
discrete case\, this problem is termed Fermi\nacceleration (dynamical bil
liards with moving boundaries). In this\ncase\, particles have been shown
to undergo unbounded energy growth if\nthe frozen billiard is chaotic. We
have shown that chaos is not\nnecessary and unbounded energy growth can be
obtained with\npseudo-integrable billiards too. In fact\, the energy grow
th in chaotic\nsystems is only quadratic-in-time whereas in pseudo-integra
ble systems\nit is exponential-in-time!\n\nhttps://indico.tifr.res.in/indi
co/conferenceDisplay.py?confId=4512
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4512
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase transitions in random k-satisfiability problems
DTSTART;VALUE=DATE-TIME:20151012T103000Z
DTEND;VALUE=DATE-TIME:20151012T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4610@cern.ch
DESCRIPTION:k-satisfiability is a constraint satisfaction problem where on
e wants to find the assignments of Boolean variables that satisfies a give
n set of constraints(or clauses). The problem is known to undergo phase tr
ansitions as a function of the ratio of constraints and variables. Phase t
ransitions in random k-satisfiability problems are believed to be connecte
d to their computational complexity. While polynomial time algorithms are
known to solve the problem for k = 2\, for k ≥ 3 the problem is known to
be NP-complete. In this talk\, we will discuss random k-satisfiability an
d many of its variants on regular trees. The solvability threshold for k =
2 matches the exact value of the threshold on regular random graphs. For
higher k\, the values are very close to those predicted using other techni
ques like the cavity method.\n\nhttps://indico.tifr.res.in/indico/conferen
ceDisplay.py?confId=4610
LOCATION:A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4610
END:VEVENT
BEGIN:VEVENT
SUMMARY:Time optimal feedback control of linear systems and minimum time c
onsensus of multiple interacting double integrators
DTSTART;VALUE=DATE-TIME:20151208T090000Z
DTEND;VALUE=DATE-TIME:20151208T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4713@cern.ch
DESCRIPTION:In first part\, we review a recently developed method to compu
te the time optimal feedback control for state transfer of a class of sing
le input linear time invariant systems with constrained input. The time op
timal control is known to switch between upper and lower limits of constra
ints based on switching surfaces in state space which are available in par
ametric form (not useful for feedback). We use Groebner basis to eliminate
these parameters and obtain an implicit representation of switching surfa
ce which is useful for state-feedback based switching.\n\nIn second part\,
We give a method to compute the minimum time to consensus for multiple do
uble integrator agents interacting with each other over a complete graph.
The method uses intersection of attainable sets and Helly's theorem to sho
w that\, for a group of N>3 agents only two or three agents determine the
final time to consensus and consensus state. This part is a joint work wit
h a fellow PhD student Ameer K. Mulla and Professor Debraj Chakraborty.\n\
nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4713
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4713
END:VEVENT
BEGIN:VEVENT
SUMMARY:Surprises in Two-species Annihilation: Logarithmic corrections t
o decay
DTSTART;VALUE=DATE-TIME:20160113T090000Z
DTEND;VALUE=DATE-TIME:20160113T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4793@cern.ch
DESCRIPTION:We describe the long-time behaviour of surviving particles n(t
) in the reaction A+B → 0 on a 1D lattice\, in the presence of exclusion
between particles of the same species. We consider initial conditions whi
ch are infinite repetitions of blocks of the type 'AB'\, 'AABB'\, 'AAABBB'
\, etc. We show\, using the independent interval approximation\, that the
number of surviving particles n(t) ~ t-1/2 for blocks of length 4n-2\, and
n(t) ~ t-1/2 log(t) for blocks of length 4n. Our predictions are confirme
d using first-passage monte-carlo simulations for very large systems.\n\nh
ttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4793
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4793
END:VEVENT
BEGIN:VEVENT
SUMMARY: Simplex solid and spin liquid phases in two dimensional frustra
ted kagome antiferromagnets
DTSTART;VALUE=DATE-TIME:20160120T090000Z
DTEND;VALUE=DATE-TIME:20160120T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4794@cern.ch
DESCRIPTION:Strongly correlated systems provide a fertile ground for disco
vering exotic states of matter\, for example\, those with topologically no
n-trivial properties. Among these are frustrated magnets\, which are now b
eing studied with advanced numerical many-body techniques. I present two o
f our works in this area\, both focusing on the kagome geometry which has
near-ideal realizations in several materials\, often with an onsite spin-m
oment that is greater than 1/2. First\, I present a study of the spin-1 He
isenberg antiferromagnet\, where contrary to several previous theoretical
proposals\, our calculations indicate that the ground state is a valence b
ond (simplex) solid with a spin gap that is consistent with experimental f
indings. In the second part\, I consider the spin-1/2 XXZ model in a magne
tic field\, equivalent to a hard-core bosonic problem with density-density
interactions at finite filling fraction. Motivated by previous field theo
retical studies\, I focus my attention to understanding the XY limit for t
he 2/3 magnetization plateau (i.e. 1/6 filling of bosons). We perform exac
t or accurate numerical computations to search for the predicted chiral sp
in liquid and based on energetics and the determination of minimally entan
gled states and the associated modular matrices\, provide evidence for thi
s phase.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=
4794
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4794
END:VEVENT
BEGIN:VEVENT
SUMMARY:Variable-range hopping through marginally localized phonons
DTSTART;VALUE=DATE-TIME:20160128T090000Z
DTEND;VALUE=DATE-TIME:20160128T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4824@cern.ch
DESCRIPTION:Recently there is a surge of activities in interacting quantum
systems subjected to strong disorder. These systems pose fundamental ques
tions about quantum dynamics in closed systems\, which might fail to therm
alize due to the phenomenon of many-body localization (MBL). After a gener
al introduction to MBL\, I will discuss the possibility to realize a MBL s
tate of particles coupled to gapless and asymptotically delocalized phonon
s. This is in contrast to the general belief that such coupling to phonons
would inevitably lead to delocalization through phonon assisted hopping a
nd the well-known variable range hopping (VRH) transport. Specifically\, w
e consider a system of electrons coupled to a one dimensional random harmo
nic chain and analyze the phonon-mediated hopping transport for both weak
and strong coupling regimes [1]. We show that the usual VRH transport via
low-order phonon processes is absent in this system and at low temperature
the system could only thermalize through arbitrary high-order process lea
ding to a modified VRH rate. If time permits\, I will briefly mention our
ongoing work on thermalization of electrons coupled to random Heisenberg c
hain and some preliminary dynamical mean-field theory (DMFT) results on MB
L in disordered Hubbard model.\n\n[1] S. Banerjee and E. Altman\, arXiv:15
11.03676 (2015).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py
?confId=4824
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4824
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics of entanglement generation in periodically driven closed
integrable quantum systems
DTSTART;VALUE=DATE-TIME:20160217T090000Z
DTEND;VALUE=DATE-TIME:20160217T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4864@cern.ch
DESCRIPTION:In this talk\, we shall study periodic dynamics of a class of
closed integrable quantum systems. We shall show that a periodic drive may
lead to controlled generation of states with non-area and non-volume law
entanglement. In addition\, we unravel a dynamical transition in such syst
ems separating regimes with distinct power law decays of all correlation f
unctions to their steady state (GGE) value. We show that this transition o
ccurs due to change in topology of the system's Floquet spectrum and discu
ss experiments which can test our theory.\n\nhttps://indico.tifr.res.in/in
dico/conferenceDisplay.py?confId=4864
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4864
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Hall effect of Bosons and beyond
DTSTART;VALUE=DATE-TIME:20160413T043000Z
DTEND;VALUE=DATE-TIME:20160413T053000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-4954@cern.ch
DESCRIPTION:Recent research has reveal the crucial role of quantum entangl
ement and symmetries in determining the nature of many-body quantum ground
states beyond phases with spontaneously broken symmetries. In this talk\,
I hope to give a general outline of this exciting development and provide
a concrete realisation of such a phase – the lattice realization of int
eger quantum Hall phase in bosons (BIQH). Interestingly\, unlike fermions\
, interactions form a crucial ingredient in stabilizing such a phase. I wi
ll also show the exciting connection between the BIQH phase and the Chiral
spin liquid phase realised in certain Kagome antiferromagnets\, obtained
through the concept of ’gauging’ a global symmetry.\n\nhttps://indico.
tifr.res.in/indico/conferenceDisplay.py?confId=4954
LOCATION: D 405
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=4954
END:VEVENT
BEGIN:VEVENT
SUMMARY:Introduction to Complex Quantum Theories
DTSTART;VALUE=DATE-TIME:20160505T090000Z
DTEND;VALUE=DATE-TIME:20160505T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5021@cern.ch
DESCRIPTION:In usual quantum theory the Hamiltonian is generally considere
d to be Hermitian operator. However it has been shown that fully consisten
t quantum theories are possible even for certain class of Non-Hermitian sy
stems. In this talk I will introduce the subject padagogically and mention
some of the applications.\n\nhttps://indico.tifr.res.in/indico/conference
Display.py?confId=5021
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5021
END:VEVENT
BEGIN:VEVENT
SUMMARY:Searching for topological phases in transition metal oxide thin fi
lms and heterostructures
DTSTART;VALUE=DATE-TIME:20160720T090000Z
DTEND;VALUE=DATE-TIME:20160720T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5118@cern.ch
DESCRIPTION:Recent years have seen intensive experimental and theoretical
research activity on topological phases. In spite of this effort\, there a
re relatively few classes of material systems that have been experimentall
y verified to support topological phases\, and most of these do not requi
re electron interactions to underpin the topological properties. In this t
alk\, I will describe some of our theoretical efforts aimed at expanding t
he known classes of topological materials to include transition metal oxid
es\, which typically have non-negligible electron interactions.\n\nhttps:/
/indico.tifr.res.in/indico/conferenceDisplay.py?confId=5118
LOCATION:DTP Seminar Room A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5118
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abelian Sandpiles: a combinatorial and algebraic geometry perspect
ive
DTSTART;VALUE=DATE-TIME:20160823T060000Z
DTEND;VALUE=DATE-TIME:20160823T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5163@cern.ch
DESCRIPTION:Abelian Sandpiles have been developed in diverse contexts incl
uding statistical physics\, combinatorics\, probability and algebraic geom
etry. This talk will survey these different viewpoints with a focus on com
binatorial and algebraic geometry aspects. We will not assume any specific
background in these topics.\n\nhttps://indico.tifr.res.in/indico/conferen
ceDisplay.py?confId=5163
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5163
END:VEVENT
BEGIN:VEVENT
SUMMARY:Probability distribution of time of detection of a quantum-mechan
ical particle at a screen
DTSTART;VALUE=DATE-TIME:20160831T053000Z
DTEND;VALUE=DATE-TIME:20160831T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5171@cern.ch
DESCRIPTION:Imagine an experiment where a quantum-mechanical particle is r
eleased from\nsome fixed region inside a box. On one side of the box there
is a screen\nwith detectors which click as soon as the particle "arrives"
at the screen. One expects that the time of arrival of the particle is a
stochastic variable and it is interesting to ask for it's probability dist
ribution.\nThis is similar to asking for the distribution of the time of
absorption of Brownian particle at some point. In this talk\, an attempt w
ill be made to explain why the quantum problem is subtle\, and our recent
attempts at understanding this in a framework where repeated projective
measurements\nare made to detect the particle. This leads to a non-unita
ry time evolution\nof the wave-function of the particle\, and we show that
this is well described by an effective non-Hermitiian Hamiltonian. For
some simple lattice models\, we find power-law tails for the probability
that the particle survives detection up to some time.\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=5171
LOCATION:DTP Seminar Room A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5171
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sample Space Reducing Stochastic Process
DTSTART;VALUE=DATE-TIME:20160929T090000Z
DTEND;VALUE=DATE-TIME:20160929T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5218@cern.ch
DESCRIPTION:Recently proposed mechanism\, namely\, sample space reducing (
SSR) stochastic process is of interest as this offers an explanation of sc
ale-invariant features associated with complex systems. In the SSR\, the s
ize of sample space or the number of allowed states stochastically decreas
es as a function of time\, while the generalized case is termed as noisy S
SR process where the size of sample space may expand occasionally. I'll ma
inly talk about the statistics of survival time\, defined as life span of
the proces\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confI
d=5218
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5218
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hyperuniformity and How to Get It
DTSTART;VALUE=DATE-TIME:20161013T090000Z
DTEND;VALUE=DATE-TIME:20161013T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5243@cern.ch
DESCRIPTION:The concept of hyperuniformity\, configurations with small num
ber fluctuations will be introduced and illustrated with examples. Althoug
h such distributions can be characterized mathematically\, it is less clea
r how they might arise in actual physical systems. I will discuss some way
s to generate disordered hyperuniform distributions\, and try to give some
intuition into when they might arise.\n\nhttps://indico.tifr.res.in/indic
o/conferenceDisplay.py?confId=5243
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5243
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hyperuniformity and How to Get It
DTSTART;VALUE=DATE-TIME:20161014T090000Z
DTEND;VALUE=DATE-TIME:20161014T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5244@cern.ch
DESCRIPTION:The concept of hyperuniformity\, configurations with small num
ber fluctuations will be introduced and illustrated with examples. Althoug
h such distributions can be characterized mathematically\, it is less clea
r how they might arise in actual physical systems. I will discuss some way
s to generate disordered hyperuniform distributions\, and try to give some
intuition into when they might arise.\n\nhttps://indico.tifr.res.in/indic
o/conferenceDisplay.py?confId=5244
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5244
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spin liquids from quadrupolar phases
DTSTART;VALUE=DATE-TIME:20161214T090000Z
DTEND;VALUE=DATE-TIME:20161214T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5345@cern.ch
DESCRIPTION:I will present various pieces of evidence using Monte Carlo si
mulations\, large-N expansions and field theoretic arguments which taken t
ogether provide strong indication that the continuous destruction of quadr
upolar order in S=1 quantum magnets results in a Z2 spin liquid.\n\nhttps:
//indico.tifr.res.in/indico/conferenceDisplay.py?confId=5345
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5345
END:VEVENT
BEGIN:VEVENT
SUMMARY:Contextuality in the presence of noise
DTSTART;VALUE=DATE-TIME:20161219T053000Z
DTEND;VALUE=DATE-TIME:20161219T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5354@cern.ch
DESCRIPTION:Contextuality is often cited as a key feature of quantum theor
y that sets it apart from classical probabilistic theories and powers many
of its computational and information-theoretic advantages. However\, the
Kochen Specker theorem -- which underpins the traditional notion of contex
tuality -is a statement about ideal quantum measurements. Indeed\, its exp
erimental testability has been a subject of intense debate in the past\, p
rimarily on account of the finite precision of real-world measurements. I
will outline a recent approach to devising tests of contextuality that can
deal with the inevitable presence of noise in experimental data. This app
roach\, initiated by Spekkens a decade ago\, does not require one to presu
me that the experimental data fits a quantum model and therefore also allo
ws for a test of contextuality robust to potential modifications of quantu
m theory. In doing so\, one gets a glimpse of contextuality beyond the Koc
hen-Specker theorem.\n\nhttps://indico.tifr.res.in/indico/conferenceDispla
y.py?confId=5354
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5354
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kagome Spin-Liquids and Herbertsmithites
DTSTART;VALUE=DATE-TIME:20170104T053000Z
DTEND;VALUE=DATE-TIME:20170104T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5361@cern.ch
DESCRIPTION:The Kagome Lattice Heisenberg Model is one of the iconic model
s of highly frustrated magnetism. We will discuss the current state of our
understanding of the physics of the model. The Herbertsmithite materials
ZnCu3(OH)6Cl2 contain structurally perfect magnetically isolated spin-half
Kagome planes. We will discuss the experimental status of these materials
and our attempts to quantitatively explain measurements of oxygen nuclear
relaxation rates in these materials.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=5361
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5361
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase bands for periodically driven integrable quantum systems
DTSTART;VALUE=DATE-TIME:20170111T053000Z
DTEND;VALUE=DATE-TIME:20170111T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5399@cern.ch
DESCRIPTION:In this talk\, we are going to chart out application of the ad
iabatic-impulse approximation method for addressing the properties of peri
odically driven integrable systems and show that this method provides us w
ith a tool for analytic computation of the phase bands (eigenvalues of the
time evolution operator) in the low drive frequency limit where the stand
ard high frequency perturbative expansions fail. Using this method and ano
ther\, more general\,argument\, we provide exact analytic conditions for c
rossings of hese bands in these driven systems. We show that such crossin
gs are related to change in topology of the driven systems and point out t
hat the signature of these crossings can be found in a certain class of co
rrelation functions of the model.\n\nhttps://indico.tifr.res.in/indico/con
ferenceDisplay.py?confId=5399
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5399
END:VEVENT
BEGIN:VEVENT
SUMMARY:Condensed Matter Lecture Series (3 lectures on 2 topics)
DTSTART;VALUE=DATE-TIME:20170118T060000Z
DTEND;VALUE=DATE-TIME:20170118T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5414@cern.ch
DESCRIPTION:What is topological order\, and is it present in the high temp
erature superconductors ? \n\nI will present an elementary introduction to
topological order\, and highlight its importance in determining the quant
um phases and phase transitions of lattice models of bosons or fermions wi
th short-range interactions. I will then highlight some puzzling features
of the phase diagram of the hole-doped cuprate compounds\, and argue that
they are most naturally understood using metallic states with topological
order.\n\nSYK models\, strange metals\, and black holes\n\nThe SYK models
provide solvable realizations of disordered metallic states without quasip
article excitations. Explicit holographic duals of the SYK models can be c
onstructed\, in terms of black holes with a near-horizon AdS2 geometry. I
will also compare the SYK models with more realistic models of the strange
metals in the cuprates. A common thread connecting these models is the re
markable connection between many-body quantum chaos and diffusive thermal
transport in states of quantum matter without quasiparticle excitations.\n
\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5414
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5414
END:VEVENT
BEGIN:VEVENT
SUMMARY:Condensed Matter Lecture Series (3 lectures on 2 topics)
DTSTART;VALUE=DATE-TIME:20170119T053000Z
DTEND;VALUE=DATE-TIME:20170119T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5415@cern.ch
DESCRIPTION:What is topological order\, and is it present in the high temp
erature superconductors ?\n\nI will present an elementary introduction to
topological order\, and highlight its importance in determining the quantu
m phases and phase transitions of lattice models of bosons or fermions wit
h short-range interactions. I will then highlight some puzzling features o
f the phase diagram of the hole-doped cuprate compounds\, and argue that t
hey are most naturally understood using metallic states with topological o
rder.\n\nSYK models\, strange metals\, and black holes\n\nThe SYK models p
rovide solvable realizations of disordered metallic states without quasipa
rticle excitations. Explicit holographic duals of the SYK models can be co
nstructed\, in terms of black holes with a near-horizon AdS2 geometry. I w
ill also compare the SYK models with more realistic models of the strange
metals in the cuprates. A common thread connecting these models is the rem
arkable connection between many-body quantum chaos and diffusive thermal t
ransport in states of quantum matter without quasiparticle excitations.\n\
nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5415
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5415
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170222T090000Z
DTEND;VALUE=DATE-TIME:20170222T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5497@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5497
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5497
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quenches\, non-analyticities and emergent topology: Ising and Hald
ane models
DTSTART;VALUE=DATE-TIME:20170222T060000Z
DTEND;VALUE=DATE-TIME:20170222T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5514@cern.ch
DESCRIPTION:Thermalization of a closed quantum system is a problem of imme
nse interest.In this talk\, we shall\, however\, focus on the early time d
ynamics of a closed quantum system evolving with the time independent fina
l Hamiltonian following a quench. The purpose is to probe the emerging non
-analyticities at different instants of time referred to as so called ``dy
namical quantum phase transitions (DQPTs)''. These non-analyticties are ma
nifested in the Loschmidt echo and can be connected to the the lines (or a
reas) of ``Fisher zeros'' in the complex time plane. Furthermore\, these a
re reflected in a dynamical topological order parameter constructed out
of the gauge-independent Pancharatnam phase implying an emerging topolog
ical structure. We shall illustrate the above scenario using the transvers
e Ising chain and topological Haldane model on a hexagonal lattice\; for t
he latter model\, we shall also illustrate the non-trivial role played by
the Haldane mass term (which determines the topology of the equilibrium Ha
ldane model).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?co
nfId=5514
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5514
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170224T090000Z
DTEND;VALUE=DATE-TIME:20170224T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5498@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5498
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5498
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170227T090000Z
DTEND;VALUE=DATE-TIME:20170227T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5499@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5499
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5499
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170301T090000Z
DTEND;VALUE=DATE-TIME:20170301T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5500@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5500
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5500
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170303T090000Z
DTEND;VALUE=DATE-TIME:20170303T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5501@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5501
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5501
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170306T090000Z
DTEND;VALUE=DATE-TIME:20170306T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5502@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5502
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5502
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mini-Course on Phase Transitions and Ordering (7 lectures with i
ntervening interactive tutorials)
DTSTART;VALUE=DATE-TIME:20170308T090000Z
DTEND;VALUE=DATE-TIME:20170308T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5503@cern.ch
DESCRIPTION:Tutorials to be announced in class\n\nOUTLINE of LECTURES\n\nO
rdered Phases and Phase Transitions: Phenomenology\; Definitions\; Models
and Mappings \n\nMean Field Theory: Variational basis\; Ornstein-Zernike
Theory\; Ginzburg Criterion\n\nGeneral Results on Ordering: Lower critical
dimension\; Peierls proof of ordering\; Mermin-Wagner result on absence o
f ordering\n\nCritical Phenomena: Fluctuations and their growth\; Scaling\
; Universality \n\nRenormalization Group: Basic idea\; Block spins\; Real-
space RG\n\nTime-dependent properties: Glauber and Kawasaki dynamics\; Pha
se ordering kinetics\n\nOrdered Phases out of Equilibrium: Nonequilibrium
steady states and phase transitions\; Fluctuation-dominated order\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5503
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5503
END:VEVENT
BEGIN:VEVENT
SUMMARY:Correlations\, transitions and early warning signals for non-equil
ibrium steady or quasi-steady states
DTSTART;VALUE=DATE-TIME:20170314T090000Z
DTEND;VALUE=DATE-TIME:20170314T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5564@cern.ch
DESCRIPTION:The spectrum of time series has found successful applications
in the understanding of financial markets but has been little used for sto
chastic dynamical systems. The reason seems to be that most systems studie
d have a clear spatial structure and many other techniques have been succe
ssfully applied. We therefore revisited some well known systems and in par
ticular found analytically that a power law in space implies a power law i
n the eigenvalues of the correlation spectra [1]. The proof is not inverti
ble and therefore we got interested in analyzing the a case where spatial
correlation are known analytically and display no power law\, named the to
tally antisymmetric simple exclusion process (TASEP) [2]. Here we found [3
] a power law for one critical line in parameter space and further interes
ting deviations from the random matrix behavior\, mainly in what is known
as the constant current region.\n\n[1] T. Prosen\, B. Buča and T.H. Selig
man\, (2014). Spectral analysis of finite-time correlation matrices near e
quilibrium phase transitions. EPL (Europhysics Letters)\, 2015\; 108(2)\,
20006.\n[2] Derrida B. Phys. Rep.. 1998\; 301(1)\, 65–83\n[3] S. Biswas\
, F. Leyvraz\, P. Monroy Castilero and T.H. Seligman\, Sci Rep. 2017\; 7:
40506.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=55
64
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5564
END:VEVENT
BEGIN:VEVENT
SUMMARY:First principles investigation on Quantum Materials
DTSTART;VALUE=DATE-TIME:20170404T090000Z
DTEND;VALUE=DATE-TIME:20170404T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5595@cern.ch
DESCRIPTION:Computer simulations based on first principles calculations pl
ay a central role in helping us understand\, predict\, and engineer physic
al\, chemical\, and electronic properties of technologically relevant mate
rials. This can solve many problems towards building faster\, smaller and
cheaper devices for processing and storing information as well as for savi
ng energy. Many of these processes involve electron excitations and strong
local magnetic fluctuation that the ‘standard model’ of electronic st
ructure\, Density Functional Theory (DFT)\, can’t capture properly. In t
his context\, I will highlight two popular approaches that go beyond the s
tandard DFT. First\, I will discuss how Dynamical Mean Field Theory (DMFT)
in combination with DFT has recently been successful for detailed modelin
g of the electronic structure of many complex materials with strong electr
on correlation. To give an example\, I will show the iron-based supercondu
ctors on both bulk and monolayer phases and their anomalous properties\, w
hich have their origin in strong Hund's coupling and give rise to the rich
physics of Hund's metals. Next\, I will discuss my collaborative effort t
oward developing a high scalable\, open-source GW software to compute elec
tronic excited states more efficiently for petascale architectures using t
he Charm++ parallel framework. At the end\, I will briefly discuss topolog
ical crystalline insulators\, which are a new class of topological materia
ls where electronic surface states are topologically protected along certa
in crystallographic directions by crystal symmetry. I will show that\, wit
hout any external perturbation\, both massless Dirac fermions protected by
the crystal symmetry and massive Dirac fermions with crystal symmetry bre
aking can coexist on a single surface.\n\nhttps://indico.tifr.res.in/indic
o/conferenceDisplay.py?confId=5595
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5595
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum spin liquids in XXZ Kagome antiferromagnets
DTSTART;VALUE=DATE-TIME:20170426T053000Z
DTEND;VALUE=DATE-TIME:20170426T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5650@cern.ch
DESCRIPTION:Quantum spin-liquids in Kagome antiferromagnets is an old prob
lem that has received much attention. In this talk\, I shall discuss a sys
tematic development of a low energy field theory to describe relevant quan
tum spin liquid phases from the point of view of "gauging" global symmetri
es. This will reveal an interesting connection between topologically order
ed phases and symmetry protected topological phases.\n\nhttps://indico.tif
r.res.in/indico/conferenceDisplay.py?confId=5650
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5650
END:VEVENT
BEGIN:VEVENT
SUMMARY:A hierarchical lattice model for the H-bond network in Water
DTSTART;VALUE=DATE-TIME:20170511T090000Z
DTEND;VALUE=DATE-TIME:20170511T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5672@cern.ch
DESCRIPTION:Many of the curious thermodynamic properties of water can be t
raced back to the unique patterns of Hydrogen bonding\, which lead to the
formation of a percolating H-bond network even in the liquid phase. We dev
elop and study a semi-empirical lattice model for this H-bond network\, an
d study it on an infinite-dimensional lattice. We show that the model give
s accurate predictions for the network correlations even at normal tempera
tures and pressures. We also study the phase diagram\, leading to a new hy
pothesis for the origin of the anomalous properties of water.\n\nhttps://i
ndico.tifr.res.in/indico/conferenceDisplay.py?confId=5672
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5672
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sub-diffusion and non-equilibrium probes of phases in incommensura
te lattice models in low dimensions
DTSTART;VALUE=DATE-TIME:20170518T090000Z
DTEND;VALUE=DATE-TIME:20170518T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5677@cern.ch
DESCRIPTION:We consider [1] an open quantum system generalization of the w
ell-known linear Aubry-Andre- Harper (AAH) Model by putting it out-of-equi
librium with the aid of two baths (at opposite ends) at unequal temperatur
es and chemical potentials. Non-equilibrium steady state (NESS) properties
are computed by a fully exact non-equilibrium Green’s function method.
We find sub-diffusive scaling of NESS current with system-size at the crit
ical point. Below and above the critical point we find ballistic and local
ized NESS transport respectively. We introduce a novel approach of probing
the phase diagram by computing spatial profiles of experimentally accessi
ble NESS quantities. These show remarkably different features below\, at a
nd above the critical point therefore proving to be a strong probe of the
rich underlying physics. We also make a detailed study of certain closed s
ystem quantities such as wavefunction spread\, dynamical susceptibility an
d current auto- correlation functions and find hints of the anomalous tran
sport but no clear evidence of sub-diffusion seen in the open system. Our
findings are valid for both the bosonic and fermionic versions.\n\n[1] A.
Purkayastha\, S. Sanyal\, A. Dhar\, M. Kulkarni\, arXiv:1702.05228\, (2017
)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5677
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5677
END:VEVENT
BEGIN:VEVENT
SUMMARY:Solvable model for a dynamical quantum phase transition from fast
to slow scrambling
DTSTART;VALUE=DATE-TIME:20170526T060000Z
DTEND;VALUE=DATE-TIME:20170526T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5684@cern.ch
DESCRIPTION:Alexei Kitaev has recently given a new interpretation to a sol
vable model of interacting fermions\, now known as Sachdve-Ye-Kitaev (SYK)
model\, connecting it to thermalization\, quantum chaos and information s
crambling in black holes. The correlations that diagnose quantum chaos has
been computed in this model leading to a scrambling rate with a universal
value 2πkBT/ℏ at temperature T. The SYK model is now understood as a f
ixed point for a certain class of quantum chaotic behavior. We propose a g
eneralized model that extends this classification. In the generalized mode
l\, we couple N sites forming the SYK model to another set of M sites\, co
nnected to each other only via quadratic coupling. In the solvable limit o
f large N\,M we find a quantum phase transition tuned by the ratio p=M/N f
rom a non Fermi liquid SYK like phase to a Fermi liquid. We show that the
entire SYK-like phase shows scrambling at the universal rate 2πkBT/ℏ at
low temperature whereas the Fermi-liquid like phase shows much slower scr
ambling\, proportional to T2.\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=5684
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5684
END:VEVENT
BEGIN:VEVENT
SUMMARY:Symmetry Protected Topological Phases of Quantum Matter (Infosys C
ondensed Matter Seminar) [Lecture 1]
DTSTART;VALUE=DATE-TIME:20170704T053000Z
DTEND;VALUE=DATE-TIME:20170704T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5725@cern.ch
DESCRIPTION:A major advance In the physics of the last decade is the theor
etical prediction and experimental discovery of topological insulators. Th
ough the topological insulator was initially discussed within the framewor
k of free electron band theory\, recent work has focused attention on the
topological insulator phenomenon in interacting many particle systems. It
is now recognized that free fermion topological insulators are a special
case of a more general class of phases of matter known as Symmetry Protect
ed Topological (SPT) phases. In these lectures I will describe these SPT p
hases with a focus on their physical (rather than mathematical) characteri
zation. Studies of SPT phases have increasingly played a central role in q
uantum many body physics and have lead to deep and surprising connections
between many different research topics. Time permitting\, I will describe
some of these as well.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=5725
LOCATION: AG 69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5725
END:VEVENT
BEGIN:VEVENT
SUMMARY:Symmetry Protected Topological Phases of Quantum Matter (Infosys C
ondensed Matter Seminar) [Lecture 2]
DTSTART;VALUE=DATE-TIME:20170705T053000Z
DTEND;VALUE=DATE-TIME:20170705T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5726@cern.ch
DESCRIPTION:A major advance In the physics of the last decade is the theor
etical prediction and experimental discovery of topological insulators. Th
ough the topological insulator was initially discussed within the framewor
k of free electron band theory\, recent work has focused attention on the
topological insulator phenomenon in interacting many particle systems. It
is now recognized that free fermion topological insulators are a special
case of a more general class of phases of matter known as Symmetry Protect
ed Topological (SPT) phases. In these lectures I will describe these SPT p
hases with a focus on their physical (rather than mathematical) characteri
zation. Studies of SPT phases have increasingly played a central role in q
uantum many body physics and have lead to deep and surprising connections
between many different research topics. Time permitting\, I will describe
some of these as well.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=5726
LOCATION: AG 69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5726
END:VEVENT
BEGIN:VEVENT
SUMMARY:Symmetry Protected Topological Phases of Quantum Matter (Infosys C
ondensed Matter Seminar) [Lecture 3]
DTSTART;VALUE=DATE-TIME:20170706T053000Z
DTEND;VALUE=DATE-TIME:20170706T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5727@cern.ch
DESCRIPTION:A major advance In the physics of the last decade is the theor
etical prediction and experimental discovery of topological insulators. Th
ough the topological insulator was initially discussed within the framewor
k of free electron band theory\, recent work has focused attention on the
topological insulator phenomenon in interacting many particle systems. It
is now recognized that free fermion topological insulators are a special
case of a more general class of phases of matter known as Symmetry Protect
ed Topological (SPT) phases. In these lectures I will describe these SPT p
hases with a focus on their physical (rather than mathematical) characteri
zation. Studies of SPT phases have increasingly played a central role in q
uantum many body physics and have lead to deep and surprising connections
between many different research topics. Time permitting\, I will describe
some of these as well.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=5727
LOCATION: AG 69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5727
END:VEVENT
BEGIN:VEVENT
SUMMARY:Frenetic aspects of nonlinear response: theory and experiment
DTSTART;VALUE=DATE-TIME:20170707T060000Z
DTEND;VALUE=DATE-TIME:20170707T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5734@cern.ch
DESCRIPTION:Away from thermal equilibrium\, the response of a statistical
mechanical system to an external stimulus is not only governed by dissipat
ion and depends explicitly on dynamical details of the system. We illustra
te this so called frenetic contribution in second order around equilibrium
in different physical examples. We also specifically discuss the example
of a colloidal particle being subjected to an anharmonic potential where t
he nonlinear response theory is experimentally verified. However\, the exp
licit dependence on the dynamical details makes application to complex sys
tems difficult. We show that this shortcoming can be overcome using a coar
se-graining approach where near-equilibrium measurements can be used to pr
edict far from equilibrium properties (i.e.\, second order responses) for
a small number of tractable degrees of freedom.\n\nhttps://indico.tifr.res
.in/indico/conferenceDisplay.py?confId=5734
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5734
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anomalous transport in perturbed Heisenberg chain
DTSTART;VALUE=DATE-TIME:20170810T084500Z
DTEND;VALUE=DATE-TIME:20170810T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5806@cern.ch
DESCRIPTION:We study high-temperature transport in quantum chains\, at and
away from integrability. Using a set of exact sum-rule moment relations\,
memory function Ansatz\, and exact diagonalization we investigate the res
ponse of the integrable XXZ model to next-nearest neighbour integrability
breaking spin-flips. In the integrable model we find a panoply of transpor
t rates as the interactions are tuned: subleading subballistic\, superdiff
usive\, and normal diffusion. We further find the sign of the integrabilit
y breaking perturbation matters: while positive spin-flips (in-plane frust
ration in the ground state) enhance spin transport\, there is a narrow int
erval of negative spin-flip amplitudes for which transport is strongly sup
pressed. The resulting (anomalous) long-time transport tails as inferred f
rom the regular conductivity of small spin chains are captured faithfully\
, qualitatively and quantitatively\, by the memory function Ansatz in all
regimes: gapless\, isotropic\, and gapped for the integrable chain\, as we
ll as across vast parametric swathes of the nonintegrable chain. In sharp
contrast\, the asymmetry with respect to the sign of the perturbation is a
bsent in the fermionic analog of the model\, which is also captured nicely
by this hybrid memory function approach.\n\nhttps://indico.tifr.res.in/in
dico/conferenceDisplay.py?confId=5806
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5806
END:VEVENT
BEGIN:VEVENT
SUMMARY:Electric field response in a three dimensional U(1) Quantum spin l
iquid
DTSTART;VALUE=DATE-TIME:20170817T090000Z
DTEND;VALUE=DATE-TIME:20170817T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5824@cern.ch
DESCRIPTION:A three dimensional U(1) quantum spin liquid\, at low energies
\, is described by an emergent electrodynamics and supports a gapless “p
hoton” mode. I shall discuss the coupling between conventional (Maxwell)
and the above emergent electrodynamics in such a U(1) QSL–the quantum s
pin Ice. In particular\, I shall discuss the effect of an external electri
c field in such a system and show that such an external electric field can
– (1) lead to experimentally measurable signatures for the dynamics spin
-structure factor characteristic to QSL\, and (2) can lead to unconvention
al quantum phase transitions between different U(1) spin liquids. The unde
rstanding of above unconventional charge response form can be of importan
ce in characterising the unconventional magnetic properties of rare-earth
pyrochlore oxides which may harbour the above QSL phases.\n\nhttps://indic
o.tifr.res.in/indico/conferenceDisplay.py?confId=5824
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5824
END:VEVENT
BEGIN:VEVENT
SUMMARY:Origin of charge density wave order in the underdoped cuprates
DTSTART;VALUE=DATE-TIME:20170913T053000Z
DTEND;VALUE=DATE-TIME:20170913T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5871@cern.ch
DESCRIPTION:The exact nature of the normal state in the underdoped cuprate
s is still debatable. Recent experimental results favor the existence of a
n unconventional charge density wave with d-wave form factor above the sup
erconducting transition. Here we study the charge density wave instability
within the Eliashberg framework. We find the full momentum structure of t
he dominant charge density wave instability and compare its strength to th
e superconductivity driven by spin-fluctuation mediated interaction.\n\nht
tps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5871
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5871
END:VEVENT
BEGIN:VEVENT
SUMMARY:Extremal statistics in the classical one dimensional Coulomb gas
DTSTART;VALUE=DATE-TIME:20171004T060000Z
DTEND;VALUE=DATE-TIME:20171004T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5907@cern.ch
DESCRIPTION:We consider a one-dimensional classical Coulomb gas of N like-
charges in a harmonic potential – also known as the one-dimensional one-
component plasma (1dOCP). We compute analytically the probability distribu
tion of the position xmax of the rightmost charge in the limit of large N.
We show that the typical fluctuations of xmax around its mean are describ
ed by a non- trivial scaling function\, with asymmetric tails. This distri
bution is different from the Tracy-Widom distribution of xmax for the Dyso
n’s log-gas. We also compute the large deviation functions of xmax expli
citly and show that the system exhibits a third-order phase transition\, a
s in the log-gas. I’ll also discuss some results on the distribution of
the index\, i.e.\, the \nnumber of charges on the positive semi-axis.\n\nh
ttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5907
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5907
END:VEVENT
BEGIN:VEVENT
SUMMARY:From sign problems to a quantum computer
DTSTART;VALUE=DATE-TIME:20171011T090000Z
DTEND;VALUE=DATE-TIME:20171011T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5941@cern.ch
DESCRIPTION:Quantum many-body systems are often plagued by sign problems t
hat make solving the theory a computationally hard problem on classical co
mputers\, where the computational difficulty scales exponentially with the
number of degrees of freedom. I show why this is the case for QCD at non
zero chemical potential. For certain computational problems it is known th
at quantum computers can provide exponential speed-up relative classical c
omputers\, and so it is natural to wonder if they can solve sign problems.
I outline some old and new approaches to finding the quantum many-body gr
ound state on a quantum computer.\n\nhttps://indico.tifr.res.in/indico/con
ferenceDisplay.py?confId=5941
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5941
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vortex and charge BKT transitions in disordered superconductor thi
n films
DTSTART;VALUE=DATE-TIME:20171026T090000Z
DTEND;VALUE=DATE-TIME:20171026T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5964@cern.ch
DESCRIPTION:There is strong experimental evidence for the surviving of coo
per pairs beyond the critical temperature for superconductivity in disorde
red superconducting thin films. This emphasizes the role of phase fluctuat
ions in the superconductor to insulator transitions (SIT). Magnetoresponse
near the SIT shows various surprising behaviors. We study the shrinking o
f superconducting islands in a magnetic field using a disordered boson mod
el. We then construct an effective Josephson junction model with field dep
endent parameters and obtain the magnetoresistance and superfluid stifness
in three extreme parameter regimes. In two of these regimes we see that a
vortex BKT transition and a modification of it by strong phase disorder p
lays a crucial role. We show that the recently reported phenomenon of supe
rinsulation can be understood as a charge BKT transition. Strong disorder
is again shown to alter the critical behavior\, resulting in the Vogel-Ful
cher-Tamann(VFT) behavior- a characteristic of glasses. We attribute this
glassy behavior to the freezing phenomenon of charge dipole excitations.\n
\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5964
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5964
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum oscillations without a Fermi surface
DTSTART;VALUE=DATE-TIME:20171102T090000Z
DTEND;VALUE=DATE-TIME:20171102T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-5973@cern.ch
DESCRIPTION:Quantum oscillations are conventionally understood to arise fr
om the Fermi level\; hence\, they are considered to be a proof of the exis
tence of an underlying Fermi surface. This understanding forms the basis f
or experiments measuring these oscillations to study metallic systems and
map the Fermi surface. In this talk\, I will show that this conventional u
nderstanding is not always true: in certain situations quantum oscillation
s can also arise from inside the Fermi sea. The necessary condition and po
ssible scenarios for such unusual behavior will be pointed out. These unco
nventional oscillations are not described by the standard Lifshitz-Kosevic
h theory valid for metals. Their temperature dependence is drastically dif
ferent from that in metals and shows rich phenomenology. Such new insight
s open the door to the possibility of using quantum oscillations to study
features in systems traditionally thought to be outside the scope of this
technique–I will point out some examples where such unconventional oscil
lations could show up.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=5973
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5973
END:VEVENT
BEGIN:VEVENT
SUMMARY:Universal Laws of Thermodynamics
DTSTART;VALUE=DATE-TIME:20171121T050000Z
DTEND;VALUE=DATE-TIME:20171121T060000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6019@cern.ch
DESCRIPTION:Thermodynamics is one of the most successful physical theories
ever formulated. Though it was initially developed to deal with steam eng
ines and\, in particular\, the problem of conversion of heat into mechanic
al work\, it has prevailed even after the scientific revolutions of relati
vity and quantum mechanics. Despite its wide range of applicability\, it i
s known that the laws of thermodynamics break down when systems are correl
ated with their environments. In the presence of correlations\, anomalous
heat flows from cold to hot baths become possible\, as well as memory eras
ure accompanied by work extraction instead of heat dissipation. Here\, we
generalize thermodynamics to physical scenarios which allow presence of co
rrelations\,\nincluding those where quantum entanglements are present. We
exploit the connection between information and physics\, and introduce a c
onsistent redefinition of heat dissipation by systematically accounting fo
r the information flow from system to bath in terms of the conditional ent
ropy. As a consequence\, the formula for the Helmholtz free energy is acco
rdingly modified. Such a remedy not only fixes the apparent violations of
Landauer’s erasure principle and the second law due to anomalous heat fl
ows\, but it also leads to a reformulation of the laws of thermodynamics t
hat are universally respected. In this information-theoretic approach\, co
rrelations between system and environment store work potential. Thus\, in
this view\, the apparent anomalous heat flows are the refrigeration proces
ses driven by such\npotentials.\n\nhttps://indico.tifr.res.in/indico/confe
renceDisplay.py?confId=6019
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6019
END:VEVENT
BEGIN:VEVENT
SUMMARY: Topological quantum paramagnet in quantum spin systems
DTSTART;VALUE=DATE-TIME:20171130T090000Z
DTEND;VALUE=DATE-TIME:20171130T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6056@cern.ch
DESCRIPTION:Topological quantum paramagnets are exotic states of matter wi
th trivial paramagnetic ground states hosting topological excitations. We
show that in the presence of spin-orbit coupling a quantum spin ladder hos
ts a topological quantum paramagnet (TQP). This phase has fractional excit
ations localized at the ends of the ladder. The excitation spectrum is top
ologically non-trivial and is characterized by a non-zero winding number.
We discuss possible experimental signatures to detect this exotic phase. A
s another example\, we show that a simple model of quantum spins on a hone
ycomb bilayer hosts a Z2 TQP in the presence of spin-orbit coupling. The Z
2 invariant is the same as that in the case of the fermionic quantum spin
Hall state. We further show that upon making one of the Heisenberg couplin
gs stronger the system undergoes a topological quantum phase transition\,
where the Z2 invariant vanishes\, to a different TQP. In this case the edg
e states are disconnected from the bulk excitations and the phase is chara
cterized by a different topological invariant. This physics is amenable to
experiments\, where an anisotropic coupling can be induced under pressure
.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6056
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6056
END:VEVENT
BEGIN:VEVENT
SUMMARY:Muon spin relaxation studies of Sr~~_{2}RuO_{4} unde
r uniaxial pressure
DTSTART;VALUE=DATE-TIME:20171213T060000Z
DTEND;VALUE=DATE-TIME:20171213T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6089@cern.ch
DESCRIPTION:For two decades\, Sr2RuO4 has been discussed as a spin triplet
p-wave superconductor\, with a chiral order parameter of the form px ± i
py . This order parameter has not been proved yet\, however\, one key piec
e of evidence is the observation of an enhanced zero-field muon spin relax
ation (μSR) rate in the superconducting state\, which implies that the or
der parameter breaks time-reversal symmetry (TRS). Nevertheless\, the abse
nce of any measureable spontaneous magnetization in scanning SQUID studies
raises questions about this interpretation. Superconducting critical temp
erature of Sr2RuO4 has been shown experimentally to be very sensitive to u
niaxial pressure\, so the changes in the muon spin relaxation rate with un
iaxial pressure could provide further information both on the origin of th
e enhanced muon relaxation rate\, and the superconductivity of Sr2RuO4. Th
erefore\, we have developed a uniaxial pressure cell dedicated for μSR. T
his cell is based on piezoelectric actuators\, allowing continuous in situ
tuning of the applied pressure. Results from first set of measurements wi
ll be presented\, anticipating many further applications for the newly dev
eloped apparatus.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.p
y?confId=6089
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6089
END:VEVENT
BEGIN:VEVENT
SUMMARY:Witnessing nonclassicality from statistical proofs of the Kochen-S
pecker theorem
DTSTART;VALUE=DATE-TIME:20180117T060000Z
DTEND;VALUE=DATE-TIME:20180117T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6167@cern.ch
DESCRIPTION:This talk will focus on the question of what precise signature
s one should look for in an experiment to rule out the possibility that it
admits a well- defined classical model. By a “classical” model\, I re
fer to a particular notion of classicality\, namely\, noncontextuality\, i
nspired by the Kochen Specker theorem. The Kochen-Specker theorem is a mat
hematical result that points out the inconsistency between quantum theory
and any putative underlying model of it where the outcomes of a measuremen
t are fixed prior to the act of measurement (that is\, deterministically)
by some (possibly hidden) physical states of the system in a manner that d
oes not depend on (operationally irrelevant) details of the measurement co
ntext\, i.e.\, the assignments are fixed noncontextually in the model. Thi
s theorem is not experimentally testable\, unlike Bell’s theorem\, becau
se of idealizations (such as noiseless measurements and outcome determinis
m) that are implicit in its statement. I will describe some recent work on
how to go from statistical proofs of the Kochen-Specker theorem to noise-
robust signatures of the failure of noncontextuality. Making minimal assum
ptions about the operational theory describing the experiment\, such signa
tures do not rely on the validity of the entire quantum formalism. In othe
r words\, they can be used to assess nonclassicality even if an experiment
admits deviations from quantum theory. Based on arXiv:1708.04793 and 1709
.01098 [quant-ph].\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=6167
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6167
END:VEVENT
BEGIN:VEVENT
SUMMARY:The spectral link in turbulent frictional drag
DTSTART;VALUE=DATE-TIME:20180129T090000Z
DTEND;VALUE=DATE-TIME:20180129T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6198@cern.ch
DESCRIPTION:I will review the spectral link in turbulent frictional drag\,
the missing link between two aspects of turbulent flows that have beenthe
subject of extensive\, but disjoint\, research effeorts: the frictional dr
ag experienced by a turbulent flow over a wall and the turbulent spectrum.
The standard theory of turbulent frictionaldrag\, which is based on the p
ioneering work of Prandtl and von Karman\, computes the frictional drag
using an indirect approach and makes no contact with the spectrum. By cont
rast\, the spectral link computes the frictional drag directly and express
es it as a functional of the turbulent spectrum. To illustrate the applica
tions of the spectral link\, I will obtain an analytical version of the ar
ch-famous Nikuradse's diagram that is in minute qualitative agreement wi
th the distinctive features in the diagram that have remained elusive to a
ny theoretical elucidation. Thereafter\, I will discuss unprecedented expe
rimental measurements of frictional drag in turbulent soap-film flows over
smooth walls and show how the results render the standard theory incomple
te. This research is pursued in close collaboration with Gustavo Gioia (O
IST)\; other collaborators include Nigel Goldenfeld (U. Illinois)\, Walter
Goldburg (U. Pittsburgh)\, and Hamid Kellay (U. Bordeaux).\n\nhttps://ind
ico.tifr.res.in/indico/conferenceDisplay.py?confId=6198
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6198
END:VEVENT
BEGIN:VEVENT
SUMMARY:Soft Disk Packings: Unjamming and Stress Localization
DTSTART;VALUE=DATE-TIME:20180328T060000Z
DTEND;VALUE=DATE-TIME:20180328T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6322@cern.ch
DESCRIPTION:We develop a scaling theory of the unjamming transition of sof
t frictionless disks in two dimensions. We show that distributions of a lo
cal order parameter\, defined as the area associated with the contacts bet
ween disks\, exhibits divergences as the transition is approached. Using a
mean-field analysis that includes three-body correlations we demonstrate
that these divergences predict several observed power-law behaviours of gl
obal quantities near the transition. The global elastic properties of such
jammed packings are governed by the constraints of vector force balance a
t the microscopic scale. We develop a framework for the stress response of
such disordered media that respects this constraint. We introduce local g
auge degrees of freedom which allow us to uniquely determine the contact f
orces that develop in response to externally imposed stresses. By mapping
this response to diffusion in the underlying contact network\, we show tha
t this naturally leads to spatial localization of forces as has been obser
ved in experiments using photoelastic soft disks.\n\nhttps://indico.tifr.r
es.in/indico/conferenceDisplay.py?confId=6322
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6322
END:VEVENT
BEGIN:VEVENT
SUMMARY:Coupling 1D Atom Arrays to an Optical Nanofiber: Platform for Wave
guide QED experiments
DTSTART;VALUE=DATE-TIME:20180412T090000Z
DTEND;VALUE=DATE-TIME:20180412T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6359@cern.ch
DESCRIPTION:The coupling of cold atoms to 1D nanoscale waveguides have ope
ned new avenues of research. The waveguide in our case is a nanofiber\, wh
ich confines light transversally to a subwavelength scale. The guided ligh
t exhibits a strong evanescent field allowing enhanced atom-photon interac
tion in the vicinity of nanofiber. In our experiment\, a cold atomic cloud
is first interfaced with an optical nanofiber. By using an optical lattic
e in the evanescent field\, the atoms are then trapped in 1D atomic arrays
close to the nanofiber. In this platform\, I will report on two experimen
ts. First\, the creation of heralded collective excitation in the atomic e
nsemble and its subsequent conversion into a single photon with high effic
iency. Second\, the observation of Bragg reflection\, as high as 75%\, fro
m 2000 trapped atoms when the period of the lattice is made close to comme
nsurate with the resonant wavelength. The reflection shows dependency on o
rientation of the probe polarization relative to the atomic arrays - a chi
ral signature in nanoscale waveguide-QED systems. The ability to control p
hoton transport in 1D waveguides coupled to spin systems would enable nove
l quantum networking capabilities and the study of many-body effects arisi
ng from long-range \ninteractions.\n\nhttps://indico.tifr.res.in/indico/co
nferenceDisplay.py?confId=6359
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6359
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Link Hamiltonians with exact gauge invariance on the latti
ce
DTSTART;VALUE=DATE-TIME:20180725T060000Z
DTEND;VALUE=DATE-TIME:20180725T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6529@cern.ch
DESCRIPTION:In this talk\, we introduce a lattice Hamiltonian which realiz
es a microscopic U(1) gauge invariance exactly with a discrete Hilbert spa
ce via quantum links as gauge degrees of freedom residing on the links joi
ning lattice sites. These so-called "Quantum Link models" are an extension
of Wilson construction of lattice gauge theories\, and show many novel pr
operties. Using a combination of analytic and newly developed numerical me
thods\, we study the phase transition of the model on a square lattice\, a
nd establish crystalline confined phases\, where confinement is realized t
hrough fractional fluxes joining static charges. A connection with the ext
ensively studied quantum dimer model (on a square lattice) is also establi
shed\, and results on the phase diagram using a novel Monte Carlo method i
s also described. Non-Abelian extensions of quantum link models are alread
y available\, and are very crucial in realizing quantum simulators for gau
ge theories on cold atoms in optical lattices.\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=6529
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6529
END:VEVENT
BEGIN:VEVENT
SUMMARY:SYK models of extremal black holes and strange metals
DTSTART;VALUE=DATE-TIME:20180730T053000Z
DTEND;VALUE=DATE-TIME:20180730T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6525@cern.ch
DESCRIPTION:The Sachdev-Ye-Kitaev (SYK) model describes fermions on a `qua
ntum dot’ with all-to-all interactions. It realizes a many-body quantum
state without quasiparticle excitations\, and is nevertheless exactly solv
able in the low temperature limit. The absence of quasiparticles leads to
fastest possible thermalization in the `Planckian time’ of order $\\hbar
/T$. Black holes also share the property of thermalization in such a Planc
kian time\, with $T$ the Hawking temperature. Moreover\, it turns out that
the theory of low energy quantum fluctuations of near-extremal black hole
s is identical to a Schwarzian theory of low energy fluctuations of the SY
K model.\n\nOn the condensed matter side\, the SYK model has been used to
build finite-dimensional strange metal states by assembling a lattice of S
YK quantum islands. Such metals exhibit a linear-in-temperature resistivit
y\, and the linearity is linked to quantum-critical exponents of the SYK m
odel. Inhomogeneity can also lead to linear-in-field magnetoresistance\, a
s observed recently in the pnictide superconductors.\n\nhttps://indico.tif
r.res.in/indico/conferenceDisplay.py?confId=6525
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6525
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Information\, Entanglement and Classification of Gapped Qu
antum Phases of Matter (Condensed Matter Lecture Series)
DTSTART;VALUE=DATE-TIME:20180731T053000Z
DTEND;VALUE=DATE-TIME:20180731T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6537@cern.ch
DESCRIPTION:The simplest many body quantum states have an energy gap to ex
citations. Ideas from quantum information have been useful in classifying
these phases\, leading to the prediction of entirely new phases of matter
with topological properties.\n\nhttps://indico.tifr.res.in/indico/conferen
ceDisplay.py?confId=6537
LOCATION: AG66
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6537
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gauge theories in Condensed Matter Physics (Condensed Matter Lectu
re Series)
DTSTART;VALUE=DATE-TIME:20180801T053000Z
DTEND;VALUE=DATE-TIME:20180801T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6538@cern.ch
DESCRIPTION:I will outline a few examples where gauge theories must be inv
oked to understand strongly interacting quantum many body systems despite
there being no gage structure in their microscopic Hamiltonians. Examples
include phase transitions between quantum hall states\, competing orders
in magnetic materials built from quantum spins and mass generation in Dir
ac fermion systems in the absence of symmetry breaking.\n\nhttps://indico.
tifr.res.in/indico/conferenceDisplay.py?confId=6538
LOCATION: AG66
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6538
END:VEVENT
BEGIN:VEVENT
SUMMARY:Imbalanced Fermi gas and exotic superfluid phases
DTSTART;VALUE=DATE-TIME:20180808T060000Z
DTEND;VALUE=DATE-TIME:20180808T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6550@cern.ch
DESCRIPTION:In this talk I would discuss about the behavior of Fermi super
fluids involving imbalance in the population of the fermionic species. The
consequence of such an imbalance is the realization of exotic superfluid
state viz. the Fulde-Ferrell- Larkin-Ovchinnikov (FFLO) state. Unlike the
conventional BCS superconductors the imbalance in population gives rise t
o finite momentum pairing between the fermions\, thereby leading to superf
luid state with spatial modulations. An other possible route to engineer i
mbalanced Fermi superfluid is as Fermi-Fermi mixture. A situation where fe
rmion species with unequal mass pair up to give rise to superfluidity. Non
trivial quasiparticle features along with multiple pseudogap regimes are
expected to serve as experimental signatures of Fermi- Fermi mixtures. I w
ould discuss the finite temperature behavior of such systems and about th
eir possible experimental realizations\n\nhttps://indico.tifr.res.in/indic
o/conferenceDisplay.py?confId=6550
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6550
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emergent SU(4) symmetry and quantum spin-orbital liquid in α-ZrCl
3
DTSTART;VALUE=DATE-TIME:20180926T090000Z
DTEND;VALUE=DATE-TIME:20180926T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6640@cern.ch
DESCRIPTION:While the enhancement of spin-space symmetry from the usual SU
(2) to SU(N) is promising for finding nontrivial quantum spin liquids\, it
s realization in magnetic materials remains challenging. Here\, we propose
a new mechanism by which SU(4) symmetry emerges in the strong spin-orbit
coupling limit. In d1 transition metal compounds with edge-sharing anion o
ctahedra\, the spin-orbit coupling gives rise to strongly bond-dependent a
nd apparently SU(4)-breaking hopping between the j=3/2 quartets. However\,
in the honeycomb structure\, a gauge transformation maps the system to an
SU(4)-symmetric Hubbard model. In the strong repulsion limit at quarter f
illing\, as realized in α-ZrCl3\, the low-energy effective model is the S
U(4) Heisenberg model on the honeycomb lattice\, which cannot have a trivi
al gapped ground state and is expected to host a quantum spin-orbital liqu
id.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6640
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6640
END:VEVENT
BEGIN:VEVENT
SUMMARY:Connections between Classical Integrable Models\, Log Gas and Rand
om Matrix Theory
DTSTART;VALUE=DATE-TIME:20190205T060000Z
DTEND;VALUE=DATE-TIME:20190205T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6896@cern.ch
DESCRIPTION:We present a deep connection between the classical Calogero-Mo
ser (CM) model\, Log-gas (LG) model and Random Matrix Theory (RMT). We sho
w that CM model has some remarkable connections with the 1D LG model. Both
models have the same minimum energy configuration with the particle posit
ions given by the zeros of the Hermite potential. Moreover the Hessian des
cribing small oscillations around equilibrium are also related for the two
models. We explore this connection further by studying finite temperature
equilibrium properties of the CM model through Monte-Carlo simulations an
d comparing them with known LG results. In particular\, our findings indic
ate that the single particle distribution and the marginal distribution of
the boundary particle of CM model are also given by Wigner semi-circle an
d the Tracy- Widom distribution respectively (similar to LG model). Compar
isons are made with analytical predictions from the small oscillation theo
ry and we find very good agreement. Parallels are also drawn with rigorous
mathematical results from RMT and implications of finite-size as well as
finite- temperature effects are observed. We also present some preliminary
results on large deviations in CM model by using field theory.\n\nhttps:/
/indico.tifr.res.in/indico/conferenceDisplay.py?confId=6896
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6896
END:VEVENT
BEGIN:VEVENT
SUMMARY:Altering the dimensionality of exciton-exciton annihilation from 1
D to 2D in atomically thin black phosphorus
DTSTART;VALUE=DATE-TIME:20190206T060000Z
DTEND;VALUE=DATE-TIME:20190206T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6899@cern.ch
DESCRIPTION:Dimensionality plays an important role in determining the fund
amental nature of excitons as well as their interactions. For example\, th
e binding energy of excitons is orders of magnitude higher in 1D (e.g.\, c
arbon nanotubes-CNT) or 2D (e.g.\, transition metal dichalcogenides-TMDC)
semiconductors as compared to conventional 3D semiconductors (e.g.\, Galli
um Arsenide-GaAs). Additionally\, the signature of excitonic interactions
is strikingly different for 1D systems as compared to 2D/3D systems. In 1D
systems (CNTs) the rate of exciton-exciton annihilation deviates from the
mean field approximation as the excitons are constrained by the physical
dimensions to interact only with their nearest neighbors\, resulting in a
time-dependent rate. However\, in 2D and 3D systems\, the excitons are les
s constrained in space compared to 1D resulting in a time- independent con
stant annihilation rate\, consistent with the mean field approximation. A
particularly interesting case is presented by excitons in black phosphorus
(BP)\, where quasi-1D excitons have been observed in atomically thin shee
ts of BP\, resulting in a unique system of 1D excitons in a 2D plane. Here
we show that the interaction between excitons in atomically thin BP shows
both 1D as well as 2D characteristics depending on exciton density and te
mperature. We use micro-transient absorption spectroscopy (μ-TAS) to stud
y the exciton-exciton annihilation process in bilayer (2L) BP. We observe
the classic 1D time-dependent exciton annihilation dynamics at low exciton
density. Interestingly\, upon increasing the exciton density the data sta
rts to show time independent rate which is characteristic of a 2D exciton-
exciton annihilation process. We also observe more 1D characteristics at l
ow temperature for all exciton densities. We attribute this effect to the
anisotropic diffusion of excitons in atomically thin BP. Our data matches
well with the phenomenological model of anisotropic diffusion-limited exci
ton-exciton annihilation. Our work highlights the importance of atomically
thin black phosphorus as a unique platform to study novel many-body excit
onic interactions.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=6899
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6899
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constrained Fluctuations in Jammed Soft Disk Packings
DTSTART;VALUE=DATE-TIME:20190227T060000Z
DTEND;VALUE=DATE-TIME:20190227T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6957@cern.ch
DESCRIPTION:Jamming\, the point at which a collection of particles begins
to exhibit global rigidity with increasing density has been the focus of i
ntense research over the last decade. Jamming is ubiquitous in nature and
occurs in systems ranging from mesoscopic lengthscales to macroscopic part
iculate matter. Although jamming transitions seem to be accompanied by 'di
vergences' in time-scales and length-scales\, they cannot be explained usi
ng existing frameworks for phase transitions. Fluctuations in such systems
are governed by microscopic constraints of force and torque balance on ev
ery particle\, and are thus greatly restricted. Developing a predictive st
atistical mechanics framework to describe jammed systems therefore represe
nts a new theoretical challenge. In this talk I will describe some of my r
esearch on an idealized model of soft disks in two dimensions where theore
tical progress can be made.\n\nhttps://indico.tifr.res.in/indico/conferenc
eDisplay.py?confId=6957
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6957
END:VEVENT
BEGIN:VEVENT
SUMMARY:Butterfly effect in frustrated magnets
DTSTART;VALUE=DATE-TIME:20190313T060000Z
DTEND;VALUE=DATE-TIME:20190313T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-6980@cern.ch
DESCRIPTION:Connections between many-body chaos and ergodicity form the ba
sis of statistical mechanics. Starting with an overview of recent interest
s in this area\, I shall discuss our numerical results characterising spat
io-temporal signatures of chaos in spin systems and point out their possib
le quantitative connection to measures of transport such as diffusion coef
ficients. I shall discuss how the physics of frustration in classical spin
systems help retain the signatures of chaos even at low temperatures.\n\n
https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6980
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6980
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aperiodically driven Integrable Systems and their emergent steady
states
DTSTART;VALUE=DATE-TIME:20190320T060000Z
DTEND;VALUE=DATE-TIME:20190320T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7002@cern.ch
DESCRIPTION:Does a closed quantum many-body system that is continually dri
ven with a time-dependent Hamiltonian finally reach a steady state? This q
uestion has only recently been answered for driving protocols that are per
iodic in time\, where the long-time behavior of the local properties synch
ronizes with the drive and can be described by an appropriate periodic ens
emble. Here\, we explore the consequences of breaking the time-periodic st
ructure of the drive with additional aperiodic noise in a class of integra
ble systems. We show that the resulting unitary dynamics leads to new emer
gent steady states in at least two cases. While any typical realization of
random noise causes eventual heating to an infinite-temperature ensemble
for all local properties in spite of the system being integrable\, noise t
hat is self-similar in time leads to an entirely different steady state (w
hich we dub the “geometric generalized Gibbs ensemble”) that emerges o
nly after an astronomically large time scale. To understand the approach t
o the steady state\, we study the temporal behavior of certain coarse-grai
ned quantities in momentum space that fully determine the reduced density
matrix for a subsystem with size much smaller than the total system. Such
quantities provide a concise description for any drive protocol in integra
ble systems that are reducible to a free-fermion representation.\n\nRefere
nces: Nandy\, Sen\, Sen\, Phys. Rev. X 7\, 031034 (2017) and Phys. Rev. B
98\, 245144 (2018)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=7002
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7002
END:VEVENT
BEGIN:VEVENT
SUMMARY:Many-body localized phase of bosonic dipoles in a tilted optical l
attice
DTSTART;VALUE=DATE-TIME:20190520T053000Z
DTEND;VALUE=DATE-TIME:20190520T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7125@cern.ch
DESCRIPTION:In this talk\, I shall discuss the ground state phase diagram
of an experimentally realizable one-dimensional constrained dipole boson m
odel. I shall demonstrate the presence of a many-body localized phase in t
he presence of an Aubry-Andre (AA) potential whose strength λ0 can be cha
nged to tune an ergodic-MBL transition. I shall discuss the significance o
f such a transition in the quantum dynamics of the model by computing its
response subsequent to a sudden quench of λ0. I shall also show that the
MBL and the ergodic phases can be clearly distinguished by the study of po
st-quench dynamics and provide an estimate for minimal time up to which ex
periments need to track the response of the system to confirm the onset of
the MBL phase. Shall suggest experiments which can test our theory.\n\nht
tps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7125
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7125
END:VEVENT
BEGIN:VEVENT
SUMMARY:Beyond semiclassical approach in the study of light-matter interac
tions
DTSTART;VALUE=DATE-TIME:20191017T093000Z
DTEND;VALUE=DATE-TIME:20191017T103000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7400@cern.ch
DESCRIPTION:The technological advances in the research of light-matter int
eraction over the last few years has led to considerable interest in the s
tudy of newer quantum protocols. The majority of theoretical and experimen
tal studies on these systems have focused on two very distinct regimes: On
the one hand\, macroscopic ensemble of emitters and their collective prop
erties have been investigated in the context of superradiance\, protection
against decoherence\, and quantum memories. In this macroscopic limit\, h
owever\, the light-matter interaction can be treated already on a semiclas
sical level. On the other hand\, in the microscopic limit\, where a single
emitter couples to a cavity\, the interaction demands full quantum soluti
ons\, resulting in exotic nonclassical phenomena such as entanglement\, ph
oton-blockade\, and single-photon emission. There also lies a largely unch
arted mesoscopic regime that offers the unique possibility to synergistica
lly combine collective with non-classical features that are otherwise rest
ricted to the two separate regimes mentioned above. In this talk\, we will
discuss theoretical approaches that take us beyond the semi-classical app
roach but are also not limited to very small systems. Using tools from man
y-body physics such as tensor-network algorithms\, along with quantum traj
ectories and quantum regression theorem\, we show how a large swathe of in
teresting physics remains to be explored ranging from non-equilibrium phas
e transitions in photon condensates to generation of nonclassical light an
d trapped entangled states in hybrid quantum systems.\n\nhttps://indico.ti
fr.res.in/indico/conferenceDisplay.py?confId=7400
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7400
END:VEVENT
BEGIN:VEVENT
SUMMARY:Many-Body Localization in the Quantum Hall Regime
DTSTART;VALUE=DATE-TIME:20191119T090000Z
DTEND;VALUE=DATE-TIME:20191119T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7470@cern.ch
DESCRIPTION:The discovery of many-body localization (MBL) in interacting q
uantum systems\, because of its wide implication for fundamental concepts
such as thermalization in isolated quantum systems\, has given rise to ext
ensive research in the intervening decade and a half. However\, its study
is complicated both on the analytical front as well as numerical\, though
definite progress is being made. It seems to be clear that MBL exists in o
ne-dimensional spin models\, as first suggested by numerical simulations.
Obtaining results in higher dimensions with the same amount of rigor appea
rs distant at present\, though studies have shown that a proper treatment
of rare fluctuations is crucial for answering this issue.\n\nOn the numeri
cal front\, models in higher dimensions as well as fully interacting fermi
onic models suffer the problem of the explosion of the Hilbert space with
size. Consequently\, we recently explored the possibility of MBL in a syst
em of two-dimensional electrons (interacting via a Coulomb interaction) in
the presence of disorder\, when placed in a large perpendicular magnetic
field in the extreme quantum (lowest Landau level) limit. While this situa
tion is significantly more challenging than one-dimensional spin models\,
we are able to consider both lattice and continuum models\; the latter byp
ass commensurability requirements imposed by lattices in higher dimensions
. Using eigenvalue statistics as well as time evolution methods to study s
everal different cases\, we find that MBL is very strongly affected by top
ology\, even more so than earlier analytic arguments suggest.\n\nhttps://i
ndico.tifr.res.in/indico/conferenceDisplay.py?confId=7470
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7470
END:VEVENT
BEGIN:VEVENT
SUMMARY:Superconductivity and topology in strongly correlated systems
DTSTART;VALUE=DATE-TIME:20191205T090000Z
DTEND;VALUE=DATE-TIME:20191205T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7503@cern.ch
DESCRIPTION:We describe exact results and broad intuition at the interface
of topology and superconductivity. We discuss briefly a rigorous upper bo
und on the superconducting transition temperature Tc in two dimensions tha
t holds for arbitrary interaction strength\, order parameter symmetry or p
airing mechanism. This follows from an exact upper bound on superfluid sti
ffness largely controlled by the non-interacting physics\, yet valid in an
y dimension and with arbitrary interactions. We demonstrate that this plac
es stringent bounds on Tc in several strongly correlated systems of intere
st\, in which estimating Tc is a notoriously hard problem. Another aspect
of physics that is well understood in non-interacting and weak coupling sy
stems is band topology. In an unrelated work\, we show how ARPES matrix el
ements provide sharp signatures of topological band inversion in the norma
l state of an iron-based superconductor. In this material\, an unusual int
erplay of spin-orbit coupling and strong correlations results in topologic
al inversion in a band with no observable dispersion. In another unrelated
work\, we show how understanding pairing within valleys in a simple latti
ce model leads to new intuition for intrinsic topological superconductivit
y in materials with valley degrees of freedom. We discuss its relevance fo
r a wide variety of materials from transition metal dichalcogenides and an
tiperovskite oxides on the brink of a topological transition\, to magic an
gle twisted bilayer graphene.\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=7503
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7503
END:VEVENT
BEGIN:VEVENT
SUMMARY:Learning to navigate in dynamic environments
DTSTART;VALUE=DATE-TIME:20191212T090000Z
DTEND;VALUE=DATE-TIME:20191212T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7516@cern.ch
DESCRIPTION:Some animals can complete very difficult navigation tasks in a
seemingly effortless way: homing pigeons can fly back home from unfamilia
r places that are hundreds of kilometres away from their loft\; male moths
can reach females from distances of several hundreds of meters\; migrator
y birds can cross the oceans with minimal energy expenditure by relying on
ascending air currents. The fundamental aspect that is common to all thes
e behaviors is the highly dynamic and unpredictable nature of the environm
ent given by the turbulent atmospheric conditions. In this talk\, I will f
ocus on the example of soaring birds that exploit thermal convection to re
ach great heights without flapping their wings. How soaring birds find and
navigate thermals within the complex landscape of a turbulent convective
atmosphere is unknown. Reinforcement learning\, a branch of machine intell
igence\, provides an appropriate framework to identify an effective naviga
tional strategy as a sequence of decisions taken in response to environmen
tal cues. I will discuss how to use it to suggest possible strategies used
by birds and also to train autonomous gliders to navigate atmospheric the
rmals.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=75
16
LOCATION: A 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7516
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thermodynamics and order beyond equilibrium -- from eigentstate th
ermalisation to time crystals
DTSTART;VALUE=DATE-TIME:20191213T090000Z
DTEND;VALUE=DATE-TIME:20191213T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7526@cern.ch
DESCRIPTION:The field of thermodynamics is one of the crown jewels of clas
sical physics. Thanks to the advent of experiments in cold atomic systems
with long coherence times\, our understanding of the connection of thermod
ynamics to quantum statistical mechanics has seen remarkable progress.\n\n
Extending these ideas and concepts to the non-equilibrium setting is a cha
llenging topic\, in itself of perennial interest. Here\, we present perhap
s the simplest non-equilibrium class of quantum problems\, namely Floquet
systems\, i.e. systems whose Hamiltonians depend on time periodically\, H(
t + T) = H(t). For these\, there is no energy conservation\, and hence not
even a natural concept of temperature.\n\nWe find that certain structures
from equilibrium thermodynamics are lost\,while entirely new non-equilibr
ium phenomena can arise\, including a spectacular spatiotemporal `time-cry
stalline' form of order.\n\nReference: for an introductory overview\, see
Nature Physics 13\, 424-428 (2017)\; for a brief history of time crystals\
, see arXiv:1910.10745\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=7526
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7526
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-abelian dualities and square lattice antiferromagnets
DTSTART;VALUE=DATE-TIME:20200108T060000Z
DTEND;VALUE=DATE-TIME:20200108T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7547@cern.ch
DESCRIPTION:Recent experiments on several cuprate compounds have identifie
d an enhanced thermal Hall response in the pseudogap phase. Most strikingl
y\, this enhancement persists even in the undoped system\, which challenge
s our understanding of the insulating parent compounds. To explain these s
urprising observations\, we study the quantum phase transition of a square
-lattice antiferromagnet from a confining Neel state to a state with coexi
sting Neel and semion topological order. The transition is driven by an ap
plied magnetic field and involves no change in the symmetry of the state.
The critical point is described by a strongly-coupled conformal field theo
ry with an emergent global SO(3) symmetry. The field theory has four diffe
rent formulations in terms of SU(2) or U(1) gauge theories\, which are all
related by dualities\; we relate all four theories to the lattice degrees
of freedom. We show how proximity of the confining Néel state to the cri
tical point can explain the enhanced thermal Hall effect seen in experimen
t.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7547
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7547
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fermionic quantum criticality in fermion-bag inspired Hamiltonian
lattice field theories [Joint Lattice Gauge Theory - Condensed Matter Sem
inar]
DTSTART;VALUE=DATE-TIME:20200203T090000Z
DTEND;VALUE=DATE-TIME:20200203T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7622@cern.ch
DESCRIPTION:Motivated by the fermion bag approach -- a quantum Monte Carlo
approach that takes advantage of grouped local degrees of freedom--we con
struct a new class of Hamiltonian lattice field theories that can help us
study fermionic quantum critical points. We construct the partition functi
on of a lattice Hamiltonian in 2+1 dimensions in discrete time\, with a te
mporal lattice spacing ϵ. When ϵ → 0\, we obtain the partition functio
n of the original lattice Hamiltonian. But when ϵ = 1\, we obtain a new t
ype of space-time lattice field theory which treats space and time differe
ntly\, but still lacks fermion doubling in the time dimension\, in contras
t to Lagrangian lattice field theories. Here we show that both continuous-
time and discrete-time lattice field theories derived from the t-V model h
ave a fermionic quantum critical point with critical exponents that match
within errors. The fermion bag algorithms run relatively faster on the dis
crete-time model and allow us to compute quantities even on 1003 lattices
near the quantum critical point. We then discuss how this class of fermion
-bag amenable Hamiltonian lattice field theories also include simple Z2 ga
uge theories coupled to fermions\, and explore one such theory in 1+1 dime
nsions with a coupling h. We demonstrate how even in such a simple theory
nontrivial behavior arises\, from the emergence of the Gauss law at low te
mperature to a nontrivial mass scaling.\n\nhttps://indico.tifr.res.in/indi
co/conferenceDisplay.py?confId=7622
LOCATION: AG80
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7622
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-equilibrium properties of resetting phenomena
DTSTART;VALUE=DATE-TIME:20200729T090000Z
DTEND;VALUE=DATE-TIME:20200729T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7735@cern.ch
DESCRIPTION:Resetting or restart is prevalent in natural and engineered sy
stems giving rise to a long series of non-equilibrium phenomena. In this t
alk\, I will discuss two complementary frameworks namely the master equati
on approach and the renewal approach to treat resetting in a wide array of
stochastic systems. Taking advantage of the latter approach\, we will sho
w how the solution to the resetting problem can be given in terms of the s
olution to the original dynamics – which reduces the overall complexity
in many folds. In the second part of the talk\, I will argue why the theor
y of instantaneous resetting is a major impediment to practical realizatio
n or experimental verification in Brownian systems\, and thus a generaliza
tion of the existing theory to incorporate non-instantaneous resetting is
very much in need. The talk will end with a general overview of treating p
ath-functionals in resetting systems.\n\nhttps://indico.tifr.res.in/indico
/conferenceDisplay.py?confId=7735
LOCATION:Zoom Webinar
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7735
END:VEVENT
BEGIN:VEVENT
SUMMARY:Superconductivity from skyrmion condensation in magic angle graphe
ne
DTSTART;VALUE=DATE-TIME:20201116T043000Z
DTEND;VALUE=DATE-TIME:20201116T053000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7858@cern.ch
DESCRIPTION:We propose and analyze a strong-coupling route to superconduct
ivity in twisted bilayer graphene near the magic angle (MATBG). Starting f
rom a promising ordered insulating state featuring Chern bands\, we argue
that topological textures/skyrmions of the order parameter carry electric
charge due to band topology. Subsequently\, we find a natural all-electron
ic mechanism of attraction between two such charge e textures. This leads
to pairing into charge 2e bosons\, whose condensation can trigger supercon
ductivity on doping away from the insulating state. We discuss microscopic
aspects of this scenario\, including energetics and an estimate of the ef
fective mass which yields Tc for the superconductor\, within the framework
of an effective field theory. We back up our analytical calculations by l
arge-scale DMRG numerics on a related model that captures the relevant sym
metry and topology of the flat bands in MATBG. In DMRG\, we find clear evi
dence for superconductivity driven by the binding of electrons into charge
-2e skyrmions\, even when Coulomb repulsion is by far the largest energy s
cale.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=785
8
LOCATION:Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7858
END:VEVENT
BEGIN:VEVENT
SUMMARY:Long-range entanglement and multiple steady states in a lossy qubi
t array
DTSTART;VALUE=DATE-TIME:20201126T103000Z
DTEND;VALUE=DATE-TIME:20201126T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7866@cern.ch
DESCRIPTION:Environmental coupling typically drives a quantum system to a
unique steady state with very little coherence\, which is a major obstacle
for quantum information processing. I will talk about a simple experiment
al setting of an array of two-level systems with localised pump and loss t
hat has multiple highly coherent steady states\, including maximally entan
gled states of nonlocal Bell pairs. Such states originate from a hidden sy
mmetry that conserves Bell pairs over long distances\, leading to controll
able long-range entanglement. I will discuss how to selectively prepare an
d observe these states in existing setups.\n\nRef: https://arxiv.org/abs/
2004.07981 (to appear in PRL).\n\nhttps://indico.tifr.res.in/indico/confer
enceDisplay.py?confId=7866
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7866
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Phases and Phase Transitions in Designer Spin Models
DTSTART;VALUE=DATE-TIME:20201126T060000Z
DTEND;VALUE=DATE-TIME:20201126T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7867@cern.ch
DESCRIPTION:We introduce a procedure to write down lattice models with spi
n-rotation invariant Hamiltonians for arbitrary spin-S\, which can be simu
lated efficiently without a sign problem in Quantum Monte Carlo studies. A
s the first application of our approach\, we design a square lattice S = 1
model that realizes a novel “Haldane nematic” phase. This phase break
s lattice rotational symmetry by the spontaneous formation of Haldane chai
ns\, while preserving spin rotations\, time reversal and lattice translati
ons. By supplementing our model with a two-spin Heisenberg interaction\, w
e present a study of the transition between N\\'eel and Haldane nematic ph
ases\, which we find to be of first order. As another application of our p
rocedure\, we study the N\\'eel to four-fold columnar valence bond solid (
cVBS) quantum phase transition in a sign free S=1 square lattice model. Ex
tensive numerical simulations of the square lattice S=1/2 N\\'eel-VBS tran
sition have found consistency with the DCP scenario with no direct evidenc
e for first order behavior. In contrast to the S=1/2 case\, in our quantum
Monte Carlo simulations for the S=1 model\, we present unambiguous eviden
ce for a direct conventional first-order quantum phase transition.\n\nhttp
s://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7867
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7867
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multipolar orders in quantum magnets
DTSTART;VALUE=DATE-TIME:20201203T130000Z
DTEND;VALUE=DATE-TIME:20201203T140000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7872@cern.ch
DESCRIPTION:Traditionally\, magnetism in solids deals with ordering patter
ns of the electron magnetic dipole moment\, as probed\, for instance\, via
neutron diffraction. However\, materials such as f-electron heavy fermion
systems are well-known candidates for more complex forms of symmetry brea
king\, involving higher-order magnetic or electric multipoles\, often term
ed as "hidden orders". In this talk\, I will discuss our recent theoretica
l proposal for Ising octupolar order in d-orbital systems\, which appears
to explain a wide range of experiments in certain 5d transition metal oxid
es with spin-orbit coupling. The proposed Ising ferro-octupolar order is s
hown to be linked to a type of orbital loop-current order. We propose NMR
experiments under strain as a further test of our proposal. This appears t
o be the first candidate for d-orbital octupolar order.\n\nhttps://indico.
tifr.res.in/indico/conferenceDisplay.py?confId=7872
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7872
END:VEVENT
BEGIN:VEVENT
SUMMARY:Resonant photovoltaic effect of doped semiconductors
DTSTART;VALUE=DATE-TIME:20201210T050000Z
DTEND;VALUE=DATE-TIME:20201210T060000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7889@cern.ch
DESCRIPTION:The rectified non-linear response of a clean\, time-reversal s
ymmetric\, undoped semiconductor to an ac electric field includes a wellkn
own intrinsic shift current. We show that when Kramers degeneracy is broke
n\, a distinct second-order rectified response appears due to Bloch state
anomalous velocities in a system with an oscillating Fermi surface. This e
ffect\, which we refer to as the resonant photovoltaic effect (RPE)\, prod
uces a resonant galvanic current peak at the interband absorption threshol
d in doped semiconductors or semimetals with approximate particle-hole sym
metry. In this talk\, I will present this new non-linear RPE effect and wi
ll discuss it for a model of the surface states of a magnetized topologica
l insulator.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?con
fId=7889
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7889
END:VEVENT
BEGIN:VEVENT
SUMMARY:Study of Dirac Electrons in BiPd and Graphene using Angle-Resolved
Photoemission Spectroscopy.
DTSTART;VALUE=DATE-TIME:20201215T113000Z
DTEND;VALUE=DATE-TIME:20201215T123000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7897@cern.ch
DESCRIPTION:In this talk\, I will describe our recent efforts to understan
d the properties of Dirac electrons in BiPd and Graphene using angle-resol
ved photoelectron spectroscopy (ARPES). Previous ARPES studies have alread
y provided a lot of insight into these material systems. But at times conf
licting results have been reported. In particular\, the dimensional nature
of Dirac state in BiPd has not unambiguously established. In the case of
graphene\, ARPES spectra of epitaxially grown samples deviate from the the
oretically predicted conical structure. To explain this observation variou
s ideas have been proposed (formation of plasmaron quasiparticles\, substr
ate-induced bandgap opening\, etc.). In this presentation\, I will show th
at our recent studies can partly answer some of these questions.\n\nhttps:
//indico.tifr.res.in/indico/conferenceDisplay.py?confId=7897
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7897
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bifurcations in coupled oscillator systems: Exact results
DTSTART;VALUE=DATE-TIME:20210120T090000Z
DTEND;VALUE=DATE-TIME:20210120T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7917@cern.ch
DESCRIPTION:In the context of a paradigmatic nonlinear dynamical system of
coupled oscillators with distributed natural frequencies and interacting
through a time-delayed mean-field\, we derive as a function of the delay e
xact results for the stability boundary between the incoherent and the syn
chronized state and the nature in which the latter bifurcates from the for
mer at the critical point. Our results are based on an unstable manifold e
xpansion in the vicinity of the bifurcation\, which we apply to both the k
inetic equation for the single-oscillator distribution function in the cas
e of a generic frequency distribution and\, in the special case of a Loren
tzian distribution\, to the corresponding reduced dynamics on a special ma
nifold in the space of all possible distribution functions. Besides elucid
ating the effects of delay on the nature of bifurcation\, we show that the
reduced dynamics gives an amplitude evolution of unstable modes close to
the bifurcation that remarkably coincides with the one derived from the ki
netic equation. The manifold thus acts as an attractor in the space of dis
tribution functions. Such an attracting property has parallel in integrabl
e systems as well in certain nonlinear dynamical systems\, albeit with a d
ifference: in these cases\, the attracting manifold exists in the phase sp
ace of the system\, while we go beyond this picture in showing the existen
ce of such an attracting manifold in the space of distribution functions.
We have demonstrated the validity of such a dynamical scenario in other sy
stems\, e.g.\, in a network of phase-locked loops widely used in electroni
c circuits\, as well as in a system of coupled nonlinear oscillators with
both a mean-field and a non-local interaction on a one-dimensional periodi
c lattice.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confI
d=7917
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7917
END:VEVENT
BEGIN:VEVENT
SUMMARY:Many-body localisation: a tale of correlations and classical perco
lation on Fock space
DTSTART;VALUE=DATE-TIME:20210311T103000Z
DTEND;VALUE=DATE-TIME:20210311T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7963@cern.ch
DESCRIPTION:Many-body localised (MBL) phases of matter fall outside the co
nventional paradigm of equilibrium statistical mechanics and thermodynamic
s. A natural question thus is\, what minimal and generic properties must r
andom many-body Hamiltonians possess for a localised phase to be stable? I
n this talk\, I will address the question by exploiting the exact mapping
between a many body Hamiltonian and a tight-binding problem on the Fock-sp
ace graph. In particular\, I will present a theory for how the strong corr
elations in the effective Fock-space disorder play a central role in stabi
lising an MBL phase. The theory is rooted in analytic but approximate cal
culations of the propagators on the Fock space. To shed further light on t
he underlying physics\, I will also introduce and discuss a classical prox
y for the MBL transition in the form of a percolation transition on the Fo
ck space. Finally\, I will discuss a novel class of Anderson localisation
problems on correlated trees\, to understand the effect of such disorder c
orrelations in a more controlled setting.\n\nReferences: Phys. Rev. B 101
\, 134202 (2020)\; Phys. Rev. Lett. 125\, 250402 (2020)\; Phys. Rev. B 99\
, 220201 (2019)\; Phys. Rev. B 99\, 104206 (2019).\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=7963
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7963
END:VEVENT
BEGIN:VEVENT
SUMMARY:Active phase separation and stochastic processes
DTSTART;VALUE=DATE-TIME:20210325T103000Z
DTEND;VALUE=DATE-TIME:20210325T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-7984@cern.ch
DESCRIPTION:Active matter systems are composed of individual units driven
away from equilibrium. Their examples include suspensions of microorganism
s and autophoretic particles. I will present a continuum theory of phase s
eparation in suspensions of active particles. I will show that the steady-
states in this theory are governed by the effective mechanical (causing fl
ow) and diffusive (causing Ostwald ripening) tensions. In the second part
of the talk\, I would present a microscopic theory to study the collective
dynamics of active particles with phoretic and hydrodynamic interactions.
Finally\, I would describe my work on the Bayesian inference of the Ornst
ein Uhlenbeck process.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=7984
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=7984
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Fock-space landscape across the many-body localisation transit
ion
DTSTART;VALUE=DATE-TIME:20210527T103000Z
DTEND;VALUE=DATE-TIME:20210527T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8052@cern.ch
DESCRIPTION:Many-body localised (MBL) phases of matter fall outside the co
nventional paradigm of equilibrium statistical mechanics and thermodynamic
s. Remarkably\, they also exhibit a novel phase transition between an ergo
dic and an MBL phase\, the nature of which is currently an active area of
research. In this talk\, I will discuss some theoretical approaches toward
s this problem by exploiting the exact mapping between a many-body Hamilto
nian and a tight-binding problem on the Fock-space graph. I will discuss h
ow strong correlations emerge in the effective Fock-space disorder and how
they play a central role in stabilising an MBL phase. I will then discuss
how the correlations in the eigenstates on the Fock space reveal the crit
ical properties of the MBL transition. I will show the existence of a corr
elation length that varies discontinuously across the transition\, and how
its critical scaling is consistent with a Kosterlitz-Thouless like scenar
io.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8052
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8052
END:VEVENT
BEGIN:VEVENT
SUMMARY: Interplay of strong correlations\, topology\, and disorder in hig
h temperature superconductors
DTSTART;VALUE=DATE-TIME:20210902T103000Z
DTEND;VALUE=DATE-TIME:20210902T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8130@cern.ch
DESCRIPTION:Topology has come to reshape modern condensed matter physics.
Still\, most attention has only been focused on materials with weak electr
on-electron interactions\, despite huge possibilities for emerging new pha
ses when combining topology with strong electron interactions. Real-world
materials bring disorder as a third important component\, but the simultan
eous interplay of strong electron interactions\, topology\, and disorder i
s yet unexplored territory. In this talk\, I will show that topology combi
ned with strong electron interactions in the copper oxide high-temperature
superconductors gives rise to a new phase of matter that is unexpectedly
robust to disorder. Our findings both explain a long-standing experimental
controversy in these superconductors and show how the combination of stro
ng electron interactions\, topology\, and disorder generates rich phenomen
a that defy conventional expectations.\n\nRef: arXiv:2103.12756\n\nhttps:/
/indico.tifr.res.in/indico/conferenceDisplay.py?confId=8130
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8130
END:VEVENT
BEGIN:VEVENT
SUMMARY: Non-local description of anomalous heat transport in one-dimensio
n
DTSTART;VALUE=DATE-TIME:20210923T103000Z
DTEND;VALUE=DATE-TIME:20210923T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8154@cern.ch
DESCRIPTION:In macroscopic systems\, the phenomenological Fourier law desc
ribes heat transport through the heat diffusion equation. Surprisingly it
fails to address heat transport in some low-dimensional systems\, where he
at conduction can be super-diffusive. In this talk\, I will try to addres
s the question if there is an equivalent of heat equation that describes s
uper diffusive heat transport. By exploring solvable open classical Hamilt
onian systems with energy-conserving noise we derive an effective non-loca
l fractional description of superdiffusive heat transport. \n\nThe talk wi
ll be based on the following papers:\n\nKundu et.al. J. Stat. Mech. (2019)
013205:\nhttps://doi.org/10.1088/1742-5468/aaf630 \nPriyanka et.al. PRE\,
(2018) 98(4)\, 042105.\nhttps://doi.org/10.1103/PhysRevE.98.042105\nRevi
ew: Dhar et.al. Frontiers in Physics\,(2019) 7\, 159. \nhttps://doi.org/10
.3389/fphy.2019.00159\n\nhttps://indico.tifr.res.in/indico/conferenceDispl
ay.py?confId=8154
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8154
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-equilibrium effects on supercurrents in multi-terminal Josephs
on junctions
DTSTART;VALUE=DATE-TIME:20211118T103000Z
DTEND;VALUE=DATE-TIME:20211118T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8225@cern.ch
DESCRIPTION:I will discuss certain non-equilibrium effects on the supercur
rent(s) in a multi-terminal Josephson Junction setup that consists of a m
esoscopic and chaotic normal dot which is coupled by tunnel barriers to mu
ltiple superconducting and normal leads. Non-equilibrium condition is pr
oduced by voltage biasing the normal leads. One of the main results is tha
t the area of the critical current hypersurface decreases with voltage\,
reaches a minimum and then grows and saturates at large voltages. I will d
iscuss how 1) thickness of the barriers \, 2) temperature of the leads and
3) intrinsic inelastic relaxation in the dot - affect the supercurrent(s)
and lead to various interesting behaviors. All my results are obtained us
ing the quasi classical Keldysh formalism in the dirty limit (usually ref
erred to as Usadel equations) and I will also try to give an overview of t
his framework and particularly how I apply it.\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=8225
LOCATION: A304 / Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8225
END:VEVENT
BEGIN:VEVENT
SUMMARY: A failed superconductor in a model with random interactions
DTSTART;VALUE=DATE-TIME:20220113T053000Z
DTEND;VALUE=DATE-TIME:20220113T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8266@cern.ch
DESCRIPTION:Experiments on disordered two-dimensional systems have reporte
d the presence of an anomalous metal phase in the proximity of superconduc
tivity. This phase\, dubbed as a failed superconductor\, is characterized
by a weakly temperature-dependent conductivity (in the low-temperature lim
it) which is much higher than that of a disordered Fermi liquid metal. We
propose a model of interacting electrons with a random and all-to-all elec
tron hopping\, Cooper-pair hopping\, and exchange interaction. This model
hosts a critical anomalous phase/point between a superconductor and a diso
rdered Fermi liquid. In particular\, we find a critical Bose metal solutio
n that could be a likely candidate for a failed superconductor. We show th
at this phase has an enhanced residual conductivity owing to the transport
by incoherent Cooper pairs. Further\, we report exact results for critica
l exponents which could be observed in spectroscopic experiments. The crit
ical metallic solutions of this model are similar to those found in Sachde
v-Ye-Kitaev (SYK) models.\n\nhttps://indico.tifr.res.in/indico/conferenceD
isplay.py?confId=8266
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8266
END:VEVENT
BEGIN:VEVENT
SUMMARY:Does robust computation exist? Some reflections on asynchronous ce
llular automata.
DTSTART;VALUE=DATE-TIME:20220203T053000Z
DTEND;VALUE=DATE-TIME:20220203T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8288@cern.ch
DESCRIPTION:Like other synchronous systems cellular automata (CAs) also as
sume a global clock that forces the cells to get updated simultaneously. A
lthough\, the synchronous CAs have been proved good in modelling natural c
omplex physical\, biological\, social) systems\, the assumption of global
clock is not very natural. In this context\, the effect in the convergent
and reversible dynamics under asynchronous updating scheme from natural co
mplex system modelling perspective is presented in this work.\n\nWe regrou
p here various results on the basins of attractor dynamics under asynchron
ous updating scheme which have been presented in different articles and ex
pose a full analysis of the behaviour. This work introduces the notion of
cloud behaviour in convergent dynamics of asynchronous CAs which has simil
arity with natural clouds across the sky\, election model of parliamentary
democratic system\, and electron cloud around nucleus. Then\, this work i
ntroduces a new notion of hidden configuration to classify recurrent syste
ms into fully and partially exposed recurrent systems. Moreover\, in anoth
er direction\, this work explores the computational ability of natural att
ractor basins which suggests some asynchronous CA are potential candidate
for solving distributed consensus problem (specifically\, density classifi
cation problem)\, designing pattern classifier\, random number generator a
nd cryptosystem.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py
?confId=8288
LOCATION: Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8288
END:VEVENT
BEGIN:VEVENT
SUMMARY:Coarsening\, Condensation and Extremes
DTSTART;VALUE=DATE-TIME:20220324T053000Z
DTEND;VALUE=DATE-TIME:20220324T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8342@cern.ch
DESCRIPTION:Stochastic models of aggregation and fragmentation predict int
eresting phases\, including a ‘condensate’ state in which a single sit
e holds a macroscopic number of particles. The time evolution towards this
state is described by coarsening theory and scaling\, but with a twist. T
he local state while coarsening is very different from the steady state: t
he condensate shows giant fluctuations\, although it is quite well behaved
in steady state.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.
py?confId=8342
LOCATION: A304 and Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8342
END:VEVENT
BEGIN:VEVENT
SUMMARY:Preventing Cyber Attacks using Data Science and Machine Learning
DTSTART;VALUE=DATE-TIME:20220404T053000Z
DTEND;VALUE=DATE-TIME:20220404T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8337@cern.ch
DESCRIPTION:As the Internet becomes more prevalent in our daily lives thr
ough new devices and services such as IoT and Cloud\, cyber attacks have b
ecome more sophisticated. Traditional approaches to cyber security such as
perimeter protection and signature or rule based detection systems are no
longer effective in detecting and preventing such attacks. Using large a
mounts of data collected in the form of logs and statistical modelling te
chniques such as Machine Learning\, it is possible to develop highly accur
ate and robust threat detection systems. In this talk I will give an overv
iew of how Data Science and Machine Learning are used to build cyber threa
t detection systems and present some examples from the Industry. \n\nAbout
the speaker: Dr. Hari Koduvely is a senior data scientist with the CyberR
es unit of Micro Focus in Ottawa\, Canada. Prior to this he has worked in
many companies such as Samsung R&D\, Amazon and Infosys Labs. He has autho
red several publications and patents including the book\, Learning Bayesia
n Methods using R. Hari has done his PhD in Tata Institute of Fundamental
Research and postdoctoral research in Weizmann Institute Israel and Georgi
a Tech Atlanta before joining the Industry.\n\nhttps://indico.tifr.res.in/
indico/conferenceDisplay.py?confId=8337
LOCATION: A369 and Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8337
END:VEVENT
BEGIN:VEVENT
SUMMARY:Critical non-Fermi-liquid metal in overdoped random t-J model
DTSTART;VALUE=DATE-TIME:20220420T090000Z
DTEND;VALUE=DATE-TIME:20220420T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8373@cern.ch
DESCRIPTION:It is often assumed that the high-doping (overdoped) region of
high-Tc cuprates is a Fermi-liquid metal. However\, careful experiments h
ave reported significant deviations from it. We will discuss a candidate n
on-Fermi-liquid phase using a Sachdev-Ye-Kitaev type random model of elect
rons. The solutions of this model will be discussed in the large-M limit\,
where SU(2) symmetry is generalized to SU(M). At large hole dopings we wi
ll establish the presence of a critical non-Fermi- liquid metal\, which ha
s doping- dependent exponents\, a linear-in-temperature resistivity\, and
a strong particle-hole asymmetry. These features have been reported in rec
ent experiments. I will also show that this critical metal has an instabil
ity to a low-doping spin-glass phase and discuss its spectral functions.\n
\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8373
LOCATION: A304 and Zoom: https://zoom.us/j/98986034768?pwd=V2xIZG9sMnFBSm
l5cVkwL00rOEhQQT09
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8373
END:VEVENT
BEGIN:VEVENT
SUMMARY:Power laws in space-time: Real and complex exponents\, Self- organ
ized criticality and Griffiths phase
DTSTART;VALUE=DATE-TIME:20220526T053000Z
DTEND;VALUE=DATE-TIME:20220526T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8426@cern.ch
DESCRIPTION:Power laws in space and time are obtained in a variety of syst
ems. Self-organized criticality was an exotic explanation proposed by PerB
ak and coworkers. We present a dynamical model of evolution on lines of th
e Bak-Sneppen model in which a species that 'appears to be less fit' is pu
nished instead of a 'least fit' species. The fitness is inferred from the
dynamics of a coupled map lattice model. Some of the exponents obtained di
ffer from the Bak-Sneppen model. Another (less exotic but more likely) rou
te to power-laws in space has been quenched disorder and Griffiths phase.
We study contact processes a) with unidirectional couplings b) with some s
ites evolving according to the rule in compact directed percolation class
and the rest following the rule in directed percolation universality class
. In the first case\, we observe continuously varying complex exponents fo
r order parameter decay (as a function of the parameter)\, i.e. power-laws
superposed with log-periodic oscillations. This demonstrates the possibil
ity of a 'complex Griffiths phase'. In another case\, we observe complex p
ersistence exponents which are continuously varying in the active phase. N
one of the systems has an underlying fractal or self-similar topology. We
propose that effective fragmentation of lattice in dynamics leads to log-p
eriodicity.\n\nReference:\n1) Maneesh Matte and PMG\, Commun. Nonlin. Sci.
Numer. Simul \, 65\, 91 (2018).\n2) Priyanka Bhoyar and PMG\, PRE\, 103\,
022115 (2021).\n3) Priyanka Bhoyar and PMG\, PRE\, 101\, 022128 (2020).\n
\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8426
LOCATION: A304 and Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8426
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics and Rheology of Glassy Active Matter
DTSTART;VALUE=DATE-TIME:20220818T103000Z
DTEND;VALUE=DATE-TIME:20220818T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8515@cern.ch
DESCRIPTION:Two major outstanding questions in theoretical condensed matte
r physics are how to describe (a) driven or active systems far from equili
brium and (b) disordered systems characterized by a very slow relaxation (
e.g. glassy dynamics). In this presentation I will attempt to provide a un
ified theoretical and computational description of an active glass\, a sy
stem that exists at the intersection of these two challenging domains. Exa
mples include Epithelial tissue\, the cellular cytoplasm\, a dense assembl
y of self- propelled colloids\, to name a few. I would like to discuss the
dynamics and phase diagram of a canonical model of active glassy matter a
nd show how the rheological perturbation in such a system can lead to a no
vel type of shear \ninduced ordering. I will also provide an outlook on pe
rtinent questions and discuss briefly about the possible future directions
.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8515
LOCATION: A304 and Zoom : https://zoom.us/j/99629280441?pwd=WW5aVGxiUnlwM2
VqWEd2UE8rVXYzQT09 Meeting ID: 996 2928 0441 Passcode: 369903
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8515
END:VEVENT
BEGIN:VEVENT
SUMMARY:Neutral Excitations of Quantum Hall States: a Density Matrix Renor
malization Group Study
DTSTART;VALUE=DATE-TIME:20220901T103000Z
DTEND;VALUE=DATE-TIME:20220901T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8520@cern.ch
DESCRIPTION:We compute the neutral excitation spectra of ν=1/3 and ν=1/2
quantum Hall states on infinite cylinders of circumferences upto 10 magne
tic lengths. At filling fraction ν=1/3\, we find a magneto-roton mode tha
t can be interpreted as a dipole-like bound state of a quasi-electron and
a quasi-hole. At ν=1/2\, the excitation spectrum contains linearly disper
sing modes at small wave-vectors and a fan of excitations at 2KF. We compa
re our results with a quasi-1D composite-fermion (CF) theory and present c
ompelling quantitative evidence for the emergence of CFs at low energies.\
n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8520
LOCATION: A304 and Zoom : https://zoom.us/j/99629280441?pwd=WW5aVGxiUnlwM2
VqWEd2UE8rVXYzQT09 Meeting ID: 996 2928 0441 Passcode: 369903
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8520
END:VEVENT
BEGIN:VEVENT
SUMMARY:The two hydrodynamic scales of the Toda lattice
DTSTART;VALUE=DATE-TIME:20221123T053000Z
DTEND;VALUE=DATE-TIME:20221123T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8688@cern.ch
DESCRIPTION:For the Toda lattice one can build generalized hydrodynamics
based either on solitons or on quasiparticles. The hydrodynamic equations
are different\, but still share a similar structure. Discussed will be whe
ther such features persist for other integrable many-body systems\, either
classical or quantum.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=8688
LOCATION: A304 and on Zoom : https://zoom.us/j/96925926188?pwd=U3NmVDhROV
YvU2VqSXc4RFd4SDd1UT09 Meeting ID: 969 2592 6188 Passcode: 699382
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8688
END:VEVENT
BEGIN:VEVENT
SUMMARY:From single-excitation to many-body physics in disordered cold ato
m clouds
DTSTART;VALUE=DATE-TIME:20221209T103000Z
DTEND;VALUE=DATE-TIME:20221209T113000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8715@cern.ch
DESCRIPTION:The interaction of light with a single atom has been explored
in great detail\, with optical cavities allowing one to select which and h
ow each optical mode couples to the atom. Such setups have been used to in
vestigate fundamental effects such as vacuum Rabi splitting to measure the
light-atom coupling\, the antibunching of photons\, or Rabi oscillations
as the atom periodically exchanges energy with the light fields.\n\nThe di
fficulty in venturing into the many-body case stems from the interference
as the light scatters over many atoms. The light mediates a long-range dip
ole-dipole interaction between the particles\, which stimulates a cooperat
ive emission\, as illustrated by the superradiance effect. On the other ha
nd\, Anderson localization which arises from the atomic disorder rather pr
events this coupling\, blocking the propagation of light. The competition
between local (localized) and global (super/subradiance) effects leads to
a rich physics\, from the single-excitation to the many-body regime.\n\nIn
this presentation\, I will discuss the interaction of light with a large
cloud of atoms\, from the single-excitation regime where Anderson localiza
tion for light turns to be much richer than for scalar waves (acoustic\, m
atter waves)\, to the several-excitation regime\, where blockade and memor
y states can be generated through dipole-dipole interactions.\n\nhttps://i
ndico.tifr.res.in/indico/conferenceDisplay.py?confId=8715
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8715
END:VEVENT
BEGIN:VEVENT
SUMMARY:Interaction effects on quantum Hall transitions: Dynamical scaling
laws and superuniversality
DTSTART;VALUE=DATE-TIME:20221212T053000Z
DTEND;VALUE=DATE-TIME:20221212T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8701@cern.ch
DESCRIPTION:We study the role of electron-electron interactions near integ
er and abelian fractional quantum Hall (QH) transitions using composite fe
rmion (CF) representations. Interaction effects are encapsulated in CF the
ories as gauge fluctuations. Without gauge fluctuations\, the CF system re
alizes a ‘dual’ representation of the noninteracting QH transition. Wi
th gauge fluctuations\, the system is governed by a gauged nonlinear sigma
model (NLSM) with a θ term. While the transition is described by a stron
g-coupling fixed point of the NLSM\, we are nevertheless able to deduce tw
o of its properties. With 1/r interactions\, (1) the transition has a dyna
mical exponent z = 1\, and (2) all transitions are “superuniversal”: f
ractional and integer QH transitions are in the same universality class. W
ith short-range interactions\, z = 2 and the fate of superuniversality rem
ains unclear.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?co
nfId=8701
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8701
END:VEVENT
BEGIN:VEVENT
SUMMARY: The Generalized Gibbs Ensemble description of a Hamiltonian disor
dered model (Lecture 1)
DTSTART;VALUE=DATE-TIME:20221214T090000Z
DTEND;VALUE=DATE-TIME:20221214T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8721@cern.ch
DESCRIPTION:In these two blackboard lectures\, I will present the statisti
cal physics description of an integrable interacting model in its thermody
namic limit. \n\nIn the field of disordered systems\, the problem we will
be dealing with is the Hamiltonian spherical (p=2) Sherrington-Kirkpatick
model. Intriguingly\, in this Hamiltonian setting\, the disordered model i
s just an extension of the Neumann integrable model of classical mechanics
.\n\nQuestions such as which is the dynamic phase diagram\, whether the dy
namics approach a steady state\, and whether the time-averaged observables
satisfy an ergodic description within a Generalised Gibbs Ensemble will b
e discussed in detail.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=8721
LOCATION: A 304 and on Zoom : Join Zoom Meeting https://zoom.us/j/92410026
263?pwd=emtiV3VvcWRBMExXVkhuK0lqNEdIQT09 Meeting ID: 924 1002 6263 Passco
de: 834414
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8721
END:VEVENT
BEGIN:VEVENT
SUMMARY: The Generalized Gibbs Ensemble description of a Hamiltonian disor
dered model (Lecture 2)
DTSTART;VALUE=DATE-TIME:20221215T060000Z
DTEND;VALUE=DATE-TIME:20221215T070000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8722@cern.ch
DESCRIPTION:In these two blackboard lectures\, I will present the statisti
cal physics description of an integrable interacting model in its thermody
namic limit. \n\nIn the field of disordered systems\, the problem we will
be dealing with is the Hamiltonian spherical (p=2) Sherrington-Kirkpatick
model. Intriguingly\, in this Hamiltonian setting\, the disordered model i
s just an extension of the Neumann integrable model of classical mechanics
.\n\nQuestions such as which is the dynamic phase diagram\, whether the dy
namics approach a steady state\, and whether the time-averaged observables
satisfy an ergodic description within a Generalised Gibbs Ensemble will b
e discussed in detail.\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=8722
LOCATION: A 304 and on Zoom : https://zoom.us/j/96774944282?pwd=bDRTQWZiVU
dTc1pQVkdWcldpK0hjdz09 Meeting ID: 967 7494 4282 Passcode: 176623
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8722
END:VEVENT
BEGIN:VEVENT
SUMMARY:Novel gapless phenomena in (1+1) D
DTSTART;VALUE=DATE-TIME:20221215T090000Z
DTEND;VALUE=DATE-TIME:20221215T100000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8723@cern.ch
DESCRIPTION:I will describe some recent work in two parts. First\, I will
provide counter examples to certain widely held assumptions about the rela
tionship between phases and phase transitions and show that (a) it is poss
ible to have multiple universality classes on a single critical surface an
d (b) a stable critical surface can exist within a single\, trivial phase
. These two phenomena\, dubbed `multiversality' and `unnecessary criticali
ty' respectively\, are not fine-tuned\, stable to arbitrary symmetric pert
urbations and demonstrate that the existence and properties of a critical
surface is not determined by the surrounding phase structure. Second\, I w
ill show that we can twist the models of the first part to produce various
symmetry enriched gapless Luttinger liquid phases. I will pay particular
attention to one of these which is a so-called `intrinsically gapless topo
logical phase' which has stable boundary modes only in the presence of a g
apless bulk. Symmetries and anomalies will play an important role which wi
ll be tracked\, along with other details\, using both a microscopic spin-c
hain description in the UV as well as a continuum field-theoretic descript
ion in the IR.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?c
onfId=8723
LOCATION: A304 and Zoom : https://zoom.us/j/95319056313?pwd=dUNXV3IrMDQvNC
96Zmp1L2NXYlVzUT09 Meeting ID: 953 1905 6313 Passcode: 357941
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8723
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SUMMARY:Measuring topological entanglement entropy using Maxwell relations
DTSTART;VALUE=DATE-TIME:20230105T053000Z
DTEND;VALUE=DATE-TIME:20230105T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8748@cern.ch
DESCRIPTION:Topological entanglement entropy (TEE) is a key diagnostic of
topological order\, allowing to detect the presence of Abelian or non-Abel
ian anyons. However\, there are currently no protocols to measure TEE in c
ondensed matter systems. Here\, we propose a scheme to measure the TEE\, b
ased on a nontrivial connection with the thermodynamic entropy change occu
rring in a quantum point contact (QPC) as it pinches off the topological l
iquid into two. We show how this entropy change can be extracted using Max
well relations from charge detection of a nearby quantum dot. We demonstra
te this explicitly for the Abelian Laughlin states\, using an exact soluti
on of the sine-Gordon model describing the universal crossover in the QPC.
Our approach might open a new thermodynamic detection scheme of topologic
al states also with non-Abelian statistics. On the experimental side\, the
re has been some remarkable progress in the last few years in measuring th
ermodynamic entropy in nano- to meso- scale systems. The scheme that we pr
opose to measure TEE is within the reach of current experimental technique
s.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8748
LOCATION: A304 and Zoom : Join Zoom Meeting https://zoom.us/j/92722085614?
pwd=Y0x6WFI2NlUzS01WWDRFR2VFM1dYdz09 Meeting ID: 927 2208 5614 Passcode:
559938
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8748
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SUMMARY:Graphene flakes\, strange metals\, and black holes: insights from
the SYK model
DTSTART;VALUE=DATE-TIME:20230117T053000Z
DTEND;VALUE=DATE-TIME:20230117T063000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8764@cern.ch
DESCRIPTION:Complex many-particle quantum entanglement is a central theme
in two major topics in physics: the strange metal state found in numerous
correlated electron compounds\, and the quantum theory of black holes in E
instein gravity. The Sachdev-Ye-Kitaev model provides a solvable theory of
entangled many-particle quantum states without quasiparticle excitations.
I will describe how the SYK model sheds light on recent experiments on gr
aphene flakes\, has led to a universal theory of strange metals\, and prov
ides new insights on the quantum states of black holes.\n\nhttps://indico.
tifr.res.in/indico/conferenceDisplay.py?confId=8764
LOCATION: A304 and Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8764
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BEGIN:VEVENT
SUMMARY:Topological transports in Weyl semi-metals
DTSTART;VALUE=DATE-TIME:20230227T083000Z
DTEND;VALUE=DATE-TIME:20230227T093000Z
DTSTAMP;VALUE=DATE-TIME:20230329T091215Z
UID:indico-event-8824@cern.ch
DESCRIPTION:In recent years\, the electronic and thermal transport propert
ies of various topological systems specially Weyl semimetal (WSMs) have at
tracted tremendous attention due to their Fermi arc surface states. For ex
ample\, in the absence (presence) of the magnetic field\, the non-trivial
Berry curvatures (chiral anomaly and chiral magnetic effect) result in ano
malous Hall conductivity (negative magneto-resistance). We show the univer
sal scaling of magneto-Hall conductivity and thermo-electric conductivity\
, respectively assisted by the chiral anomaly and chiral magnetic effect\,
for multi-WSMs (mWSMs) in planar Hall set up [1]. We investigate the eff
ect of tilt and intriguing Fermi surface properties of mWSMs in the ballis
tic limit through the Magnus Hall conductivity [2\,3]. We further extend o
ur analysis to the quantum limit with Landau levels where we study the thr
ee-dimensional quantum Hall effect [4]. Apart from the above first-order t
ransport signatures\, we show that the topological charge of the activated
Weyl nodes can be directly captured by the quantized circular photogalvan
ic effect which is a second-order response [5\,6]. We then connect our pre
dictions\, based on models\, with the recent theoretical as well as experi
mental findings obtained from real materials. Finally\, we summarize the p
ossible applicability of our framework to analyze various response propert
ies in more realistic and experimentally viable platforms. \n\n[1] Magneto
-transport phenomena of type-I multi-Weyl semimetals in co-planar setups\,
T. Nag and S. Nandy\, J. Phys.: Condens. Matter 33 (2021) 075504.\n\n[2]
Topological Magnus responses in two and three-dimensional systems\, S. K.
Das\, T. Nag\, and S. Nandy\, Phys. Rev. B 104\, 115420 (2021).\n\n[3] Dis
tinct signatures of particle-hole symmetry breaking in transport coefficie
nts for generic multi-Weyl semimetals\, T. Nag\, and D. M. Kennes\, Phys.
Rev. B 105\, 214307 (2022)\n\n[4] Understanding the three-dimensional qua
ntum Hall effect in generic multi-Weyl semimetals\, F. Xiong\, C. Honerkam
p\, D. M. Kennes\, and T. Nag\, Phys. Rev. B 106\,\n045424 (2022).\n\n[5]
Electronic structure and unconventional non-linear response in double Wey
l semimetal SrSi_2\, B. Sadhukhan and T. Nag\, Phys. Rev. B 104\, 245122 (
2021).\n\n[6] Role of time-reversal symmetry and tilting in circular photo
galvanic responses\, B. Sadhukhan and T. Nag\, Phys. Rev. B 103\, 144308 (
2021).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=88
24
LOCATION: A304 and on Zoom
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=8824
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