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VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Exact Particle Correlation in Ordered Zero Range Process
DTSTART;VALUE=DATE-TIME:20091123T090000Z
DTEND;VALUE=DATE-TIME:20091123T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-258@cern.ch
DESCRIPTION:A one dimensional exclusion process on a ring is introduced w
ith a dynamics equivalent to that of a zero range process (ZRP). Although
the model shares the same steady state distribution with ZRP\, spatial co
rrelations can not be calculated directly from this equivalence. We prov
ide a generic method to calculate these correlations\, illustrate it wit
h an example and discuss possible applications.\n\nhttps://indico.tifr.res
.in/indico/conferenceDisplay.py?confId=258
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=258
END:VEVENT
BEGIN:VEVENT
SUMMARY:A report on Statistical Properties of directed avalanches
DTSTART;VALUE=DATE-TIME:20101103T090000Z
DTEND;VALUE=DATE-TIME:20101103T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-928@cern.ch
DESCRIPTION:The critical exponents for directed Manna sandpile model were
derived by Paczuski and Bassler [Phys. Rev. E 62\, 5347 (2000)]\, and by
Kloster et al [Phys. Rev. E 63\, 026111 (2001)] using field theory techni
ques. This paper re-examines this issue\, and argues that while the expone
nt values may still be correct\, the derivations make several assumptions
that are indeed incorrect. In fact\, important qualitative features of ac
tual avalanches\, seen in extensive numerical simulations\, are not corre
ctly described by the field-theory description. I will summarize the orig
inal arguments\, and Bunzarova's criticism.\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=928
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=928
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mechanics of Active Matter
DTSTART;VALUE=DATE-TIME:20101201T090000Z
DTEND;VALUE=DATE-TIME:20101201T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1007@cern.ch
DESCRIPTION:I will talk about self-propelled organisms (active matter)\, e
specially in 2D. Self-propelled directed organisms (Toner and Tu) are foun
d to have an ordered broken-symmetry phase even in 2D\, whereas apolar org
anisms on a substrate display only quasi-long-range order. If I have time
I will also talk about some experimental realisations of these systems. \n
\nReferences: \nToner J\, Tu Y. 1998. Phys. Rev. E 58:4828–58\nRamaswamy
S\, Simha RA\, Toner J. 2003. Europhys. Lett. 62:196–202\nRamaswamy S.
Annu. Rev. Condens.Matter Phys. 2010. 1:323–45\n\nhttps://indico.tifr.re
s.in/indico/conferenceDisplay.py?confId=1007
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1007
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pattern Formation in Reaction-Diffusion Systems: Nonlocality in In
teractions and the Allee Phenomenon
DTSTART;VALUE=DATE-TIME:20101208T090000Z
DTEND;VALUE=DATE-TIME:20101208T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1020@cern.ch
DESCRIPTION:The emergence of patterns is a fascinating phenomenon wherever
it appears. Reaction-diffusion systems are ubiquitous in biology or ecolo
gy. The talk will discuss reaction-diffusion systems such as those governe
d by the Fisher equation with long-range influence functions describing th
e competition between the members of a population. Interesting patterns wi
ll be shown to result. The Allee phenomenon\, found in diverse ecological
contexts\, will be discussed and a brief mention will be made of the conse
quences of its incorporation on the emergence of the patterns.\n\nhttps://
indico.tifr.res.in/indico/conferenceDisplay.py?confId=1020
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1020
END:VEVENT
BEGIN:VEVENT
SUMMARY:Calculus on Fractal Curves in R^n and Physical Applications
DTSTART;VALUE=DATE-TIME:20110105T090000Z
DTEND;VALUE=DATE-TIME:20110105T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1059@cern.ch
DESCRIPTION:I will present an overview of a new Calculus on fractal curves
\, which will begin with defining a mass function on fractal curves. This
mass function will then be used to define new integrals and derivatives\,
namely the $F^\\alpha$-integral and differential operators. Thus after pre
senting a newly developed Calculus for fractal curves\, I will talk about
a conjugacy between this and Riemann Calculus which gives a method to eval
uate $F^\\alpha$ integral and derivatives for many simple cases. In the se
cond part of my talk\, I will discuss and demonstate some Physical applica
tions of $F^\\alpha$ Calculus. This will include Fokker-Planck Equation\,
Random walk problems and the Langevin approach on fractal curves. Some int
eresting results obtained by exact or heuristic methods\, regarding the ab
ove Physical Applications will be presented.\n\nhttps://indico.tifr.res.in
/indico/conferenceDisplay.py?confId=1059
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1059
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics of non-conservative voters
DTSTART;VALUE=DATE-TIME:20110119T090000Z
DTEND;VALUE=DATE-TIME:20110119T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1099@cern.ch
DESCRIPTION:I will discuss two models of opinion dynamics. The first one i
s a non-conservative voter model in 1D where the propensity of a voter to
align with its local environment depends non-linearly on the fraction of d
isagreeing neighbors. Depending on this non-linearity in the voting rule\,
the population may exhibit a bias toward zero magnetization or toward con
sensus\, and the average magnetization is generally not conserved. The sec
ond model which is a non-consensus voter model is more realistic in the se
nse that it allows for stable coexistence of two opinions by forming clust
ers of voters holding the same opinion. The model displays a phase transit
ion behavior characterized by a large spanning cluster of voters holding t
he same opinion appearing when the concentration of voters holding the sam
e opinion (even minority) is above a certain threshold. Simulation studies
suggest that the model belong to the same universality class as invasion
percolation.\n\nReferences:\n\nDynamics of non-conservative voters \, R. L
ambiotte and S. Redner\, EPL\, 82 (2008) 18007\n\nDynamic opinion model an
d invasion percolation\, J. Shao\, S. Havlin and H. E. Stanley PRL\, 103\,
018701 (2009)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?c
onfId=1099
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1099
END:VEVENT
BEGIN:VEVENT
SUMMARY:Regular Expressions and Finite Automata
DTSTART;VALUE=DATE-TIME:20110202T023000Z
DTEND;VALUE=DATE-TIME:20110202T033000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1144@cern.ch
DESCRIPTION:Regular Expressions play an all-pervading role in computation.
For the purpose of checking whether a given sequence falls in the languag
e described by a regular expression (matching)\, they are usually converte
d into finite automata.\n\nThe talk will begin by defining regular express
ions and finite automata. An algorithm given by Berri and Sethi (1986) for
converting regular expressions into nondeterministic finite automata will
be discussed.\n\nA transformation of regular expression into the so-calle
d Star-Normal Form (Bruggmann-Klein\, 1993) will be discussed. It turns ou
t that the above algorithm has improved time efficiency once a regular exp
ression is in this form.\n\nA compressed representation of nondeterministi
c finite automata will be discussed\, which further improves space and tim
e requirements. It is also expected that it will improve the "matching" ti
me.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1144
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1144
END:VEVENT
BEGIN:VEVENT
SUMMARY:A phase diagram for jammed matter
DTSTART;VALUE=DATE-TIME:20110209T090000Z
DTEND;VALUE=DATE-TIME:20110209T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1170@cern.ch
DESCRIPTION:Experiments show that the loosest way to pack spheres (random
loose packing) gives a density of approx 55 per cent. On the other hand\,
the most compact way to pack spheres (random close packing) results in a m
aximum density of approx 64 per cent. These values are experimentally robu
st\, although not very well understood theoretically. In this paper the au
thors present an approximate statistical theory of different kinds of rand
om packings ('jammed' states) of spheres. From their formulation\, random
close packing emerges as the ground state of the ensemble of jammed matter
. They also find that random packings of spheres in three dimensions canno
t exceed a density limit of approx 63.4 per cent. Random close packing and
random loose packing states appear as special lines on a phase diagram il
lustrating the effects of density and friction on the system.\n\nReference
: Song\, C.\, Wang\, P. and Makse\, H. A. Nature 453\, 629-632 (2008).\n\n
https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1170
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1170
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heis
enberg to a Quantum Compass and Kitaev Models
DTSTART;VALUE=DATE-TIME:20110223T090000Z
DTEND;VALUE=DATE-TIME:20110223T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1201@cern.ch
DESCRIPTION:I will talk about this recent proposal for realising the honey
comb lattice Kitaev model in certain iridates.\n\nRef: G. Jackeli and G. K
haliullin\, Phys. Rev. Lett. 102\, 017205 (2009).\n\nhttps://indico.tifr.r
es.in/indico/conferenceDisplay.py?confId=1201
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1201
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vibrational Spectrum of Spider Networks
DTSTART;VALUE=DATE-TIME:20110323T090000Z
DTEND;VALUE=DATE-TIME:20110323T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1261@cern.ch
DESCRIPTION:A 2^N x M - node spider network is a set of M-layers each of w
hich has 2^N nodes which can be represented by N-bit binary numbers. Each
site in a layer is connected to two sites in the next layer by a set of ru
les and this procedure is continued for the next layer and so on to genera
te the entire set of connections in the network. The last layer is connect
ed back to the first layer. An example of a 4-layer\, 2-bit network is sho
wn in the attached figure. (Rule: ab->b0(colored red) and ab->b1(colored g
reen) where a and b are either 0 or 1).\n\nConsider an atom of mass M plac
ed at each node. Each site is connected by a spring of spring constant K t
o the atoms to which it has connections. In the talk I will find the norma
l modes of this lattice.\n\nhttps://indico.tifr.res.in/indico/conferenceDi
splay.py?confId=1261
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1261
END:VEVENT
BEGIN:VEVENT
SUMMARY:Witten effect in a crystalline topological insulator
DTSTART;VALUE=DATE-TIME:20110330T060000Z
DTEND;VALUE=DATE-TIME:20110330T070000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1269@cern.ch
DESCRIPTION:A term of the form θ(e^2/2πh)B.E may be added to the standar
d Maxwell Lagrangian without modifying the familiar laws of electricity an
d magnetism. θ is known as the "axion" field. The axion term gives the Wi
tten effect: a unit magnetic monopole placed inside a medium with θ $\\ne
q$ 0 is predicted to bind a (generally fractional) electric charge -e(θ/2
π+n) with n integer. It has been recently shown that the axion term with
θ=π emerges naturally in the description of the electromagnetic response
of topological insulators. In this paper the authors demonstrate the exis
tence of a fractional charge bound to a monopole by an explicit numerical
calculation and also propose a scheme for generating an "artificial" magne
tic monopole in a topological insulator film that may be used to facilitat
e an experimental test of Witten's prediction.\n\nReference: "Witten effec
t in a crystalline topological insulator"\, G. Rosenberg and M. Franz\, Ph
ys. Rev. B 82\, 035105 (2010)\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=1269
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1269
END:VEVENT
BEGIN:VEVENT
SUMMARY:A semi-classical approach to electron spin resonance in quantum sp
in systems
DTSTART;VALUE=DATE-TIME:20110406T090000Z
DTEND;VALUE=DATE-TIME:20110406T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1292@cern.ch
DESCRIPTION:We develop a semi-classical approximation to electron spin res
onance in quantum spin systems\, based on the rotor or non-linear sigma mo
del. The classical time evolution is studied using molecular dynamics whil
e random initial conditions are sampled using classical Monte Carlo method
s. Although the approximation may be especially powerful in two dimensions
\, we apply it here to one-dimensional systems of large spin at intermedia
te temperatures\, in the presence of staggered and uniform magnetic fields
. We first test the validity of the semi-classical approximation by compar
ing the magnetization to quantum Monte Carlo results on S = 2 chains. Then
we calculate the ESR spectrum\, finding broad coexisting paramagnetic and
spin wave resonances.\n\nReference: arXiv:1102.3239v1\n\nhttps://indico.t
ifr.res.in/indico/conferenceDisplay.py?confId=1292
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1292
END:VEVENT
BEGIN:VEVENT
SUMMARY:SU(2)-Invariant Continuum Theory for an Unconventional Phase Trans
ition in a Three-Dimensional Classical Dimer Model
DTSTART;VALUE=DATE-TIME:20110420T090000Z
DTEND;VALUE=DATE-TIME:20110420T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1307@cern.ch
DESCRIPTION:In this paper the authors derived a continuum theory for the p
hase transition in a classical dimer model on the cubic lattice\, observed
in recent Monte Carlo simulations. The derivation relies on the mapping f
rom a three-dimensional classical problem to a two-dimensional quantum pro
blem\, by which the dimer model is related to a model of hard-core bosons
on the kagome lattice. The dimer-ordering transition becomes a superfluid-
Mott insulator quantum phase transition at fractional filling\, described
by an SU(2)-invariant continuum theory.\n\nRef: Phys. Rev. Lett. 101\, 155
702 (2008)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confI
d=1307
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1307
END:VEVENT
BEGIN:VEVENT
SUMMARY:SU(2)-Invariant Continuum Theory for an Unconventional Phase Trans
ition in a Three-Dimensional Classical Dimer Model: Part II
DTSTART;VALUE=DATE-TIME:20110427T090000Z
DTEND;VALUE=DATE-TIME:20110427T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1335@cern.ch
DESCRIPTION:In this paper the authors derived a continuum theory for the p
hase transition in a classical dimer model on the cubic lattice\, observed
in recent Monte Carlo simulations. The derivation relies on the mapping f
rom a three-dimensional classical problem to a two-dimensional quantum pro
blem\, by which the dimer model is related to a model of hard-core bosons
on the kagome lattice. The dimer-ordering transition becomes a superfluid-
Mott insulator quantum phase transition at fractional filling\, described
by an SU(2)-invariant continuum theory.\n\nhttps://indico.tifr.res.in/indi
co/conferenceDisplay.py?confId=1335
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1335
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fluid-Solid Transition in a Hard-Core System
DTSTART;VALUE=DATE-TIME:20110504T090000Z
DTEND;VALUE=DATE-TIME:20110504T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1346@cern.ch
DESCRIPTION:These papers discuss a proof of a solid-liquid phase transitio
n in 2 dimensions (continuum) for objects of a single species\, with hard
core exclusion. The most stable configuration at high densities for hard-s
phere models can at present only be conjectured by expansions about an ord
ered state or through simulations. The authors study "zipper" molecules wi
th constraints that prevent the sliding of layers at high densities\, and
are thus able to prove the stability of the ordered state.\n\nhttps://indi
co.tifr.res.in/indico/conferenceDisplay.py?confId=1346
LOCATION:Colaba Campus A-304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1346
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adiabatic condition and the quantum hitting time of Markov chains
DTSTART;VALUE=DATE-TIME:20110511T090000Z
DTEND;VALUE=DATE-TIME:20110511T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1355@cern.ch
DESCRIPTION:The paper presents an adiabatic quantum algorithm for spatial
search (finding marked vertices in a graph). Given a random walk (or Marko
v chain) P on a graph with a set of unknown marked vertices\, one can defi
ne a related absorbing walk P' where outgoing transitions from marked vert
ices are replaced by self-loops. They build a Hamiltonian H(s) from the in
terpolated Markov chain P(s)=(1-s)P+sP' and use it in an adiabatic quantum
algorithm to drive an initial superposition over all vertices to a superp
osition over marked vertices. The running time of the adiabatic algorithm
is given by the square root of the classical hitting time. This algorithm
therefore demonstrates a novel connection between the adiabatic condition
and the classical notion of hitting time of a random walk.\n\nReference: H
ari Krovi\, Maris Ozols\, and Jeremie Roland\, Phys. Rev. A 82\, 022333 (2
010)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1355
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1355
END:VEVENT
BEGIN:VEVENT
SUMMARY:On reduced density matrices for disjoint subsystems
DTSTART;VALUE=DATE-TIME:20110518T090000Z
DTEND;VALUE=DATE-TIME:20110518T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1383@cern.ch
DESCRIPTION:The authors show that spin and fermion representations for sol
vable quantum chains lead in general to different reduced density matrices
if the subsystem is not singly connected. They study the effect for two s
ites in XX and XY chains as well as for sublattices in XX and transverse I
sing chains.\n\nReference: F. Igloi and I. Peschel\, 2010 EPL 89 40001\n\n
https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1383
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1383
END:VEVENT
BEGIN:VEVENT
SUMMARY:Derivatives of Regular Expressions
DTSTART;VALUE=DATE-TIME:20110601T090000Z
DTEND;VALUE=DATE-TIME:20110601T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1417@cern.ch
DESCRIPTION:In the advent of functional programming\, the interest in the
concept of derivatives of regular expressions [1] has been revived [2]. Ap
art from being elegant\, it seems to be the only automata way of handling
extended regular expressions\, i. e. expressions including logical AND and
NOT\, which then can describe any boolean operations.\n\nIn this talk the
notion of a derivative of a regular expression [1] will be introduced and
the properties of derivatives will be discussed. This will lead in a natu
ral way to the construction of a deterministic finite automaton from an ex
tended regular expression.\n\n[1] J. A. Brzozowski\, "Derivatives of regul
ar expressions"\, Journal of the Association for Computing Machinery\, 11(
4) (1964) 481-494\n\n[2] Scott Owens\, John Reppy\, Aaron Turon\, "Regular
expression derivatives reexamined"\, Journal of Functional Programming\,
19(2) (2009) 173-190\n\nhttps://indico.tifr.res.in/indico/conferenceDispla
y.py?confId=1417
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1417
END:VEVENT
BEGIN:VEVENT
SUMMARY:Interaction-driven Real-space Condensation
DTSTART;VALUE=DATE-TIME:20110608T090000Z
DTEND;VALUE=DATE-TIME:20110608T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1428@cern.ch
DESCRIPTION:The authors study condensation in mass transfer models with in
teractions between neighbouring sites. For a broad class of mass transfer
rates\, the steady state of the model is found to have a pair factorised f
orm. Interaction between particles at neighbouring sites\, also changes th
e nature of condensation\, giving rise to spatially extended condensates\,
as oppposed to a single condensate found in models without interaction su
ch as the Zero Range Process. The authors examine in detail\, a form of in
teraction for which the model maps on to models of solid on solid interfac
es and show that the criterion for condensation in the mass transfer model
is related to the binding-unbinding transition in the interface model.\n\
nReference: M. R. Evans\, T. Hanney\, and S. N. Majumdar\, Phys. Rev. Lett
. 97\, 010602 (2006)\n\nhttp://prl.aps.org/abstract/PRL/v97/i1/e010602\n\n
https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1428
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1428
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anderson Localization makes Adiabatic Quantum Computation Fail
DTSTART;VALUE=DATE-TIME:20110622T090000Z
DTEND;VALUE=DATE-TIME:20110622T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1453@cern.ch
DESCRIPTION:Recently there has been a great deal of interest in the possib
le application of adiabatic quantum optimization for solving NP-complete p
roblems. The efficiency of these schemes is limited by small spectral gaps
between the ground state and excited states of the Hamiltonian of the qua
ntum computer. One such problem\, the Exact Cover 3\, can be mapped to a d
isordered quantum spin system where Anderson localization can occur in the
Hilbert space. It is argued that the spectral gaps in this system are eve
n smaller than exponential in the number N of qubits\; thus\, adiabatic qu
antum optimization fails.\n\nhttps://indico.tifr.res.in/indico/conferenceD
isplay.py?confId=1453
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1453
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mixing of Diffusing Particles
DTSTART;VALUE=DATE-TIME:20110706T090000Z
DTEND;VALUE=DATE-TIME:20110706T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1501@cern.ch
DESCRIPTION:We study how the order of N independent random walks in one di
mension evolves with time. Our focus is statistical properties of the inve
rsion number m\, defined as the number of pairs that are out of sort with
respect to the initial configuration. In the steady state\, the distributi
on of the inversion number is Gaussian with the average ⟨m⟩≃N2/4 and
the standard deviation σ≃N3/2/6. The survival probability\, Sm(t)\, wh
ich measures the likelihood that the inversion number remains below m unti
l time t\, decays algebraically in the long-time limit\, Sm∼t−βm. Int
erestingly\, there is a spectrum of N(N−1)/2 distinct exponents βm(N).
We also find that the kinetics of first passage in a circular cone provide
s a good approximation for these exponents. When N is large\, the first-pa
ssage exponents are a universal function of a single scaling variable\, β
m(N)→β(z)\, with z=(m−⟨m⟩)/σ. In the cone approximation\, the sc
aling function is a root of a transcendental equation involving the parabo
lic cylinder equation\, D2β(−z)=0\, and surprisingly\, numerical simula
tions show this prediction to be exact.\n\nReferences: E Ben-Naim Phys. Re
v. E 82\, 061103 (2010)\nE Ben-Naim and P L Krapivsky\, J. Phys. A: Math.
Theor. 43 (2010)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py
?confId=1501
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1501
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topological insulators from the point of view of the Dirac equatio
n
DTSTART;VALUE=DATE-TIME:20110720T090000Z
DTEND;VALUE=DATE-TIME:20110720T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1526@cern.ch
DESCRIPTION:I will present a general description of topological insulators
from the point of view of the Dirac equation. From the calculation of Z2
indices and solutions of bound states near the boundary I will show that a
modified version of the Dirac equation can provide a description of a lar
ge family of topological insulators. If time permits I will also discuss s
ome minimal lattice models for topological insulators.\n\nReference (among
st others): Shun-Qing Shen\, Wen-Yu Shan\, Hai-Zhou Lu\, arXiv:1009.5502v1
(2010)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1
526
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1526
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topological insulators from the point of view of the Dirac equatio
n (Part II)
DTSTART;VALUE=DATE-TIME:20110727T090000Z
DTEND;VALUE=DATE-TIME:20110727T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1533@cern.ch
DESCRIPTION:I will present a general description of topological insulators
from the point of view of the Dirac equation. From the calculation of Z2
indices and solutions of bound states near the boundary I will show that a
modified version of the Dirac equation can provide a description of a lar
ge family of topological insulators. If time permits I will also discuss s
ome minimal lattice models for topological insulators. Reference: Shun-Qin
g Shen\, Wen-Yu Shan\, Hai-Zhou Lu\, arXiv:1009.5502v1 (2010)\n\nhttps://i
ndico.tifr.res.in/indico/conferenceDisplay.py?confId=1533
LOCATION:Colaba Campus AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1533
END:VEVENT
BEGIN:VEVENT
SUMMARY:Odd-Parity Topological Superconductors: Theory and Application to
CuxBi2Se3
DTSTART;VALUE=DATE-TIME:20110809T210000Z
DTEND;VALUE=DATE-TIME:20110809T220000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1585@cern.ch
DESCRIPTION:Topological superconductors have a full pairing gap in the bul
k and gapless surface Andreev bound states. In this paper\, we provide a s
ufficient criterion for realizing time-reversal-invariant topological supe
rconductors in centrosymmetric superconductors with odd-parity pairing. We
next study the pairing symmetry of the newly discovered superconductor Cu
xBi2Se3 within a two-orbital model\, and find that a novel spin-triplet pa
iring with odd parity is favored by strong spin-orbit coupling. Based on o
ur criterion\, we propose that CuxBi2Se3 is a good candidate for a topolog
ical superconductor. We close by discussing experimental signatures of thi
s new topological phase.\n\n\n Reference: Phys. Rev. Lett. 105\, 097001 (2
010)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1585
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1585
END:VEVENT
BEGIN:VEVENT
SUMMARY: Critical Correlations for Short-Range Valence-Bond Wave Functions
on the Square
DTSTART;VALUE=DATE-TIME:20110824T090000Z
DTEND;VALUE=DATE-TIME:20110824T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1613@cern.ch
DESCRIPTION:I will summarize recent results by Alet and Albuquerque and by
Tang\, Henley and Sandvik on properties of nearest neighbour resonating v
alence bond wavefunctions that were introduced by Anderson more than twent
y years ago to describe putative spin-liquid states of quantum magnets.\n\
nReferences:\n1) A. Fabricio Albuquerque and Fabien Alet\, Phys. Rev. B 82
\, 180408(R) (2010)\n2) Ying Tang\, Anders W. Sandvik\, Christopher L. Hen
ley\, arXiv:0910.5708\n3) Jennifer Cano\, Paul Fendley\, Phys. Rev. Lett.
105\, 067205 (2010)\n4) S. Liang\, B. Doucot\, and P. W. Anderson\, Phys.
Rev. Lett.\, 61\, 365 (1988)\n5) P. W. Anderson\, Mater. Res. Bull.\, 8\,
153 (1973)\n6) P. Fazekas and P.W. Anderson\, Philos. Mag.\, 30\, 474 (197
4)\n7) P. W. Anderson\, Science\, 235\, 1196 (1987)\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=1613
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1613
END:VEVENT
BEGIN:VEVENT
SUMMARY:Equilibration of quantum systems and subsystems
DTSTART;VALUE=DATE-TIME:20110928T090000Z
DTEND;VALUE=DATE-TIME:20110928T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1716@cern.ch
DESCRIPTION:The problem of the 'derivation' of statistical mechanics from
quantum mechanics has been approached in recent literature from two (relat
ed) directions: (i) Equilibration: showing that an initial ensemble approa
ches a stationary long-time behaviour\, and (ii) Thermalization: proving t
hat this long-time average is equal to a microcanonical average with a sui
table energy or a canonical one with a suitably defined temperature. I wil
l talk about the former\, and present a proof showing that the expectation
values of 'realistic' quantum observables equilibrate under very general
conditions.\n\nReference:\nAnthony J Short 2011 New J. Phys. 13 053009\n\n
Further reading:\nPeter Reimann 2010 New J. Phys. 12 055027\nM. Rigol\, V.
Dunjko\, and M. Olshanii\, Nature 452\, 854 (2008)\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=1716
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1716
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lattice Coulomb gas representations of two-dimensional problems
DTSTART;VALUE=DATE-TIME:20111012T090000Z
DTEND;VALUE=DATE-TIME:20111012T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1732@cern.ch
DESCRIPTION:Many of the standard two-dimensional problems of statistical p
hysics can be transformed into 'Coulomb gas' problems in which there are t
wo kinds of 'charges' represented by integers n and m. Such a transformati
on works for the Ising model\, the three- and four-state Potts models\, th
e Ashkin-Teller model\, any many others. In general the n-n and m-m intera
ctions have the Coulomb character in which the interaction is\, for large
separations\, proportional to the logarithm of the distance. On the other
hand\, the n(r)-m(R) interaction is for large distances proportional to i
times the angle Phi (r-R) which measures the angular position of R relativ
e to r. This latter interaction is akin to that between a magnetic monopol
e and an electric charge.\n\n\nReference:\nL P Kadanoff\, J. Phys. A: Math
. Gen. 11 1399 (1978)\n\nhttps://indico.tifr.res.in/indico/conferenceDispl
ay.py?confId=1732
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1732
END:VEVENT
BEGIN:VEVENT
SUMMARY:Exact First-Passage Exponents of 1D Domain Growth: Relation to a R
eaction-Diffusion Model
DTSTART;VALUE=DATE-TIME:20111102T090000Z
DTEND;VALUE=DATE-TIME:20111102T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-1757@cern.ch
DESCRIPTION:The authors study persistence in the q-state Potts model\, whe
n it is quenched to zero temperature. It is known that the fraction r(q\,t
) of spins\, which have never flipped up to time t\, decays like the power
law r(q\,t)∼t-θ(q) with a nontrivial dependence of the exponent θ(q)
on q and on space dimension. By mapping the problem onto an exactly solubl
e one-species coagulation model ( A+A→A)\, an exact expression for θ(q)
is obtained in one dimension.\n\nReference:\nB. Derrida\, V. Hakim\, and
Vincent Pasquier\, Phys. Rev. Lett. 75\, 751 (1995)\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=1757
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=1757
END:VEVENT
BEGIN:VEVENT
SUMMARY: Ergodicity Breaking and Parametric Resonances in Systems with Lo
ng-Range Interactions
DTSTART;VALUE=DATE-TIME:20120215T090000Z
DTEND;VALUE=DATE-TIME:20120215T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2019@cern.ch
DESCRIPTION:The paper explores the mechanism responsible for the ergodicit
y breaking in a system with long-range forces\, namely the HMF (Hamtiltoni
an Mean-Field) Model. In thermodynamic limit such systems do not evolve to
the Boltzmann-Gibbs equilibrium\, but become trapped in an out-of-equilib
rium quasi-stationary-state (QSS)\, which can be described by Lyden-Bell s
tatistics. However\, they show that only if the initial distribution satis
fies a specific constraint - a generalized virial condition - theQSS is ve
ry close to ergodic and can be described by Lynden-Bell statistics. On the
other hand if the generalized virial condition is violated\, parametric r
esonances are excited\, leading to chaos and ergodicity breaking (relaxati
on to the Lyden-Bell state is incomplete).\n\n\nReferences:\nhttp://arxiv.
org/abs/1202.1810\nLynden-Bell and Tsallis distributions for the HMF model
\, P. H. Chanavis\, EJPB 53\, 4\n\nhttps://indico.tifr.res.in/indico/confe
renceDisplay.py?confId=2019
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2019
END:VEVENT
BEGIN:VEVENT
SUMMARY:The nematic phase of a system of long hard rods
DTSTART;VALUE=DATE-TIME:20120321T090000Z
DTEND;VALUE=DATE-TIME:20120321T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2097@cern.ch
DESCRIPTION:This paper [1] considers a two-dimensional lattice model for l
iquid crystals consisting of long rods interacting via purely hard core in
teractions\, with two allowed orientations defined by the underlying latti
ce. The authors rigorously prove the existence of a nematic phase (shown t
o exist for rods of length k \\ge 7 via numerical simulations [2])\, i.e.\
, they show that at intermediate densities the system exhibits orientation
al order\, either horizontal or vertical\, but no positional order. The pr
oof is based on a two-scales cluster expansion: they first coarse grain th
e system on a scale comparable with the rods' length\; then express the re
sulting effective theory as a contour model\, which can be treated by Piro
gov-Sinai methods [3].\n\nReferences:\n[1] M. Disertori and A. Giuliani\,
arXiv:1112.5564 (2012)\n[2] A. Ghosh and D. Dhar\, Europhysics Letters 78\
, 20003 (2007)\n[3] R. Kotecky\, Encyclopedia of Mathematical Physics\, El
sevier\, pp.60-65 (2006\n\nhttps://indico.tifr.res.in/indico/conferenceDis
play.py?confId=2097
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2097
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multiband magnetism and superconductivity in Fe-based compounds
DTSTART;VALUE=DATE-TIME:20120404T090000Z
DTEND;VALUE=DATE-TIME:20120404T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2108@cern.ch
DESCRIPTION:A model Hamiltonian describing FeAs layers is introduced\, hig
hlighting the crucial role of puckering of As atoms in promoting d electro
n itinerancy and warding off large local-moment magnetism of Fe ions\, the
main enemy of superconductivity. Quantum many-particle effects in charge\
, spin and multiband channels are explored and a nesting-induced spin dens
ity-wave order is found in the parent compund. We argue that this largely
itinerant antiferromagnetism and high Tc itself are essentially tied to th
e multiband nature of the Fermi surface.\n\nReference:\nV. Cvetkovic and Z
. Tesanovic\, EPL 85\, 37002 (2009)\n\nhttps://indico.tifr.res.in/indico/c
onferenceDisplay.py?confId=2108
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2108
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multiband magnetism and superconductivity in Fe-based compounds
DTSTART;VALUE=DATE-TIME:20120411T090000Z
DTEND;VALUE=DATE-TIME:20120411T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2128@cern.ch
DESCRIPTION:A model Hamiltonian describing FeAs layers is introduced\, hig
hlighting the crucial role of puckering of As atoms in promoting d electro
n itinerancy and warding off large local-moment magnetism of Fe ions\, the
main enemy of superconductivity. Quantum many-particle effects in charge\
, spin and multiband channels are explored and a nesting-induced spin dens
ity-wave order is found in the parent compund. We argue that this largely
itinerant antiferromagnetism and high Tc itself are essentially tied to th
e multiband nature of the Fermi surface.\n\nReference:\nV. Cvetkovic and Z
. Tesanovic\, EPL 85\, 37002 (2009)\n\nhttps://indico.tifr.res.in/indico/c
onferenceDisplay.py?confId=2128
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2128
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase of Ising spins on modular networks analogous to social polar
ization
DTSTART;VALUE=DATE-TIME:20120425T090000Z
DTEND;VALUE=DATE-TIME:20120425T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2177@cern.ch
DESCRIPTION:Critical phenomena associated with order-disorder transitions
have significant implications for understanding social phenomena\, like co
nsensus formation in society. Investigating the order-disorder transition
for Ising spins on modular random networks\, corresponding to consensus fo
rmation in society\, two distinct phases have been observed : (i) ordering
within each module at a critical temperature followed by (ii) global orde
ring at a lower temperature. This indicates polarization of society into g
roups having contrary opinions can persist indefinitely even when mutual i
nteractions between agents favor consensus.\n\nReference:\nSubinay Dasgupt
a\, Raj Kumar Pan\, and Sitabhra Sinha\, Phys. Rev. E 80\, 025101(R) (2009
)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2177
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2177
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamics of random graphs with bounded degrees
DTSTART;VALUE=DATE-TIME:20120523T090000Z
DTEND;VALUE=DATE-TIME:20120523T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2262@cern.ch
DESCRIPTION:We investigate the dynamic formation of regular random graphs.
In our model\, we pick a pair of nodes at random and connect them with a
link if both of their degrees are smaller than d. Starting with a set of i
solated nodes\, we repeat this linking step until a regular random graph\,
where all nodes have degree d\, forms. We view this process as a multivar
iate aggregation process\, and formally solve the evolution equations usin
g the Hamilton-Jacobi formalism. We calculate the non trivial percolation
thresholds for the emergence of the giant component when d >= 3. Also\, we
estimate the number of steps that have occurred before the giant componen
t spans the entire system and the total number of steps that have occurred
before the regular random graph forms.\n\nReference:\nE Ben-Naim and P L
Krapivsky J. Stat. Mech. (2011) P11008\n\nhttps://indico.tifr.res.in/indic
o/conferenceDisplay.py?confId=2262
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2262
END:VEVENT
BEGIN:VEVENT
SUMMARY:Analysis of a fully packed loop model arising in a magnetic Coulom
b phase
DTSTART;VALUE=DATE-TIME:20120530T090000Z
DTEND;VALUE=DATE-TIME:20120530T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2277@cern.ch
DESCRIPTION:I will first show how the Coulomb phase of spin ice can be rea
lized on a fully packed two-colour loop model. Then I will discuss the sta
tistics of these loops\, which avoid themselves and other loops of the sam
e colour\, and contrast their behavior to an analogous two-dimensional mod
el. I will also discuss the properties of another extended degree of freed
om (worms)\, ﬂux lines of the emergent gauge ﬁeld of the Coulomb phase
\, which appear as ”Dirac strings” in spin ice. Finally (depending on
time) I will mention mention implications of these results for related mod
els\, and experiments.\n\nReference:\nL. D. C. Jaubert\, M. Haque and R. M
oessner\, Phys. Rev. Lett. 107\, 177202 (2011)\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=2277
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2277
END:VEVENT
BEGIN:VEVENT
SUMMARY:Order in glassy systems
DTSTART;VALUE=DATE-TIME:20120613T090000Z
DTEND;VALUE=DATE-TIME:20120613T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2288@cern.ch
DESCRIPTION:A directly measurable correlation length may be defined for sy
stems having a two-step relaxation\, based on the geometric properties of
density profile that remains after averaging out the fast motion. We argue
that the length diverges if and when the slow timescale diverges\, whatev
er the microscopic mechanism at the origin of the slowing down. Measuring
the length amounts to determining explicitly the complexity from the obser
ved particle configurations. One may compute in the same way the Renyi com
plexities Kq\, their relative behavior for different q characterizes the m
echanism underlying the transition. In particular\, the 'Random First Orde
r' scenario predicts that in the glass phase Kq=0 for q > x\, and Kq > 0 f
or q < x\, with x the Parisi parameter. The hypothesis of a nonequilibrium
effective temperature may also be directly tested directly from configura
tions.\n\nReference:\nJorge Kurchan\, Dov Levine: arXiv:1008.4068\n\nhttps
://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2288
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2288
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Excitations in Quantum Spin Ice
DTSTART;VALUE=DATE-TIME:20120620T090000Z
DTEND;VALUE=DATE-TIME:20120620T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2294@cern.ch
DESCRIPTION:This paper uses inelastic neutron scattering in high magnetic
field to determine the parameters of the Hamiltonian of Yb2Ti2O7. The resu
lts suggest that this material at low temperature may be in a so-called Co
ulomb liquid phase. I will explain how the experiment extracts the model H
amiltonian parameters\, and then explain what signatures could perhaps be
measured in future experiments of the quantum Coulomb liquid phase.\n\nRef
erence:\nKate A. Ross\, Lucile Savary\, Bruce D. Gaulin\, and Leon Balents
\, Phys. Rev. X 1\, 021002 (2011)\n\nhttps://indico.tifr.res.in/indico/con
ferenceDisplay.py?confId=2294
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2294
END:VEVENT
BEGIN:VEVENT
SUMMARY:Breakdown of Kolmogorov Scaling in Aggregation Models
DTSTART;VALUE=DATE-TIME:20120627T090000Z
DTEND;VALUE=DATE-TIME:20120627T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2306@cern.ch
DESCRIPTION:The authors study a model with diffusing and aggregating parti
cles in the presence of a source of monomers\, which provides an example
of an analytically tractable turbulent system. The steady state is charact
erized by a constant mass flux from small masses to large. Thus it can be
studied using a phenomenological theory\, inspired by Kolmogorov’s 1941
theory\, which assumes constant flux and self-similarity. In dimensions le
ss than or equal to two\, this self similarity is violated. By constructin
g a statistical field theory and using renormalization group techniques\,
the authors show that the multipoint correlation functions exhibit a non-t
rivial multiscaling.\n\nReferences:\n[1] C. Connaughton\, R. Rajesh\, O. Z
aboronski\, Phys. Rev. Lett. 94\, 194503 (2005)\n[2] C. Connaughton\, R.
Rajesh\, O. Zaboronski\, Physica D 222\, 97 (2006)\n\nhttps://indico.tifr
.res.in/indico/conferenceDisplay.py?confId=2306
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2306
END:VEVENT
BEGIN:VEVENT
SUMMARY:Two-Component Coulomb Glass in Insulators with Local Attraction
DTSTART;VALUE=DATE-TIME:20120704T090000Z
DTEND;VALUE=DATE-TIME:20120704T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2327@cern.ch
DESCRIPTION:I will review the well-known arguments of Efros and Shklovskii
on how long-range Coulomb interaction of charges in a strongly disordered
insulator give rise to a Coulomb-gap in the density of states and a stret
ched-exponential temperature dependence of resistivity. Thereafter I will
discuss how these results are modified if two-particle processes such as C
ooper pair tunnelling are also significant. Of particular interest is the
prediction of a non-monotonous temperature or magnetic field dependence of
resistivity. Experimental motivation for this work comes from the magneto
resistance peak seen in strongly disordered superconductors.\n\nReference:
\nJ. Mitchell\, A. Gangopadhyay\, V. Galitski\, and M. Müller\, Phys. Rev
. B 85\, 195141 (2012)\n\nhttps://indico.tifr.res.in/indico/conferenceDisp
lay.py?confId=2327
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2327
END:VEVENT
BEGIN:VEVENT
SUMMARY:Free Cooling of Wet Granular Gases
DTSTART;VALUE=DATE-TIME:20120711T090000Z
DTEND;VALUE=DATE-TIME:20120711T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2339@cern.ch
DESCRIPTION:I will talk about the free cooling of wet granular gases start
ing from a homogeneous initial configuration. Wet granular gases are disti
nguished from the dry or sticky ones by the formation of a capillary bridg
e between two colliding spheres which takes a finite amount of energy to b
reak. The two papers referenced below study the decay of the average kinet
ic energy and formation of clusters in 1D and 3D respectively by molecular
dynamics simulations and mean field equations.\n\nReferences:\n[1] V. Yu.
Zaburdaev\, M. Brinkmann\, and S. Herminghaus\, Phys. Rev. Lett. 97\, 018
001 (2006)\n[2] S. Ulrich\, T. Aspelmeier\, K. Roeller\, A. Fingerle\, S.
Herminghaus\, and A. Zippelius\, Phys. Rev. Lett. 102\, 148002 (2009)\n\nh
ttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2339
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2339
END:VEVENT
BEGIN:VEVENT
SUMMARY:Identifying topological order in a spin liquid using entanglement
entropy
DTSTART;VALUE=DATE-TIME:20120822T090000Z
DTEND;VALUE=DATE-TIME:20120822T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2413@cern.ch
DESCRIPTION:I will talk about some recent works[1\,2] which uses an intere
sting combination of ideas from quantum information and DMRG(density matri
x renormalization group) method to study the ground state of kagome antife
rromagnet as a quantum spin liquid. There are various proposals for the gr
ound state of this system ranging from magnetic order to valence bond soli
ds and quantum spin liquid(QSL). In another recent paper by Yan\, Huse and
White[3] it was shown using DMRG technique that the ground state of this
system is gapped and shows no sign of valence bond or magnetic order in la
rge system sizes. However the question of identifying a positive signature
of spin liquid was left open. The featured papers provides a strong posit
ive evidence of a QSL on the kagome lattice by computing topological entan
glement entropy and showing it is consistent with what is expected from a
topological spin liquid of Z_2 type.\n\nRef: \n[1] H C Jiang\, Z W and L B
alents\, arxiv:1205.4289.\n[2] S Depenbrock\, I P McCulloch and U Schollwo
ck\, arxiv:1205.4858.\n[3] S Yan\, D Huse and S White\, Science 332\, 1173
(2011).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2
413
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2413
END:VEVENT
BEGIN:VEVENT
SUMMARY: Identifying topological order in a spin liquid using entanglement
entropy
DTSTART;VALUE=DATE-TIME:20120829T090000Z
DTEND;VALUE=DATE-TIME:20120829T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2430@cern.ch
DESCRIPTION:I will talk about some recent works[1\,2] which uses an intere
sting combination of ideas from quantum information and DMRG(density matri
x renormalization group) method to study the ground state of kagome antife
rromagnet as a quantum spin liquid. There are various proposals for the gr
ound state of this system ranging from magnetic order to valence bond soli
ds and quantum spin liquid(QSL). In another recent paper by Yan\, Huse and
White[3] it was shown using DMRG technique that the ground state of this
system is gapped and shows no sign of valence bond or magnetic order in la
rge system sizes. However the question of identifying a positive signature
of spin liquid was left open. The featured papers provides a strong posit
ive evidence of a QSL on the kagome lattice by computing topological entan
glement entropy and showing it is consistent with what is expected from a
topological spin liquid of Z_2 type.\n\nRef: \n[1] H C Jiang\, Z W and L B
alents\, arxiv:1205.4289.\n[2] S Depenbrock\, I P McCulloch and U Schollwo
ck\, arxiv:1205.4858.\n[3] S Yan\, D Huse and S White\, Science 332\, 1173
(2011).\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2
430
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2430
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimizing the success of random searches
DTSTART;VALUE=DATE-TIME:20120905T090000Z
DTEND;VALUE=DATE-TIME:20120905T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2444@cern.ch
DESCRIPTION:We address the general question of what is the best statistica
l strategy to adapt in order to search efficiently for randomly located ob
jects (target sites). It is often assumed in foraging theory that the flig
ht lengths of a forager have a characteristic scale: from this assumption
Gaussian\, Rayleigh and other classical distributions with well defined va
riances have arisen. However such theories can't explain the long tailed p
ower-law distributions of flight lengths or flight times that are observed
experimentally.Here we study how the search efficiency depends on the pro
bability distribution of flight lengths taken by a forager that can detect
target sites only in its limited vicinity. We show that when target sites
are sparse and can be visited any number of times\, an inverse square pow
er-law distribution of flight lengths\, corresponding to Levy flight motio
n\, is an optimal strategy. We test the theory by analyzing experimental f
oraging data on selected insect\, mammal and bird species and find that th
ey are consistent with the predicted inverse square power-law distribution
s.\nIn the second part we will discuss a more recent work which shows that
the distribution of target sites plays a crucial role in the random searc
h problem. The main result is\, in the case of a single target site in a
bounded domain or regular patterns of targets\; in contrast to repeated st
atements in the literature\, persistent random walk can minimize the searc
h time and in that sense perform better than any Levy walk.\n\nRef: \n[1]
G M Viswanathan et al.\, Nature Letters 401\, 911 (1999). http://www.natur
e.com/nature/journal/v401/n6756/full/401911a0.html\n[2] G M Viswanathan et
al.\, Physics of life reviews\, 5 (2008) 133-150. http://www.sciencedirec
t.com/science/article/pii/S1571064508000146\n[3] V. Tejedor et al.\, PRL 1
08\, 088103 (2012). http://prl.aps.org/abstract/PRL/v108/i8/e088103\n\nhtt
ps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2444
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2444
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simulating Interesting Quantum Spin Models with Trapped Ions
DTSTART;VALUE=DATE-TIME:20120926T090000Z
DTEND;VALUE=DATE-TIME:20120926T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2478@cern.ch
DESCRIPTION:I will review recent experiments from Chris Monroe's group in
University of Maryland\, College Park\, where they implement spin models
like the Quantum Ising model with trapped ions. I will use a particular pa
per from the group\, R. Islam et. al\, Nature Communications\, 2\, 377 (20
11)\, which studies "phase transitions" in ferromagnetic quantum Ising mod
el\, to detail how spin models can be implemented with trapped ions. Beyon
d this\, I will also discuss how tunable long range interactions of both f
erro and antiferromagnetic type can be generated with these systems. Final
ly\, I will also discuss current plans to implement more interesting graph
s of couplings in the physical 1D lattice to mimic 2D systems. \n\nReferen
ces:\nR. Islam et. al\, Nature Communications 2\, 377 (2011)\,\nA. Sorense
n and K Molmer\, Phys. Rev. A 62\, 022311 (2000) ( Gives useful backgroun
d\, but couched in Quantum computation language)\nS. Korenblit et. al\, ar
Xiv:1201.0776\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?co
nfId=2478
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2478
END:VEVENT
BEGIN:VEVENT
SUMMARY:Correlations of record events as a test for heavy-tailed distribut
ions
DTSTART;VALUE=DATE-TIME:20121121T090000Z
DTEND;VALUE=DATE-TIME:20121121T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2592@cern.ch
DESCRIPTION:If a time series consists of independent\, identically distrib
uted\nrandom variables with a superimposed linear trend\, record events ar
e\npositively (negatively) correlated when the tail of the distribution\ni
s heavier (lighter) than exponential. The nature of correlations\nbetween
record events can thus\, be used to detect heavy-tailed\nbehavior in small
sets of independent random variables. The method\nconsists of converting
random subsets of the data into time series\nwith a tunable linear drift a
nd computing the resulting record\ncorrelations.\n\nReferences:\nJ. Franke
\, G. Wergen\, J. Krug\, Phys. Rev. Lett. 108\, 064101 (2012)\nG. Wergen\,
J. Franke\, and J. Krug\, J. Stat. Phys. 144\, 1206 (2011)\n\nhttps://ind
ico.tifr.res.in/indico/conferenceDisplay.py?confId=2592
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2592
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mathematics and the internet: A source of enormous confusion and g
reat potential
DTSTART;VALUE=DATE-TIME:20121127T090000Z
DTEND;VALUE=DATE-TIME:20121127T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2612@cern.ch
DESCRIPTION:There has been a lot of activity in recent years in attempting
to model complex systems like the internet\, or social networks. In 1999
\, Barabasi and Albert proposed a model (BA model) in which the internet i
s described as a growing random graph\, where new nodes are added\, and jo
ined to pre-existing nodes with a finite number of links\, with higher pro
bability of attaching to links with higher degree. This model\, called pr
eferential attachment model has generated a lot of activity (over 15000 ci
tations). In particular\, in the BA model\, the nodes have a power-law in
the degree-distribution of nodes\, and the nodes with high degree (called
hubs) are critical for connectivity of the network.\n\n In this paper\, t
he authors have argued that the BA model is based on bad analysis of data
\, and gives a description of internet that is qualitatively incorrect a
bout their predicted susceptibility to sabotage. They also propose an alte
rnative approach to modelling networks like the internet as a growing netw
ork\, engineered using heuristic optimization.\n\nReferences: W. Willinger
\, D. Alderson\, and J. C. Doyle\, Notices of the American Mathematical So
ciety\, vol. 56\, no. 5\, pp. 586-599\, 2009\n\nhttps://indico.tifr.res.in
/indico/conferenceDisplay.py?confId=2612
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2612
END:VEVENT
BEGIN:VEVENT
SUMMARY:Weakly interacting Bose gas in a random environment
DTSTART;VALUE=DATE-TIME:20121212T090000Z
DTEND;VALUE=DATE-TIME:20121212T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2644@cern.ch
DESCRIPTION:The authors discuss the effects of potential disorder and weak
interparticle repulsion on phase separation in a system of bosons. This i
s an alternate approach to the superfluid-insulator quantum phase transiti
on in dirty Boson systems.\n\nReferences: G. M. Falco\, T. Nattermann and
V. L. Pokrovsky\, Phys. Rev. B 80\, 104515 (2009)\n\nhttps://indico.tifr.r
es.in/indico/conferenceDisplay.py?confId=2644
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2644
END:VEVENT
BEGIN:VEVENT
SUMMARY: Weakly interacting Bose gas in a random environment
DTSTART;VALUE=DATE-TIME:20121226T090000Z
DTEND;VALUE=DATE-TIME:20121226T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2668@cern.ch
DESCRIPTION:The authors discuss the effects of potential disorder and weak
interparticle repulsion on phase separation in a system of bosons. This i
s an alternate approach to the superfluid-insulator quantum phase transiti
on in dirty Boson systems.\n\nReferences: G. M. Falco\, T. Nattermann and
V. L. Pokrovsky\, Phys. Rev. B 80\, 104515 (2009)\n\nhttps://indico.tifr.r
es.in/indico/conferenceDisplay.py?confId=2668
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2668
END:VEVENT
BEGIN:VEVENT
SUMMARY:Demographic noise can lead to spontaneous formation of species
DTSTART;VALUE=DATE-TIME:20130102T090000Z
DTEND;VALUE=DATE-TIME:20130102T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2677@cern.ch
DESCRIPTION:Various theoretical ecologists have studied how competition an
d differing local conditions lead to speciation\, that is\, how an initial
ly diverse population evolves into clusters of similar individuals. Past s
tudies have neglected the effect of demographic fluctuations and focused o
n the effect of the exact way in which the effect of competition decays wi
th (phenotypic) distance. In this paper\, the authors show that including
the effects of demographic noise leads to the formation of species even wh
en the functional form of the competition is not enough to induce speciati
on.\n\nReferences: T. Rogers\, A. J. McKane and A. G. Rossberg\, 2012 EPL
97 40008\nBackground: Szabó P\, Meszéna G (2006) Limiting similarity rev
isited Oikos 112(3):612–619\n\nhttps://indico.tifr.res.in/indico/confere
nceDisplay.py?confId=2677
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2677
END:VEVENT
BEGIN:VEVENT
SUMMARY:Modularity and Extreme Edges of the Internet
DTSTART;VALUE=DATE-TIME:20130206T090000Z
DTEND;VALUE=DATE-TIME:20130206T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2760@cern.ch
DESCRIPTION:The spectral properties of a diffusion process taking place on
the Internet network have studied focusing on the slowest decaying modes.
These modes identify an underlying modular structure roughly correspondin
g to individual countries. For instance\, in the slowest decaying mode the
diffusion current flows from Russia to U.S. military sites. Quantitativel
y the modular structure manifests itself in a 10 times larger participatio
n ratio of its slow decaying modes compared to a random scale-free network
. The authors have proposed to use the fraction of nodes participating in
slow decaying modes as a general measure of the modularity of a network. F
or the 100 slowest decaying modes of the Internet this fraction is ∼30%.
Finally\, they have suggested that the degree of isolation of an individu
al module can be assessed by comparing its participation in different diff
usion modes.\n\nRef: K. A. Eriksen\, I. Simonsen\, S. Maslov and K. Snep
pen\; Phys. Rev. Lett. 90\, 148701 (2003)\n\nhttps://indico.tifr.res.in/i
ndico/conferenceDisplay.py?confId=2760
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2760
END:VEVENT
BEGIN:VEVENT
SUMMARY:Popularity driven networking
DTSTART;VALUE=DATE-TIME:20130313T090000Z
DTEND;VALUE=DATE-TIME:20130313T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2841@cern.ch
DESCRIPTION:The authors investigate the growth of connectivity in a networ
k. In our model\, starting with a set of disjoint nodes\, links are added
sequentially. Each link connects two nodes\, and the connection rate gover
ning this random process is proportional to the degrees of the two nodes.
Interestingly\, this network exhibits two abrupt transitions\, both occurr
ing at finite times. The first is a percolation transition in which a gian
t component\, containing a finite fraction of all nodes\, is born. The sec
ond is a condensation transition in which the entire system condenses into
a single\, fully connected\, component. They derive the size distribution
of connected components as well as the degree distribution\, which is pur
ely exponential throughout the evolution. Furthermore\, they also present
a criterion for the emergence of sudden condensation for general homogeneo
us connection rates.\n\nRef: E. Ben-Naim and P. L. Krapivsky\, 2012 EPL 97
48003\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=28
41
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2841
END:VEVENT
BEGIN:VEVENT
SUMMARY: Interfaces of Transition Metal Oxides: A novel platform to study
correlated electrons.
DTSTART;VALUE=DATE-TIME:20130417T090000Z
DTEND;VALUE=DATE-TIME:20130417T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2925@cern.ch
DESCRIPTION:I will give a general review of transition metal oxide interfa
ces and their novel properties\, which have created a lot of excitement am
ong physicists working on strongly interacting systems. e.g. the interface
between two insulating materials can be metallic and interface between pa
ramagnetic (or antiferromagnetic) materials can be ferromagnetic. The wide
variety of phenomena has led to the idea of making "designer interfaces"
having some desired property. More specifically\, I would focus on a recen
t paper\, by Sumilan Bannerjee and others\, which tries to provide a model
for magnetism at the LaAlO3 - SrTiO3 interface and predicts a spiral magn
etic order in this case. \n\nReferences: \n1) S. Bannerjee\, O. Erten and
M. Randeria\, arXiv:1303.3275\n2) H Y Hwang et al\, Nature Materials\, 11
\, 103 (2012)\n3) J. Chakhalian\, A. J. Millis and J. Rondinelli\, Nature
Materials 11\, 92 (2012)\n\nhttps://indico.tifr.res.in/indico/conferenceDi
splay.py?confId=2925
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2925
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fluctuations of 1/f noise in systems with power law intermittency
DTSTART;VALUE=DATE-TIME:20130516T090000Z
DTEND;VALUE=DATE-TIME:20130516T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-2991@cern.ch
DESCRIPTION:Experiments on systems such as blinking quantum dots suggest t
hat 1/f noise can arise due to power law intermittency (power law switchi
ng times between microstates of a system). In such systems\, the power spe
ctrum shows large fluctuations and does not self average even for very lon
g observation times. The authors obtain the distribution of the power spec
trum for a theoretical model and suggest that this can be used to identify
whether 1/f noise in a system is due to power law intermittency. They fur
ther show that although the lower cutoff frequency of 1/f noise in the mod
el can become arbitrarily small as observation time is increased\, the pow
er spectrum remains integrable. \n\nReferences: M. Niemann\, H. Kantz\, E.
Barkai\, Phys. Rev. Lett. 110\, 140603 (2013)\n\nhttps://indico.tifr.res.
in/indico/conferenceDisplay.py?confId=2991
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=2991
END:VEVENT
BEGIN:VEVENT
SUMMARY:Voter models with conserved dynamics
DTSTART;VALUE=DATE-TIME:20130718T090000Z
DTEND;VALUE=DATE-TIME:20130718T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3100@cern.ch
DESCRIPTION:The authors propose a modified voter model with locally conser
ved magnetization and investigate its phase ordering dynamics in two dimen
sions in numerical simulations. Imposing a local constraint on the dynamic
s has the surprising effect of speeding up the phase ordering process. The
system is shown to exhibit a scaling regime characterized by algebraic do
main growth\, at odds with the logarithmic coarsening of the standard vote
r model. Their analysis exposes unexpected complexity in the phase orderin
g dynamics without thermodynamic potential.\n\nReferences: Fabio Caccioli\
, Luca Dall’Asta\, Tobias Galla\, and Tim Rogers\, Phys. Rev. E 87\, 052
114 (2013)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confI
d=3100
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3100
END:VEVENT
BEGIN:VEVENT
SUMMARY: Noisy quantum phase transitions
DTSTART;VALUE=DATE-TIME:20130808T090000Z
DTEND;VALUE=DATE-TIME:20130808T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3135@cern.ch
DESCRIPTION:I will describe various effects of a nonequilibrium 1/f noise
source on the quantum phase transition in a Josephson junction.\n\nReferen
ces:\n1. E. D. Torre\, E. Demler\, T. Giamarchi\, and E. Altman\, Nat. Ph
ys. 6\, 806 (2010).\n2. E. D. Torre\, E. Demler\, T. Giamarchi\, and E. Al
tman\, Phys. Scr. T151 (2012) 014026\n\nhttps://indico.tifr.res.in/indico/
conferenceDisplay.py?confId=3135
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3135
END:VEVENT
BEGIN:VEVENT
SUMMARY:Trajectory Phase Transitions in the Glauber-Ising Chain
DTSTART;VALUE=DATE-TIME:20130822T090000Z
DTEND;VALUE=DATE-TIME:20130822T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3159@cern.ch
DESCRIPTION:Using the generating function of the time-integrated energy fo
r the 1D Glauber-Ising model\, the authors study phase transitions between
between paramagnetic and ferromagnetic space-time trajectories. They had
earlier used this approach to study the phase transitions in the East mode
l of a glass-former.\n\nReferences:\nJ. M. Hickey\, C. Flindt and J. P. Ga
rrahan\, Phys. Rev. E 88\, 012119 (2013)\nD. A. Ivanov and A. G. Abanov\,
Phys. Rev. E 87\, 022114 (2013)\n\nhttps://indico.tifr.res.in/indico/confe
renceDisplay.py?confId=3159
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3159
END:VEVENT
BEGIN:VEVENT
SUMMARY:hase Coexistence in Driven One-Dimensional Transport
DTSTART;VALUE=DATE-TIME:20130905T090000Z
DTEND;VALUE=DATE-TIME:20130905T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3180@cern.ch
DESCRIPTION:The authors have studied a one-dimensional totally asymmetric
exclusion process with random particle attachments and detachments in the
bulk. The resulting dynamics leads to unexpected stationary regimes for l
arge but finite systems. Such regimes are characterized by a phase coexist
ence of low and high density regions separated by domain walls. They have
used a mean-field approach to interpret the numerical results obtained by
Monte Carlo simulations\, and predicted the phase diagram of this nonconse
rved dynamics in the thermodynamic limit.\n\nReferences:\n\nA. Parmeggiani
\, T. Franosch and E. Frey\; PRL 90\, 086601 (2003)\nA. Parmeggiani\, T. F
ranosch and E. Frey\; Physical Review E 70\, 046101 (2004)\n\nhttps://indi
co.tifr.res.in/indico/conferenceDisplay.py?confId=3180
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3180
END:VEVENT
BEGIN:VEVENT
SUMMARY:Localization of interacting fermions at high temperature
DTSTART;VALUE=DATE-TIME:20130919T090000Z
DTEND;VALUE=DATE-TIME:20130919T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3209@cern.ch
DESCRIPTION:The authors propose the existence of a many body localized sta
te in a high temperature regime at strong disorder and interactions. To th
is effect they study a one-dimensional lattice model of interacting spinle
ss fermions in a random potential. \n\nReferences:\n1. V Oganesyan\, David
Huse\, Localization of interacting fermions at high temperature\, PRB 75\
, 155111 (2007)\n\n2. Subroto Mukherjee\, V Oganesyan\, David Huse\, Stat
istical theory of transport by strongly interacting lattice fermions\, PRB
73\, 035113 (2006)\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay
.py?confId=3209
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3209
END:VEVENT
BEGIN:VEVENT
SUMMARY:RMT for spin conductance
DTSTART;VALUE=DATE-TIME:20130926T090000Z
DTEND;VALUE=DATE-TIME:20130926T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3230@cern.ch
DESCRIPTION:**Outline random matrix theory notions for conductance without
proof.\n\n**Describe without algebra what can be done in this case and in
several related cases (analytical results for large channel-number asympt
otics).\n\n**Describe the formulation of the spin conductance in this lang
uage\, and how we are stuck when it comes to calculating large-channel num
ber asymptotics. Ask audience to think of possible alternate strategies.\n
\n**Outline the only success we have had\, which is Vikram's method of usi
ng L'hospital rule type manipulations to get very answers for several fini
te N.\n\n**Describe some made-up quantities for which we can do the calcul
ation and ask the audience if they know of contexts in which such made-up
quantities are the natural objects.\n\nhttps://indico.tifr.res.in/indico/c
onferenceDisplay.py?confId=3230
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3230
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase Transitions in the Long-range Quantum Ising Model
DTSTART;VALUE=DATE-TIME:20131010T090000Z
DTEND;VALUE=DATE-TIME:20131010T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3253@cern.ch
DESCRIPTION:I will review the problem of a quantum Ising model with long r
ange anti-ferromagnetic interactions\, which scale as 1/rα in 1D. The pha
se transition from ordered to paramagnetic in a standard short range quant
um Ising model occurs when the magnetic field is of the order of the excha
nge coupling\, and is perhaps the most studied example of a quantum phase
transition. In this talk\, I will argue that there is a possibility that t
he antiferromagnetic order may be destroyed at a lower field by a differen
t (possibly first order) mechanism. The forum will then be open for sugges
tions on the best way to study this problem.\n\nhttps://indico.tifr.res.in
/indico/conferenceDisplay.py?confId=3253
LOCATION:Colaba Campus 304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3253
END:VEVENT
BEGIN:VEVENT
SUMMARY:Heavy solitons in a fermionic superfluid?
DTSTART;VALUE=DATE-TIME:20131024T090000Z
DTEND;VALUE=DATE-TIME:20131024T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3268@cern.ch
DESCRIPTION:The title of the talk (apart from the question mark) is borrow
ed from the paper by Yefsah et. al. (Nature 499\, 426-430 (2013)\, 10.1038
/nature12338) where experimental evidence for anomalously slow moving soli
tons in ultracold trapped fermionic gases is presented. Recent papers (arx
iv.org/1307.3717)\, (arxiv.org/abs/1308.1691)\, (arxiv.org/abs/1309.7012)
question this interpretation and build up the case that the slow dynamics
are a consequence of the formation of a different kind of topological obje
ct -- vortex rings.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay
.py?confId=3268
LOCATION:Colaba Campus
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3268
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collapse transition in directed branched polymers
DTSTART;VALUE=DATE-TIME:20140116T100000Z
DTEND;VALUE=DATE-TIME:20140116T110000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3410@cern.ch
DESCRIPTION:In a recent paper\, M. Knezevic and D. Knezevic [J. Chem. Phys
. 139\, 164904 (2013)] have studied numerically the collapse transition in
directed branched polymers. This seems to show a rather anomalously large
deviations from expected scaling behaviour\, with numerically observed va
lues of correlation length exponent $\\nu$ taking two different values on
two sides of transition. The possibility of $\\nu \\neq \\nu'$ was discuss
ed in the early days of critical phenomena\, but the standard linearized R
G analysis gives ν = ν'.\n\nhttps://indico.tifr.res.in/indico/conferenc
eDisplay.py?confId=3410
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3410
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collapse transition in directed branched polymers
DTSTART;VALUE=DATE-TIME:20140130T103000Z
DTEND;VALUE=DATE-TIME:20140130T113000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3443@cern.ch
DESCRIPTION:In a recent paper\, M. Knezevic and D. Knezevic [J. Chem. Phys
. 139\, 164904 (2013)] have studied numerically the collapse transition in
directed branched polymers. This seems to show a rather anomalously large
deviations from expected scaling behaviour\, with numerically observed va
lues of correlation length exponent $\\nu$ taking two different values on
two sides of transition. The possibility of $\\nu \\neq \\nu'$ was discuss
ed in the early days of critical phenomena\, but the standard linearized R
G analysis gives ν = ν'.\n\nhttps://indico.tifr.res.in/indico/conferenc
eDisplay.py?confId=3443
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3443
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phase diagram for brittle fracture in the disorder-system size pla
ne
DTSTART;VALUE=DATE-TIME:20140220T090000Z
DTEND;VALUE=DATE-TIME:20140220T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3491@cern.ch
DESCRIPTION:The authors present a unified theory of fracture in disordered
brittle media using a renormalization group based approach\, which yields
a phase diagram in which the percolation fixed point\, expected for infin
ite disorder\, is unstable for finite disorder and flows to a zero-disorde
r nucleation-type fixed point\, thus showing that fracture has a mixed fir
st order and continuous character. In a region of intermediate disorder an
d finite system sizes\, they predict a crossover with mean-field avalanche
scaling.\n\nReferences: \n[1] A. Shekhawat\, S. Zapperi\, and J. P. Sethn
a\, Phys. Rev. Lett. 110\, 185505 (2013)\n[2] E. Bouchard\, The Breaking o
f Brittle Materials\, Physics 6\, 50 (2013)\n[3] A. A. Moreira\, C. L. N.
Oliveira\, A. Hansen\, N. A. M. Araújo\, H. J. Herrmann\, and J. S. Andra
de Jr.\, Phys. Rev. Lett. 110\, 185505 (2013)\n\nhttps://indico.tifr.res.i
n/indico/conferenceDisplay.py?confId=3491
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3491
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum Monte Carlo studies of spinons in one-dimensional spin sys
tems
DTSTART;VALUE=DATE-TIME:20140619T090000Z
DTEND;VALUE=DATE-TIME:20140619T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-3738@cern.ch
DESCRIPTION:Outline (Abstract from the paper):\n\nObserving constituent pa
rticles with fractional quantum numbers in confined and deconfined states
is an interesting and challenging problem in quantum many-body physics. He
re we further explore a computational scheme [Y. Tang and A. W. Sandvik\,
Phys. Rev. Lett. {\\bf 107}\, 157201 (2011)] based on valence-bond quantum
Monte Carlo simulations of quantum spin systems. Using several different
one-dimensional models\, we characterize S=1/2 spinon excitations using th
e spinon size and confinement length (the size of a bound state). The spin
ons have finite size in valence-bond-solid states\, infinite size in the c
ritical region\, and become ill-defined in the N\\'eel state. We also veri
fy that pairs of spinons are deconfined in these uniform spin chains but b
ecome confined upon introducing a pattern of alternating coupling strength
s (dimerization) or coupling two chains (forming a ladder). In the dimeriz
ed system an individual spinon can be small when the confinement length is
large---this is the case when the imposed dimerization is weak but the gr
ound state of the corresponding uniform chain is a spontaneously formed va
lence-bond-solid (where the spinons are deconfined). Based on our numerica
l results\, we argue that the situation \\lambda \\ll \\Lambda is associat
ed with weak repulsive short-range spinon-spinon interactions. In principl
e both the length-scales can be individually tuned from small to infinite
(with \\lambda \\le \\Lambda) by varying model parameters. In the ladder s
ystem the two lengths are always similar\, and this is the case also in th
e dimerized systems when the corresponding uniform chain is in the critica
l phase. In these systems the effective spinon-spinon interactions are pur
ely attractive and there is only a single large length scale close to crit
icality\, which is reflected in the standard spin correlations as well as
in the spinon characteristics.\n\nReferences:\nhttp://arxiv.org/abs/1404.6
697\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3738
LOCATION:Colaba Campus A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=3738
END:VEVENT
BEGIN:VEVENT
SUMMARY:Characterizing eigenstate thermalization via measures in the Fock
space of operators
DTSTART;VALUE=DATE-TIME:20160711T090000Z
DTEND;VALUE=DATE-TIME:20160711T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-5107@cern.ch
DESCRIPTION:A common question of interest in quantum statistical mechanics
\, especially in the context of eigenstate thermalization and many-body lo
calization\, is\, ``how well can two operators or states be distinguished
using measurements on just a few sites at a time?" In this work\,we define
two easily computable measures -- he ``n-weight" and the ``n-distinguis
hability“ that quantify the difference between two operators when given
access to strictly n-site measurements. We then define a construction that
allows viewing a general operator or many-body state as a single particle
wavefunction on a complicated graph. Interestingly\, the two measures acq
uire intuitive\, geometric interpretations on this graph. The utility of t
he mapping to the graph will be demonstrated in the context of eigenstate
thermalization\, and related ongoing work on distinguishing between variou
s quantum statistical phases will be mentioned.\n\nhttps://indico.tifr.res
.in/indico/conferenceDisplay.py?confId=5107
LOCATION: AG69
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=5107
END:VEVENT
BEGIN:VEVENT
SUMMARY:Strange correlations in Symmetry Protected Topological phases
DTSTART;VALUE=DATE-TIME:20180607T090000Z
DTEND;VALUE=DATE-TIME:20180607T100000Z
DTSTAMP;VALUE=DATE-TIME:20230330T121919Z
UID:indico-event-6465@cern.ch
DESCRIPTION:Due to the lack of long range entanglement and absence of any
local order\, identifying a Symmetry Protected Topological phase in an arb
itrary Hamiltonian with competing interactions remains a challenge. Recent
ly\, a “strange correlator” has been proposed as a direct probe for th
e topological character of interacting Symmetry Protected Topological (SPT
) phases. Using projective quantum Monte Carlo\, we are able to directly a
ccess the strange correlator in a variety of phases\, as well as to examin
e its critical behavior at the quantum phase transition between trivial an
d non-trivial symmetry protected topological phases. We demonstrate the un
derlying principles of the strange correlator within the context of the S=
1 Heisenberg model with an easy-plane single ion anisotropy. We show that
the evolution of the ground state from the topologically non-trivial Halda
ne phase to the topologically trivial quantum paramagnetic state with incr
easing single ion anisotropy can be accurately tracked by the strange corr
elator. Next we go on to verify the topological nature of two-leg and thre
e-leg spin-1 Heisenberg antiferromagnetic ladders. This demonstrates the p
ower of the strange correlator in distinguishing between trivial and non-t
rivial symmetry protected topological phases.\n\nhttps://indico.tifr.res.i
n/indico/conferenceDisplay.py?confId=6465
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6465
END:VEVENT
END:VCALENDAR