Astronomy and Astrophysics Seminars

Fluctuating gravitational field as an explanation for quantum decoherence: its implication and detection

by Ms. Sayantani Bera, (Dept. of Astronomy & Astrophysics, Tata Institute of Fundamental Resear)

Tuesday, March 21, 2017 from to (Asia/Kolkata)
at DAA ( A269 )
The theory of quantum mechanics, despite being highly successful, is plagued with

foundational issues such as the “measurement problem”. Understanding the process of

“measurement” and the random collapse of the wavefunctions from a more profound

perspective than the standard Copenhagen picture have been one of the major aims in

foundational quantum mechanics. Possibilities that the wavefunction collapse is a

manifestation of the non-standard coupling of the quantum particles with the background

gravitational field have also been explored in this context. In this talk, I will focus on one

such proposal called the “Schrodinger-Newton scheme” in the semi-classical theory of

gravity. This theory deals with the effect of self-gravity of a quantum particle on its

wavefunction evolution leading to a spontaneous collapse. However, this is a deterministic

theory and in order to account for the random outcomes one has to introduce stochasticity

in the evolution equation. I will discuss possible ways to introduce stochasticity in the

dynamics by considering separately an external stochastic gravity background and by taking

into account the higher order fluctuation terms to the Schrodinger-Newton equation itself. I

will derive the “decoherence time” in these two cases and show that they match with the

previously known “Diosi-Penrose” criterion, which might be an indication of a universal

scale at which the interplay of gravity and quantum mechanics becomes important. Lastly, I

will briefly talk about scenarios where such effects can be experimentally detected.