Non-equilibrium dynamics: Studies of reflection of Bose-Einstein condensates

TL;DR

This paper revisits the classical field approach to non-equilibrium Bose-Einstein condensate dynamics, emphasizing the importance of quantum noise and thermal effects in accurately modeling condensate reflection experiments.

Contribution

It introduces a stochastic classical field method that incorporates quantum noise and thermal effects, improving the modeling of condensate reflection from surfaces.

Findings

Quantum noise significantly affects reflection dynamics.

Thermal effects can be incorporated into the classical field model.

The approach aligns well with recent experimental results.

Abstract

The study of the non-equilibrium dynamics in Bose-Einstein condensed gases has been dominated by the zero-temperature, mean field Gross-Pitaevskii formalism. Motivated by recent experiments on the reflection of condensates from silicon surfaces, we revisit the so-called {\em classical field} description of condensate dynamics, which incorporates the effects of quantum noise and can also be generalized to include thermal effects. The noise is included in a stochastic manner through the initial conditions. We show that the inclusion of such noise is important in the quantitative description of the recent reflection experiments.