Stochastic Gross-Pitaevskii Equation for the Dynamical Thermalization of Bose-Einstein Condensates

TL;DR

This paper introduces a stochastic Gross-Pitaevskii equation framework to model energy relaxation in nonequilibrium Bose-Einstein condensates, incorporating thermal bath interactions, particle interactions, and dynamic effects, with applications to microcavity exciton polaritons.

Contribution

It develops a comprehensive stochastic model for nonequilibrium condensate dynamics, including thermalization, particle interactions, and external driving, applied to solid-state systems.

Findings

Successfully models energy relaxation in Bose-Einstein condensates.

Reproduces experimental observations in microcavity exciton polaritons.

Provides a versatile framework for nonequilibrium condensate studies.

Abstract

We present a theory for the description of energy relaxation in a nonequilibrium condensate of bosonic particles. The approach is based on coupling to a thermal bath of other particles (e.g., phonons in a crystal, or noncondensed atoms in a cold atom system), which are treated with a Monte Carlo type approach. Together with a full account of particle-particle interactions, dynamic driving, and particle loss, this offers a complete description of recent experiments in which Bose-Einstein condensates are seen to relax their energy as they propagate in real space and time. As an example, we apply the theory to the solid-state system of microcavity exciton polaritons, in which nonequilibrium effects are particularly prominent.