Number-conserving master equation theory for a dilute Bose-Einstein condensate

TL;DR

This paper develops a number-conserving quantum master equation framework to describe the formation of a Bose-Einstein condensate, capturing the dynamics and equilibrium properties of the condensate in a dilute, weakly interacting atomic system.

Contribution

It introduces a novel master equation approach that conserves particle number and accounts for all two-body interactions during condensate formation.

Findings

Numerical monitoring of condensate particle number distribution.

Derivation of a condition for the equilibrium Gibbs-Boltzmann state.

Validation of the theory for dilute, weakly interacting Bose gases.

Abstract

We describe the transition of $N$ weakly interacting atoms into a Bose-Einstein condensate within a number-conserving quantum master equation theory. Based on the separation of time scales for condensate formation and non-condensate thermalization, we derive a master equation for the condensate subsystem in the presence of the non-condensate environment under the inclusion of all two body interaction processes. We numerically monitor the condensate particle number distribution during condensate formation, and derive a condition under which the unique equilibrium steady state of a dilute, weakly interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal state of $N$ non-interacting atoms.