Bose-Einstein condensate in a double-well potential as an open quantum system

TL;DR

This paper investigates the dynamics of a Bose-Einstein condensate in a double-well potential, focusing on how dissipation and measurement influence coherence and population imbalance, revealing rapid decoherence but potential coherence restoration through measurements.

Contribution

It introduces a model of a BEC in a double-well as an open quantum system with dissipation and shows how measurement can recover coherence despite decoherence.

Findings

Self-locked population imbalance decays due to dissipation.

Spontaneous symmetry breaking states decohere rapidly.

Fast measurement of relative phase can restore matter wave coherence.

Abstract

We study the dynamics of a Bose-Einstein condensate in a double-well potential in the two-mode approximation. The dissipation of energy from the condensate is described by the coupling to a thermal reservoir of non-condensate modes. As a consequence of the coupling the self-locked population imbalance in the macroscopic quantum self-trapping decays away. We show that a coherent state predicted by spontaneous symmetry breaking is not robust and decoheres rapidly into a statistical mixture due to the interactions between condensate and non-condensate atoms. However, via stochastic simulations we find that with a sufficiently fast measurement rate of the relative phase between the two wells the matter wave coherence is established even in the presence of the decoherence.