Purity oscillations in Bose-Einstein condensates with balanced gain and loss

TL;DR

This paper investigates the many-particle dynamics of PT-symmetric Bose-Einstein condensates with balanced gain and loss, revealing periodic purity oscillations that influence interference contrast beyond mean-field predictions.

Contribution

It introduces a many-particle master equation approach to study purity oscillations in PT-symmetric BECs, highlighting phenomena not captured by mean-field models.

Findings

Purity periodically drops and recovers in the condensate.

Purity oscillations affect interference contrast.

Mean-field approximation cannot describe these purity dynamics.

Abstract

In this work we present a new generic feature of PT-symmetric Bose-Einstein condensates by studying the many-particle description of a two-mode condensate with balanced gain and loss. This is achieved using a master equation in Lindblad form whose mean-field limit is a PT-symmetric Gross-Pitaevskii equation. It is shown that the purity of the condensate periodically drops to small values but then is nearly completely restored. This has a direct impact on the average contrast in interference experiments which cannot be covered by the mean-field approximation, in which a completely pure condensate is assumed.