Hannover 2016 – scientific programme

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A: Fachverband Atomphysik

A 32: Ultra-cold atoms, ions and BEC III (with Q)

A 32.2: Talk

Thursday, March 3, 2016, 11:15–11:30, f107

Purity oscillations in Bose-Einstein condensates with balanced gain and loss — Dennis Dast, Daniel Haag, •Holger Cartarius, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany

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’s single-particle density matrix periodically drops to small values but then is nearly completely restored. This indicates that during the oscillations the particles leave the single-particle orbital of the condensed phase and return afterwards to an almost perfect mean-field state. We show that this has a direct impact on the average contrast in interference experiments which periodically vanishes and recurs.