# Heidelberg 2015 – wissenschaftliches Programm

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# A: Fachverband Atomphysik

## A 15: Ultra-cold atoms, ions and BEC II (with Q)

### A 15.8: Vortrag

### Dienstag, 24. März 2015, 16:15–16:30, C/HSW

**Quantum master equation for a BEC with balanced gain and loss** — •Dennis Dast, Daniel Haag, Holger Cartarius, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart

BECs with balanced gain and loss have been extensively studied in the
mean-field limit using a non-Hermitian but *PT*-symmetric
Gross-Pitaevskii equation. However, a microscopic description is desirable
since the only physical process capable of describing a gain and loss of the
condensate’s wave function is the injection and removal of single particles. We
present a quantum master equation in Lindblad form whose mean-field limit is a
*PT*-symmetric Gross-Pitaevskii equation. The master equation
supports the characteristic properties of *PT*-symmetric systems such
as the existence of stationary states even for a relatively small number of
particles. Furthermore it allows us to investigate many-particle effects of
systems with balanced gain and loss which are not accessible in the mean-field
limit.