Noise-induced transition from superfluid to vortex state in two-dimensional nonequilibrium polariton condensates -- semi-analytical treatment

TL;DR

This paper presents a semi-analytical model for the noise-induced superfluid to vortex transition in nonequilibrium polariton condensates, aligning well with numerical results and relevant for microcavity polariton experiments.

Contribution

It introduces a semi-analytical approach to determine the BKT-like transition point in nonequilibrium condensates using a noisy Gross-Pitaevskii equation, incorporating nonlinear corrections.

Findings

Critical noise strength increases with losses.

Transition point approaches equilibrium BKT in certain regimes.

Losses stabilize the ordered phase.

Abstract

We develop a semi-analytical description for the Berezinskii-Kosterlitz-Thouless (BKT) like phase transition in nonequilibrium Bose-Einstein condensates. Our theoretical analysis is based on a noisy generalized Gross-Pitaevskii equation. Above a critical strength of the noise, spontaneous vortex-antivortex pairs are generated. We provide a semi-analytical determination of the transition point based on a linearized Bogoliubov analysis, to which some nonlinear corrections are added. We present two different approaches that are in agreement with our numerical calculations in a wide range of system parameters. We find that for small losses and not too small energy relaxation, the critical point approaches that of the equilibrium BKT transition. Furthermore, we find that losses tend to stabilize the ordered phase: keeping the other parameters constant and increasing the losses leads to a higher critical noise strength for the spontaneous generation of vortex-antivortex pairs. Our theoretical analysis is relevant for experiments on microcavity polaritons.