Single vortex-antivortex pair in an exciton polariton condensate

TL;DR

This paper demonstrates a novel experimental method to identify a single vortex-antivortex pair in a two-dimensional exciton polariton condensate, providing insights into superfluid phase stabilization mechanisms.

Contribution

It introduces an experimental technique using Michelson interferometry to detect vortex-antivortex pairs in exciton polariton condensates, a system previously inaccessible for such studies.

Findings

Successful identification of a vortex-antivortex pair in the condensate.

The pair formation is influenced by inhomogeneous pumping.

Numerical models show different dynamics compared to atomic condensates.

Abstract

In a homogeneous two-dimensional system at non-zero temperature, although there can be no ordering of infinite range, a superfluid phase is predicted for a Bose liquid. The stabilization of phase in this superfluid regime is achieved by the formation of bound vortex-antivortex pairs. It is believed that several different systems share this common behaviour, when the parameter describing their ordered state has two degrees of freedom, and the theory has been tested for some of them. However, there has been no direct experimental observation of the phase stabilization mechanism by a bound pair. Here we present an experimental technique that can identify a single vortex-antivortex pair in a two-dimensional exciton polariton condensate. The pair is generated by the inhomogeneous pumping spot profile, and is revealed in the time-integrated phase maps acquired using Michelson interferometry, which show that the condensate phase is only locally disturbed. Numerical modelling based on open dissipative Gross-Pitaevskii equation suggests that the pair evolution is quite different in this non-equilibrium system compared to atomic condensates. Our results demonstrate that the exciton polariton condensate is a unique system for studying two-dimensional superfluidity in a previously inaccessible regime.