Vortex-antivortex pair dynamics in an exciton-polariton condensate
  The study of superfluid and Berezinskii-Kosterlitz-Thouless phases in exciton-polaritons requires an understanding of vortex dynamics in a dissipative unconfined condensate. In this article we study the motion of dynamic vortex-antivortex pairs and show that vortex pair stability defined as ordered motion as opposed to rapid separation or recombination is the result of balance between dissipative velocities in the condensate and interaction with thermal polaritons. The addition of a trapping potential is further shown to considerably enhance the lifetime of a single vortex pair in this system. These investigations have important consequences for interpretation of recent results and future investigations of two-dimensional superfluid phases in polariton condensates. 
M. D. Fraser, G. Roumpos and Y. Yamamoto
cond-mat.quant-gas