  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.
