Stability and Excitations of Spontaneous Vortices in Homogeneous   Polariton Condensates
  We study the dynamics of spontaneously formed vortices in homogeneous microcavity-polariton condensates (MPCs). We find that vortices are stable and appear spontaneously without stirring or rotating MPCs. The dip of the vortex core contains some background of reservoir polaritons and the visibility of a vortex is increasing with respect to the pump strength. The vortex radius is inversely proportional to the square root of the condensate density. Excitation energies of vortices at high and low pump powers are finite and zero, respectively. Vortices at low pump powers exhibit the short lifetime. 
Ting-Wei Chen, Szu-Cheng Cheng, and Wen-Feng Hsieh
cond-mat.quant-gas