Oscillating vorticity in single ring exciton polariton condensates

We study annular flows of exciton polaritons in exciton polariton condensates emerging in cylindrical optical micropillar cavities under the spatially localised non-resonant laser pumping. Annular flows indicate nonzero vorticity of the polariton condensate associated with the appearance of polariton vortices around the center of the micropillar. We report an experimental observation of single ring shaped condensates in the regime of vorticity oscillating in time. We reproduce the vorticity oscillations numerically and reveal possible control parameters for manipulating by the oscillation period.