  Quantised vortices are remarkable manifestations on a macroscopic scale of
the coherent nature of quantum fluids, and the study of their properties is of
fundamental importance for the understanding of this peculiar state of matter.
Cavity-polaritons, due to their double light-matter nature, offer a unique
controllable environment to investigate these properties. In this work we
theoretically investigate the possibility to deterministically achieve the
annihilation of a vortex with an antivortex through the increase of the
polariton density in the region surrounding the vortices. Moreover we
demonstrate that by means of this mechanism an array of vortex-antivortex pairs
can be completely washed out.
