Interaction-shaped vortex-antivortex lattices in polariton fluids

Topological defects such as quantized vortices are one of the most striking manifestations of the superfluid nature of Bose-Einstein condensates and typical examples of quantum mechanical phenomena on a macroscopic scale. Here we demonstrate the formation of a lattice of vortex-antivortex pairs and study its properties in the nonlinear regime at high polariton-density where polariton-polariton interactions dominate the behavior of the system. In this work first we demonstrate that the array of vortex-antivortex pairs can be generated in a controllable way in terms of size of the array and in terms of size and shape of its fundamental unit cell. Then we demonstrate that polariton-polariton repulsion can strongly deform the lattice unit cell and determine the pattern distribution of the vortex-antivortex pairs, reaching a completely new behavior with respect to geometrically generated vortex lattices whose shape is determined only by the geometry of the system. © 2014 American Physical Society.