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 controlable 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 systemThis work has been partially funded by the Quandyde project of the ANR France, by the PO-LATOM ESF Research Network Program and by the CLERMONT4 Network Progam. FMM acknowledges - financial support from the programs Ramon y Cajal and Intelbiomat (ESF) and MHS from the EPSRC (grant EP/I028900/1). A. B. is member of Institut Universitaire de France (IUF