Observation of a supersolid phase in a spin-orbit coupled exciton-polariton Bose-Einstein condensate

Abstract

In Bose-Einstein condensates, spin-orbit coupling (SOC) produces supersolidity. It is a peculiar state of matter, which, in addition to the superfluid behavior, shows periodic density modulation typical for crystals. Here, we report the fabrication of an original type of optical microcavity, allowing the achievement of room-temperature supersolidity for a quantum fluid of light. The microcavity is filled with a nematic liquid crystal (LC) and two layers of the organic polymer methyl-substituted ladder-type poly( p -phenylene) (MeLPPP) hosting exciton resonances. We demonstrate exciton-polariton condensation in the two distinct degenerate minima of the dispersion created by the LC-induced Rashba-Dresselhaus SOC. The condensate real-space distribution shows density stripes located randomly from one condensate realization to another despite the presence of a random disorder potential. This demonstrates the immunity of stripes against disorder and the spontaneous breaking of translational invariance. We also report the random appearance of vortices, another feature of superfluids.