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

TL;DR

This paper reports the first observation of a room-temperature supersolid phase in a spin-orbit coupled exciton-polariton Bose-Einstein condensate within a specially fabricated microcavity filled with liquid crystal and organic polymers, demonstrating superfluidity and spontaneous translational symmetry breaking.

Contribution

It introduces a novel microcavity setup enabling room-temperature supersolidity in light-based quantum fluids, with experimental evidence of density stripes and vortices.

Findings

Observation of density stripes indicating supersolidity.

Demonstration of superfluidity via vortex formation.

Room-temperature realization of a supersolid phase.

Abstract

In Bose-Einstein condensates (BEC), spin-orbit coupling (SOC) produces supersolidity. It is a peculiar state of matter, which, in addition to the superfluid behaviour shows periodic density modulation typical for crystals. Here, we report the fabrication of a new type of optical microcavity allowing to achieve 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 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 (RD) 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 (that is, superfluidity) and the spontaneous breaking of translational invariance. We also report the random appearance of vortices via the Kibble-Zurek mechanism, another smoking gun of superfluidity.