Self-ordered supersolid phase beyond Dicke superradiance in a ring cavity

TL;DR

This paper reports the discovery of a self-ordered supersolid phase with a gapless Goldstone mode in a ring cavity, revealing new long-lived supersolid states driven by dynamical spin-orbit coupling.

Contribution

It demonstrates a novel self-ordered supersolid phase with a gapless mode, extending understanding beyond Dicke superradiance in optical cavities.

Findings

Observation of a gapless Goldstone mode in the supersolid phase

Identification of a superradiant anti-Tavis-Cummings phase transition

Potential for long-lived supersolid matter in optical cavities

Abstract

The supersolid phase characterized by the superfluid and long-range spatial periodicity of crystalline order is central to many branches of science ranging from condensed matter physics to ultracold atomic physics. Here we study a self-ordered checkerboard supersolid phase originating from dynamical spin-orbit coupling for a transversely pumped atomic Bose-Einstein condensate trapped in a ring cavity, corresponding to a superradiant anti-Tavis-Cummings phase transition. In particular, an undamped gapless Goldstone mode is observed in contrast to the experimentally realized lattice supersolid with a gapped roton mode for Dicke superradiance. This zero energy mode reveals the rigidity of the self-ordered superradiant phase, which spontaneously breaks a continuous translational symmetry. Our work will highlight the significant opportunities for exploring long-lived supersolid matter by utilizing dynamical spin-orbit coupling in controllable optical cavities.