Probing supersolidity through excitations in a spin-orbit-coupled Bose-Einstein condensate

Spin-orbit coupling of Bose-Einstein condensates (BEC) creates optically dressed states with an engineered dispersion relation and momentum-dependent scattering properties. These systems host a supersolid phase of matter, the so-called stripe phase. The peculiar excitation spectrum of the stripe phase, a definite footprint of its supersolidity, has so far remained out of experimental reach. In my talk I will present our direct observations of both superfluid and crystal excitations in the stripe phase [1]. We investigate superfluid hydrodynamics of the system and reveal the particle flow between stripes caused by the Goldstone mode. We furthermore show the dynamic oscillation of the stripe spacing, demonstrating that the system possesses a compressible crystalline structure. Our results establish spin-orbit-coupled supersolids as a platform of choice to investigate supersolidity and its rich dynamics.

[1] Chisholm et al. arXiv:2412.13861 (2024)