Emerging long-range magnetic phenomena in a quantum gas coupled to a cavity

Fabian Finger

ETH Zurich -

The interplay of dissipative and coherent processes is at the core of the evolution of many-body systems. However, finding a well-defined, controllable setting often proves challenging. In our setup, we realize such a system using a 87Rb spinor Bose-Einstein condensate (BEC) strongly coupled to an optical cavity. Two transverse laser fields incident on the BEC allow for cavity-assisted Raman transitions between different motional states of two spin levels. Imbalancing the drives enables us to tune the competition between coherent dynamics and dissipation, giving rise to a dissipation-stabilized phase. We relate the phases to the properties of the underlying polariton modes. Moreover, we present collective spin dynamics in a cavity via superradiant Raman scattering. We leverage the leaking photon field to gain real-time, non-destructive readout of the system’s dynamics. Our results open new avenues for investigating non-Hermitian systems, and transport phenomena in light-matter systems.

Related paper: https://arxiv.org/abs/2104.12782