Erlangen 2022 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 57: Quantum Gases II

Q 57.2: Poster

Thursday, March 17, 2022, 16:30–18:30, P

Emerging long-range magnetic phenomena in a quantum gas coupled to a cavity — •Nicola Reiter, Rodrigo Rosa-Medina, Fabian Finger, Francesco Ferri, Tobias Donner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland

Dissipative and coherent processes are at the core of the evolution of many-body systems. Their interplay can lead to new phases of matter and complex non-equilibrium dynamics. However, probing these phenomena microscopically in a setting of controllable coherent and dissipative couplings proves challenging.

We realize such a system using a ⁸⁷Rb spinor Bose-Einstein condensate (BEC) strongly coupled to a single optical mode of a lossy cavity. Two transverse laser fields incident on the BEC allow for cavity-assisted Raman transitions between different motional states of two neighboring spin levels. Adjusting the drive imbalance controls coherent dynamics and dissipation, with the appearance of a dissipation-stabilized phase and bistability. By characterizing the properties of the underlying polariton modes, we give a microscopic interpretation of our observations.

Moreover, we realize dynamical superradiant currents in a spin-textured lattice in momentum space. Real-time, frequency-resolved measurements of the leaking cavity field allow us to locally resolve individual tunneling events and cascaded dynamics. Together, our results open new avenues for investigating spin-orbit coupling in dissipative settings and dynamical gauge fields in driven-dissipative settings.