SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 26: Quantum Gases: Bosons III

Q 26.8: Talk

Wednesday, March 8, 2023, 12:45–13:00, E214

Condensation and Thermalization of an Easy-Plane Ferromagnet in a Spinor Bose Gas — •Maximilian Prüfer², Daniel Spitz³, Stefan Lannig¹, Helmut Strobel¹, Jürgen Berges³, and Markus K. Oberthaler¹ — ¹Kirchhoff-Institute for Physics, Heidelberg, Germany — ²Vienna Center for Quantum Science and Technology, Vienna, Austria — ³Institute for Theoretical Physics, Heidelberg, Germany

Bose-Einstein condensates are ideally suited to investigate dynamical phenomena emerging in the many-body limit, such as the build-up of long-range coherence, superfluidity or spontaneous symmetry breaking. We study the thermalization dynamics of an easy-plane ferromagnet in a homogeneous one-dimensional spinor Bose gas of ⁸⁷Rb. This is demonstrated by the dynamic emergence of effective long-range coherence of the spin field. For a thermalized state we verify spin-superfluidity by experimentally testing Landau’s criterion and reveal the structure of one massive and two massless modes, which are a consequence of explicit and spontaneous symmetry breaking, respectively. Our experiments allow us to observe the thermalization of an easy-plane ferromagnetic Bose gas. The relevant momentum-resolved observables are in agreement with a thermal prediction obtained from a microscopic model in the Bogoliubov approximation.

Prüfer et al., Nature Physics (2022), DOI: 10.1038/s41567-022-01779-6