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A: Fachverband Atomphysik

A 41: Poster Session IIIa

A 41.22: Poster

Donnerstag, 8. März 2018, 16:15–18:15, Orangerie

Self-organization in an opto-magnetically coupled quantum gas — •Nishant Dogra, Manuele Landini, Lorenz Hruby, Katrin Kröger, Tobias Donner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland

We report on the observation of strong opto-magnetical effects on the self-organization of a degenerate atomic system coupled to a single-mode high-finesse optical cavity and subjected to an off-resonant pump field, propagating transversely to the cavity axis. The opto-magnetical effects are a result of multiple atomic transitions which gives rise to non-zero vectorial polarizability and hence spin dependent atom-cavity (vectorial) coupling. The relative strength of the vectorial coupling with respect to the scalar coupling can be tuned by the polarization of the pump field. We observe spin dependent self-organization threshold and phase of the scattered light in the organized phase as a function of pump field polarization. By starting with a mixture of two spin states, we identify two regimes. In the regime of strong scalar coupling, the self-organization process generates density modulations in the system. By increasing the strength of vectorial coupling beyond a critical point, we observe the appearance of a new self-organization pattern consisting of magnetization modulations, a spin texture. We locate the transition point by analysing the phase of the light scattered by the atoms in the organized phase. Our findings pave the way to the exploitation of opto-magnetic effects for generation of long-range magnetic interactions.