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Q: Fachverband Quantenoptik und Photonik

Q 56: Quantum Gases: Fermions II

Q 56.7: Vortrag

Donnerstag, 9. März 2023, 16:00–16:15, F342

Feshbach molecules in an optical orbital lattice — •Max Hachmann, Yann Kiefer, and Andreas Hemmerich — Institut für Laserphysik, Universität Hamburg

We experimentally study strongly interacting degenerate Fermi gases exposed to an optical lattice. Previous studies focussed on the case, where only the lowest Bloch band is populated, such that the orbital degree of freedom is excluded. We report our experimental findings studying ultracold Feshbach molecules of fermionic 40K atoms selectively prepared in the second Bloch band of a bipartite optical square lattice, covering a wide range of interaction strengths including the regime of unitarity. Binding energies and band relaxation dynamics are measured by means of a method resembling mass spectrometry. The longest lifetimes arise for strongly interacting Feshbach molecules at the onset of unitarity with values around 300ms for the lowest band and 100ms for the second band. In the case of strong confinement in a deep lattice potential, we observe bound dimers also for negative values of the s-wave scattering length, extending previous findings for molecules in the lowest band. Our work prepares the stage for orbital BEC-BCS crossover physics.