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Q: Fachverband Quantenoptik und Photonik
Q 22: Posters: Quantum Optics and Photonics II
Q 22.57: Poster
Dienstag, 10. März 2020, 16:30–18:30, Empore Lichthof
Phase Coherence and Superfluidity in Ultracold 2D Fermi Gases — •Hauke Biss1,3, Niclas Luick1,3, Lennart Sobirey1,3, Markus Bohlen1,3,4, Vijay Pal Singh2,3, Ludwig Mathey2,3, Thomas Lompe1,3, and Henning Moritz1,3 — 1Institut für Laserphysik, Universität Hamburg, Hamburg, Germany — 2Zentrum für optische Quantentechnologien, Universität Hamburg — 3The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg, Germany — 4Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, Sorbonne
In this contribution we present our studies of phase coherence and superfluidity in strongly interacting two-dimensional Fermi gases. We demonstrate phase coherence by realizing a Josephson junction in the BEC-BCS crossover. We measure the frequency of Josephson oscillations as a function of the phase difference across the junction and find excellent agreement with the sinusoidal current phase relation of an ideal Josephson junction. We probe superfluidity by dragging a red-detuned lattice through the system and observing the characteristic onset of dissipation above a critical velocity. We measure the critical velocity over the crossover at varying interaction strengths. In the limit of tightly bound molecules, as expected from the Landau criterion, the critical velocity approaches the speed of sound, whereas in the BCS limit, pair breaking excitations are the lowest mode of dissipation.