SAMOP 2023 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 50: Quantum Gases: Fermions I
Q 50.7: Vortrag
Donnerstag, 9. März 2023, 12:30–12:45, F342
Excitation Spectrum and Superfluid Gap of an Ultracold Fermi gas — •Hauke Biss1,2, Lennart Sobirey1, René Henke1, Cesar Cabrera1,2, and Henning Moritz1,2 — 1Institute of Laser Physics, University of Hamburg, Hamburg, Germany — 2The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
Ultracold Fermi gases with tunable interactions have allowed realizing the famous BEC-BCS crossover from a Bose-Einstein condensate (BEC) of molecules to a Bardeen-Cooper-Schrieffer (BCS) superfluid of weakly bound Cooper pairs. In this contribution, I will present how we use Bragg spectroscopy to measure the full momentum-resolved low-energy excitation spectrum of spin-balanced strongly interacting ultracold Fermi gases. This enables us to observe the smooth transformation from a bosonic to a fermionic superfluid in the BEC-BCS crossover. We use our spectra to determine the evolution of the superfluid gap and find excellent agreement with previous experiments and theory. As a next step, we reduce the dimensionality of the gas to probe the excitation spectrum of two-dimensional (2D) Fermi gases. This allows us to demonstrate superfluidity of 2D Fermi gases and to observe the influence of the reduced dimensionality on the stability of the superfluid phase. Finally, I will present our progress towards creating and probing spin-imbalanced mixtures in 2D.