Freiburg 2024 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 24: Poster II
Q 24.31: Poster
Dienstag, 12. März 2024, 17:00–19:00, KG I Foyer
Kapitza-Dirac scattering of strongly interacting Fermi gases — •Max Hachmann1, Yann Kiefer1,2, and Andreas Hemmerich1 — 1Universität Hamburg, Hamburg, Deutschland — 2ETH, Zürich, Schweiz
We experimentally probe properties of interacting spin-mixtures of fermionic (40K) atoms by studying their interaction with light. An elementary scattering scenario is resonant Bragg diffraction, also referred to as Bragg spectroscopy, where matter is diffracted from a onedimensional (1D) optical standing wave. A Feshbach resonance is used to tune the interactions across the entire BEC-BCS crossover regime, including the point of unitarity. With the preparation schemes available in our experiment, the scattering lengths can be dynamically tuned, such that either repulsively bound molecular dimers (Feshbach molecules) or pairs of unbound fermions can be studied. To benchmark our scattering protocol, we apply it to a sample of spin-polarized non-interacting fermionic atoms and study the dynamical behaviour. In this case, a simple model using a time-dependent Schrödinger equation yields surprisingly accurate results, well matching the experimental observations. For spin-mixtures in the unitarity regime, the higher order diffraction peaks are observed to disappear with no conclusive theoretical description presently available.
Keywords: Kapitza-Dirac scattering; BEC-BCS crossover; Feshbach molecules; Fermi gas