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Q: Fachverband Quantenoptik und Photonik
Q 66: Ultracold Matter (Fermions) II (joint session Q/A)
Q 66.2: Vortrag
Freitag, 14. März 2025, 11:30–11:45, HS V
Using ultracold Fermi gases to theoretically probe atomic scattering properties — •Nikolai Kaschewski1, Axel Pelster1, and Carlos A. R. Sá de Melo2 — 1Department of Physics and Research Center OPTIMAS RPTU Kaiserslautern-Landau, Germany — 2School of Physics, Georgia Institute of Technology, Atlanta, USA
In cold atomic gases microscopic details of interactions are thought to be irrelevant as the interaction range is much smaller than typical inter-particle spacings. Thus, in a degenerate quantum gas of neutral atoms interactions are modelled as contact interaction potentials ignoring properties besides scattering lengths. In other fields, for instance in nuclear physics, the shape of the interaction potential is believed to play a larger role due to high densities [1]. So far no methods currently exist to directly probe interatomic interactions as in nuclear physics.
Here we present a theoretical method to introduce leading-order effects of the interatomic potential shape, i.e. the effective range, by generalizing Bethe's theory of nuclear scattering [2] to ultracold atomic gases. Using a degenerate BCS-type Fermi gas at low temperature as an example we show, that the influence of the effective range for most thermodynamic properties adds a small correction to the zero-range theory. However, our qualitative investigation reveals that quantities, like correlation functions, capture the short-range behaviour of the gas and hence are sensitive to changes in the effective range parameter offering a prospect to measure the effective range.
[1] M. Jin, M. Urban and P. Schuck, Phys. Rev. C 82, 024911 (2010) [2] H. A. Bethe, Phys. Rev. 76, 38 (1949)
Keywords: Fermi Gases; Scattering properties; ultracold; superfluidity; BCS