SAMOP 2021 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 9: Quantum Gases

Q 9.2: Hauptvortrag

Mittwoch, 22. September 2021, 11:15–11:45, H2

Zooming in on Fermi Gases in Two Dimensions — •Philipp Preiss, Luca Bayha, Jan Hendrik Becher, Marvin Holten, Ralf Klemt, Philipp Lunt, Keerthan Subramanian, and Selim Jochim — Physics Institute, Heidelberg University

Interacting Fermi systems in two dimensions display intriguing phenomena such as pseudogap physics and high temperature superfluidity. Their central features, such as fermion pairing and collective excitations, can approximately be understood in the many-particle limit. It is an open question how large a system has to be for such a many-body picture to apply.

I will report on experiments that realize microscopic two-dimensional systems with ultracold fermionic lithium. With the ability to deterministically prepare few-body ground states and to observe individual atoms in momentum space, they enable a microscopic view of strongly interacting two-dimensional Fermi systems.

Surprisingly, we find that characteristic features of many-body Fermi gases can already be found in systems of no more than a dozen particles: In spectroscopy, we observe collective excitations that are the few-body precursor of the Higgs amplitude mode of a superfluid. Moreover, in spin-resolved momentum space probes, we can directly image individual ‘Cooper pairs’ and show the presence of fermionic pairing even in a microscopic setting. These findings confirm our qualitative picture of fermionic pairing in two dimensions and may be compared to other finite-size Fermi systems, such as atomic nuclei and superconducting grains.