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Q: Fachverband Quantenoptik und Photonik

Q 28: Fermionic Quantum Gases I (joint session Q/A)

Q 28.4: Talk

Wednesday, March 13, 2024, 11:45–12:00, HS 1199

Emergence of a collective excitation in a mesoscopic Fermi gas — •Johannes Reiter, Philipp Lunt, Paul Hill, Maciej Galka, and Selim Jochim — Physikalisches Institut, Univeristät Heidelberg, 69120 Heidelberg, Deutschland

Understanding the elementary excitations of strongly interacting many-body systems in terms of the independent motion of individual particles and their collective behaviour constitutes a pervasive problem in many fields ranging from nuclear physics to cold atoms [1,2].

In this talk, we present the spectroscopic observation of the emergence of the radial quadrupole mode from the confinement dominated excitation spectrum in a mesoscopic Fermi gas trapped in an optical tweezer. By systematically tuning the interparticle interactions across the BEC-BCS crossover we investigate the stability of the mode against single particle excitations and showcase the measurement of its coherent properties. Finally, we discuss the prevailing competition between the confinement and interaction energy delineating constraints on the manifestation of collective behaviour in finite-size quantum systems.

[1] B. Mottelson, Science 193 (4250), 287-294 (1976) [2] S. Giorgini et al., Rev.Mod.Phys. 80, 125 (2008)

Keywords: Fermi gas; collective excitation; emergence; ultracold quantum gas experiment; strongly-interacting many-body systems