Quasiparticle Lifetime of the Repulsive Fermi Polaron

Year: 2020

Authors: Adlon, HS., Liu WE., Scazza F., Zaccanti M., Oppong, ND., Foelling, S., Parish MM., Levinsen J.

Autors Affiliation: Monash University, Sch Phys & Astron, Clayton, Vic 3800, Australia

Monash University, ARC Ctr Excellence Future Low Energy Elect Techno, Clayton, Vic 3800, Australia

CNR, Istituto Nazionale di Ottica, I-50019 Sesto Fiorentino, Italy

European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy

Ludwig Maximilians Univ Munchen, Schellingstr 4, D-80799 Munich, Germany

Max Planck Inst Quantum Opt, Hans Kopfertnann Str 1, D-85748 Garching, Germany

Munich Ctr Quantum Sci & Technol MCQST, Schellingstr 4, D-80799 Munich, Germany

Abstract: We investigate the metastable repulsive branch of a mobile impurity coupled to a degenerate Fermi gas via short-range interactions. We show that the quasiparticle lifetime of this repulsive Fermi polaron can be experimentally probed by driving Rabi oscillations between weakly and strongly interacting impurity states. Using a time-dependent variational approach, we find that we can accurately model the impurity Rabi oscillations that were recently measured for repulsive Fermi polarons in both two and three dimensions. Crucially, our theoretical description does not include relaxation processes to the lower-lying attractive branch. Thus, the theory-experiment agreement demonstrates that the quasiparticle lifetime is dominated by many-body dephasing within the upper repulsive branch rather than by relaxation from the upper branch itself. Our findings shed light on recent experimental observations of persistent repulsive correlations, and have important consequences for the nature and stability of the strongly repulsive Fermi gas


Volume: 125 (13)      Pages from: 133401-1  to: 133401-18

DOI: 10.1103/PhysRevLett.125.133401

Citations: 12
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