Year: 2019
Type: article
Abstract: We study the thermal evolution of a highly spin-imbalanced, homogeneous Fermi gas with unitarity limited interactions, from a Fermi liquid of polarons at low temperatures to a classical Boltzmann gas at high temperatures. Radio-frequency spectroscopy gives access to the energy, lifetime, and short-range correlations of Fermi polarons at low temperatures T. In this regime, we observe a characteristic T^{2} dependence of the spectral width, corresponding to the quasiparticle decay rate expected for a Fermi liquid. At high T, the spectral width decreases again towards the scattering rate of the classical, unitary Boltzmann gas, ∝T^{-1/2}. In the transition region between the quantum degenerate and classical regime, the spectral width attains its maximum, on the scale of the Fermi energy, indicating the breakdown of a quasiparticle description. Density measurements in a harmonic trap directly reveal the majority dressing cloud surrounding the minority spins and yield the compressibility along with the effective mass of Fermi polarons.
Source: Physical Review Letters
Authors: Zhenjie Yan, Parth B. Patel, Biswaroop Mukherjee, Richard J. Fletcher, Julian Struck, Martin W. Zwierlein
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: ENS- International Center for Fundamental Physics and its interfaces, G149988304, G2478312157, Paris Sciences et Lettres, G4190806336, G4504108201, G471331628, G4831133332, G5937554774, G6098521345, G6759105742, Center for Ultracold Atoms, G7240651115, G7425413337, G7679410528, Strongly Interacting Fermi Gases of Ultracold Atoms, G782245399, G8876996369
OpenAlex ID: W2899163467