Comment on "Excitation Spectrum and Superfluid Gap of an Ultracold Fermi Gas"

Abstract

We present simple arguments suggesting that H. Biss et al [PRL 128, 100401 (2022)] did not measure with the required accuracy the low-wavenumber curvature of the acoustic excitation branch of the ground-state unitary Fermi gas. This difficult-to-calculate quantity is crucial for the relaxation dynamics of the gas at low temperature.

Published version in English (2 pages) and extended version in French (2 pages)

References in corpus (7)

• General coordinate invariance and conformal invariance in nonrelativistic physics: Unitary Fermi gas
• Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
• Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy
• Epsilon expansion for a Fermi gas at infinite scattering length
• Excitation Spectrum and Superfluid Gap of an Ultracold Fermi Gas
• Density Functional Theory for non-relativistic Fermions in the Unitarity Limit
• Phonon damping in a 2D superfluid: insufficiency of Fermi's golden rule at low temperature