Hydrodynamic Excitations of Trapped Fermi Gases

TL;DR

This paper analyzes collective excitations in trapped dilute Fermi gases using hydrodynamic theory, providing analytical results for different temperature regimes and proposing experimental signatures of Fermi degeneracy.

Contribution

It offers new analytical insights into the collective modes of Fermi gases at various temperatures and identifies spectral signatures for detecting Fermi degeneracy.

Findings

Spectral signatures for Fermi degeneracy detection

Analytical results for high- and low-temperature limits

Identification of internal excitations with unusual spectra

Abstract

We discuss collective excitations of a trapped dilute Fermi gas within a hydrodynamic approximation. Analytical results are derived for both high- and low-temperature limits and are applied to $^{40}$K and $^6$Li systems of current experimental interest. We identify spectral signatures which can be used to detect the onset of Fermi degeneracy. Also, we find an interesting class of internal excitations with an unusual spectrum. Some of our results are relevant to the case of trapped bosons as well. Our analysis suggests several experiments which address fundamental problems of collective motion in quantum fluids.