Collective excitations of a trapped Fermi gas at finite temperature

TL;DR

This paper investigates the collective excitations in a trapped Fermi gas at finite temperature, identifying novel modes such as Higgs-like oscillations, second sound analogues, and a prominent edge mode near the phase transition.

Contribution

It introduces a combined Bogoliubov-deGennes and random phase approximation approach to analyze collective modes at finite temperature in trapped Fermi gases, revealing new excitation phenomena.

Findings

Identification of Higgs mode-like pairing amplitude modulations

Observation of second sound analogues in trapped gases

Discovery of a dominant edge mode in the response spectrum

Abstract

We study collective excitations of a trapped Fermi gas at finite temperature using the Bogoliubov-deGennes mean-field theory in conjunction with the generalized random phase approximation. The collective excitations are analyzed through the density response of a monopole excitation. We show the appearance of several modes at the normal fluid - superfluid phase transition temperature: Higgs mode-like pairing amplitude modulations, analogues of the second sound in the trapped gas, and an edge mode that is also the strongest mode in the response.