Anderson-Bogoliubov collective excitations in superfluid Fermi gases at nonzero temperatures

TL;DR

This paper investigates the collective excitations in superfluid Fermi gases at finite temperatures across the BCS-BEC crossover, providing theoretical spectra that align with recent experimental observations of Goldstone modes.

Contribution

It introduces a Gaussian pair fluctuation effective bosonic action to analyze Anderson-Bogoliubov modes at nonzero temperatures in Fermi gases, extending understanding across the BCS-BEC crossover.

Findings

Spectra of collective excitations match experimental data

Quantitative and qualitative agreement with observed Goldstone modes

Analysis covers finite temperature and momentum regimes

Abstract

The Anderson-Bogoliubov branch of collective excitations in a condensed Fermi gas is treated using the effective bosonic action of Gaussian pair fluctuations. The spectra of collective excitations are treated for finite temperature and momentum throughout the BCS-BEC crossover. The obtained spectra explain, both qualitatively and quantitatively, recent experimental results on Goldstone modes in atomic Fermi superfluids.