Axial collective excitations of a degenerate Fermi gas in the BEC to unitarity crossover

TL;DR

This paper models the relationship between axial collective modes in a degenerate Fermi gas and key interaction parameters across the BEC to unitarity crossover, highlighting experimental conditions needed to observe Bose-like behavior.

Contribution

It provides a simple theoretical link between experimental measurements of collective modes and the interaction parameters in the crossover regime.

Findings

Established a relation between collective mode frequencies and scattering length

Identified the dilute conditions needed to observe Bose limit features

Suggested experimental directions for clearer Bose regime observation

Abstract

We show that, with reasonable hypotheses leading to a simple modeling,a link can be obtained from experiments on the axial low frequency collective modes between the molecular scattering length $a_M$ and the energy parameter $\xi \equiv 1 + \beta$ of the gas at the unitarity limit. We also point out that, in order to reach the range where the features of the Bose limit can be clearly seen, experiments have to go to more dilute situations than have been achieved presently.