Collective oscillations of a Fermi gas near a Feshbach resonance

TL;DR

This paper uses a sum rule approach within a local density approximation to calculate zero temperature collective oscillation frequencies of a two-component Fermi gas near a Feshbach resonance, revealing non-monotonic breathing mode behavior.

Contribution

It introduces a method that explicitly includes Feshbach molecules to accurately predict collective modes across the BCS-BEC crossover.

Findings

Breathing modes exhibit non-monotonic dependence on interaction strength.

Quadrupole modes are largely unaffected by interactions.

Results agree quantitatively with experiments on $^6Li$ and other theories.

Abstract

A sum rule approach is used to calculate the zero temperature oscillation frequencies of a two component trapped atomic Fermi gas in the BCS-Bose Einstein condensation crossover region. These sum rules are evaluated using a local density approximation which explicitly includes Feshbach molecules. Breathing modes show non-monotonic behavior as a function of the interaction strength, while quadrupole modes are insensitive to interactions for both spherically symmetric and axially symmetric traps. Quantitative agreement is found with experiments on atomic $^6Li$ system and with other theoretical approaches.