Acoustic attenuation probe for fermion superfluidity in ultracold atom gases

TL;DR

This paper proposes using the damping rate of Bose-Einstein condensate acoustic excitations as a novel probe to detect superfluidity, measure the superfluid gap, and analyze fermionic quasi-particle properties in ultracold atom gases.

Contribution

It introduces a new method to identify fermion superfluidity and extract key parameters through BEC phonon damping measurements in ultracold gases.

Findings

Damping rate as a signature of BCS superfluidity

Measurement of the superfluid gap parameter

Prediction of kinks revealing fermion dispersion relations

Abstract

Dilute gas Bose-Einstein condensates (BEC's), currently used to cool fermionic atoms in atom traps, can also probe the superfluidity of these fermions. The damping rate of BEC-acoustic excitations (phonon modes), measured in the middle of the trap as a function of the phonon momentum, yields an unambiguous signature of BCS-like superfluidity, provides a measurement of the superfluid gap parameter and gives an estimate of the size of the Cooper-pairs in the BEC-BCS crossover regime. We also predict kinks in the momentum dependence of the damping rate which can reveal detailed information about the fermion quasi-particle dispersion relation.