Sound propagation in a Fermi gas near a Feshbach resonance

TL;DR

This study investigates sound wave behavior in a degenerate Fermi gas with tunable interactions, covering the entire crossover from weakly interacting fermions to molecular Bose-Einstein condensates, testing theoretical models.

Contribution

It provides experimental measurements of sound velocities across the Fermi gas crossover, confirming the universal equation of state in this regime.

Findings

Sound velocities match theoretical predictions

Universal behavior confirmed across the crossover

Supports the equation of state in strongly interacting Fermi gases

Abstract

Sound waves are observed and studied in an optically trapped degenerate Fermi gas of spin-up and spin-down atoms with magnetically tunable interactions. Measurements are made throughout the crossover region, from a weakly-interacting Fermi gas through the resonant Fermi superfluid regime to a Bose condensate of dimer molecules. The measured sound velocities test the equation of state and confirm the universal hypothesis.