Collective oscillations of a Fermi gas in the unitarity limit: Temperature effects and the role of pair correlations

TL;DR

This study investigates the collective oscillations of a resonantly interacting ultracold Fermi gas across various temperatures, revealing that Pauli blocking and pair correlations nearly cancel out, making the gas behave classically.

Contribution

It provides detailed experimental data on collective modes in a Fermi gas at unitarity, highlighting the interplay of temperature, pair correlations, and Pauli blocking in the normal state.

Findings

Pauli blocking and pair correlations nearly cancel each other.

The gas exhibits classical behavior despite strong interactions.

Experimental measurements align with theoretical models.

Abstract

We present detailed measurements of the frequency and damping of three different collective modes in an ultracold trapped Fermi gas of $^6$Li atoms with resonantly tuned interactions. The measurements are carried out over a wide range of temperatures. We focus on the unitarity limit, where the scattering length is much greater than all other relevant length scales. The results are compared to theoretical calculations that take into account Pauli blocking and pair correlations in the normal state above the critical temperature for superfluidity. We show that these two effects nearly compensate each other and the behavior of the gas is close to the one of a classical gas.