Spin oscillations of the normal polarized Fermi gas at Unitarity

TL;DR

This paper uses density functional theory to analyze the frequencies of collective oscillations in a polarized Fermi gas at unitarity, highlighting the importance of collisional effects and proposing new experiments for collisionless regimes.

Contribution

It introduces a time-dependent density functional approach incorporating Fermi liquid elasticity to study collective modes in polarized Fermi gases at unitarity.

Findings

Frequencies depend on polarization and collisional effects.

Comparison with experiments shows bias due to collisions.

Collisionless regime experiments are needed for validation.

Abstract

Using density functional theory in a time dependent approach we determine the frequencies of the compressional modes of the normal phase of a Fermi gas at unitarity as a function of its polarization. Our energy functional accounts for the typical elastic deformations exhibited by Landau theory of Fermi liquids. The comparison with the available experiments is biased by important collisional effects affecting both the {\it in phase} and the {\it out of phase} oscillations even at the lowest temperatures. New experiments in the collisionless regime would provide a crucial test of the applicability of Landau theory to the dynamics of these strongly interacting normal Fermi gases.