Spin Drag of a Fermi Gas in a Harmonic Trap

TL;DR

This paper uses a Boltzmann equation approach to analyze spin drag in a trapped fermionic gas, revealing how system geometry and regimes affect spin damping and conductance, with results matching recent experiments.

Contribution

It provides an analytical characterization of spin conductance in elongated traps, bridging hydrodynamic and collisionless regimes, and offers a quantitative benchmark for ultracold gas studies.

Findings

Spin damping rate relates to spin conductance in elongated geometries.

Analytical expressions for spin conductance in different regimes.

Good agreement with recent experimental data.

Abstract

Using a Boltzmann equation approach, we analyze how the spin drag of a trapped interacting fermionic mixture is influenced by the non-homogeneity of the system in a classical regime where the temperature is much larger than the Fermi temperature. We show that for very elongated geometries, the spin damping rate can be related to the spin conductance of an infinitely long cylinder. We characterize analytically the spin conductance both in the hydrodynamic and collisionless limits and discuss the influence of the velocity profile. Our results are in good agreement with recent experiments and provide a quantitative benchmark for further studies of spin drag in ultracold gases.