Evaporative depolarization and spin transport in a unitary trapped Fermi gas

TL;DR

This paper investigates how evaporative cooling induces non-equilibrium spin polarization in a trapped unitary Fermi gas, potentially explaining experimental discrepancies in spin-imbalanced systems.

Contribution

It introduces a model for evaporative depolarization in a high-aspect-ratio trap, revealing non-equilibrium polarization patterns in spin-imbalanced Fermi gases.

Findings

Evaporative cooling can produce significant non-equilibrium polarization.

The model explains discrepancies in recent experimental results.

Non-equilibrium effects are important in spin transport studies.

Abstract

We consider a partially spin-polarized atomic Fermi gas in a high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the center of the trap. We argue that such a scenario can be produced by evaporative cooling, and we find that it can result in a substantially non-equilibrium polarization pattern for typical experimental parameters. We offer this as a possible explanation for the quantitative discrepancies in recent experiments on spin-imbalanced unitary Fermi gases.