Controlling spin current in a trapped Fermi gas

TL;DR

This paper demonstrates control over spin currents in a weakly interacting Fermi gas of lithium-6 atoms, showing how to reverse spin flow and explaining the underlying physics with a simple theoretical model.

Contribution

It introduces an experimental method to control and reverse spin currents in ultra-cold Fermi gases, supported by a theoretical framework linking spin and energy evolution.

Findings

Successful reversal of spin current flow.

Correlation between spin and energy states of atoms.

Theoretical model explaining large amplitude and slow evolution.

Abstract

We study fundamental features of spin current in a very weakly interacting Fermi gas of $^6$Li. By creating a spin current and then reversing its flow, we demonstrate control of the spin current. This reversal is predicted by a spin vector evolution equation in energy representation, which shows how the spin and energy of individual atoms become correlated in the nearly undamped regime of the experiments. The theory provides a simple physical description of the spin current and explains both the large amplitude and the slow temporal evolution of the data. Our results have applications in studying and controlling fundamental spin interactions and spin currents in ultra-cold gases.