Chirality-Induced Spin Currents in a Fermi Gas

TL;DR

This paper demonstrates the generation and control of spin currents in a Fermi gas induced by chirality, revealing a new extension of CISS phenomena to ultracold atomic systems.

Contribution

It introduces a method to induce and observe chirality-driven spin currents in a Fermi gas, modeling the behavior with a driven oscillator equation, and extends CISS concepts to quantum gases.

Findings

Spin currents are generated by spatially varying spin rotations due to chirality.

The spin current behavior follows a driven oscillator model.

Chirality induces spin selectivity in the direction of current flow.

Abstract

We observe and model spin currents arising from chirality and effective spin-exchange interactions in a weakly interacting $^6$Li Fermi gas. Chirality is introduced by a static displacement between the center of the trapped atoms and the center of an applied magnetic bowl, which produces left- or right-handed spatially varying spin rotation. Spin current is directly observed via oscillations in the centers of mass of the spin-up and spin-down components, which appear to bounce off of or pass through one another, depending on the degree of handedness and s-wave scattering length. We show that this behavior obeys a driven oscillator equation with an effective spin-dependent driving force. Our measurements demonstrate chirality-induced spin selectivity via the direction of the current flow, extending CISS phenomena to Fermi gases.