Cumulative identical spin rotation effects in collisionless trapped atomic gases

TL;DR

This paper investigates how the identical spin rotation effect causes strong spin segregation in a collisionless trapped Fermi gas, leading to energy-dependent spin-position correlations observed over large time scales.

Contribution

It provides a detailed analysis of the cumulative ISRE effects in collisionless regimes, explaining the observed spin segregation phenomena in trapped atomic gases.

Findings

Strong spin segregation observed in dilute Fermi gases

Energy-dependent spin-position correlations established

Large time scale spin dynamics explained by ISRE

Abstract

We discuss the strong spin segregation in a dilute trapped Fermi gas recently observed by Du et al. with "anomalous" large time scale and amplitude. In a collisionless regime, the atoms oscillate rapidly in the trap and average the inhomogeneous external field in an energy dependent way, which controls their transverse spin precession frequency. During interactions between atoms with different spin directions, the identical spin rotation effect (ISRE) transfers atoms to the up or down spin state, depending on their motional energy. Since low energy atoms are closer to the center of the trap than high energy atoms, the final outcome is a strong correlation between spins and positions.