Dynamics of interacting fermions in spin-dependent potentials

TL;DR

This paper develops a theoretical framework to understand how weak interactions influence spin transport and collective phenomena in dilute trapped Fermi gases with spin-dependent potentials, aligning well with experimental observations.

Contribution

It introduces a lattice spin model approach to analyze the interplay of spin, motion, and interactions in fermionic gases after spin-dependent potential changes.

Findings

Good agreement with previous experimental measurements

Reveals the long-range nature of spin couplings causes collective effects

Suggests new directions for experimental exploration

Abstract

Recent experiments with dilute trapped Fermi gases observed that weak interactions can drastically modify spin transport dynamics and give rise to robust collective effects including global demagnetization, macroscopic spin waves, spin segregation, and spin self-rephasing. In this work we develop a framework for studying the dynamics of weakly interacting fermionic gases following a spin-dependent change of the trapping potential which illuminates the interplay between spin, motion, Fermi statistics, and interactions. The key idea is the projection of the state of the system onto a set of lattice spin models defined on the single-particle mode space. Collective phenomena, including the global spreading of quantum correlations in real space, arise as a consequence of the long-ranged character of the spin model couplings. This approach achieves good agreement with prior measurements and suggests a number of directions for future experiments.