Hysteresis of noninteracting and spin-orbit coupled atomic Fermi gases with relaxation

TL;DR

This paper demonstrates rate-dependent hysteresis in driven atomic Fermi gases with dissipation, revealing universal energy dissipation behaviors and highlighting the potential of cold-atom systems to explore hysteresis phenomena beyond traditional magnetic systems.

Contribution

It introduces the concept of rate-dependent hysteresis in atomic Fermi gases with artificial gauge fields and spin-orbit coupling, expanding the understanding of hysteresis in quantum gases.

Findings

Hysteresis loops of atomic current are observed due to competition between driving and relaxation times.

Universal linear and inverse-linear dependence of dissipated energy on relaxation time is identified.

Atomic Fermi gases with spin-orbit coupling exhibit hysteresis, unlike noninteracting gases without it.

Abstract

Hysteresis can be found in driven many-body systems such as magnets and superfluids. Rate-dependent hysteresis arises when a system is driven periodically while relaxing towards equilibrium. A two-state paramagnet driven by an oscillating magnetic field in the relaxation approximation clearly demonstrates rate-dependent hysteresis. A noninteracting atomic Fermi gas in an optical ring potential, when driven by a periodic artificial gauge field and subjected to dissipation, is shown to exhibit hysteresis loops of atomic current due to a competition of the driving time and the relaxation time. This is in contrast to electronic systems exhibiting equilibrium persistent current driven by magnetic flux due to rapid relaxation. Universal behavior of the dissipated energy in one hysteresis loop is observed in both the magnetic and atomic systems, showing linear and inverse-linear dependence on the relaxation time in the strong and weak dissipation regimes. While interactions in general invalidate the framework for rate-dependent hysteresis, an atomic Fermi gas with artificial spin-orbit coupling exhibits hysteresis loops of atomic currents. Cold-atoms in ring-shape potentials are thus promising in demonstrating rate-dependent hysteresis and its associated phenomena.