Viscosity of a Multi-channel One-Dimensional Fermi Gas

TL;DR

This paper investigates how the bulk viscosity of a weakly interacting multi-channel one-dimensional Fermi gas is significantly affected by multiple band occupations, impacting relaxation and equilibration processes relevant to quantum wires and cold gases.

Contribution

It introduces a detailed analysis of bulk viscosity in multi-channel 1D Fermi gases, highlighting the effects of multiple band occupation on relaxation dynamics and viscosity.

Findings

Bulk viscosity is dramatically altered by multiple band occupation.

Multi-channel systems relax and equilibrate more rapidly than single-channel systems.

The study provides estimates of viscosity based on microscopic interactions.

Abstract

Many one-dimensional systems of experimental interest possess multiple bands arising from shallow confining potentials. In this work, we study a gas of weakly interacting fermions and show that the bulk viscosity is dramatically altered by the occupation of more than one band. The reasons for this are two-fold: a multichannel system is more easily displaced from equilibrium and the associated relaxation processes lead to more rapid equilibration than in the single channel case. We estimate the bulk viscosity in terms of the underlying microscopic interactions. The experimental relevance of this physics is discussed in the context of quantum wires and trapped cold atomic gases.