Shear viscosity and spin diffusion coefficient of a two-dimensional Fermi gas

TL;DR

This paper uses kinetic theory to calculate shear viscosity and spin diffusion in a 2D Fermi gas, revealing how these properties depend on temperature, coupling, polarization, and mass ratio, and compares results with experiments.

Contribution

It provides a detailed theoretical analysis of viscosity and spin diffusion in 2D Fermi gases, including the effects of mass ratio and polarization, and connects with experimental observations.

Findings

Minimum viscosity decreases with mass ratio due to less efficient Fermi blocking.

Qualitative agreement with experimental quadrupole mode damping without fitting parameters.

Viscous damping explains recent experimental results.

Abstract

Using kinetic theory, we calculate the shear viscosity and the spin diffusion coefficient as well as the associated relaxation times for a two-component Fermi gas in two dimensions, as a function of temperature, coupling strength, polarization, and mass ratio of the two components. It is demonstrated that the minimum value of the viscosity decreases with the mass ratio, since Fermi blocking becomes less efficient. We furthermore analyze recent experimental results for the quadrupole mode of a 2D gas in terms of viscous damping obtaining a qualitative agreement using no fitting parameters.