Viscosity of an ideal relativistic quantum fluid: A perturbative study

TL;DR

This paper investigates the quantum-induced viscosity in an ideal relativistic fluid using perturbation theory, providing estimates that could inform the fundamental quantum limit on fluid viscosity.

Contribution

It introduces a perturbative approach to estimate quantum viscosity in ideal fluids, highlighting quantum backreaction effects.

Findings

Quantum soundwaves induce a small viscosity in ideal fluids.

First-order perturbation theory provides quantitative estimates of this viscosity.

Results suggest potential bounds on quantum fluid viscosity.

Abstract

We show that a quantized ideal fluid will generally exhibit a small but non-zero viscosity due to the backreaction of quantum soundwaves on the background. We use an effective field theory expansion to estimate this viscosity to first order in perturbation theory. We discuss our results, and whether this estimate can be used to obtain a more model-independent estimate of the "quantum bound" on the viscosity of physical systems