Gravity-analogy in one-dimensional ideal Fermi fluids and Burgers' equation

TL;DR

This paper develops a hydrodynamic model of a one-dimensional ideal Fermi fluid, revealing a gravity-like wave equation for density perturbations and discussing stability and turbulence, with applications to ultra-cold gases.

Contribution

It introduces a semiclassical hydrodynamic framework linking Fermi fluids to gravity analogies and analyzes stability and turbulence in this context.

Findings

Linear long-wavelength density perturbations are stable.

Density perturbations obey a wave equation analogous to gravity.

The model has applications in ultra-cold atomic gases.

Abstract

An hydrodynamic description of a one-dimensional flow of an ideal Fermi fluid is constructed from a semiclassical approximation. For an initially fully degenerate fluid, Euler and continuity hydrodynamic equations are dual to two uncoupled inviscid Burgers' equations. Yet the price for the initial simplicity of the description is paid by the complexity of non-linear instabilities towards possible turbulent evolutions. Nevertheless, it is shown that linear long-wavelength density perturbations on a stationary flow are generically stable. Consequently, linear sound obeys a wave equation with analogy to gravity. The results have applications for ultra-cold atomic gases.