Visco-elastic spectra of a dilute Bose fluid

TL;DR

This paper calculates the visco-elastic spectra of a dilute Bose superfluid at finite temperature using a first-order correction beyond the Bogolubov approximation, revealing uniformity among the spectra.

Contribution

It introduces a method to evaluate visco-elastic spectra for superfluids beyond the Bogolubov approximation, advancing the understanding of superfluid dynamics.

Findings

Visco-elastic spectra are nearly identical except for simple factors.

The spectra are evaluated in the collisionless regime at finite temperature.

The approach extends the local-density current functional formalism.

Abstract

A recently developed local-density current functional formalism for confined Bose-condensed superfluids requires visco-elastic spectra which are defined through a finite-frequency extension of the dissipative coefficients entering the linearized hydrodynamic equations of the two-fluid model. We evaluate these spectra for a superfluid with contact interactions in the collisionless regime at finite temperature, by working to first order beyond the Bogolubov approximation. We find that within this approximation all the visco-elastic spectra take the same value aside from simple multiplicative factors.