Superfluid Mutual-friction Coefficients from Vortex Dynamics in the Two-dimensional Galerkin-truncated Gross-Pitaevskii Equation

TL;DR

This paper develops algorithms to determine the temperature-dependent mutual-friction coefficients and normal-fluid density in a 2D quantum fluid system, addressing challenges posed by large fluctuations and exploring implications for the Iordanskii force.

Contribution

The paper introduces new algorithms for ab-initio measurement of mutual-friction coefficients in 2D Gross-Pitaevskii systems, accounting for large fluctuations.

Findings

Successful determination of $ ho_{ m n}(T)$, $eta(T)$, and $eta'(T)$ in 2D systems.

Insights into the existence of the Iordanskii force based on $eta'(T)$ measurements.

Abstract

We present algorithms for the ab-initio determination of the temperature ($T$) dependence of the mutual-friction coefficients $\alpha$ and $\alpha'$ and the normal-fluid density $\rho_{\rm n}$ in the two-dimensional (2D) Galerkin-truncated Gross-Pitaevskii system. Our algorithms enable us to determine $\alpha(T)$, even though fluctuations in 2D are considerably larger than they are in 3D. We also examine the implications of our measurements of $\alpha'(T)$ for the Iordanskii force, whose existence is often questioned.