Vortex configuration dependent equilibrium and non-equilibrium states in two-dimensional quantum turbulence

TL;DR

This study investigates how different vortex configurations in two-dimensional quantum turbulence evolve towards equilibrium or non-equilibrium states, revealing configuration-dependent dynamics and scaling behaviors using the Gross-Pitaevskii equation.

Contribution

It provides a detailed analysis of four vortex configurations, highlighting their distinct decay patterns, spectral scalings, and statistical distributions, advancing understanding of quantum turbulence dynamics.

Findings

Cluster configuration reaches equilibrium faster than others.

Different vortex configurations exhibit distinct spectral scaling laws.

Cluster shows Gaussian transfer function, others show skewed or exponential distributions.

Abstract

In this work, we analyze the evolution of four vortex configurations, namely, dipole, plasma, cluster, and lattice, using the two-dimensional mean-field Gross-Pitaevskii equation, focusing on their dynamical decay and approach to the equilibrium. Our analysis reveals that the cluster vortex configuration reaches equilibrium more rapidly than the others, while the dipole, plasma, and lattice configurations exhibit persistent non-equilibrium behavior, tending toward non-thermal fixed points. Specifically, the cluster configuration follows Kolmogorov-like scaling ($\varepsilon^{i}(k)\sim k^{-5/3}$) in the incompressible spectrum, while the other configurations follow Vinen-like scaling ($\varepsilon^{i}(k)\sim k^{-1}$). In the compressible spectrum, the cluster case exhibits a $k$ scaling, indicating full mode equilibration, while for the other configurations, the modes thermalize only above a critical wave number. Additionally, the transfer function for the cluster configuration displays a Gaussian distribution, typical of equilibrium states, while the other configurations exhibit skewed Gaussian or exponential distributions, indicative of their non-equilibrium nature. Finally, the particle number spectra show that the cluster case follows dynamical scaling closer to equilibrium, while the dipole, plasma, and lattice configurations evolve towards non-thermal fixed points. Our findings provide new insights into the dynamics of vortex configurations and their approach to equilibrium or non-equilibrium states, offering guidance for future studies on quantum turbulence and its control.