Anomalous Landau damping and algebraic thermalization in two-dimensional superfluids far from equilibrium

TL;DR

This paper investigates the complex thermalization process in two-dimensional Bose superfluids far from equilibrium, revealing unique Landau damping behavior and algebraic transport mechanisms through a quantum kinetic approach.

Contribution

It introduces a detailed quantum kinetic framework to describe the two-stage relaxation and algebraic thermalization in 2D superfluids, highlighting novel damping dynamics.

Findings

Landau damping differs from exponential relaxation in 2D superfluids.

Algebraic transport emerges at late times due to energy conservation.

A two-regime relaxation process is identified in the thermalization dynamics.

Abstract

We present a quantitative description of the thermalization dynamics of far-from-equilibrium, two-dimensional (2D) Bose superfluids. Our analysis leverages a quantum kinetic formalism and allows us to identify two successive regimes of relaxation: an initial damping of quasi-particles due to Landau scattering processes, followed by the slower establishment of a global equilibrium at long time. For a far-from-equilibrium initial state, we find that Landau damping differs from the conventional picture of exponentially relaxing quasi-particles. Moreover, our results showcase a pronounced mechanism of algebraic transport at late times, rooted in energy conservation and compatible with 2D diffusion. Using theoretical and numerical arguments, we construct a detailed dynamical portrait of global equilibration in 2D superfluids.