Non-thermal fixed points: Universal dynamics far from equilibrium

TL;DR

This paper reviews the concept of non-thermal fixed points in isolated quantum many-body systems, highlighting universal dynamics, theoretical frameworks, and recent developments like prescaling.

Contribution

It introduces a non-perturbative kinetic theory and an effective field theory to predict universal scaling exponents near non-thermal fixed points.

Findings

Universal scaling exponents predicted for quantum systems.

Role of wave turbulence in non-thermal fixed points.

Introduction of prescaling as a generic evolution feature.

Abstract

In this article we give an overview of the concept of universal dynamics near non-thermal fixed points in isolated quantum many-body systems. We outline a non-perturbative kinetic theory derived within a Schwinger-Keldysh closed-time path-integral approach, as well as a low-energy effective field theory which enable us to predict the universal scaling exponents characterizing the time evolution at the fixed point. We discuss the role of wave-turbulent transport in the context of such fixed points and discuss universal scaling evolution of systems bearing ensembles of (quasi) topological defects. This is rounded off by the recently introduced concept of prescaling as a generic feature of the evolution towards a non-thermal fixed point.