Non-Thermal Fixed Points in Bose Gas Experiments

TL;DR

This paper reviews recent experimental observations of non-thermal fixed points in Bose gases, highlighting their universal dynamics and potential for categorizing out-of-equilibrium phenomena.

Contribution

It synthesizes recent experimental findings on NTFPs in Bose gases and discusses their theoretical framework and implications for universality in non-equilibrium quantum systems.

Findings

Experimental evidence of NTFPs in Bose gases

Universal scaling behavior observed near NTFPs

Analogy with equilibrium critical phenomena

Abstract

One of the most challenging tasks in physics has been understanding the route an out-of-equilibrium system takes to its thermalized state. This problem can be particularly overwhelming when one considers a many-body quantum system. However, several recent theoretical and experimental studies have indicated that some far-from-equilibrium systems display universal dynamics when close to a so-called non-thermal fixed point (NTFP), following a rescaling of both space and time. This opens up the possibility of a general framework for studying and categorizing out-of-equilibrium phenomena into well-defined universality classes. This paper reviews the recent advances in observing NTFPs in experiments involving Bose gases. We provide a brief introduction to the theory behind this universal scaling, focusing on experimental observations of NTFPs. We present the benefits of NTFP universality classes by analogy with renormalization group theory in equilibrium critical phenomena.