Nonthermal fixed points and solitons in a one-dimensional Bose gas

TL;DR

This paper investigates the universal scaling behavior of a one-dimensional Bose gas's momentum spectra during non-equilibrium dynamics, highlighting the role of solitons and nonthermal fixed points.

Contribution

It introduces a random-soliton model to analytically describe transient power-law spectra and explores their connection to nonthermal fixed points and strong wave turbulence.

Findings

Identification of transient power-law spectra in the momentum distribution.

Development of an analytical soliton-based model for spectra.

Discussion of the relation between soliton dynamics and critical phenomena.

Abstract

Single-particle momentum spectra for a dynamically evolving one-dimensional Bose gas are analysed in the semi-classical wave limit. Representing one of the simplest correlation functions these give information about possible universal scaling behaviour. Motivated by the previously discovered connection between (quasi-)topological field configurations, strong wave turbulence, and nonthermal fixed points of quantum field dynamics, soliton formation is studied with respect to the appearance of transient power-law spectra. A random-soliton model is developed to describe the spectra analytically, and the analogies and difference between the appearing power laws and those found in a field theory approach to strong wave turbulence are discussed. The results open a view on solitary wave dynamics from the point of view of critical phenomena far from thermal equilibrium and on a possibility to study this dynamics in experiment without the necessity of detecting solitons in situ.