Universal scaling of unequal-time correlation functions in ultracold Bose gases far from equilibrium

TL;DR

This paper investigates the universal behavior of unequal-time correlation functions in ultracold Bose gases far from equilibrium, revealing new scaling functions and dynamic exponents that deepen understanding of nonthermal fixed points.

Contribution

It introduces the computation of unequal-time correlation scaling functions and dynamic exponent z, extending previous studies focused on equal-time correlations.

Findings

Determined the dynamic exponent z for Bose gases far from equilibrium.

Identified universal scaling functions for unequal-time correlations.

Compared condensation and correlation times via finite-size scaling analysis.

Abstract

We explore the far-from-equilibrium dynamics of Bose gases in a universal regime associated to nonthermal fixed points. While previous investigations concentrated on scaling functions and exponents describing equal-time correlations, we compute the additional scaling functions and dynamic exponent $z$ characterizing the frequency dependence or dispersion from unequal-time correlations. This allows us to compare the characteristic condensation and correlation times from a finite-size scaling analysis depending on the system's volume.