Dynamical Correlation of the Post-quench Non-thermal Equilibrium State

TL;DR

This paper investigates the non-thermal equilibrium states in integrable quantum systems after a quench, revealing unique spectral features and broadening understanding of their correlation properties.

Contribution

It combines quench action and form factor methods to compute correlations in the Lieb-Liniger model's NTES, highlighting a new spectral dispersion branch.

Findings

Spectral distribution differs from thermal states

A new dispersion branch appears in the spectral analysis

Root density tail causes the novel spectral feature

Abstract

After a quantum quench, the integrable system is expected to relax to a non-thermal equilibrium state (NTES) whose local properties are believed to be governed by a generalized Gibbs ensemble (GGE). Combining quench action and the form factor approach, we compute the field-field correlation in the NTES produced by an interaction quench of the Lieb-Liniger model. The spectral distribution is shown to be qualitatively different from that of a thermal equilibrium state (TES): a new dispersion branch appears whose microscopic mechanism can be traced to the algebraic decaying tail for the root density distribution function, and indicates the existence of a broader family of NTES featuring similar spectral property.