Quantum quench influenced by an excited-state phase transition

TL;DR

This paper investigates how excited-state quantum phase transitions influence quantum relaxation after a sudden parameter change in bosonic atom-field models, revealing clear effects in integrable systems and blurred effects in chaotic nonintegrable systems.

Contribution

It demonstrates the impact of ESQPTs on quantum dynamics in both integrable and nonintegrable models, highlighting differences due to chaos.

Findings

ESQPTs affect quantum relaxation dynamics

Clear ESQPT effects observed in integrable models

Chaotic behavior blurs ESQPT signatures in nonintegrable models

Abstract

We analyze excited-state quantum phase transitions (ESQPTs) in three schematic (integrable and nonintegrable) models describing a single-mode bosonic field coupled to a collection of atoms. It is shown that the presence of the ESQPT in these models affects the quantum relaxation processes following an abrupt quench in the control parameter. Clear cut evidence of the ESQPT effects is presented in integrable models, while in the nonintegrable model the evidence is blurred due to chaotic behavior of the system in the region around the critical energy.