Exploring dynamical quantum phase transition from pure states to mixed states through extended Su-Schrieffer-Heeger models

TL;DR

This study explores how dynamical quantum phase transitions manifest in extended SSH models with different symmetries, revealing the effects of temperature and initial states on topological and symmetry-driven phase transitions.

Contribution

It introduces analysis of DQPTs in extended SSH models with chiral-like and chiral symmetries, highlighting the role of temperature and initial state conditions.

Findings

DQPTs occur after topological transitions in pure states even with open energy gaps.

At low temperatures, mixed-state DQPTs resemble pure-state behavior; at high temperatures, they show multiple critical times.

Pure-state DQPTs require crossing a topological point from a gapless initial state in the SSH-4 model.

Abstract

We investigate dynamical quantum phase transitions (DQPTs) in both pure and mixed states within the extended SSH model framework, focusing on the SSH-3 and SSH-4 variants, which differ in symmetry properties. The SSH-3 model, characterized by a chiral-like point symmetry rather than true chiral symmetry, supports robust localized edge states tied to its topological nature. Our results show that for pure states, DQPTs occur after quenches crossing the topological transition, even when the energy band gap remains open. For mixed states, DQPT behavior aligns with pure states at low temperatures but undergoes significant changes at higher temperatures, including the emergence of multiple critical times. In contrast, the SSH-4 model, which possesses chiral symmetry, features four distinct energy spectrum configurations. We find that pure-state DQPTs arise only when the quench starts from a gapless initial state and crosses the critical topological point. At finite temperature, mixed-state DQPTs persist at low temperatures only if the corresponding pure-state quench induces DQPTs, but they disappear at elevated temperatures. These findings elucidate the interplay between symmetry, topology, and temperature in governing DQPTs within generalized SSH models.