Floquet dynamical quantum phase transitions in periodically flux-quenched systems

TL;DR

This paper investigates Floquet dynamical quantum phase transitions in a periodically flux-quenched XY spin chain, analyzing their mechanisms and conditions using physical quantities like Loschmidt echo and topological order parameters.

Contribution

It introduces the concept of Floquet quench fidelity and establishes conditions for FDQPTs in periodically driven quantum systems.

Findings

FDQPTs depend on Floquet fidelity condition and segment duration.

Flux difference within each micromotion influences FDQPT emergence.

Framework applicable to arbitrary periodic driving parameters.

Abstract

Floquet dynamical quantum phase transitions (FDQPTs) reveal many nonequilibrium critical phenomena in periodically driven quantum systems, and their underlying mechanisms have attracted deep attention in recent years. In this paper, we consider an extended XY spin chain under a periodic flux-quench protocol, and demonstrate the effect of the flux difference within each micromotion period on the emergence of FDQPTs, by analyzing physical quantities such as the Loschmidt echo, rate function, and dynamical topological order parameter (DTOP), etc. We also generalize the concept of quench fidelity to periodically driven systems, i.e., Floquet quench fidelity, and discuss the necessary and sufficient conditions for FDQPTs. In contrast to conventional single-quench scenarios, the occurrence of FDQPTs is determined by the requirement of Floquet fidelity condition and segment duration. Our framework may be applied generally to arbitrary periodically driven parameters, providing fundamental insights into how periodic protocols control nonequilibrium phase transitions in quantum many-body systems.