Quantum phase transition in a non-Hermitian XY spin chain with global complex transverse field

TL;DR

This paper studies quantum phase transitions in a non-Hermitian XY spin chain with a complex transverse field, revealing expanded critical zones and new phase distinctions through gap and correlation analyses.

Contribution

It introduces a novel analysis of phase diagrams in non-Hermitian XY models, highlighting how non-Hermitian effects alter critical behavior and phase boundaries.

Findings

Critical points expand into a transition zone due to non-Hermitian effects.

Different phases can be distinguished by gap features and correlation decay.

The study reveals relationships among phase diagram regions, energy gap, and correlation functions.

Abstract

In this work, we investigate the quantum phase transition in a non-Hermitian XY spin chain. The phase diagram shows that the critical points of Ising phase transition expand into a critical transition zone after introducing a non-Hermitian effect. By analyzing the non-Hermitian gap and long-range correlation function, one can distinguish different phases by means of different gap features and decay properties of correlation function, a tricky problem in traditional XY model. Furthermore, the results reveal the relationship among different regions of the phase diagram, non-Hermitian energy gap and long-range correlation function.