Continuous phase transition induced by non-Hermiticity in the quantum contact process model

TL;DR

This paper investigates how non-Hermiticity induces a continuous phase transition in a quantum contact process model, revealing unique critical behavior and a new universality class distinct from Hermitian systems.

Contribution

The study demonstrates a non-Hermitian-induced continuous phase transition in a quantum many-body system, with detailed analysis of critical exponents and singularities, highlighting a novel universality class.

Findings

Non-Hermiticity induces a continuous phase transition in QCP.

Order parameter and susceptibility show infinite singularity even in finite systems.

The phase transition belongs to a new universality class, different from Hermitian cases.

Abstract

Non-Hermitian quantum system recently have attracted a lots of attentions theoretically and experimentally. However, the results based on the single-particle picture may not apply to understand the property of non-Hermitian many-body system. How the property of quantum many-body system especially the phase transition will be affected by the non-hermiticity remains unclear. Here we study non-Hermitian quantum contact process (QCP) model, whose effective Hamiltonian is derived from Lindbladian master equation. We show that there is a continuous phase transition induced by the non-hermiticity in QCP. We also determine the critical exponents $\beta$ of order parameter, $\gamma$ of susceptibility and study the correlation and entanglement near phase transition. We observe that the order parameter and susceptibility display infinitely singularity even for finite size system, since non-hermiticity endow many-body system with different singular behaviour from classical phase transition. Moreover our results show that the phase transition have no counterpart in Hermitian case and belongs to completely different universality class.