Probing quantum phase transition in a staggered Bosonic Kitaev chain via layer-resolved localization-delocalization transition

TL;DR

This paper reveals that exceptional points in a non-Hermitian matrix accurately identify quantum phase transitions in a staggered bosonic Kitaev chain, linking spectral singularities to localization-delocalization phenomena in many-body systems.

Contribution

It introduces an analytically tractable EP-based criterion for detecting quantum criticality in interacting bosonic systems, bridging non-Hermitian spectral features with many-body phase transitions.

Findings

EPs coincide with many-body localization-delocalization transitions

Analytic conditions for EP emergence in the Bloch core matrix

Numerical results confirm EPs mark phase boundaries across parameters

Abstract

The bosonic statistics, which allow for macroscopic multi-occupancy of single-particle states, pose significant challenges for analyzing quantum phase transitions in interacting bosonic systems, both analytically and numerically. In this work, we systematically investigate the non-Hermitian Bloch core matrix of a Hermitian staggered bosonic Kitaev chain, formulated within the Nambu framework. We derive explicit analytic conditions for the emergence of exceptional points (EPs) in the $4\times 4$ Bloch core matrix, with each EP marking the onset of complex-conjugate eigenvalue pairs. By mapping the full many-body Hamiltonian onto an effective tight-binding network in Fock-space and introducing layer-resolved inverse participation ratio, we demonstrate that these EPs coincide precisely with sharp localization--delocalization transitions of collective eigenstates. Comprehensive numerical analyses across hopping amplitudes, pairing strengths, and on-site potentials confirm that the EP of effective Hamiltonian universally capture the global many-body phase boundaries. Our results establish an analytically tractable, EP-based criterion for detecting critical behavior in interacting bosonic lattices, with direct relevance to photonic and cold-atom experimental platforms.