Scale-free localization and PT symmetry breaking from local non-Hermiticity

• URL: http://arxiv.org/abs/2302.04256v2
• Date: Thu, 26 Oct 2023 08:28:10 GMT
• Title: Scale-free localization and PT symmetry breaking from local non-Hermiticity
• Authors: Bo Li, He-Ran Wang, Fei Song and Zhong Wang
• Abstract summary: We show that a local non-Hermitian perturbation in a Hermitian lattice system generically induces scale-free localization for the continuous-spectrum eigenstates. Our results uncover a series of unexpected generic phenomena induced by a local non-Hermitian perturbation.
• Score: 7.414433047076195
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We show that a local non-Hermitian perturbation in a Hermitian lattice system generically induces scale-free localization for the continuous-spectrum eigenstates. When the perturbation lies at a finite distance to the boundary, the scale-free eigenstates are promoted to exponentially localized modes, whose number is proportional to the distance. Furthermore, when the local non-Hermitian perturbation respects parity-time (PT) symmetry, the PT symmetry breaking is always accompanied by the emergence of scale-free or exponential localization. Intriguingly, we find a concise band-structure condition, which tells not only when the continuous-spectrum PT breaking of scale-free modes can occur, but also the precise PT-breaking energy window. Our results uncover a series of unexpected generic phenomena induced by a local non-Hermitian perturbation, which has interesting interplay with PT symmetry.

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