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

• DOI: 10.48550/arxiv.2302.04256
• Publication Date: 2023-01-01
• Authors: Bo Li; He-Ran Wang; Fei Song; Zhong Wang
• Keywords: Lattice (music)

We show that a local non-Hermitian perturbation in Hermitian lattice system generically induces scale-free localization for the continuous-spectrum eigenstates. When lies at finite distance to boundary, eigenstates are promoted exponentially localized modes, whose number is proportional distance. Furthermore, when respects parity-time (PT) symmetry, PT symmetry breaking always accompanied by emergence of or exponential localization. Intriguingly, we find concise band-structure condition, which tells not only modes can occur, but also precise PT-breaking energy window. Our results uncover series unexpected generic phenomena induced perturbation, has interesting interplay with symmetry.