Exact anomalous mobility edges in one-dimensional non-Hermitian quasicrystals

TL;DR

This paper analytically derives exact anomalous mobility edges in two non-Hermitian quasiperiodic models, revealing critical states and spectral transitions with implications for understanding localization phenomena.

Contribution

It provides the first analytical derivation of anomalous mobility edges in non-Hermitian quasicrystals using Avila's global theory, supported by numerical analysis.

Findings

Analytical expressions for Lyapunov exponents and anomalous MEs.

Identification of robust critical states in both models.

Insights into real-to-complex spectral transitions and topological origins.

Abstract

Recent research has made significant progress in understanding localization transitions and mobility edges (MEs) that separate extended and localized states in non-Hermitian (NH) quasicrystals. Here we focus on studying critical states and anomalous MEs, which identify the boundaries between critical and localized states within two distinct NH quasiperiodic models. Specifically, the first model is a quasiperiodic mosaic lattice with both nonreciprocal hopping term and on-site potential. In contrast, the second model features an unbounded quasiperiodic on-site potential and nonreciprocal hopping. Using Avila's global theory, we analytically derive the Lyapunov exponent and exact anomalous MEs. To confirm the emergence of the robust critical states in both models, we conduct a numerical multifractal analysis of the wave functions and spectrum analysis of level spacing. Furthermore, we investigate the transition between real and complex spectra and the topological origins of the anomalous MEs. Our results may shed light on exploring the critical states and anomalous MEs in NH quasiperiodic systems.