Topological Anderson insulators with different bulk states in quasiperiodic chains

TL;DR

This paper explores how quasiperiodic disorder induces various topological and localization phases, including gapped topological Anderson insulators with different bulk states, in both Hermitian and non-Hermitian one-dimensional chains.

Contribution

It uncovers three types of quasiperiodic-disorder-induced gapped TAIs with distinct bulk states and analyzes their robustness under non-Hermitian effects, expanding understanding of disorder-induced topological phases.

Findings

Identification of three types of quasiperiodic-disorder-induced gapped TAIs

Demonstration of the preservation of topological phases under non-Hermitian perturbations

Discovery of unique localization and topological properties in non-Hermitian TAIs

Abstract

We investigate the topology and localization of one-dimensional Hermitian and non-Hermitian Su-Schrieffer-Heeger chains with quasiperiodic hopping modulations. In the Hermitian case, phase diagrams are obtained by numerically and analytically calculating various topological and localization characters. We show the presence of topological extended, intermediate, and localized phases due to the coexistence of independent topological and localization phase transitions driven by the quasiperiodic disorder. Unlike the gapless and localized TAI phase in one-dimensional random disordered systems, we uncover three types of quasiperiodic-disorder-induced gapped topological Anderson insulators (TAIs) with extended, intermediate (with mobility edges), and localized bulk states in this chiral chain. Moreover, we study the non-Hermitian effects on the TAIs by considering two kinds of non-Hermiticities from the non-conjugate complex hopping phase and asymmetric hopping strength, respectively. We demonstrate that three types of TAIs preserve under the non-Hermitian perturbations with some unique localization and topological properties, such as the non-Hermitian real-complex and localization transitions and their topological nature. Our work demonstrates that the disorder-induced TAIs in Hermitian and non-Hermitian quasiperiodic systems are not tied to Anderson transitions and have various localization properties.