Dimerization induced mobility edges and multiple reentrant localization transitions in non-Hermitian quasicrystals

TL;DR

This paper demonstrates how lattice dimerization combined with non-Hermitian effects in one-dimensional quasicrystals induces mobility edges, multiple localization transitions, and reentrant localization phenomena, expanding the understanding of non-Hermitian topological phases.

Contribution

It introduces non-Hermitian extensions of the Aubry-André-Harper model with dimerized hopping and staggered potential, revealing new localization behaviors and topological phase transitions.

Findings

Reentrant localization transitions due to gain/loss and dimerization

Presence of mobility edges in non-Hermitian quasicrystals

Quantized winding numbers characterize phase transitions

Abstract

Non-Hermitian effects could create rich dynamical and topological phase structures. In this work, we show that the collaboration between lattice dimerization and non-Hermiticity could generally bring about mobility edges and multiple localization transitions in one-dimensional quasicrystals. Non-Hermitian extensions of the Aubry-Andr\'e-Harper (AAH) model with staggered onsite potential and dimerized hopping amplitudes are introduced to demonstrate our results. Reentrant localization transitions due to the interplay between quasiperiodic gain/loss and lattice dimerization are found. Quantized winding numbers are further adopted as topological invariants to characterize transitions among phases with distinct spectrum and transport nature. Our study thus enriches the family of non-Hermitian quasicrystals by incorporating effects of lattice dimerization, and offering a convenient way to modulate localization transitions and mobility edges in non-Hermitian systems.