Floquet engineering of topological localization transitions and mobility edges in one-dimensional non-Hermitian quasicrystals

TL;DR

This paper demonstrates how periodic driving fields can control localization transitions and mobility edges in non-Hermitian quasicrystals, revealing new topological and transport phenomena through Floquet engineering.

Contribution

It introduces a Floquet engineering approach to manipulate localization and topological phases in non-Hermitian quasicrystals, including conditions for transitions and expressions for Lyapunov exponents.

Findings

Controlled localization transitions via periodic driving.

Identification of mobility edges in non-Hermitian quasicrystals.

Topological winding numbers distinguish different phases.

Abstract

Time-periodic driving fields could endow a system with peculiar topological and transport features. In this work, we find dynamically controlled localization transitions and mobility edges in non-Hermitian quasicrystals via shaking the lattice periodically. The driving force dresses the hopping amplitudes between lattice sites, yielding alternate transitions between localized, mobility edge and extended non-Hermitian quasicrystalline phases. We apply our Floquet engineering approach to five representative models of non-Hermitian quasicrystals, obtain the conditions of photon-assisted localization transitions and mobility edges, and find the expressions of Lyapunov exponents for some models. We further introduce topological winding numbers of Floquet quasienergies to distinguish non-Hermitian quasicrystalline phases with different localization nature. Our discovery thus extend the study of quasicrystals to non-Hermitian Floquet systems, and provide an efficient way of modulating the topological and transport properties of these unique phases.