Floquet Exceptional Topological Insulator

TL;DR

This paper introduces Floquet engineering in non-Hermitian topological insulators, revealing novel surface states, exceptional points, and NH skin effects induced by light-matter interaction, expanding the understanding of non-Hermitian topological phases.

Contribution

It presents a new class of Floquet exceptional topological insulators with unique surface states and NH skin effects, driven by light-matter interaction in non-Hermitian systems.

Findings

Surface states fill the point gap in the complex spectrum.

Existence of NH skin effect in momentum slices.

Wave dynamics illustrate NH surface skin effect.

Abstract

We propose a novel way of modulating exceptional topology by implementing Floquet engineering in non-hermitian (NH) systems. We introduce Floquet exceptional topological insulator which results from shining light on a conventional three-dimensional NH topological insulator. Lightmatter interaction facilitates the quantum phases of matter to exhibit a novel phenomenon, where, the point gaps in the bulk host surface states. These distinct surface states either fill the point gap in the complex eigenspectrum or exhibit exceptional points in the presence of a magnetic field. We also highlight the existence of a quantum anomaly generated by photo-induced modulation. The existence of the Floquet biorthogonal Chern number and spectral winding number show that the momentum slices exhibit NH skin effect, even though the system as a whole does not. We also employ wave-dynamics evolution to illustrate the NH surface skin effect.