Floquet topological phase in a generalized PT-symmetric lattice

TL;DR

This paper demonstrates that periodic driving in a non-Hermitian lattice model can induce a Floquet topological phase with real quasienergy spectra, revealing unbroken PT symmetry and novel topological properties.

Contribution

It introduces a driven non-Hermitian AAH model showing Floquet topological phases with real spectra, expanding understanding of non-Hermitian topological systems.

Findings

Periodic driving yields real quasienergy spectra in non-Hermitian systems.

Generalized PT symmetry can be realized within Floquet formalism.

The model exhibits a Floquet topological phase with unbroken PT symmetry.

Abstract

We consider a driven, non-Hermitian generalization of the Aubry-Andre-Harper (AAH) model. We show that the introduction of periodic driving allows us to obtain fully real quasienergy spectra in configurations where the corresponding static system has complex energy eigenvalues for any non-Hermitian degree. We illustrate how generalized parity-time (PT) symmetry can be applied within the Floquet formalism and show that our model's fully real quasienergy spectrum corresponds to an unbroken symmetry. This model exhibits a Floquet topological phase, few examples of have been found in non-Hermitian potentials.