Non-Hermitian Boundary State Engineering in Anomalous Floquet Topological Insulators

Bastian Höckendorf, Andreas Alvermann, and Holger Fehske
Phys. Rev. Lett. 123, 190403 – Published 7 November 2019
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Abstract

In Hermitian topological systems, the bulk-boundary correspondence strictly constrains boundary transport to values determined by the topological properties of the bulk. We demonstrate that this constraint can be lifted in non-Hermitian Floquet insulators. Provided that the insulator supports an anomalous topological phase, non-Hermiticity allows us to modify the boundary states independently of the bulk, without sacrificing their topological nature. We explore the ensuing possibilities for a Floquet topological insulator with non-Hermitian time-reversal symmetry, where the helical transport via counterpropagating boundary states can be tailored in ways that overcome the constraints imposed by Hermiticity. Non-Hermitian boundary state engineering specifically enables the enhancement of boundary transport relative to bulk motion, helical transport with a preferred direction, and chiral transport in the same direction on opposite boundaries. We explain the experimental relevance of our findings for the example of photonic waveguide lattices.

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  • Received 28 July 2019

DOI:https://doi.org/10.1103/PhysRevLett.123.190403

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsAtomic, Molecular & Optical

Authors & Affiliations

Bastian Höckendorf, Andreas Alvermann*, and Holger Fehske

  • Institut für Physik, Universität Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany

  • *Corresponding author. alvermann@physik.uni-greifswald.de

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Issue

Vol. 123, Iss. 19 — 8 November 2019

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