Infernal and exceptional edge modes: non-hermitian topology beyond the skin effect
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Published version
Author(s)
Denner, Marco Michael
Neupert, Titus
Schindler, Frank
Type
Journal Article
Abstract
The classification of point gap topology in all local non-Hermitian (NH) symmetry classes has been recently established. However, many entries in the resulting periodic table have only been discussed in a formal setting and still lack a physical interpretation in terms of their bulk-boundary correspondence. Here, we derive the edge signatures of all two-dimensional phases with intrinsic point gap topology. While in one dimension point gap topology invariably leads to the NH skin effect, NH boundary physics is significantly richer in two dimensions. We find two broad classes of non-Hermitian edge states: (1) infernal points, where a skin effect occurs only at a single edge momentum, while all other edge momenta are devoid of edge states. Under semi-infinite boundary conditions, the point gap thereby closes completely, but only at a single edge momentum. (2) NH exceptional point dispersions, where edge states persist at all edge momenta and furnish an anomalous number of symmetry-protected exceptional points. Surprisingly, the latter class of systems allows for a finite, non-extensive number of edge states with a well defined dispersion along all generic edge terminations. Concomitantly, the point gap only closes along the real and imaginary eigenvalue axes, realizing a novel form of NH spectral flow.
Date Issued
2023-10
Date Acceptance
2023-08-22
Citation
Journal of Physics: Materials, 2023, 6 (4), pp.1-9
Publisher
IOP Publishing
Start Page
1
End Page
9
Journal / Book Title
Journal of Physics: Materials
Volume
6
Issue
4
Copyright Statement
© 2023 The Author(s). Published by IOP Publishing Ltd. Original Content from
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License URL
Identifier
http://dx.doi.org/10.1088/2515-7639/acf2ca
Publication Status
Published
Article Number
045006
Date Publish Online
2023-08-31