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arXiv · 2207.09014

Fundamental constraints on the observability of non-Hermitian effects in passive systems

Henning Schomerus
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Abstract

Utilizing scattering theory, we quantify the consequences of physical constraints that limit the visibility of non-Hermitian effects in passive devices. The constraints arise from the fundamental requirement that the system obeys causality, and can be captured concisely in terms of an internal time-delay operator, which furthermore provides a direct quantitative measure of the visibility of specific non-Hermitian phenomena in the density of states. We illustrate the implications by contrasting different symmetry classes and non-Hermitian effects, including exceptional points and the non-Hermitian skin effect, whose underlying extreme mode nonorthogonality turns out to be effectively disguised.

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Henning Schomerus. 2022-07-19. Fundamental constraints on the observability of non-Hermitian effects in passive systems. https://doi.org/10.1103/physreva.106.063509

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