Lack of near-sightedness principle in non-Hermitian systems

Helene Spring, Viktor Könye, Anton R. Akhmerov, Ion Cosma Fulga

Published 2023-08-01Version 1

The non-Hermitian skin effect is a phenomenon in which an extensive number of states accumulates at the boundaries of a system. It has been associated to nontrivial topology, with nonzero bulk invariants predicting its appearance and its position in real space. Here we demonstrate that the non-Hermitian skin effect is not a topological phenomenon in general: when translation symmetry is broken by a single non-Hermitian impurity, skin modes are depleted at the boundary and accumulate at the impurity site, without changing any bulk invariant. This may occur even for a fully Hermitian bulk.