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arXiv · 2112.04988

Selective and tunable excitation of topological non-Hermitian skin modes

Stefano Longhi
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Abstract

Non-Hermitian lattices under semi-infinite boundary conditions sustain an extensive number of exponentially-localized states, dubbed non-Hermitian skin modes. Such states can be predicted from the nontrivial topology of the energy spectrum under periodic boundary conditions via a bulk-edge correspondence. However, the selective excitation of the system in one among the infinitely-many topological skin edge states is challenging both from practical and conceptual viewpoints. In fact, in any realistic system with a finite lattice size most of skin edge states collapse and become metastable states. Here we suggest a route toward the selective and tunable excitation of topological skin edge states which avoids the collapse problem by emulating semi-infinite lattice boundaries via tailored on-site potentials at the edges of a finite lattice. We illustrate such a strategy by considering a non-Hermitian topological interface obtained by connecting two Hatano-Nelson chains with opposite imaginary gauge fields, which is amenable for a full analytical treatment.

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Stefano Longhi. 2021-12-09. Selective and tunable excitation of topological non-Hermitian skin modes. https://doi.org/10.1098/rspa.2021.0927

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