Selective and tunable excitation of topological non-Hermitian skin modes

TL;DR

This paper proposes a method to selectively excite and control topological skin modes in non-Hermitian lattices by emulating semi-infinite boundaries through tailored edge potentials, overcoming collapse issues in finite systems.

Contribution

It introduces a novel approach to selectively excite topological skin modes in finite non-Hermitian systems using tailored edge potentials, avoiding collapse problems.

Findings

Successful emulation of semi-infinite boundaries with edge potentials.

Analytical demonstration on a non-Hermitian topological interface.

Enhanced control over skin mode excitation in finite lattices.

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.