Journal
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
Volume 478, Issue 2261, Pages -Publisher
ROYAL SOC
DOI: 10.1098/rspa.2021.0927
Keywords
non-Hermitian skin effect; topological phases; wave self-healing
Categories
Funding
- Spanish State Research Agency, through the Severo-Ochoa and Maria de Maeztu Program for Centers and Units of Excellence in RD [MDM-2017-0711]
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Non-Hermitian quasi-edge modes are exponentially localized states in systems with non-Hermitian skin effect. By tailoring on-site potentials at the edges of a finite lattice, selective and tunable excitation of topological quasi-edge states can be achieved.
Non-Hermitian lattices under semi-infinite boundary conditions sustain an extensive number of exponentially localized states, dubbed non-Hermitian quasi-edge modes. Quasi-edge states arise rather generally in systems displaying the non-Hermitian skin effect and can be predicted from the non-trivial 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 quasi-edge states is challenging both from practical and conceptual viewpoints. In fact, in any realistic system with a finite lattice size most of the quasi-edge states collapse and become metastable states. Here we suggest a route toward the selective and tunable excitation of topological quasi-edge states that 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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