Universal platform of point-gap topological phases from topological materials

Daichi Nakamura; Kazuya Inaka; Nobuyuki Okuma; Masatoshi Sato

doi:10.1103/physrevlett.131.256602

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arXiv · 2304.08110

Universal platform of point-gap topological phases from topological materials

Daichi Nakamura·Kazuya Inaka·Nobuyuki Okuma·Masatoshi Sato

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Abstract

Whereas point-gap topological phases are responsible for exceptional phenomena intrinsic to non-Hermitian systems, their realization in quantum materials is still elusive. Here we propose a simple and universal platform of point-gap topological phases constructed from Hermitian topological insulators and superconductors. We show that (d-1)-dimensional point-gap topological phases are realized by making a boundary in d-dimensional topological insulators and superconductors dissipative. A crucial observation of the proposal is that adding a decay constant to boundary modes in d-dimensional topological insulators and superconductors is topologically equivalent to attaching a (d-1)-dimensional point-gap topological phase to the boundary. We furthermore establish the proposal from the extended version of the Nielsen-Ninomiya theorem, relating dissipative gapless modes to point-gap topological numbers. From the bulk-boundary correspondence of the point-gap topological phases, the resultant point-gap topological phases exhibit exceptional boundary states or in-gap higher-order non-Hermitian skin effects.

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Daichi Nakamura, Kazuya Inaka, Nobuyuki Okuma, Masatoshi Sato. 2023-04-17. Universal platform of point-gap topological phases from topological materials. https://doi.org/10.1103/physrevlett.131.256602

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