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We propose a general principle of constructing non-Hermitian (NH) operators for insulating and gapless topological phases in any dimension ($d$) that over an extended NH parameter regime feature real eigenvalues and zero-energy topological…

Mesoscale and Nanoscale Physics · Physics 2026-03-04 Daniel J. Salib , Sanjib Kumar Das , Bitan Roy

The non-Hermitian skin effect refers to the accumulation of eigenstates near the boundary in open boundary lattice models, which can be systematically characterized using the non-Bloch band theory. Here, we apply the non-Bloch band theory…

Quantum Physics · Physics 2024-09-11 Bo Li , He-Ran Wang , Fei Song , Zhong Wang

One of the important features of non-Hermitian Hamiltonians is the existence of a unique type of singularities, the so-called exceptional points (EPs). When the corresponding systems operate around such singularities, they exhibit…

Optics · Physics 2025-08-26 Ioannis Kiorpelidis , Konstantinos G. Makris

We provide a reviewlike introduction into the quantum mechanical formalism related to non-Hermitian Hamiltonian systems with real eigenvalues. Starting with the time-independent framework we explain how to determine an appropriate domain of…

Quantum Physics · Physics 2015-06-26 Carla Figueira de Morisson Faria , Andreas Fring

The hallmark of symmetry-protected topological (SPT) phases is the existence of anomalous boundary states, which can only be realized with the corresponding bulk system. In this work, we show that for every Hermitian anomalous boundary mode…

Mesoscale and Nanoscale Physics · Physics 2019-11-20 Jong Yeon Lee , Junyeong Ahn , Hengyun Zhou , Ashvin Vishwanath

Spectra of bulk or edges in topological insulators are often made complex by non-Hermiticity. Here, we show that symmetry protection enables entirely real spectra for both bulk and edges even in non-Hermitian topological insulators. In…

Mesoscale and Nanoscale Physics · Physics 2020-09-11 Kohei Kawabata , Masatoshi Sato

We establish a non-Bloch band theory for one-dimensional(1D) non-Hermitian topological superconductors. The universal physical properties of non-Hermitian topological superconductors are revealed based on the theory. According to the…

Superconductivity · Physics 2023-10-20 Yang Cao , Yang Li , Yuanping Chen , Xiaosen Yang

We demonstrate that Hermitian, nonlocal parametric pairing processes can induce non-Hermitian topology and skin modes, offering a simple alternative to complex bath engineering. Our model, stabilized by local dissipation and operating in…

Mesoscale and Nanoscale Physics · Physics 2025-05-06 Markus Bestler , Alexander Dikopoltsev , Oded Zilberberg

We relate topological properties of non-Hermitian systems and observables of quantum open systems by using the Keldysh path-integral method. We express Keldysh Green's functions in terms of effective non-Hermitian Hamiltonians that contain…

Quantum Physics · Physics 2022-07-27 Álvaro Gómez-León , Tomás Ramos , Alejandro González-Tudela , Diego Porras

The traditional bulk-boundary correspondence assuring robust gapless modes at the edges and surfaces of insulating and nodal topological materials gets masked in non-Hermitian (NH) systems by the skin effect, manifesting an accumulation of…

Mesoscale and Nanoscale Physics · Physics 2022-07-14 Archisman Panigrahi , Roderich Moessner , Bitan Roy

Non-Hermitian skin effects are conventionally manifested as boundary localization of eigenstates in linear systems. In nonlinear settings, however, where eigenstates are no longer well defined, it becomes unclear how skin effects should be…

Mesoscale and Nanoscale Physics · Physics 2026-01-08 Shu Hamanaka

We study the one-dimensional non-Hermitian lattices with linearly varying nonreciprocal hopping, where the non-Hermitian skin effect (NHSE) is found to be dissolved gradually as the strength of nonreciprocity increases. The energy spectrum…

Quantum Physics · Physics 2024-03-27 Bo Hou , Han Xiao , Rong Lü , Qi-Bo Zeng

The classification of point gap topology in all local non-Hermitian symmetry classes has been recently established. However, many entries in the resulting periodic table have only been discussed in a formal setting and still lack a physical…

Mesoscale and Nanoscale Physics · Physics 2023-09-04 M. Michael Denner , Titus Neupert , Frank Schindler

We examine the properties and consequences of pseudo-supersymmetry for quantum systems admitting a pseudo-Hermitian Hamiltonian. We explore the Witten index of pseudo-supersymmetry and show that every pair of diagonalizable (not necessarily…

Mathematical Physics · Physics 2008-11-26 Ali Mostafazadeh

We theoretically study the non-Hermitian systems, the non-Hermiticity of which arises from the unequal hopping amplitude (UHA) dimers. The distinguishing features of these models are that they have full real spectra if all of the…

Quantum Physics · Physics 2013-09-17 X. Z. Zhang , Z. Song

We consider different properties of small open quantum systems coupled to an environment and described by a non-Hermitian Hamilton operator. Of special interest is the non-analytical behavior of the eigenvalues in the vicinity of singular…

Quantum Physics · Physics 2015-04-15 Hichem Eleuch , Ingrid Rotter

We illuminate the fundamental mechanism responsible for the transition between the non-Hermitian skin effect and defect-induced localization in the bulk. We study a Hamiltonian with non-reciprocal couplings that exhibits the skin effect…

Mesoscale and Nanoscale Physics · Physics 2024-03-20 Bryn Davies , Silvio Barandun , Erik Orvehed Hiltunen , Richard V. Craster , Habib Ammari

In spite of extensive works on the non-Hermitian topology, correlations effects remain crucial questions. We hereby analyze correlated non-Hermitian systems with special emphasis on the one-dimensional point-gap topology. Specifically, our…

Quantum Physics · Physics 2022-11-29 Tsuneya Yoshida , Yasuhiro Hatsugai

Recent experimental advances in controlling dissipation have brought about unprecedented flexibility in engineering non-Hermitian Hamiltonians in open classical and quantum systems. A particular interest centers on the topological…

Mesoscale and Nanoscale Physics · Physics 2018-09-25 Zongping Gong , Yuto Ashida , Kohei Kawabata , Kazuaki Takasan , Sho Higashikawa , Masahito Ueda

Non-Hermitian skin effect (NHSE) has emerged as a distinctive phenomenon enabling non-Bloch wave manipulation. However, it has been limited to discrete lattices requiring fine-tuned onsite gain/loss or asymmetric couplings. Here, moving…

Applied Physics · Physics 2025-08-21 Yuan Tian , Nankun Gao , Xiujuan Zhang , Ming-Hui Lu , Yan-Feng Chen