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Exceptional points (EPs) are spectral degeneracies unique to non-Hermitian systems which underpin phenomena from enhanced sensing to unconventional topology. While disorder is usually viewed as detrimental, it can also drive topological…

Disordered Systems and Neural Networks · Physics 2026-01-28 Xiaoyu Cheng , Tiantao Qu , Yaqing Yang , Jun Chen , Lei Zhang

Non-Hermitian systems can produce branch singularities known as exceptional points (EPs). Different from singularities in Hermitian systems, the topological properties of an EP can involve either the winding of eigenvalues that produces a…

Quantum Physics · Physics 2021-07-21 Weiyuan Tang , Kun Ding , Guancong Ma

Non-Hermitian physics predicts open quantum system dynamics with unique topological features such as exceptional points and the non-Hermitian skin effect. We show that this new paradigm of topological systems can serve as probes for bulk…

Quantum Physics · Physics 2024-08-28 Saubhik Sarkar , Francesco Ciccarello , Angelo Carollo , Abolfazl Bayat

We show the existence of non-Hermitian degeneracies, known as exceptional points, in the collective mode spectrum of Fermi liquids with quadrupolar interactions. Through a careful analysis of the analytic properties of the dynamic…

Strongly Correlated Electrons · Physics 2020-11-26 Rui Aquino , Daniel G. Barci

Intrinsic topological superconductors have protected gapless Majorana modes, bound and/or propagating, at the natural boundaries of the sample, without requiring field, defect, or heterostructure. We establish the complete…

Mesoscale and Nanoscale Physics · Physics 2022-09-23 Zhongyi Zhang , Jie Ren , Yang Qi , Chen Fang

Exceptional points (EPs) in non-Hermitian photonic systems have attracted considerable research interest due to their singular eigenvalue topology and associated anomalous physical phenomena. These properties enable diverse applications…

Optics · Physics 2025-10-17 Kaiyuan Wang , Qi Jie Wang , Matthew R. Foreman , Yu Luo

We show that a composite quantum system described by the tensor product of multiple systems each with a leading-order exceptional point (a non-Hermitian degeneracy at which not only eigenvalues but also eigenstates coalesce) exhibits a…

Quantum Physics · Physics 2025-07-28 Jan Wiersig , Weijian Chen

Exceptional points (EPs) with their intriguing spectral topology have attracted considerable attention in a broad range of physical systems, with potential sensing applications driving much of the present research in this field. Here we…

Optics · Physics 2026-01-29 Jan Wingenbach , Stefan Schumacher , Xuekai Ma

This work unveils how geometric features of two-band non-Hermitian Hamiltonians can completely classify the topology of their eigenstates and energy manifolds. Our approach generalizes the Bloch sphere visualization of Hermitian systems to…

Mesoscale and Nanoscale Physics · Physics 2019-08-07 Linhu Li , Ching Hua Lee , Jiangbin Gong

We propose a novel type of exceptional points, dubbed interaction-enabled $n$-fold exceptional points [EP$n$s ($n=2,3$)] -- EP$n$s protected by topology that are prohibited at the non-interacting level. Specifically, we demonstrate that…

Mesoscale and Nanoscale Physics · Physics 2026-02-17 Musashi Kato , Tsuneya Yoshida

Recent years have seen a growing interest in topological phases beyond the standard paradigm of gapped, isolated systems. One recent direction is to explore topological features in non-hermitian systems that are commonly used as effective…

Mesoscale and Nanoscale Physics · Physics 2026-02-03 Carlos Ortega-Taberner , Maria Hermanns

The multipartite non-Hermitian Su-Schrieffer-Heeger model is explored as a prototypical example of one-dimensional systems with several sublattice sites for unveiling intriguing insulating and metallic phases with no Hermitian counterparts.…

Mesoscale and Nanoscale Physics · Physics 2022-05-10 Ritu Nehra , Dibyendu Roy

Recent experimental advancements in dissipation control have yielded significant insights into non-hermitian Hamiltonians for open quantum systems. Of particular interest are the topological characteristics exhibited by these non-hermitian…

Mesoscale and Nanoscale Physics · Physics 2025-11-06 David Christian Ohnmacht , Valentin Wilhelm , Hannes Weisbrich , Wolfgang Belzig

Recently, there has been a lot of activity in the research field of topological non-Hermitian physics, partly driven by fundamental interests and partly driven by applications in photonics. However, despite these activities, a general…

Mesoscale and Nanoscale Physics · Physics 2019-06-26 W. B. Rui , Y. X. Zhao , Andreas P. Schnyder

The physics of systems that cannot be described by a Hermitian Hamiltonian, has been attracting a great deal of attention in recent years, motivated by their nontrivial responses and by a plethora of applications for sensing, lasing, energy…

Optics · Physics 2021-03-16 Alex Krasnok , Nikita Nefedkin , Andrea Alu

Exceptional points (EPs) are degeneracies in open wave systems with coalescence of at least two energy levels and their corresponding eigenstates. In higher dimensions, more complex EP physics not found in two-state systems is observed. We…

Band structures of metamaterials described by a nonlinear eigenvalue problem are beyond the existing topological band theory. In this paper, we analyze non-Hermitian topology under the nonlinearity of eigenvalues. Specifically, we elucidate…

Mesoscale and Nanoscale Physics · Physics 2025-02-19 Tsuneya Yoshida , Takuma Isobe , Yasuhiro Hatsugai

Exceptional points (EPs) are non-Hermitian degeneracies, where both eigenvalues and eigenvectors coalesce, which are fundamentally distinct from their Hermitian counterparts. In this study, we investigate the influence of hexagonal warping…

Mesoscale and Nanoscale Physics · Physics 2026-01-13 Md Afsar Reja , Awadhesh Narayan

We develop a complete theory of symmetry and topology in non-Hermitian physics. We demonstrate that non-Hermiticity ramifies the celebrated Altland-Zirnbauer symmetry classification for insulators and superconductors. In particular, charge…

Mesoscale and Nanoscale Physics · Physics 2019-10-23 Kohei Kawabata , Ken Shiozaki , Masahito Ueda , Masatoshi Sato

The advent of non-Hermitian physics has enriched the plethora of topological phases to include phenomena without Hermitian counterparts. Despite being among the most well-studied uniquely non-Hermitian features, the topological properties…

Mesoscale and Nanoscale Physics · Physics 2025-06-05 Marcus Stålhammar , Lukas Rødland