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Exceptional points (EPs) associated with a square-root singularity have been found in many non-Hermitian systems. In most of the studies, the EPs found are isotropic meaning that the same singular behavior is obtained independent of the…

Classical Physics · Physics 2018-08-28 Kun Ding , Guancong Ma , Z. Q. Zhang , C. T. Chan

Exceptional points (EPs) are non-Hermitian degeneracies where eigenvalues and eigenvectors coalesce, giving rise to unusual physical effects across scientific disciplines. The concept of EPs has recently been extended to nonlinear physical…

Dynamical encirclement of an Exceptional Point (EP) and corresponding time-asymmetric mode evolution properties due to breakdown in adiabatic theorem have been a key to range of exotic physical effects in various open atomic, molecular and…

Optics · Physics 2019-04-17 Arnab Laha , Sibnath Dey , Harsh K. Gandhi , Abhijit Biswas , Somnath Ghosh

The gain-loss coupling in optical cavities induces exceptional points (EPs), where two optical modes coalesce. The large modal overlap near an EP intensifies gain competition, favoring single-mode lasing. Recent studies further revealed…

Optics · Physics 2026-01-30 Xingwei Gao , Cheng Guo , David Burghoff

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

Exceptional bound (EB) states represent an unique new class of robust bound states protected by the defectiveness of non-Hermitian exceptional points. Conceptually distinct from the more well-known topological states and non-Hermitian skin…

Quantum Physics · Physics 2024-07-02 Deyuan Zou , Tian Chen , Haiyu Meng , Yee Sin Ang , Xiangdong Zhang , Ching Hua Lee

Exceptional points as branch singularities describe peculiar degeneracies of non-Hermitian systems that do not obey energy conservation. This work shows that exceptional points can emerge in a topological photonic system, for example, the…

Optics · Physics 2021-07-13 Junhua Dong , Chang-Yin Ji , Qingmei Hu , Bingsuo Zou , Yongyou Zhang

Exceptional points (EPs) are spectral defects displayed by non-Hermitian systems in which multiple degenerate eigenvalues share a single eigenvector. This distinctive feature makes systems exhibiting EPs more sensitive to external…

Quantum Physics · Physics 2025-12-11 Subhajyoti Bid , Henning Schomerus

By engineering an anti-parity-time (anti-PT) symmetric cavity magnonics system with precise eigenspace controllability, we observe two different singularities in the same system. One type of singularity, the exceptional point (EP), is…

Mesoscale and Nanoscale Physics · Physics 2020-10-07 Y. Yang , Yi-Pu Wang , J. W. Rao , Y. S. Gui , B. M. Yao , W. Lu , C. -M. Hu

Exceptional points are universal level degeneracies induced by non-Hermiticity. Whereas past decades witnessed their new physics, the unified understanding has yet to be obtained. Here we present the complete classification of generic…

Mesoscale and Nanoscale Physics · Physics 2019-08-13 Kohei Kawabata , Takumi Bessho , Masatoshi Sato

Nonlinearity and non-Hermiticity, for example due to environmental gain-loss processes, are a common occurrence throughout numerous areas of science and lie at the root of many remarkable phenomena. For the latter, parity-time-reflection…

Biological Physics · Physics 2025-04-03 Alexander Felski , Flore K. Kunst

We report an open three-state perturbed system with quasi-statically varying Hamiltonian depending on the topological parameters. The effective system hosts two second order exceptional points (EP2s). Here a third order exceptional point…

Optics · Physics 2018-09-19 Sayan Bhattacherjee , Arnab Laha , Somnath Ghosh

Spontaneous symmetry breaking (SSB) and exceptional points (EPs) are often assumed to be inherently linked. Here we investigate the intricate relationship between SSB and specific classes of EPs across three distinct, real-world scenarios…

Recent study demonstrated that steady states of a polariton system may show a first-order dissipative phase transition with an exceptional point that appears as an endpoint of the phase boundary [R. Hanai et al., Phys. Rev. Lett. 122,…

Quantum Physics · Physics 2023-07-11 Amir Rahmani , Andrzej Opala , Michał Matuszewski

Exceptional points (EPs) are non-Hermitian singularities associated with the coalescence of individual eigenvectors accompanied by the degeneracy of their complex energies. Here, we report the discovery of a generalization to the concept of…

Quantum Physics · Physics 2026-05-07 Zhen Li , Xulong Wang , Rundong Cai , Kenji Shimomura , Congwei Lu , Zhesen Yang , Masatoshi Sato , Guancong Ma

Higher-order exceptional points (EPs) govern non-Hermitian system dynamics through their enriched and sharpened spectral topology, yet the intrinsic topological fragility hinders robust experimental realization. Here, we present a scalable…

An exceptional point is a special point in parameter space at which two (or more) eigenvalues and eigenvectors coincide. The discovery of exceptional points within mechanical and optical systems has uncovered peculiar effects in their…

Quantum Physics · Physics 2025-04-24 C. A. Downing , V. A. Saroka

Bound states in the continuum (BICs) and exceptional points (EPs) are unique singularities of non-Hermitian systems. BICs demonstrate enhancement of the electromagnetic field at the nanoscale, while EPs exhibit high sensitivity to small…

Exceptional points describe the coalescence of the eigenmodes of a non-Hermitian matrix. When an exceptional point occurs in the unitary evolution of a many-body system, it generically leads to a dynamical instability with a finite…

Quantum Gases · Physics 2019-09-04 Mati Aharonyan , Emanuele G. Dalla Torre

We study how symmetry can enrich strong-randomness quantum critical points and phases, and lead to robust topological edge modes coexisting with critical bulk fluctuations. These are the disordered analogues of gapless topological phases.…

Strongly Correlated Electrons · Physics 2021-04-02 Carlos M. Duque , Hong-Ye Hu , Yi-Zhuang You , Vedika Khemani , Ruben Verresen , Romain Vasseur