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Exceptional points (EPs) are spectral singularities in non-Hermitian systems where eigenvalues and their corresponding eigenstates coalesce simultaneously. In this study, we calculate scattering poles in an open spherical solid and propose…

Classical Physics · Physics 2024-09-16 Hiroaki Deguchi , Kei Matsushima , Takayuki Yamada

We demonstrate the existence of exceptional points of degeneracy (EPD) of periodic eigenstates in non-Hermitian coupled chains of dipolar scatterers. Guided modes supported by these structures can exhibit an EPD in their dispersion diagram…

Optics · Physics 2017-03-22 Mohamed A. K. Othman , Vincenzo Galdi , Filippo Capolino

For a system consisting of a quantum emitter coupled near threshold (band edge) to a one-dimensional continuum with a van Hove singularity in the density of states, we demonstrate general conditions such that a characteristic triple level…

Quantum Physics · Physics 2021-07-13 Savannah Garmon , Gonzalo Ordonez , Naomichi Hatano

We consider an N-level non-Hermitian Hamiltonian with an exceptional point of order N. We define adiabatic equivalence in such systems and explore topological phase. We show that the topological exceptional states appear at the interface of…

Quantum Physics · Physics 2019-06-26 C. Yuce

At thermal equilibrium, we find that generalized susceptibilities encoding the static physical response properties of Hermitian many-electron systems possess inherent non-Hermitian (NH) matrix symmetries. This leads to the generic…

Strongly Correlated Electrons · Physics 2024-05-08 Matthias Reitner , Lorenzo Crippa , Dominik Robert Fus , Jan Carl Budich , Alessandro Toschi , Giorgio Sangiovanni

The emergence of exceptional points in non-Hermitian systems represents an intriguing phenomenon characterized by the coalescence of eigenenergies and eigenstates. When a system approaches an exceptional point, it exhibits a heightened…

Mesoscale and Nanoscale Physics · Physics 2025-05-21 Shu-Xuan Wang , Zhongbo Yan

The existence of surface electromagnetic waves in the dielectric-metal interface is due to the sign change of real parts of permittivity across the interface. In this work, we demonstrate that the interface constructed by two semi-infinite…

Optics · Physics 2019-12-16 Xiaohan Cui , Kun Ding , Jian-Wen Dong , Che Ting Chan

Almost a decade ago, physicists encountered a strange quantum phenomenon that predicts an unusual death of entanglement under the influence of local noisy environment,known as entanglement sudden death (ESD). This could be an immediate…

Quantum Physics · Physics 2020-01-01 Subhadeep Chakraborty , Amarendra K. Sarma

We predict and analyze boundary-driven exceptional points in semi-infinite Hermitian photonic waveguide lattices with a side-coupled defect. The exceptional points arise from coherent reflections at the lattice termination, which induce…

Optics · Physics 2026-03-10 Stefano Longhi

In open, driven systems where parity-time symmetry is preserved, phenomena that defy conventional wisdom emerge near exceptional points, promising advances in photonics. While most studies focus on two-level systems of a conventional…

Optics · Physics 2024-01-19 Chulwon Lee , Kai Zhang , Jinyan Miao , Kai Sun , Hui Deng

We propose an exceptional-point (EP) framework for black-hole ringdown beyond the standard quasinormal-mode (QNM) paradigm. It provides a first-principles characterization of the resonance associated with avoided crossings near EPs, an…

General Relativity and Quantum Cosmology · Physics 2026-05-20 Rodrigo Panosso Macedo , Takuya Katagiri , Kei-ichiro Kubota , Hayato Motohashi

Exceptional points, at which two or more eigenfunctions of a Hamiltonian coalesce, occur in non-Hermitian systems and lead to surprising physical effects. In particular, the behaviour of a system under parameter variation can differ…

Quantum Physics · Physics 2019-12-04 Bradley Longstaff , Eva-Maria Graefe

Band degeneracies, ranging from Hermitian Dirac points to non-Hermitian exceptional points (EPs), play a central role in topological phase transitions. Beyond the topology of individual degeneracies, their mutual interactions yield richer…

Mesoscale and Nanoscale Physics · Physics 2026-01-07 Weijia Wang , Qicheng Zhang , Kun Zhang , Shuaishuai Tong , Chunyin Qiu

Recently, the intriguing interplay between topology and quantum criticality has been unveiled in one-dimensional topological chains with extended nearest-neighbor couplings. In these systems, topologically distinct critical phases emerge…

Disordered Systems and Neural Networks · Physics 2025-07-25 Ranjith R Kumar , Pasquale Marra

Exceptional point (EP) denotes the non-Hermitian degeneracy, in which both eigenvalues and eigenstates become identical. By the conventional local Markovian master equation, EP can be constructed by parity-time (PT) or anti-PT symmetry in a…

Quantum Physics · Physics 2023-08-30 Dong Xie , Chunling Xu

Exceptional points (EPs) are singularities in the parameter space of a non-Hermitian system where eigenenergies and eigenstates coincide. They hold promise for enhancing sensing applications, but this is limited by the divergence of shot…

Optics · Physics 2025-04-07 Xu Zheng , Y. D. Chong

Non-Hermitian topological systems simultaneously posses two antagonistic features: ultra sensitivity due to exceptional points and robustness of topological zero energy modes, and it is unclear which one prevails under different…

Optics · Physics 2022-03-08 I. Komis , D. Kaltsas , S. Xia , H. Buljan , Z. Chen , K. G. Makris

Chiral exceptional points (CEPs) have been shown to emerge in traveling wave resonators via asymmetric back scattering from two or more nano-scatterers. Here, we provide a new perspective on the formation of CEPs based on the coupled…

Optics · Physics 2021-04-26 A. Hashemi , S. M. Rezaei , S. K. Ozdemir , R. El-Ganainy

We present a new method to diagnose strong coupling in multi-mode open systems. Our method presents a non-trivial extension of exceptional point (EP) analysis employed for such systems; specifically, we show how eigenvectors can not only…

Quantum Physics · Physics 2021-05-12 C. Kow , Z. Xiao , A. Metelmann , A. Kamal

We introduce the exceptional topological insulator (ETI), a non-Hermitian topological state of matter that features exotic non-Hermitian surface states which can only exist within the three-dimensional topological bulk embedding. We show…

Mesoscale and Nanoscale Physics · Physics 2021-10-04 M. Michael Denner , Anastasiia Skurativska , Frank Schindler , Mark H. Fischer , Ronny Thomale , Tomáš Bzdušek , Titus Neupert