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Bound states in the continuum (BICs) and exceptional points (EPs), as two distinct physical singularities represented by complex frequencies in non-Hermitian systems, have garnered significant attention and clear definitions in their…

We investigate the impact of quantum noise on non-Hermitian resonators at an exceptional point (EP). The system's irreversible Markovian dynamics is modeled using the Lindblad master equation, which accounts for the incoherent pump,…

Quantum Physics · Physics 2025-01-15 Dmitrii N. Maksimov , Andrey A. Bogdanov

We investigate the exceptional points (EPs) and their pseudospectra in black hole perturbation theory. By considering a Gaussian bump modification to the Regge-Wheeler potential with variable amplitude, position, and width parameters,…

General Relativity and Quantum Cosmology · Physics 2025-11-24 Li-Ming Cao , Ming-Fei Ji , Liang-Bi Wu , Yu-Sen Zhou

We observe natural exceptional points in the excitation spectrum of an exciton-polariton system by optically tuning the light-matter interactions. The observed exceptional points do not require any spatial or polarization degrees of freedom…

A coupled oscillator system displays enhanced sensitivity of its saturated steady-state (SS) oscillation frequency to small parameter perturbations near an exceptional point degeneracy (EPD), a property that can be used to realize EPD-based…

Applied Physics · Physics 2026-02-03 Benjamin Bradshaw , Amin Hakimi , Filippo Capolino

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

The unique properties of exceptional point (EP) singularities, arising from non-Hermitian physics, have unlocked new possibilities for manipulating light-matter interactions. A tailored gain-loss variation, while encircling higher-order EPs…

We have investigated the exceptional points (EPs) which are degeneracies of a non-Hermitian Hamiltonian, in the case that three modes are interacting with each other. Even though the parametric evolution of the modes cannot be uniquely…

Quantum Physics · Physics 2015-05-30 Jung-Wan Ryu , Soo-Young Lee , Sang Wook Kim

The exceptional points of non-Hermitian systems, where $n$ different energy eigenstates merge into an identical one, have many intriguing properties that have no counterparts in Hermitian systems. In particular, the $\epsilon^{1/n}$…

Quantum Physics · Physics 2019-09-04 Chong Chen , Liang Jin , Ren-Bao Liu

Non-Hermitian systems distinguish themselves from Hermitian systems by exhibiting a phase transition point called an exceptional point (EP), which is the point at which two eigenstates coalesce under a system parameter variation. Many…

Mesoscale and Nanoscale Physics · Physics 2016-04-20 Kun Ding , Guancong Ma , Meng Xiao , Z. Q. Zhang , C. T. Chan

Exceptional points (EPs) of non-Hermitian (NH) systems have recently attracted increasing attention due to their rich phenomenology and intriguing applications. Compared to the predominantly studied second-order EPs, higher-order EPs have…

Mesoscale and Nanoscale Physics · Physics 2023-09-07 Kunkun Wang , Lei Xiao , Haiqing Lin , Wei Yi , Emil J. Bergholtz , Peng Xue

Exceptional points (EPs) represent a distinct type of spectral singularity in non-Hermitian systems, and intriguing physics concepts have been studied with optical EPs recently. As a system beyond photonics, the mechanical oscillators…

Optics · Physics 2023-02-09 Ning Wu , Kaiyu Cui , Qiancheng Xu , Xue Feng , Fang Liu , Wei Zhang , Yidong Huang

We study the elastodynamics of a periodic metastructure incorporating a defect pair that enforces a parity-time (PT) symmetry due to a judiciously engineered imaginary impedance elements - one having energy amplification (gain) and the…

Applied Physics · Physics 2022-09-21 Yanghao Fang , Tsampikos Kottos , Ramathasan Thevamaran

Exceptional points, resulting from non-Hermitian degeneracies, have the potential to enhance the capabilities of quantum sensing. Thus, finding exceptional points in different quantum systems is vital for developing such future sensing…

Mesoscale and Nanoscale Physics · Physics 2020-01-22 Po-Chen Kuo , Neill Lambert , Adam Miranowicz , Hong-Bin Chen , Guang-Yin Chen , Yueh-Nan Chen , Franco Nori

Non-orthogonality in non-Hermitian quantum systems gives rise to tremendous exotic quantum phenomena, which can be fundamentally traced back to non-unitarity and is much more fundamental and universal than complex energy spectrum. In this…

Quantum Physics · Physics 2023-11-06 Yue-Yu Zou , Yao Zhou , Li-Mei Chen , Peng Ye

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

Systems exhibiting degeneracies known as exceptional points have remarkable properties with powerful applications, particularly in sensor design. These degeneracies are formed when eigenstates coincide, and the remarkable effects are…

Analysis of PDEs · Mathematics 2020-08-04 Habib Ammari , Bryn Davies , Erik Orvehed Hiltunen , Hyundae Lee , Sanghyeon Yu

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

Non-Hermitian systems exhibit many peculiar dynamic behaviors which never showed up in Hermitian systems. The existence of spectral singularity (SS) for a non-Hermitian scattering center provides a lasing mechanism in the context of quantum…

Quantum Physics · Physics 2019-04-11 K. L. Zhang , P. Wang , Z. Song

One of the key features of non-Hermitian systems is the occurrence of exceptional points (EPs), spectral degeneracies where the eigenvalues and eigenvectors merge. In this work, we propose applying neural networks to characterize EPs by…

Disordered Systems and Neural Networks · Physics 2023-12-05 Md. Afsar Reja , Awadhesh Narayan