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Exceptional points (EPs), branch singularities parameter space of non-Hermitian eigenvalue manifolds, display unique topological phenomena linked to eigenvalue and eigenvector switching: the parameter space states are highly sensitive to…

Mesoscale and Nanoscale Physics · Physics 2024-12-24 K. Ho , S. Perna , S. Wittrock , S. Tsunegi , H. Kubota , S. Yuasa , P. Bortolotti , M. d'Aquino , C. Serpico , V. Cros , R. Lebrun

Systems operating at exceptional points (EPs) are highly responsive to small perturbations, making them suitable for sensing applications. Although this feature impedes the system working exactly at an EP due to imperfections arising during…

Optics · Physics 2024-01-19 Shahab Ramezanpour

Higher-order exceptional points in non-Hermitian systems have recently been used as a tool to engineer high-sensitivity devices, attracting tremendous attention from multidisciplinary fields. Here, we present a simple yet effective scheme…

Optics · Physics 2022-08-31 Ambaresh Sahoo , Amarendra K. Sarma

We investigate experimentally and analytically the coalescence of reflectionless (RL) states in symmetric complex wave-scattering systems. We observe RL-exceptional points (EPs), first, with a conventional Fabry-Perot system for which the…

Classical Physics · Physics 2022-06-01 Clément Ferise , Philipp del Hougne , Simon Félix , Vincent Pagneux , Matthieu Davy

Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been…

Non-Hermitian systems can exhibit unconventional spectral singularities called exceptional points (EPs). Various EP sensors have been fabricated in recent years, showing strong spectral responses to external signals. Here we propose how to…

Optics · Physics 2021-12-28 Huilai Zhang , Meiyu Peng , Xun-Wei Xu , Hui Jing

Exceptional points (EPs) are degeneracy of non-Hermitian Hamiltonians, at which the eigenvalues, along with their eigenvectors, coalesce. Their orders are given by the Jordan decomposition. Here, we focus on higher-order EPs arising in…

Quantum Physics · Physics 2023-04-18 Kang Yang , Ipsita Mandal

Exceptional point (EP) degeneracies in coupled cavities with gain and loss provide on-chip photonic devices with unconventional features and performance. However, such systems with realistic structures often miss the exact EPs even in…

Optics · Physics 2022-01-26 Kenta Takata , Nathan Roberts , Akihiko Shinya , Masaya Notomi

Non-conservative physical systems admit a special kind of spectral degeneracy, known as exceptional point (EP), at which eigenvalues and eigenvectors of the corresponding non-Hermitian Hamiltonian coalesce. Dynamical parametric encircling…

Mesoscale and Nanoscale Physics · Physics 2019-10-21 Alexey Galda , Valerii M. Vinokur

A noteworthy discovery is that the minimal evolution time is smaller for parity-time ($\mathcal{PT}$) symmetric systems compared to Hermitian setups. Moreover, there is a significant acceleration of two-qubit quantum entanglement…

Quantum Physics · Physics 2024-10-02 B. -B. Liu , Shi-Lei Su , Y. -L. Zuo , Qiongyi He , Gang Chen , F. Nori , H. Jing

Exceptional points (EPs) have been extensively explored in mechanical, acoustic, plasmonic, and photonic systems. However, little is known about the role of EPs in tailoring the dynamic tunability of optical devices. A specific type of EPs…

The nontrivial degeneracies in non-Hermitian systems, exceptional points (EPs), have attracted extensive attention due to intriguing phenomena. Compared with commonly observed second-order EPs, high-order EPs show rich physics due to their…

Quantum Physics · Physics 2024-12-16 Yue Li , Yang Wu , Yuqi Zhou , Mengxiang Zhang , Xingyu Zhao , Yibo Yuan , Xu Cheng , Yi Li , Xi Qin , Xing Rong , Yiheng Lin , Jiangfeng Du

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…

In this paper, we experimentally demonstrate a non-Hermitian open PT-symmetric terahertz metasurface comprising complementary plasmonic structures capable of exhibiting an exceptional point (EP). The metasurface consists of two resonators…

Optics · Physics 2025-06-24 Anshul Bhardwaj , Maidul Islam , Chandan Kumar , Anuraj Panwar , Gagan Kumar

Exceptional points (EPs), at which more than one eigenvalue and eigenvector coalesce, are unique spectral features of Non-Hermiticity (NH) systems. They exist widely in open systems with complex energy spectra. We experimentally demonstrate…

Phase transitions can dramatically alter system dynamics, unlocking new behavior and improving performance. Exceptional points (EPs), where the eigenvalues and corresponding eigenvectors of a coupled linear system coalesce, are particularly…

Quantum Physics · Physics 2025-07-15 Hanfeng Wang , Kurt Jacobs , Donald Fahey , Yong Hu , Dirk R. Englund , Matthew E. Trusheim

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

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

Exceptional points (EPs) are central to non-Hermitian physics because of their unique properties and broad application prospects. While extensively studied in parity-time ($\mathcal{P}\mathcal{T}$)-symmetric systems and under Markovian…

Optics · Physics 2026-01-15 H. Z. Shen , X. C. Zhang , L. Y. Ning , Zhi-Guang Lu , Yan-Hui Zhou , Cheng Shang

This paper theoretically and numerically studies the response characteristics of non-Hermitian resonant photonic systems operating near an exceptional point (EP), where two resonant eigenmodes coalesce. It is shown that a system near an EP…

Optics · Physics 2018-04-06 Satoshi Sunada