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Rydberg atoms, with their large transition dipole moments and extreme sensitivity to electric fields, have attracted widespread attention as promising candidates for next-generation quantum precision electrometry. Meanwhile, exceptional…

Atomic Physics · Physics 2026-02-10 Chao Liang , Ce Yang , Wei Huang , Li You

We derive new exceptional point (EP) conditions of the coupled microring resonators using coupled mode theory in space, a more accurate approach than the commonly used coupled mode theory in time. Transmission spectra around EPs obtained…

Optics · Physics 2024-10-24 Kunpeng Zhu , Xiaoyan Zhou , Yinxin Zhang , Zhanhua Huang , Lin Zhang

One of the most remarkable features that distinguish open systems from closed ones is the presence of exceptional points (EPs), where two or more eigenvectors of a non-Hermitian operator coalesce, accompanying the convergence of the…

Quantum Physics · Physics 2026-01-27 Hao-Long Zhang , Pei-Rong Han , Fan Wu , Wen Ning , Zhen-Biao Yang , Shi-Biao Zheng

We propose an analysis technique for the exceptional points (EPs) occurring in the discrete spectrum of open quantum systems (OQS), using a semi-infinite chain coupled to an endpoint impurity as a prototype. We outline our method to locate…

Quantum Physics · Physics 2012-10-16 Savannah Garmon , Ingrid Rotter , Naomichi Hatano , Dvira Segal

Sensors play a crucial role in advanced apparatuses and it is persistently pursued to improve their sensitivities. Recently, the singularity of a non-Hermitian system, known as the exceptional point (EP), has drawn much attention for this…

Quantum Physics · Physics 2024-01-04 Yao-Dong Hu , Yi-Pu Wang , Rui-Chang Shen , Zi-Qi Wang , Wei-Jiang Wu , J. Q. You

A laser exhibits both controllable gain and loss and, under proper design conditions, is an ideal non-Hermitian system allowing the direct observation and engineering of spectral singularities such as exceptional points (EPs). A dual…

Exceptional points(EPs), branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce, are ubiquitous in non-Hermitian systems. Many novel properties and applications have been proposed around the EPs. One of the…

Exceptional points are singularities of eigenvalues and eigenvectors for complex values of, say, an interaction parameter. They occur universally and are square root branch point singularities of the eigenvalues in the vicinity of level…

Quantum Physics · Physics 2007-05-23 W. D. Heiss

In non-Hermitian physics, high-order exceptional points(HOEPs) with eigenvalues and eigenvectors coalesce are known for their enhanced sensitivity to perturbations. Typically, they exhibit eigenvalue splitting that scales as…

Optics · Physics 2025-12-16 Teng Yin , Hao Zhang

In this paper we study exceptional-point (EP) effects and quantum sensing in a parity-time (PT)-symmetric two-qubit system with the Ising-type interaction. We explore EP properties of the system by analyzing degeneracy of energy eigenvalues…

Quantum Physics · Physics 2023-05-31 J. Zhang , Y. L. Zhou , Y. L. Zuo , P. X. Chen , H. Jing , L. M. Kuang

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…

The interplay between coherent and dissipative dynamics required in various control protocols of quantum technology has motivated studies of open-system degeneracies, referred to as exceptional points (EPs). Here, we introduce a scheme for…

Quantum Physics · Physics 2023-08-23 Wallace S. Teixeira , Vasilii Vadimov , Timm Mörstedt , Suman Kundu , Mikko Möttönen

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

We present a general theory of exceptional points of degeneracy (EPD) in periodically time-variant systems that do not necessarily require the presence of loss or gain, and we show that even a single resonator with a time-periodic component…

Applied Physics · Physics 2019-01-09 Hamidreza Kazemi , Mohamed Y. Nada , Tarek Mealy , Ahmed F. Abdelshafy , Filippo Capolino

We present a general theory of spontaneous emission at exceptional points (EPs)---exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light--matter interaction described by the local density…

Exceptional points of order $n$ (EP$n$s) appear in non-Hermitian systems as points where the eigenvalues and eigenvectors coalesce. They emerge if $2(n-1)$ real constraints are imposed, such that EP2s generically appear in two dimensions…

Mesoscale and Nanoscale Physics · Physics 2024-06-07 Anton Montag , Flore K. Kunst

Exceptional points, also known as non-Hermitian degeneracies, have been observed in parity-time symmetric metasurfaces as the parity-time symmetry breaking point. However, the parity-time symmetry condition puts constraints on the…

Mesoscale and Nanoscale Physics · Physics 2020-12-08 Sang Hyun Park , Sung-Gyu Lee , Taewoo Ha , Sanghyup Lee , Soo-Jeong Baek , Bumki Min , Shuang Zhang , Mark Lawrence , Teun-Teun Kim

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 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

Non-Hermitian systems have recently attracted significant attention in photonics. One of the hallmarks of these systems is the possibility of realizing asymmetric mode switching and omnipolarizer action through the dynamic encirclement of…

Optics · Physics 2020-10-22 J. B. Khurgin , Y. Sebbag , E. Edrei , R. Zektzer , K. Shastri , U. Levy , F. Monticone