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Related papers: Exceptional-point-like Sensing near Hermitian Crit…

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Non-Hermitian classical and open quantum systems near an exceptional point (EP) are known to undergo strong deviations in their dynamical behavior under small perturbations or slow cycling of parameters as compared to Hermitian systems.…

Quantum Physics · Physics 2021-02-19 Stefano Longhi

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

Motivated by the prospect of chiral-mode control in compact photonic systems, we analyze discrete coupled single-mode resonators. Using the minimal three-resonator model, we show that an infinitesimal complex onsite perturbation near a…

Optics · Physics 2026-05-18 Kota Yagi , Takahiro Uemura , Yuto Moritake , Adam Mock , Masaya Notomi

A novel anti-P-pseudo-Hermitian mechanical system that integrates piezoelectric actuators and sensors with non-reciprocal coupling into mechanical beams is proposed. This configuration enables the system to exhibit programmable exceptional…

Applied Physics · Physics 2026-03-10 Yanzheng Wang , Jianlei Zhao , Qian Wu , Xiaoming Zhou , Heng Jiang , Weiqiu Chen , Mu Wang , Guoliang Huang

Distinct from closed quantum systems, non-Hermitian system can have exceptional points (EPs) where both eigenvalues and eigenvectors coalesce. Recently, it has been proposed and demonstrated that EPs can enhance the performance of sensors…

Quantum Physics · Physics 2019-11-05 Mengzhen Zhang , William Sweeney , Chia Wei Hsu , Lan Yang , A. D. Stone , Liang Jiang

Higher-order exceptional points (EPs), resulting from non-Hermitian degeneracies, have shown greater advantages in sensitive enhancement than second-order EPs (EP2s). Therefore, seeking higher-order EPs in various quantum systems is…

Quantum Physics · Physics 2021-12-15 Wei Xiong , Zhuanxia Li , Yiling Song , Jiaojiao Chen , Guoqiang Zhang , Mingfeng Wang

Exceptional points (EPs) are exotic degeneracies of non-Hermitian systems, where the eigenvalues and the corresponding eigenvectors simultaneously coalesce in parameter space, and these degeneracies are sensitive to tiny perturbations on…

The fidelity susceptibility has been used to detect quantum phase transitions in the Hermitian quantum many-body systems over a decade, where the fidelity susceptibility density approaches $+\infty$ in the thermodynamic limits. Here the…

Quantum Physics · Physics 2021-01-08 Yu-Chin Tzeng , Chia-Yi Ju , Guang-Yin Chen , Wen-Min Huang

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 points (EPs) are special spectral degeneracies of non-Hermitian Hamiltonians governing the dynamics of open systems. At the EP two or more eigenvalues and the corresponding eigenstates coalesce. Recently, it has been proposed…

Optics · Physics 2020-02-19 Yu-Hung Lai , Yu-Kun Lu , Myoung-Gyun Suh , Kerry Vahala

Exceptional points (EPs) are singularities that arise in non-Hermitian physics. Current research efforts focus only on systems supporting isolated EPs characterized by increased sensitivity to external perturbations, which makes them…

The nonorthogonality of modes in open systems significantly modifies their resonant response, resulting in quantitative and qualitative deviations from Breit-Wigner resonance relations. For isolated resonances with a Lorentzian lineshape,…

Optics · Physics 2025-12-10 Julius Kullig , Jan Wiersig , Henning Schomerus

Quantum physics can be extended into the complex domain by considering non-Hermitian Hamiltonians that are $\mathcal{PT}$-symmetric. These exhibit exceptional points (EPs) where the eigenspectrum changes from purely real to purely imaginary…

Quantum Physics · Physics 2025-06-23 Jia-Jia Wang , Yu-Hong He , Chang-Geng Liao , Rong-Xin Chen , Jacob A. Dunningham

Exceptional points (EPs) in non-Hermitian systems have recently attracted wide interests and spawned intriguing prospects for enhanced sensing. However, EPs have not yet been realized in thermal atomic ensembles, which is one of the most…

Quantum Physics · Physics 2023-06-30 Chao Liang , Yuanjiang Tang , An-Ning Xu , Yong-Chun Liu

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

Non-Hermitian Hamiltonians can give rise to exceptional points (EPs) which have been extensively explored with nominally identical coupled resonators. Here a non-Hermitian electromechanical system is developed which hosts vibration modes…

Mesoscale and Nanoscale Physics · Physics 2019-02-06 P. Renault , H. Yamaguchi , I. Mahboob

Experiments near the lock-in region in maximally dissipative non-Hermitian systems, e.g., conventional laser gyroscopes near the deadband, have run up against the Petermann limit, where excess noise exactly cancels any scale-factor…

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

One of the unique features of non-Hermitian~(NH) systems is the appearance of non-Hermitian degeneracies known as exceptional points~(EPs). The extensively studied defective EPs occur when the Hamiltonian becomes non-diagonalizable. Aside…

Quantum Physics · Physics 2023-12-11 Sharareh Sayyad , Marcus Stalhammar , Lukas Rodland , Flore K. Kunst

Transmission peak degeneracies (TPDs) have emerged as a promising alternative to exceptional points (EPs) for non-Hermitian sensing, providing square-root frequency splitting without the eigenbasis collapse and associated noise…