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We report an unusual buildup of the quantum coherence in a qubit subjected to non-Hermitian evolution generated by a Parity-Time ($\mathcal{PT}$) symmetric Hamiltonian, which is reinterpreted as a Hermitian system in a higher dimensional…

Quantum Physics · Physics 2021-06-14 Javid Naikoo , Swati Kumari , A. K. Pan , Subhashish Banerjee

We investigate the topological properties of multiple exceptional points in non-Hermitian two-level systems, emphasizing vorticity as a topological invariant arising from complex energy structures. We categorize EP pairs as fundamental…

Optics · Physics 2025-12-19 Jung-Wan Ryu , Chang-Hwan Yi , Jae-Ho Han

We demonstrate third-order conjugate exceptional points (EPs) in a gain-loss assisted multi-mode 1D complementary photonic bandgap waveguide. Our study reveals the higher-order mode conversion phenomenon facilitated by parametrically…

Optics · Physics 2025-04-02 Sibnath Dey , Harish N S Krishnamoorthy , Somnath Ghosh

The exotic physics emerging at singularities has long attracted intense theoretical and experimental attention. In non-Hermitian systems, exceptional points (EPs), unique spectral singularities, have given rise to a host of intriguing wave…

Optics · Physics 2026-04-14 Kai Bai , Chen Lin , Jia-Zheng Li , Meng Xiao

Exceptional points (EPs) in anti-parity-time (APT)-symmetric systems have attracted significant interest. While linear APT-symmetric systems exhibit structural similarities with nonlinear dissipative systems, such as mutually…

Optics · Physics 2025-09-03 Takahiro Uemura , Kenta Takata , Masaya Notomi

Exceptional points (EPs), the degeneracy point of non-Hermitian systems, have recently attracted great attention after its ability to greatly enhance the sensitivity of micro-cavities is demonstrated experimentally. Unlike the usual…

Quantum Physics · Physics 2021-08-04 Geng-Li Zhang , Di Liu , Xi-Ming Wang , Man-Hong Yung

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

An astroid-shaped loop of exceptional points (EPs), comprising four cusps, is found to spawn from the triple degeneracy point in the Brillouin zone (BZ) of a Lieb lattice with nearest-neighbor hoppings when non-Hermiticity is introduced.…

Mesoscale and Nanoscale Physics · Physics 2021-01-01 Yi-Xin Xiao , Kun Ding , Ruo-Yang Zhang , Zhi Hong Hang , C. T. Chan

A special kind of degeneracies known as the exceptional points (EPs), for resonant states on a dielectric periodic slab, are investigated. Due to their unique properties, EPs have found important applications in lasing, sensing,…

Optics · Physics 2018-06-20 Amgad Abdrabou , Ya Yan Lu

One of the most intriguing topological features of open systems is exhibiting exceptional point (EP) singularities. Apart from the widely explored second-order EPs (EP2s), the explorations of higher-order EPs in any system requires more…

Optics · Physics 2020-07-01 Arnab Laha , Dinesh Beniwal , Sibnath Dey , Abhijit Biswas , Somnath Ghosh

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…

We investigate exceptional points of degeneracy (EPDs) in electromagnetic scattering of a sphere dimer from the electroquasistatic limit to the fully retarded regime. In the quasistatic limit, we prove that $\parity\trev$-symmetric…

Optics · Physics 2026-05-29 Emanuele Corsaro , Filippo Capolino , Carlo Forestiere

We investigate local high chirality inside a microcavity near exceptional points (EPs) achieved via asymmetric backscattering by two internal weak scatterers. At EPs, coalescent eigenmodes exhibit position-dependent and symmetric high…

Optics · Physics 2024-10-08 Jingnan Yang , Hancong Li , Sai Yan , Qihuang Gong , Xiulai Xu

Exceptional points (EPs) correspond to degeneracies of open systems. These are attracting much interest in optics, optoelectronics, plasmonics, and condensed matter physics. In the classical and semiclassical approaches, Hamiltonian EPs…

Quantum Physics · Physics 2020-05-13 Fabrizio Minganti , Adam Miranowicz , Ravindra W. Chhajlany , Franco Nori

Exceptional point (EP) associated with eigenstates coalescence in non-Hermitian systems has many exotic features. The EPs are generally sensitive to system parameters, here we report symmetry protected isolated EPs in the Brillouin zone…

Quantum Physics · Physics 2019-05-07 S. Lin , L. Jin , Z. Song

As an exclusive feature of a non-Hermitian system, the existence of exceptional points (EPs) depends not only on the details of the Hamiltonian but also on the particle-number filling and the particle statistics. In this paper, we study…

Strongly Correlated Electrons · Physics 2025-09-24 J. Y. Liu-Sun , Z. Song

We study a non-Hermitian $PT-$symmetric generalization of an $N$-particle, two-mode Bose-Hubbard system, modeling for example a Bose-Einstein condensate in a double well potential coupled to a continuum via a sink in one of the wells and a…

Mathematical Physics · Physics 2008-05-31 E. M. Graefe , U. Guenther , H. J. Korsch , A. E. Niederle

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

Non-Hermitian systems exhibit a variety of unique features rooted in the presence of exceptional points (EP). The distinct topological structure in the proximity of an EP gives rise to counterintuitive behaviors absent in Hermitian systems,…

Quantum Physics · Physics 2025-05-13 He Zhang , Tong Liu , Zhongcheng Xiang , Kai Xu , Heng Fan , Dongning Zheng

We investigate the impact on basic quantum transport properties of disorder-induced exceptional points (EPs) that emerge in a disorder-averaged Green's function description of two-dimensional (2D) Dirac semimetals with spin- or…

Mesoscale and Nanoscale Physics · Physics 2023-01-27 Benjamin Michen , Jan Carl Budich