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Time is the odd dimension out: Unlike space, it follows the arrow of time, forbidding back-reflections and requiring momentum yet not energy conservation. Tailored temporal variations manipulate momentum bands and engineer waves in time. We…

The emergence of various types of degeneracies plays a crucial role in optimizing and engineering different physical phenomena in non-Hermitian physics. In our work, we focus on the derogatory Exceptional Points (EPs), which are…

Quantum Physics · Physics 2026-04-22 Grigory A. Starkov , Sharareh Sayyad

A nonsmooth fold is where an equilibrium or limit cycle of a nonsmooth dynamical system hits a switching manifold and collides and annihilates with another solution of the same type. We show that beyond the bifurcation the leading-order…

Dynamical Systems · Mathematics 2025-01-24 D. J. W. Simpson

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

Several works have recently addressed the emergence of exceptional points (EPs), i.e., spectral singularities of non-Hermitian Hamiltonians, in the long-wavelength dynamics of coupled magnetic systems. Here, by focusing on the driven…

Mesoscale and Nanoscale Physics · Physics 2023-01-04 Xin Li , Kuangyin Deng , Benedetta Flebus

Eigenvalue problems for electromagnetic resonant states on open dielectric structures are non-Hermitian and may have exceptional points (EPs) at which two or more eigenfrequencies and the corresponding eigenfunctions coalesce. EPs of…

Optics · Physics 2020-04-07 Amgad Abdrabou , Ya Yan Lu

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

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…

Non-Hermitian systems host band degeneracies that are fundamentally distinct from those in Hermitian systems, most notably exceptional points (EPs) where both eigenvalues and eigenvectors coalesce. In three dimensional (3D) non-Hermitian…

Mesoscale and Nanoscale Physics · Physics 2026-03-12 Bin Jiang , Aolong Guo , Qilin Cai , Jian-Hua Jiang

Exceptional points (EPs) are distinct characteristics of non-Hermitian Hamiltonians that have no counterparts in Hermitian systems. In this study, we focus on EPs in continuous systems rather than discrete non-Hermitian systems, which are…

Quantum Physics · Physics 2025-05-13 Y. T. Wang , R. Wang , X. Z. Zhang

Despite many similarities between electronics and optics, the hopping of the electron on a discrete atomic lattice gives rise to energy band nonparabolicity and anisotropy. The crucial influences of this effect on material properties and…

Mesoscale and Nanoscale Physics · Physics 2019-04-30 Shu-Hui Zhang , Wen Yang , Kai Chang

Localization in non-Hermitian quasicrystals can differ fundamentally from its Hermitian counterpart when non-reciprocity is spatially disordered. Here we study a one-dimensional non-Hermitian Aubry-Andr\'{e}-Harper chain with a Bernoulli…

Disordered Systems and Neural Networks · Physics 2026-04-21 Guolin Nan , Zhijian Li , Feng Mei , Zhihao Xu

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

We consider nonequilibrium time evolution in quantum spin chains after a global quench. Usually a nonequilibium quantum many-body system locally relaxes to a (generalised) Gibbs ensemble built from conserved operators with quasilocal…

Statistical Mechanics · Physics 2024-03-13 Maurizio Fagotti , Vanja Marić , Lenart Zadnik

Open systems with gain and loss, described by non-trace-preserving, non-Hermitian Hamiltonians, have been a subject of intense research recently. The effect of exceptional-point degeneracies on the dynamics of classical systems has been…

Quantum Physics · Physics 2019-11-01 M. Naghiloo , M. Abbasi , Yogesh N. Joglekar , K. W. Murch

When a flat elastic strip is compressed along its axis, it is bent in one of two possible directions via spontaneous symmetry breaking and forms a cylindrical arc, a phenomenon well known as Euler buckling. When this cylindrical section is…

Soft Condensed Matter · Physics 2018-01-31 Tomohiko G. Sano , Hirofumi Wada

Non-Hermitian theory is a theoretical framework that excels at describing open systems. It offers a powerful tool in the characterization of both the intrinsic degrees of freedom (DOFs) of a system and the interactions with the external…

Quantum Physics · Physics 2024-05-28 Kun Ding , Chen Fang , Guancong Ma

This paper extends sliding-mode control theory to nonlinear systems evolving on smooth manifolds. Building on differential geometric methods, we reformulate Filippov's notion of solutions, characterize well-defined vector fields on quotient…

Optimization and Control · Mathematics 2025-09-17 Fernando Castaños

Bound states of the Hamiltonian describing a quantum particle living on three dimensional straight strip of width $d$ are investigated. We impose the Neumann boundary condition on the two concentric windows of the radii $a$ and $ b$ located…

Mathematical Physics · Physics 2015-05-20 Hatem Najar , Oleg Olendski

The fundamental concept underlying topological phenomena posits the geometric phase associated with eigenstates. In contrast to this prevailing notion, theoretical studies on time-varying Hamiltonians allow for a new type of topological…

Quantum Physics · Physics 2025-11-27 Pengfei Lu , Yang Liu , Qifeng Lao , Teng Liu , Xinxin Rao , Ji Bian , Hao Wu , Feng Zhu , Le Luo