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Exceptional points (EPs) are non-Hermitian degeneracies, where both eigenvalues and eigenvectors coalesce, which are fundamentally distinct from their Hermitian counterparts. In this study, we investigate the influence of hexagonal warping…

Mesoscale and Nanoscale Physics · Physics 2026-01-13 Md Afsar Reja , Awadhesh Narayan

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-point (EP) sensors are characterized by a square-root resonant frequency bifurcation in response to an external perturbation. This has lead numerous suggestions for using these systems for sensing applications. However, there is…

Quantum Physics · Physics 2024-08-14 Hudson A. Loughlin , Vivishek Sudhir

Exceptional points (EPs) in non-Hermitian photonics offer singular sensitivity enhancements but have thus far been realized almost exclusively in spatially engineered platforms with fixed geometries and limited tunability. Here we extend EP…

The amplitude of resonant oscillations in a non-Hermitian environment can either decay or grow in time, corresponding to a mode with either loss or gain. When two coupled modes have a specific difference between their loss or gain, a…

Classical Physics · Physics 2025-11-07 N. J. Lambert , A. Schumer , J. J. Longdell , S. Rotter , H. G. L. Schwefel

Non-Hermitian systems can manifest rich static and dynamical properties at their exceptional points (EPs). Here, we identify yet another class of distinct phenomena that is hinged on EPs, namely, the emergence of a series of non-Hermitian…

Quantum Physics · Physics 2025-04-03 Zuo Wang , Liang He

In non-Hermitian coulped-resonator networks, the eigenvectors of degenerate eigenmodes may become parallel due to the singularity at so-called Exceptional Points (EP). To exploit the parametric sensitivity at EPs, an important problem is,…

Quantum Physics · Physics 2019-01-31 Re-Bing Wu , Yu Zheng , Qi-Ming Chen , Yu-xi Liu

Conventional mode switching mechanisms, which rely on dynamically encircling exceptional points (EPs) through non-adiabatic transitions (NATs), suffer from intrinsic nonlinear dynamics that hinder precise control and reproducibility in…

Optics · Physics 2026-02-04 Kyu-Won Park , KyeongRo Kim , Jinuk Kim , Muhan Choi , Kabgyun Jeong

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

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

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

The responsivity of perturbation sensing can be effectively enhanced by using higher-order exceptional points (HOEPs) due to their nonlinear response to frequency perturbations. However, experimental realization can be difficult due to the…

Optics · Physics 2024-12-02 Todd Darcie , J. Stewart Aitchison

The topological structure associated with the branchpoint singularity around an exceptional point (EP) provides new tools for controlling the propagation of electromagnetic waves and their interaction with matter. To date, observation of…

We classify gapped phases and characteristic nodal points of non-Hermitian band structures on two-dimensional nonorientable parameter spaces. Such spaces arise in a wide range of physical systems in the presence of nonsymmorphic parameter…

Mesoscale and Nanoscale Physics · Physics 2026-03-30 J. Lukas K. König , Kang Yang , André Grossi Fonseca , Sachin Vaidya , Marin Soljačić , Emil J. Bergholtz

Systems with an effectively non-Hermitian Hamiltonian display an enhanced sensitivity to parametric and dynamic perturbations, which arises from the nonorthogonality of their eigenstates. This enhanced sensitivity can be quantified by the…

Quantum Physics · Physics 2023-12-15 Henning Schomerus

Exceptional points (EPs) are complex singularities of parametric linear operators where two or more eigenvalues and eigenvectors coalesce. EPs are attracting increasing interest in mechanical metamaterials due to their strong potentials for…

Applied Physics · Physics 2022-04-05 Weidi Wang , Alireza V. Amirkhizi

Non-Hermitian singularities known as exceptional-points (EPs) have been shown to exhibit increased sensitivities but the observation of EPs has so far been limited to wavelength scaled systems subject to diffraction limit. We propose a…

Optics · Physics 2019-04-03 J. -H. Park , A. Ndao , W. Cai , L. -Y. Hsu , A. Kodigala , T. Lepetit , Y. -H. Lo , B. Kanté

Non-Hermitian (NH) systems can display exceptional topological defects without Hermitian counterparts, exemplified by exceptional rings in NH two-dimensional systems. However, exceptional topological features associated with…

Quantum Physics · Physics 2026-01-06 Shou-Bang Yang , Pei-Rong Han , Wen Ning , Fan Wu , Zhen-Biao Yang , Shi-Biao Zheng

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

Spatially periodic elastic metamaterials, comprising hard inclusions within a soft matrix in $d$-dimensional space ($d\geq 2$), exhibit a rich spectrum of physical phenomena. This paper investigates such a model and presents the following…

Analysis of PDEs · Mathematics 2025-09-09 Yixian Gao , Shuguan Ji , Shangling Song