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Exceptional points (EPs) play a vital role in non-Hermitian (NH) systems, driving unique dynamical phenomena and promising innovative applications. However, the NH dynamics at EPs remains obscure due to the incomplete biorthogonal…

Quantum Physics · Physics 2025-08-06 Yan Xing , Xuedong Zhao , Hui Jing , Shi-Lei Su

Higher-order exceptional points (EPs) govern non-Hermitian system dynamics through their enriched and sharpened spectral topology, yet the intrinsic topological fragility hinders robust experimental realization. Here, we present a scalable…

We present the experimental demonstration of the occurrence of exceptional points of degeneracy (EPDs) in a single resonator by introducing a linear time-periodic variation of one of its components, in contrast to EPDs in parity time…

Exceptional points (EPs), at which both eigenvalues and eigenvectors coalesce, are ubiquitous and unique features of non-Hermitian systems. Second-order EPs are by far the most studied due to their abundance, requiring only the tuning of…

Optics · Physics 2023-01-02 Ipsita Mandal , Emil J. Bergholtz

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

The discovery of novel topological phase advances our knowledge of nature and stimulates the development of applications. In non-Hermitian topological systems, the topology of band touching exceptional points is very important. Here we…

Mesoscale and Nanoscale Physics · Physics 2020-09-23 X. M. Yang , P. Wang , L. Jin , Z. Song

Non-Hermitian systems with parity-time ($\mathcal{PT}$) symmetry give rise to exceptional points (EPs) with exceptional properties that arise due to the coalescence of eigenvectors. Such systems have been extensively explored in the…

We introduce the exceptional topological insulator (ETI), a non-Hermitian topological state of matter that features exotic non-Hermitian surface states which can only exist within the three-dimensional topological bulk embedding. We show…

Mesoscale and Nanoscale Physics · Physics 2021-10-04 M. Michael Denner , Anastasiia Skurativska , Frank Schindler , Mark H. Fischer , Ronny Thomale , Tomáš Bzdušek , Titus Neupert

A large number of symmetry-protected topological (SPT) phases have been hypothesized for strongly interacting spin-1/2 systems in one dimension. Realizing these SPT phases, however, often demands fine-tunings hard to reach experimentally.…

Quantum Gases · Physics 2019-05-21 Haiyuan Zou , Erhai Zhao , Xi-Wen Guan , W. Vincent Liu

Non-Hermitian systems with parity-time (PT) symmetry have been realized using optical constructs in the classical domain, leading to a plethora of non-intuitive phenomena. However, PT-symmetry in purely quantum non-Hermitian systems like…

Mesoscale and Nanoscale Physics · Physics 2023-06-01 Devarshi Chakrabarty , Avijit Dhara , Pritam Das , Kritika Ghosh , Ayan Roy Chaudhuri , Sajal Dhara

Exceptional points in an optical dimer of spheres, which have the same size and operate in the spectral region of the dipolar resonance, are considered. By choosing different materials of these spheres, we can offset the radiative loss and…

Optics · Physics 2023-07-31 Alexey A. Dmitriev , Mikhail V. Rybin

This paper reports on the experimental observation of topologically protected edge state and exceptional point in an open and Non-Hermitian system. While the theoretical underpinning is generic to wave physics, the simulations and…

Mesoscale and Nanoscale Physics · Physics 2018-09-26 Weiwei Zhu , Xinsheng Fang , Dongting Li , Yong Sun , Yong Li , Yun Jing , Hong Chen

Exceptional points (EPs) are singularities of energy levels in non-Hermitian systems. In this Letter, we demonstrate the surface of EPs on a magnon polariton platform composed of coupled magnons and microwave photons. Our experiments show…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 Xufeng Zhang , Kun Ding , Dafei Jin , Xianjing Zhou , Jing Xu

A pair of anisotropic exceptional points (EPs) of arbitrary order are found in a class of non-Hermitian random systems with asymmetric hoppings. Both eigenvalues and eigenvectors exhibit distinct behaviors when these anisotropic EPs are…

Mesoscale and Nanoscale Physics · Physics 2019-06-12 Yi-Xin Xiao , Zhao-Qing Zhang , Zhi Hong Hang , C. T. Chan

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…

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

An exceptional point is a special point in parameter space at which two (or more) eigenvalues and eigenvectors coincide. The discovery of exceptional points within mechanical and optical systems has uncovered peculiar effects in their…

Quantum Physics · Physics 2025-04-24 C. A. Downing , V. A. Saroka

Exceptional points (EPs) determine the dynamics of open quantum systems and cause also PT symmetry breaking in PT symmetric systems. From a mathematical point of view, this is caused by the fact that the phases of the wavefunctions…

Dynamical Systems · Mathematics 2014-04-30 Hichem Eleuch , Ingrid Rotter

We propose a diagnostic tool for detecting non-trivial symmetry protected topological (SPT) phases protected by a symmetry group $G$ in 2+1 dimensions. Our method is based on directly studying the 1+1-dimensional anomalous edge conformal…

Strongly Correlated Electrons · Physics 2017-09-13 Bo Han , Apoorv Tiwari , Chang-Tse Hsieh , Shinsei Ryu

Exceptional points are a ubiquitous concept widely present in driven-dissipative coupled systems described by a non-Hermitian Hamiltonian. It is characterized by the degeneracy of the Hamiltonian's eigenvalues and coalescence of…