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We show that arbitrarily high-order exceptional points (EPs) can be achieved in a repulsively interacting two-species Bose gas in one dimension. By exactly solving the non-Hermitian two-boson problem, we demonstrate the existence of…

Quantum Gases · Physics 2019-01-23 Lei Pan , Shu Chen , Xiaoling Cui

Non-Hermiticity has emerged as a new paradigm for controlling coupled-mode systems in ways that cannot be achieved with conventional techniques. One aspect of this control that has received considerable attention recently is the encircling…

Exceptional points (EPs) are spectral degeneracies unique to non-Hermitian systems which underpin phenomena from enhanced sensing to unconventional topology. While disorder is usually viewed as detrimental, it can also drive topological…

Disordered Systems and Neural Networks · Physics 2026-01-28 Xiaoyu Cheng , Tiantao Qu , Yaqing Yang , Jun Chen , Lei Zhang

The physics of topological singularities, namely exceptional points (EPs), has been a key to wide range of intriguing and unique physical effects in non-Hermitian systems. In this context, the mutual interactions among four coupled states…

Optics · Physics 2020-01-01 Sayan Bhattacherjee , Harsh K. Gandhi , Arnab Laha , Somnath Ghosh

Exceptional points (EPs) are special singularities of non-Hermitian Hamiltonians. At an EP, two or more eigenvalues and the corresponding eigenstates coalesce. Recently, EP-based optical gyroscope near an EP was extensively investigated to…

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…

Hamiltonian exceptional points (HEPs) are spectral degeneracies of non-Hermitian Hamiltonians describing classical and semiclassical open systems with losses and/or gain. However, this definition overlooks the occurrence of quantum jumps in…

Quantum Physics · Physics 2024-12-11 Shilan Abo , Patrycja Tulewicz , Karol Bartkiewicz , Şahin K. Özdemir , Adam Miranowicz

One of the key features of non-Hermitian systems is the occurrence of exceptional points (EPs), spectral degeneracies where the eigenvalues and eigenvectors merge. In this work, we propose applying neural networks to characterize EPs by…

Disordered Systems and Neural Networks · Physics 2023-12-05 Md. Afsar Reja , Awadhesh Narayan

In the past few decades, many works have been devoted to the study of exceptional points (EPs), i.e., exotic degeneracies of non-Hermitian systems. The usual approach in those studies involves the introduction of a phenomenological…

Quantum Physics · Physics 2020-01-16 Ievgen I. Arkhipov , Adam Miranowicz , Fabrizio Minganti , Franco Nori

Eigenstate coalescence in non-Hermitian systems is widely observed in diverse scientific domains encompassing optics and open quantum systems. Recent investigations have revealed that adiabatic encircling of exceptional points (EPs) leads…

Quantum Physics · Physics 2023-06-13 Jung-Wan Ryu , Jae-Ho Han , Chang-Hwan Yi , Moon Jip Park , Hee Chul Park

Defective spectral degeneracy, known as exceptional point (EP), lies at the heart of various intriguing phenomena in optics, acoustics, and other nonconservative systems. Despite extensive studies in the past two decades, the…

Mesoscale and Nanoscale Physics · Physics 2023-04-13 Cui-Xian Guo , Shu Chen , Kun Ding , Haiping Hu

Non-Hermitian (NH) systems can display exotic topological phenomena without Hermitian counterparts, enabled by exceptional points (EPs). So far, investigations of NH topology have been restricted to EPs of the NH Hamiltonian, which governs…

We develop a systematic framework for determining the nature of exceptional points of $n^{\rm th}$ order (EP$_n$s) in non-Hermitian (NH) systems, represented by complex square matrices. By expressing symmetry-preserving perturbations in the…

Mesoscale and Nanoscale Physics · Physics 2026-03-27 Ipsita Mandal

Non-Hermitian systems at the exceptional point (EP) degeneracy are demonstrated to be highly sensitive to environmental perturbation. Here, we propose and theoretically investigate a novel multilayered heterostructure favoring double EPs…

Optics · Physics 2019-03-21 Jieun Yim , Han Zhao , Bikashkali Midya , Liang Feng

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 peculiar band singularities and play a vital role in a rich array of unusual optical phenomena and non-Hermitian band theory. In this paper, we provide a topological classification of isolated EPs based on…

Mesoscale and Nanoscale Physics · Physics 2022-06-29 Haiping Hu , Shikang Sun , Shu Chen

Higher-order exceptional points (EPs), which appear as multifold degeneracies in the spectra of non-Hermitian systems, are garnering extensive attention in various multidisciplinary fields. However, constructing higher-order EPs still…

Current progress in electro-optical modulation within silicon integrated photonics, driven by the unique capabilities of advanced functional materials, has led to significant improvements in device performance. However, inherent constraints…

Optics · Physics 2025-10-30 Shahab Ramezanpour , Amr Helmy

Non-Hermitian systems and their topological singularities, such as exceptional points (EPs), lines, and surfaces, have recently attracted intense interest. The investigation of these exceptional constituents has led to fruitful…

Optics · Physics 2024-08-08 Liang Fang , Kai Bai , Cheng Guo , Tian-Rui Liu , Jia-Zheng Li , Meng Xiao

Exceptional points (EPs), singularities in non-Hermitian systems where eigenvalues and eigenstates coalesce, exhibit a dramatically enhanced response to perturbations compared to Hermitian degeneracies. This makes them exceptional…

Quantum Physics · Physics 2025-11-24 Shu-Xuan Wang , Zhongbo Yan