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The emergence of parity-time ($\mathcal{PT}$) symmetry has greatly enriched our study of symmetry-enabled non-Hermitian physics, but the realization of quantum $\mathcal{PT}$-symmetry faces an intrinsic issue of unavoidable…

Quantum Physics · Physics 2022-05-11 Xi-Wang Luo , Chuanwei Zhang , Shengwang Du

Intrinsic defects in optomechanical devices are generally viewed to be detrimental for achieving coherent amplification of phonons, and great care has thus been exercised in fabricating devices and materials with no (or a minimal number of)…

Quantum Physics · Physics 2017-11-07 H. Lü , S. K. Özdemir , Franco Nori , L. -M. Kuang , H. Jing

We investigate in the framework of quantum noise theory how the striking boundary-sensitivity recently discovered in the context of non-Hermitian (NH) topological phases may be harnessed to devise novel quantum sensors. Specifically, we…

Quantum Physics · Physics 2022-02-15 Florian Koch , Jan Carl Budich

Exceptional points (EPs) in non-Hermitian systems give rise to enhanced sensitivity and chiral state transfer, which are important for quantum technologies. Although parameter trajectories encircling EPs can control symmetric and chiral…

Quantum Physics · Physics 2026-03-26 Qi-Cheng Wu , Yan-Hui Zhou , Biao-liang Ye , Tong Liu , Yi-Hao Kang , Qi-Ping Su , Chui-Ping Yang

Exceptional point (EP) is exclusive for non-Hermitian system and distinct from that at a degeneracy point (DP), supporting intriguing dynamics, which can be utilized to probe quantum phase transition and prepare eigenstates in a Hermitian…

Quantum Physics · Physics 2021-12-10 P. Wang , K. L. Zhang , Z. Song

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

The quantum metric, a geometric measure of state-space distance, has recently attracted growing attention for capturing anomalous state responses to parameter variations. Especially in non-Hermitian systems, the quantum metric has been…

Quantum Physics · Physics 2026-03-31 Teng Liu , Xiaohang Zhang , Jiawei Zhang , Le Luo

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…

The fascinating realm of non-Hermitian physics with the interplay of parity (P) and time-reversal (T) symmetry has been witnessing immense attention in exploring unconventional physics at Exceptional Point (EP) singularities. Particularly,…

Optics · Physics 2024-05-20 Dinesh Beniwal , Arnab Laha , Adam Miranowicz , Somnath Ghosh

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…

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

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

Emulation of energy transfer processes in natural systems on quantum platforms can further our understanding of complex dynamics in nature. One notable example is the demonstration of vibrationally assisted energy transfer (VAET) on a…

Quantum Physics · Physics 2024-05-14 Zeng-Zhao Li , K. Birgitta Whaley

Exceptional points (EPs) have been suggested for ultra-sensitive sensing because the eigenfrequency splitting grows as the nth-root of a perturbation, suggesting divergent responsivity. In ideal linear devices, however, this responsivity…

Optics · Physics 2025-09-25 Todd Darcie , J. Stewart Aitchison

Open systems possess unique potentials in high-precision sensing, yet the majority of previous studies rely on the spectral singularities known as exceptional points. Here we theoretically propose and experimentally demonstrate universal…

Quantum Physics · Physics 2025-01-06 Lei Xiao , Yaoming Chu , Quan Lin , Haiqing Lin , Wei Yi , Jianming Cai , Peng Xue

We study the parity and time-reversal ($\mathcal{PT}$) symmetric quantum physics in a non-Hermitian non-relativistic hydrogen molecule with local (Hubbard type) Coulomb interaction. We consider non-Hermiticity generated from both kinetic…

Quantum Physics · Physics 2022-03-23 Himadri Barman , Suriyaa Valliapan

Pseudo-Hermitian operators generalize the concept of Hermiticity. This class of operators includes the quasi-Hermitian operators, which reformulate quantum theory while retaining real-valued measurement outcomes and unitary time evolution.…

Quantum Physics · Physics 2023-06-08 Jacob L. Barnett

Exceptional points (EPs) are special parameter values of a non-Hermitian eigenvalue problem where eigenfunctions corresponding to a multiple eigenvalue coalesce. In optics, EPs are associated with a number of counter-intuitive wave…

Optics · Physics 2019-10-08 Amgad Abdrabou , Ya Yan Lu

Exceptional points (EPs) refer to degeneracies in non-Hermitian systems where two or more eigenvalues and their corresponding eigenvectors coalesce. Recently, there has been growing interest in harnessing EPs to enhance the responsivity of…

Applied Physics · Physics 2024-02-06 Xingyu Lu , Yang Yuan , Fa Chen , Xiaoxiao Hou , Yanlong Guo , Leonhard Reindl , Wei Luo , Degang Zhao

The Hamilton operator of an open quantum system is non-Hermitian. Its eigenvalues are, generally, complex and provide not only the energies but also the lifetimes of the states of the system. The states may couple via the common environment…

Quantum Physics · Physics 2017-02-17 Hichem Eleuch , Ingrid Rotter