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Time modulation can cause gain and loss in photonic media, leading to complex modal behaviors and enhanced wave controllability in the non-Hermitian regime. Conversely, we reveal that Hermiticity and parity-time $\mathcal{PT}$-symmetry…

Optics · Physics 2025-07-08 Rui-Chuan Zhang , Shu Yang , Yixin Sha , Zetao Xie , Yi Yang

Topological insulators have been studied intensively over the last decades. Earlier research focused on Hermitian Hamiltonians, but recently, peculiar and interesting properties were found by introducing non-Hermiticity. In this work, we…

Statistical Mechanics · Physics 2024-05-29 Chao Chen Ye , W. L. Vleeshouwers , S. Heatley , V. Gritsev , C. Morais Smith

We present a phase space study of non-Hermitian Hamiltonian with $\mathcal{PT}$-symmetry based on the Wigner distribution function. For an arbitrary complex potential, we derive a generalized continuity equation for the Wigner function flow…

Quantum Physics · Physics 2016-05-25 Ludmila Praxmeyer , Popo Yang , Ray-Kuang Lee

We study time-reversal symmetry breaking in non-Hermitian fluctuating field theories with conserved dynamics, comprising the mesoscopic descriptions of a wide range of nonequilibrium phenomena. They exhibit continuous parity-time…

Statistical Mechanics · Physics 2023-09-08 Thomas Suchanek , Klaus Kroy , Sarah A. M. Loos

By investigating information flow between a general parity-time (PT) -symmetric non-Hermitian system and an environment, we find that the complete information retrieval from the environment can be achieved in the PT-unbroken phase, whereas…

Quantum Physics · Physics 2017-11-07 Kohei Kawabata , Yuto Ashida , Masahito Ueda

In this paper, we experimentally demonstrate a non-Hermitian open PT-symmetric terahertz metasurface comprising complementary plasmonic structures capable of exhibiting an exceptional point (EP). The metasurface consists of two resonators…

Optics · Physics 2025-06-24 Anshul Bhardwaj , Maidul Islam , Chandan Kumar , Anuraj Panwar , Gagan Kumar

Dynamically varying system parameters along a path enclosing an exceptional point is known to lead to chiral mode conversion. But is it necessary to include this non-Hermitian degeneracy inside the contour for this process to take place? We…

We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently-prepared four-level N-type atomic system. By appropriately tuning the pertinent atomic parameters, the onset of PT-symmetry…

We outline a theoretical framework for quantum metrology in non-Hermitian systems, demonstrating both significant failure and exceptional regimes in PT-symmetric Bardeen-Cooper-Schrieffer chains. Through biorthogonal quantum Fisher…

Quantum Physics · Physics 2025-08-08 Harshank Matkar

Optical second-harmonic generation (SHG) is studied for the confined geometry of a circular cylindrical waveguide or optical fiber. A model situation of high symmetry is considered where the material with nonlinear susceptibility is…

Optics · Physics 2013-09-17 B. U. Felderhof , G. Marowsky

Here we employ the quasi-bound state in the continuum (quasi-BIC) resonance in all-dielectric metasurfaces for efficient nonlinear processes in consideration of the backward frequency conversion. We theoretically study the second-harmonic…

Optics · Physics 2024-06-28 Xu Tu , Siqi Feng , Jiajun Li , Yangguang Xing , Feng Wu , Tingting Liu , Shuyuan Xiao

We study a non-Hermitian two-level system with square-wave modulated dissipation and coupling. Based on the Floquet theory, we achieve an effective Hamiltonian from which the boundaries of the $\mathcal{PT}$ phase diagram are captured…

Quantum Physics · Physics 2020-08-18 Liwei Duan , Yan-Zhi Wang , Qing-Hu Chen

We explore the effect of self-orthogonality at exceptional points (EPs) in non-Hermitian Parity-Time-symmetric systems. Using a driven three-band lattice model, we show that the Rabi frequency diverges as the system approaches an EP due to…

Other Condensed Matter · Physics 2025-07-15 Alexander Fritzsche , Riccardo Sorbello , Ronny Thomale , Alexander Szameit

We describe an approach based on topology optimization that enables automatic discovery of wavelength-scale photonic structures for achieving high-efficiency second-harmonic generation (SHG). A key distinction from previous formulation and…

Higher-order exceptional points (EPs) in non-Hermitian systems showcase diverse physical phenomena but require more parameter space freedom or symmetries. It leads to a challenge for the exploration of high-order EP geometries in…

Quantum Physics · Physics 2025-10-22 Hao Chen , Xiao Qin , Jian-Jun Dong , Yu-Yu Zhang , Zi-Xiang Hu

We investigate topological and disorder effects in non-Hermitian systems with chiral symmetry. The system under consideration consists in a finite Su-Schrieffer-Heeger chain to which two semi-infinite leads are attached. The system lacks…

Mesoscale and Nanoscale Physics · Physics 2020-12-30 B. Ostahie , A. Aldea

We investigate localization-delocalization transition in one-dimensional non-Hermitian quasiperiodic lattices with exponential short-range hopping, which possess parity-time ($\mathcal{PT}$) symmetry. The localization transition induced by…

Disordered Systems and Neural Networks · Physics 2020-05-27 Yanxia Liu , Xiang-Ping Jiang , Junpeng Cao , Shu Chen

Transmission peak degeneracies (TPDs) have emerged as a promising alternative to exceptional points (EPs) for non-Hermitian sensing, providing square-root frequency splitting without the eigenbasis collapse and associated noise…

A noteworthy discovery is that the minimal evolution time is smaller for parity-time ($\mathcal{PT}$) symmetric systems compared to Hermitian setups. Moreover, there is a significant acceleration of two-qubit quantum entanglement…

Quantum Physics · Physics 2024-10-02 B. -B. Liu , Shi-Lei Su , Y. -L. Zuo , Qiongyi He , Gang Chen , F. Nori , H. Jing

The efficient sensing of weak environmental perturbations via special degeneracies called exceptional points in non-Hermitian systems has gained enormous traction in the last few decades. However, in contrast to the extensive literature on…

Quantum Physics · Physics 2022-03-02 J. Wang , D. Mukhopadhyay , G. S. Agarwal
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