Article
Nanoscience & Nanotechnology
Zhicheng Xiao, Andrea Alu
Summary: The study explores a hybrid parity-time and anti-parity-time symmetric system that supports highly tunable Fano resonances. This system can be implemented in nanophotonic and microwave circuits for real-time control of scattering line shapes, demonstrating the opportunities enabled by non-Hermitian platforms in controlling scattering line shapes for various photonic, electronic, and quantum systems. The potential applications include high-resolution imaging, switching, sensing, and multiplexing.
Article
Physics, Multidisciplinary
Roman Rausch, Robert Peters, Tsuneya Yoshida
Summary: The paper presents a new method of analyzing and interpreting spectra in the presence of interactions using non-Hermitian phenomena. By utilizing the density-matrix renormalization group, the existence of exceptional points in the one-dimensional Hubbard chain with chiral symmetry is demonstrated, showing a Fermi arc at zero frequency in the spectrum. These points are a result of the non-Hermiticity of the effective Hamiltonian and are only present at finite temperature.
NEW JOURNAL OF PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yanghao Fang, Tsampikos Kottos, Ramathasan Thevamaran
Summary: The research introduces a class of parity-time symmetric elastodynamic metamaterials with unfolding (fractal) spectral symmetries, revealing a scale-free formation of exceptional points. By using finite element models and a coupled mode theory model, the study establishes a universal route for exceptional point formation in Ed-MetaMaters with specific fractal spectra, which may enable the rational design of novel Ed-MetaMater for hypersensitive sensing and elastic wave control.
NEW JOURNAL OF PHYSICS
(2021)
Article
Physics, Multidisciplinary
Clement Ferise, Philipp del Hougne, Simon Felix, Vincent Pagneux, Matthieu Davy
Summary: In this study, we experimentally and analytically investigate the coalescence of reflectionless (RL) states in symmetric complex wave-scattering systems. We observe that there are exceptional points (EPs) associated with the parity-time (PT)-symmetric RL operator when the spacing between central frequencies matches the decay rate into incoming and outgoing channels. Furthermore, we demonstrate the implementation of first- and second-order analog differentiation using the transfer functions of RL and RL-EP states.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Matheus INc Rosa, Matteo Mazzotti, Massimo Ruzzene
Summary: The study focuses on exceptional points in continuous elastic media and their potential application in detecting mass and stiffness perturbations. By introducing balanced gain and loss to induce degenerate states, the sensitivity of the system is enhanced, making it promising for applications involving sensing of disturbances such as point masses and surface cracks.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Physics, Multidisciplinary
Liangyu Ding, Kaiye Shi, Qiuxin Zhang, Danna Shen, Xiang Zhang, Wei Zhang
Summary: Observing exceptional points of a non-Hermitian Hamiltonian with parity-time-reversal symmetry can enhance metrology and sensing capabilities by increasing sensitivity to external perturbations. This exploration allows for detailed quantum phase transitions and extraction of eigenvalues, leading to the measurement of time-dependent perturbations through EP enhancement.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Maryam Sakhdari, Zhilu Ye, Mohamed Farhat, Pai-Yen Chen
Summary: The emergence of exceptional points and divergent exceptional points in PT symmetric trimer opens up a new pathway for highly sensitive RF telemetric sensor systems. In this study, a rigorous analysis of PT symmetric electronic multimers is provided, shedding light on the lower bound of inductive coupling coefficient required to achieve divergent exceptional points. The results suggest a subtle compromise among the degree of bifurcation, critical inductive coupling strength, and spectral noises arising from modal interferences.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Multidisciplinary Sciences
Ayan Banerjee, Rimika Jaiswal, Madhusudan Manjunath, Awadhesh Narayan
Summary: In this study, a unified tropical geometric framework is introduced and developed to characterize different aspects of non-Hermitian systems. The versatility of this approach is demonstrated through several examples, including selecting from a spectrum of higher-order exceptional points (EPs) in gain and loss models, predicting the skin effect in the non-Hermitian Su-Schrieffer-Heeger model, and extracting universal properties in the presence of disorder in the Hatano-Nelson model. This work provides a framework for studying non-Hermitian physics and reveals a connection between tropical geometry and this field.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Acoustics
Runcheng Cai, Yabin Jin, Yong Li, Jie Zhu, Hehua Zhu, Timon Rabczuk, Xiaoying Zhuang
Summary: In this study, we investigate the Parity-Time (PT) symmetric metaplate with balanced loss and gain, and achieve coherent perfect absorption and lasing effects for flexural waves. We also explore the exceptional points (EP) as thresholds of phase transitions and realize unidirectional reflectionless behavior for incident waves by adjusting circuit parameters. Our study provides insights into the origins and sensitivities of non-Hermitian exceptional points for elastic waves.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Optics
Xiao-Hu Lu, Liu-Gang Si, Xiao-Yun Wang, Ying Wu
Summary: This paper theoretically analyzes the generation of frequency components at the sum sideband in a non-Hermitian system by considering the nonlinear terms of the optomechanical dynamics. It demonstrates that the efficiency of sum sideband generation can be significantly enhanced in exceptional points, leading to a potential improvement in light transmission and conversion in chip-scale optical communications.
Article
Multidisciplinary Sciences
Guoqiang Xu, Wei Li, Xue Zhou, Huagen Li, Ying Li, Shanhui Fan, Shuang Zhang, Demetrios N. Christodoulides, Cheng-Wei Qiu
Summary: By establishing a three-dimensional parameter space to simulate thermal spinor field, we discovered the existence of non-Hermitian exceptional ring (WER) in a hybrid conduction-advection system and observed its thermal signatures. Coupling two WERs of opposite topological charges, the system exhibited different thermal processes, revealing the long-ignored topological nature in thermal diffusion.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Multidisciplinary
Charles Andrew Downing, Vasil Arkadievich Saroka
Summary: This article introduces a quantum theory describing the non-Hermitian physics of chains of coupled modes, elucidating the origin of exceptional points governing parity-time symmetry and their influence on quantum transport and correlations. It is found that the locations of exceptional points evolve with chain length and parity, capturing the transition from unbroken to broken symmetric phase in oligomer chains.
COMMUNICATIONS PHYSICS
(2021)
Review
Engineering, Electrical & Electronic
Zhipeng Li, Guangtao Cao, Chenhui Li, Shaohua Dong, Yan Deng, Xinke Liu, John S. Ho, Cheng-Wei Qiu
Summary: Exceptional points are spectral singularities that occur in non-Hermitian systems where multiple eigenvalues and their corresponding eigenvectors coalesce. These points have attracted significant attention in optics and photonics due to their emergence in systems with nonconservative gain and loss elements, leading to counterintuitive phenomena. Metasurfaces, structured at the subwavelength scale, offer a versatile platform for exploring non-Hermitian phenomena through the addition of dissipation and amplification, enabling a range of exotic phenomena with potential technological applications. The review discusses recent advances in exceptional points and non-Hermitian metasurfaces, highlighting achievements, applications, and future opportunities in the field.
PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER
(2021)
Article
Optics
Konrad Tschernig, Kurt Busch, Demetrios N. Christodoulides, Armando Perez-Leija
Summary: Exceptional points are complex-valued spectral singularities that can lead to loss-induced transparency, where system's overall loss can enhance transmission. The enhancements scale with the order of the exceptional points, making it interesting to devise strategies for high-order exceptional points. It is shown that high-order N-photon exceptional points can be generated by exciting non-Hermitian waveguide arrangements with coherent light states, allowing observation of N-photon enhanced loss-induced transparency in the quantum realm. Further analysis shows that number-resolved dynamics in nonconservative waveguide arrays can exhibit several exceptional points associated with different eigenmodes and dissipation rates.
LASER & PHOTONICS REVIEWS
(2022)
Article
Physics, Applied
Yingying Zhang, Shiqiang Xia, Lu Qin, Qi Wang, Pengbo Jia, Wenrong Qi, Xuejing Feng, Yajing Jiang, Zunlue Zhu, Xingdong Zhao, Wuming Liu, Yufang Liu
Summary: In this study, a new multiband photonic lattice structure is proposed, which can achieve multiple phase transitions. By adjusting the couplings and gain/loss, multiple exceptional points can be generated. At the same time, the study also reveals the impact of non-Hermitian diagonal disorder and off-diagonal disorder on the system.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Eva-Maria Graefe, Steve Mudute-Ndumbe, Matthew Taylor
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2015)
Article
Physics, Multidisciplinary
Eva-Maria Graefe, Hans Juergen Korsch, Alexander Rush, Roman Schubert
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2015)
Article
Optics
Eva-Maria Graefe, Maria Graney, Alexander Rush
Article
Engineering, Electrical & Electronic
Eva-Maria Graefe, Alexander Rush, Roman Schubert
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2016)
Article
Physics, Multidisciplinary
E. M. Graefe, H. J. Korsch, A. Rush
NEW JOURNAL OF PHYSICS
(2016)
Article
Physics, Multidisciplinary
E. M. Graefe, B. Longstaff, T. Plastow, R. Schubert
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2018)
Article
Physics, Multidisciplinary
Eva-Maria Graefe, Hans Juergen Korsch, Martin P. Strzys
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2014)
News Item
Optics
Eva-Maria Graefe
Article
Optics
Bradley Longstaff, Eva-Maria Graefe
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2020)
Article
Physics, Multidisciplinary
Steve Mudute-Ndumbe, Eva-Maria Graefe
NEW JOURNAL OF PHYSICS
(2020)
Article
Physics, Multidisciplinary
Robson Christie, Jessica Eastman, Roman Schubert, Eva-Maria Graefe
Summary: This study examines the dynamics of Gaussian states in open quantum systems and obtains the solutions to Lindblad dynamics using analytical methods. It finds that Gaussian states remain Gaussian under stochastic Schrödinger dynamics but not necessarily under quantum-jump evolution. The study also proposes a method to generate quantum-jump trajectories based entirely on the evolution of an underlying Gaussian state.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Physics, Multidisciplinary
Katherine Holmes, Wasim Rehman, Simon Malzard, Eva-Maria Graefe
Summary: The dynamics generated by non-Hermitian Hamiltonians are often more complex than those of conventional Hermitian systems. This is demonstrated even in simple models like the complexified harmonic oscillator, where the dynamics for generic initial states exhibit surprising features. In this study, we analyze the dynamics of the Husimi distribution in a semiclassical limit and provide insights into the foundations of the full quantum evolution. By studying the classical Husimi evolution, we reveal how the full quantum dynamics manifests on top of the classical dynamics for two informative examples.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Rishindra Melanathuru, Simon Malzard, Eva-Maria Graefe
Summary: This paper introduces a PT-symmetric non-Hermitian quantum system with two Nth order exceptional points and derives the Landau-Zener transition probabilities, showing a binomial behavior. It demonstrates that, despite the breakdown of adiabaticity often associated with non-Hermitian systems, the behavior can still be understood based on adiabatic analysis.
Article
Optics
Bradley Longstaff, Eva-Maria Graefe
Article
Optics
Eva-Maria Graefe, Hans Juergen Korsch, Alexander Rush