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
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
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
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
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
Quantum Science & Technology
Hossein Rangani Jahromi, Rosario Lo Franco
Summary: This paper introduces an easily computable tool based on HSS to detect exceptional points in non-Hermitian systems, especially in high-dimensional systems. The tool does not require modification of the Hilbert space and the theoretical predictions are consistent with experimental results. The paper also addresses the loss of certain important characteristics in non-Hermitian systems.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Physics, Multidisciplinary
Xi-guang Wang, Lu-lu Zeng, Guang-hua Guo, Jamal Berakdar
Summary: This study presents a method for realizing spatiotemporally driven PT-symmetric magnonics and demonstrates the transition between PT-symmetric and broken PT-symmetric phases under different conditions. The magnetization auto-oscillations in the broken PT-symmetric phase occur at low currents and do not require further adjustments, showing potential applications in computing and sensorics.
PHYSICAL REVIEW LETTERS
(2023)
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, Applied
Yiran Jian, Yuqian Wang, Zhiwei Guo, Shengyu Hu, Bintao Wu, Yaping Yang, Hong Chen
Summary: This study proposes an effective anti-parity-time symmetry through external excitation to control the chirality of a non-Hermitian system, and experimentally demonstrates the chirality reversal from resonance EP to absorption EP. The critical condition for chirality reversal between the two types of EPs is analytically determined. This externally controlled EP not only provides an effective approach to study fundamental non-Hermitian physics in open systems, but also has great potential in applications such as photonic devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Wei-Chen Wang, Yan-Li Zhou, Hui-Lai Zhang, Jie Zhang, Man-Chao Zhang, Yi Xie, Chun-Wang Wu, Ting Chen, Bao-Quan Ou, Wei Wu, Hui Jing, Ping-Xing Chen
Summary: This translation introduces the spontaneous PT symmetry breaking in a single cold Ca-40(+) ion and the counterintuitive effect of perfect quantum coherence occurring at the exceptional point (EP). The excellent agreement between experimental results and theoretical predictions demonstrates the potential of cold ions in exploring PT-symmetric physics and utilizing pure quantum EP effects.
Article
Crystallography
Ming Fang, Yang Wang, Pu Zhang, Haihong Xu, Dong Zhao
Summary: This study investigates the anisotropic reflection of light waves around exceptional points (EPs) in anti-parity-time-symmetric (APT-symmetric) Cantor dielectric multilayers. The Cantor multilayers, governed by the Cantor substitution law, are modulated to satisfy APT symmetry and support optical fractal resonances. Multiple EPs can be induced in the parameter space by modulating the loss coefficient of materials and optical frequency, resulting in unidirectional suppression and enhancement of reflection anisotropy for light waves incident from two opposite directions. This research has potential applications in photonic suppressors and reflectors for multiple wavelengths.
Article
Materials Science, Multidisciplinary
Qinxin Yue, Weiming Zhen, Yiping Ding, Xiang Zhou, Dongmei Deng
Summary: We theoretically studied the Goos-Hanchen shifts of Gaussian beams reflected in parity-time symmetric multilayered structure coating graphene structures. The exceptional points in the structure can be adjusted to control the GH shifts, and the Fermi energy of graphene and the period number of the PT-symmetric structure can also affect the GH shifts. The system may produce the Bragg resonance with specific frequency and exhibit special GH shifts independent of the incident direction with large reflectivity.
OPTICAL MATERIALS EXPRESS
(2021)
Article
Multidisciplinary Sciences
Ievgen I. I. Arkhipov, Adam Miranowicz, Fabrizio Minganti, Sahin K. Ozdemir, Franco Nori
Summary: Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects, such as controlled asymmetric-symmetric mode switching in a two-mode photonic system by dynamically winding around an exceptional point (EP). However, for multimode systems with higher-order EPs or multiple low-order EPs, controlling asymmetric-symmetric mode switching can be impeded due to the breakdown of adiabaticity. In this work, we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. Our findings provide alternative routes for light manipulations in non-Hermitian photonic setups.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
David Kramar
Summary: We investigate non-self-adjoint PT-symmetric operators with complex boundary conditions of Sturm-Liouville type, studying the existence of a similarity transformation to a self-adjoint operator depending on the boundary parameter. We determine the parameter values for quasi-self-adjoint models and find the self-adjoint counterpart in closed form. If a similar self-adjoint operator does not exist, we construct a generalized similarity transformation taking root vectors into account to find the similar operator in closed form as well.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Physics, Multidisciplinary
Jin-Yi Zhang, Chang-Rui Yi, Long Zhang, Rui-Heng Jiao, Kai-Ye Shi, Huan Yuan, Wei Zhang, Xiong-Jun Liu, Shuai Chen, Jian-Wei Pan
Summary: Floquet engineering allows for the creation of new topological states that cannot be achieved in static systems. In this study, we experimentally realize and characterize anomalous topological states using high-precision Floquet engineering for ultracold atoms trapped in a shaking optical Raman lattice.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Mingsheng Tian, Fengxiao Sun, Kaiye Shi, Haitan Xu, Qiongyi He, Wei Zhang
Summary: We investigated the transport properties of a driven-dissipative photonic network with multiple photonic cavities coupled through a nonreciprocal bus. For short-range coupling, the occurrence of nonreciprocal amplification is linked to a topological phase transition of the underlying dynamic Hamiltonian. However, for long-range coupling, the correspondence between the nonreciprocal amplification transition and the topological phase transition breaks down. We found the exact transition condition for nonreciprocal amplification and studied its stability, crossover, and bandwidth. Our work has potential applications in signal transmission and amplification, and opens up avenues for studying other topological and non-Hermitian systems with long-range coupling and nontrivial boundary effects.
PHOTONICS RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Kaiye Shi, Mingsheng Tian, Feng-Xiao Sun, Wei Zhang
Summary: The search for novel topological states of matter has been a major research focus in recent decades. In this study, we investigated a generalized one-dimensional Su-Schrieffer-Heeger model with semi-infinite long-range hopping and discovered a new type of topological phase called a Hermitian non-Bloch topological phase. This phase exhibits symmetry-protected edge modes and can be characterized by a topological invariant defined in real space wave functions. Additionally, we observed a large number of localized bulk modes near the band edges, which are determined by the ratio between hopping range and system size. Our findings have implications for the realization of Hermitian non-Bloch topological phases in metamaterials such as topolectrical circuits and mechanical oscillator lattices.
Article
Optics
Kai-Ye Shi, Rui-Qi Chen, Shuaining Zhang, Wei Zhang
Summary: In this paper, a scheme is proposed to fully characterize Floquet topological phases using bulk dispersions and a set of topological invariants associated with the band-touching points.
Article
Optics
Liangyu Ding, Kaiye Shi, Yuxin Wang, Qiuxin Zhang, Chenhao Zhu, Ludan Zhang, Jiaqi Yi, Shuaining Zhang, Xiang Zhang, Wei Zhang
Summary: Non-Hermitian systems with PT or anti-PT symmetry have unique properties and counterintuitive phenomena, with one of the most notable features being the presence of an exceptional point where the PT symmetry is spontaneously broken.
