Article
Materials Science, Multidisciplinary
Haotian Wu, Xinxin Gao, Shuo Liu, Qian Ma, Hao Chi Zhang, Xiang Wan, Tie Jun Cui
Summary: A new mechanism for controlling electromagnetic wave flow based on spatiotemporal metasurface assisted with parity-time (PT) symmetric modulations is proposed and experimentally verified in the microwave regime. The generated spin-momentum coupling can be flexibly switched in real time, providing a powerful platform for exploring physical effects that are hard to realize in traditional photonic topological systems.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Optics
Yanxian Wei, Hailong Zhou, Dongmei Huang, Feng Li, Jianji Dong, Xinliang Zhang, P. K. A. Wai
Summary: This article discusses how loss can induce modal gain in non-Hermitian systems, and observes this phenomenon experimentally. By utilizing polarization-dependent loss in a single laser cavity, a new method for manipulating active cavity lasing is demonstrated.
Article
Optics
Martino De Carlo, Francesco De Leonardis, Luciano Lamberti, Vittorio M. N. Passaro
Summary: In this study, a resonator-bus-resonator anti-parity-time-symmetric integrated optical gyroscope designed on the InP platform is proposed for the first time. This new architecture significantly reduces fabrication tolerance problems and enhances robustness against external perturbations. The proposed configuration also enables an electrical fine-tuning method to set the system at the exceptional point.
OPTICS AND LASERS IN ENGINEERING
(2022)
Article
Physics, Multidisciplinary
Yuanjiang Tang, Chao Liang, Xin Wen, Weipeng Li, An-Ning Xu, Yong-Chun Liu
Summary: We propose a PT-symmetric feedback method to narrow the linewidths of resonance systems, achieving remarkable linewidth narrowing and enhancement of measurement sensitivity. By transforming a dissipative resonance system into a PT-symmetric system, using a quadrature measurement-feedback loop, the method only requires a single resonance mode, greatly extending its scope of applications. In a thermal ensemble of atoms, we demonstrate a 48-fold narrowing of the magnetic resonance linewidth and a 22-times improvement in measurement sensitivity in magnetometry, opening new avenues for studying nonHermitian physics and high-precision measurements in resonance systems with feedback.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Dongdong Hao, Lin Wang, Xingda Lu, Xuzhen Cao, Suotang Jia, Ying Hu, Yanhong Xiao
Summary: Recent experimental advances in creating dissipative couplings provide a new route for engineering exotic lattice systems and exploring topological dissipation. Using a spatial lattice of atomic spin waves, we experimentally realize a dissipative version of the Su-Schrieffer-Heeger (SSH) model. The dissipative spectrum of the topological lattices shows edge modes within a dissipative gap. This work opens up the possibility of realizing non-Hermitian topological quantum optics through dissipative couplings.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Max Ehrhardt, Matthias Heinrich, Alexander Szameit
Summary: The ability of indistinguishable particles to interfere with one another is a fundamental principle in quantum mechanics. In this study, the researchers experimentally demonstrate the tunability of coincidence statistics for boson pairs, from full suppression to enhancement, by selecting an appropriate observation basis. This finding could have important implications for manipulating multi-particle quantum states and using non-Hermitian settings as functional elements in quantum simulation.
Article
Optics
Da Huo, Shuo Hua, Xue-dong Tian, Yi-mou Liu
Summary: We propose a theoretical scheme in a cold rubidium-87 (87Rb) atomic ensemble that achieves a lopsided optical diffraction grating through a non-Hermitian optical structure with single spatially periodic modulation and loop-phase. The modulation between parity-time (PT) symmetric and parity-time antisymmetric (APT) can be controlled by adjusting relative phases of the applied beams. Our scheme demonstrates robust PT symmetry and PT antisymmetry, enabling precise modulation of optical response without symmetry breaking. The nontrivial optical properties exhibited in our system include lopsided diffraction, single-order diffraction, asymmetric Dammam-like diffraction, etc. Our work contributes to the development of versatile non-Hermitian/asymmetric optical devices.
Article
Multidisciplinary Sciences
Geva Arwas, Sagie Gadasi, Igor Gershenzon, Asher Friesem, Nir Davidson, Oren Raz
Summary: Non-Hermitian Hamiltonians, such as parity-time (PT) and anti-PT symmetric Hamiltonians, have significant implications in various branches of physics. In this study, we investigate these novel symmetries theoretically and demonstrate them experimentally in coupled laser systems. We also discover a new relation between laser synchronization and the symmetry of the underlying non-Hermitian Hamiltonian.
Article
Physics, Multidisciplinary
Xin Yang, Jiawen Li, Yifei Ding, Mengwei Xu, Xue-Feng Zhu, Jie Zhu
Summary: The transient parity-time (PT) symmetry in electronics is demonstrated in this study. By equivalent circuit transformation according to the switching states of electronic systems, the PT symmetry is revealed. Using the phasor method and Laplace transformation, the hidden PT-symmetric Hamiltonian in the switching oscillation is derived, which is characterized by free oscillation modes. The spectral and dynamic properties of the PT electronic structure demonstrate the phase transition and eigenmode orthogonality. Importantly, the observed transient PT symmetry enables optimal switching oscillation suppression induced by exceptional points, showing the significance of PT symmetry in electronic systems with temporary responses. The study paves the way for breakthroughs in PT symmetry theory and has essential applications such as anti-interference in switch-mode electronics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Julien Cornelius, Zhenyu Xu, Avadh Saxena, Aurelia Chenu, Adolfo del Campo
Summary: The study finds that balanced gain and loss in non-Hermitian evolution can enhance the manifestation of quantum chaos and provide a feasible experimental mechanism for spectral filtering.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
H. S. Xu, L. Jin
Summary: We investigate the properties of two anti-parity-time-symmetric four-site scattering centers and find that the coupling method significantly affects the scattering properties, with imaginary coupling leading to nonunitary scattering and real coupling leading to unitary scattering.
Article
Optics
Ambaresh Sahoo, Amarendra K. Sarma
Summary: By tuning the coupling parameters of a non-Hermitian system, device sensitivity to small perturbations can be enhanced, and a phase transition in exceptional points can be achieved. The adjustable coupling also leads to a sharp change in sensitivity slope, enabling precise measurement of perturbations as a function of coupling.
Article
Materials Science, Multidisciplinary
Weitao Chen, Liangtao Peng, Hantao Lu, Xiancong Lu
Summary: This paper investigates the relationship between edge entanglement entropy and topological properties in non-Hermitian systems, and extends it to non-Hermitian interacting systems. It is found that the presence of interactions weakens the breakdown of the bulk-boundary correspondence.
Article
Materials Science, Multidisciplinary
Miguel A. N. Araujo, Pedro Ninhos, Pedro Ribeiro
Summary: The study investigates the impact of discrete symmetries on charge and heat pumping through noninteracting Floquet systems, particularly focusing on the role of particle-hole symmetry in determining the odd-even nature of charge and heat pumping in relation to the chemical potential. Breaking the particle-hole symmetry can influence the direction of charge and heat pumping, while coupling to the leads can result in the simultaneous breaking of particle-hole symmetry and spatial symmetry.
Article
Materials Science, Multidisciplinary
Denis V. Novitsky, Alexander S. Shalin, Dmitrii Redka, Vjaceslavs Bobrovs, Andrey V. Novitsky
Summary: This study proposes a novel mechanism for the quasi-BIC manifestation driven by the PT symmetry breaking in optical structures. Singularities separating PT symmetric and broken-PT symmetry states in the parametric space are revealed, coinciding with BIC positions at the frequency of volume plasmon excitation. The quasi-BICs with ultrahigh quality factors and almost perfect transmission show promise in sensing, nonlinear optics, and other applications.
Article
Physics, Multidisciplinary
Tongtong Song, Jie Luo, Yun Lai
Summary: This study demonstrates a potential approach to achieve zero-spacing photonic waveguides by designing pure-dielectric photonic crystal waveguides with shifted spatial dispersion and arranging them with normal dielectric waveguides alternately. This finding opens up a new avenue for ultra-compact photonic waveguides and circuits with 100% space utilization efficiency.
Article
Acoustics
Qi Wang, Jun Lan, Zhaoyu Deng, Yun Lai, Xiaozhou Liu
Summary: In this study, a heterogeneous structure acoustic leaky-wave antenna (LWA) is proposed to achieve spatial directional radiation and acoustic source localization. The designed antenna has unique frequency-scanning characteristics for directional radiation of sound waves with diverse incident frequencies. Additionally, it exhibits explicit directional frequency characteristics for spatial acoustic source localization, showing potential applications in high-precision acoustic source localization.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(2023)
Article
Multidisciplinary Sciences
Bo Xiong, Yu Liu, Yihao Xu, Lin Deng, Chao-Wei Chen, Jia-Nan Wang, Ruwen Peng, Yun Lai, Yongmin Liu, Mu Wang
Summary: By introducing engineered noise to the precise solution of Jones matrix elements, we have surpassed the fundamental limit of polarization multiplexing capacity of metasurfaces. Through experiments, we have achieved up to 11 independent holographic images using a single metasurface illuminated by visible light with different polarizations, which is the highest reported capacity for polarization multiplexing. With the combination of position multiplexing, the metasurface is capable of generating 36 distinct images, forming a holographic keyboard pattern. This discovery opens up new possibilities for high-capacity optical display, information encryption, and data storage.
Article
Optics
Shuai Lin, Hao Luo, Hainan He, Hongchen Chu, Yun Lai
Summary: In this work, broadband binary-reflection-phase metasurfaces with undistorted transmission wavefront are realized by leveraging mirror symmetry in the metasurface design. The cross-polarized reflection can be flexibly manipulated without distorting the wavefront in transmission by designing the binary-phase pattern induced in the cross-polarized reflection. The experimental validation of reflected-beam splitting and undistorted transmission wavefront in a broad bandwidth from 8 GHz to 13 GHz is presented.
Article
Materials Science, Multidisciplinary
Jiawei Xi, Jian Shen, Man To Chow, Tan Li, Jack Ng, Jensen Li
Summary: Multiplexing holography combined with metasurfaces using different degrees of light freedom has provided new applications in display and information processing. Polarization-multiplexed holograms can store the maximum amount of information, but it requires using bianisotropic metasurfaces instead of conventional single-layer nanostructures, which complicates the design and generation of holograms. In this study, an integrated neural network approach is developed to directly obtain metasurface profiles from independent holograms, allowing for complex polarization holograms without detailed knowledge of physical constraints.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Wenjie Ji, Jie Luo, Hongchen Chu, Xiaoxi Zhou, Xiangdong Meng, Ruwen Peng, Mu Wang, Yun Lai
Summary: By using epsilon-near-zero materials as claddings, the crosstalk between adjacent waveguides in photonic integrated circuits can be effectively prevented, leading to ultra-compact waveguide systems with extremely thin thickness.
Article
Nanoscience & Nanotechnology
Yongxin Jing, Hongchen Chu, Bo Huang, Jie Luo, Wei Wang, Yun Lai
Summary: The scattering matrix is a mathematical representation of scattering characteristics, but it lacks analytical forms for scatterers without high symmetry. We developed a deep neural network (DNN) that can calculate the scattering matrix of asymmetric scatterers thousands of times faster than finite element solvers. The DNN satisfies fundamental physical principles and enables inverse design using the gradient descent algorithm.
Article
Physics, Multidisciplinary
Hong Liang, Hammad Ahmed, Wing Yim Tam, Xianzhong Chen, Jensen Li
Summary: In this study, a geometric phase metasurface is used to remotely and continuously control the vortex states of a heralded photon. Metasurfaces, which utilize engineered nanostructures, offer control over different dimensions of light and have versatile applications. By selecting the polarization of the heralding photon, the orbital angular momentum (OAM) of the signal photon can be remotely controlled. This research has important implications for quantum communication and information processing.
COMMUNICATIONS PHYSICS
(2023)
Article
Physics, Applied
Yi-jun Guan, Cheng-hao Wu, Qiao-rui Si, Yong Ge, Hong-xiang Sun, Yun Lai, Shou-qi Yuan
Summary: A low-frequency acoustic absorber has been experimentally demonstrated by using double split-ring resonators backed with a rigid wall. This absorber achieves near-perfect sound absorption at a subwavelength thickness and can increase the bandwidth by assembling supercells with distinct structure parameters.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Optics
Tianyu Hou, Xiangteng Li, Hao Luo, Yufeng Hao, Hongchen Chu, Yun Lai
Summary: This study proposes a wireless communication scheme using an optically-transparent metasurface to construct a functionalized metal window, which can significantly enhance the intensity of microwave signals and improve network and data transfer speeds.
Article
Optics
Jin Qin, Hainan He, Changqing Xu, Jie Luo, Yun Lai
Summary: Zero-index materials, specifically epsilon-near-zero (ENZ) gratings, have attracted significant scientific interest due to their unique polarization selectivity and blocking capability. Hybrid gratings combining perfect conductors and ENZ materials can effectively block omnidirectional electromagnetic waves of any polarization. Our research presents a promising approach for flexible polarization manipulation using ENZ gratings.
Article
Chemistry, Physical
Tianyu Hou, Di Li, Yan Qu, Yufeng Hao, Yun Lai
Summary: This study reports the large-scale synthesis of molybdenum disulfide (MoS2) thin films, accompanied by the formation of amorphous carbon layers. It confirms the combination of polycrystalline MoS2 with extraneous amorphous carbon layers and demonstrates the transformation of traditional n-type MoS2 into p-type semiconductors due to carbon incorporation. This unexpected behavior expands our understanding of TMDC properties and opens up new avenues for exploring novel device applications.
Article
Nanoscience & Nanotechnology
Zhonghan Fei, Jun Lan, Menyang Gong, Yun Lai, Xiaozhou Liu
Summary: In this paper, an unbalanced gain-loss acoustic metasurface is designed as an energy amplifier and can be used in acoustic signal detection. By combining two of these metasurfaces, an acoustic negative refraction system is established, allowing for negative refraction, focusing, and imaging. This work provides a new approach to using gain/loss materials and achieving multifunctionality without complex design.
Article
Materials Science, Multidisciplinary
Qing Tong, Jensen Li, Shubo Wang
Summary: This research investigates the circular dichroism effect in acoustic systems. It is found that the effect is negligible in lossy metamaterials with C4 rotational symmetry but can be strongly enhanced in C2-symmetric systems with inhomogeneous loss. This enhancement is attributed to the presence of polarization band gaps and non-Hermitian exceptional points.
Article
Nanoscience & Nanotechnology
Pengfei Zhao, Liyou Luo, Yongquan Liu, Jensen Li
Summary: This study develops a transformation theory for manipulating the illusion effects of flexural waves. By introducing tailor-made thickness profiles on different curved shapes, the flexural waves can propagate in a way that is different from the actual configuration. Numerical simulations and experimental mapping confirm the effectiveness of this approach and reveal its potential applications in structural designs.
