Article
Materials Science, Multidisciplinary
Yi-Xin Xiao, C. T. Chan
Summary: This study investigates the bulk-boundary correspondence in a Chern insulator model with non-Hermitian skin effect, using the biorthogonal approach and non-Bloch approach to suppress the skin effect. The biorthogonal inverse participation ratio and non-Bloch Chern number are utilized as metrics and tools for predicting topological features. Moreover, the occurrence of crossing degeneracies between bulk and edge bands enriches the localization behavior of edge states.
Article
Materials Science, Multidisciplinary
Qi-Bo Zeng
Summary: This work discusses the energy dependence of the non-Hermitian skin effect (NHSE) by introducing nonreciprocity beyond nearest-neighboring hopping in one-dimensional lattices. It is found that the direction of NHSE reverses as the eigenenergy of the system under open boundary conditions (OBCs) crosses critical energies. The concept of non-Hermitian skin effect edges, which separate the localized eigenstates at opposite ends of the lattice in the OBC spectrum, is introduced to characterize this phenomenon. The skin effect edges are determined by self-intersections in the spectrum under periodic boundary conditions (PBCs) and have topological properties.
Article
Quantum Science & Technology
C. Martinez-Strasser, M. A. J. Herrera, A. Garcia-Etxarri, G. Palumbo, F. K. Kunst, D. Bercioux
Summary: The spectral properties of two possible non-Hermitian diamond chains with a flat band in the band structure, namely dimerized diamond chains, are investigated in this study. The systems are characterized using biorthogonal polarization and quantum metric, and the presence of non-Hermitian skin effect is observed. The study also shows the equivalence between the two non-Hermitian diamond chains and the non-Hermitian Su-Schrieffer-Heeger chains after a unitary rotation.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Materials Science, Multidisciplinary
Hui-Qiang Liang, Sen Mu, Jiangbin Gong, Linhu Li
Summary: The quantized response is a distinguishing feature of a topological system. In non-Hermitian systems, the spectral winding topology yields a quantized steady-state response. By considering two weakly coupled non-Hermitian chains, the spectral winding topology of one chain can be probed by a steady-state response defined solely on the other chain, revealing unexpected physics of spectral winding topology vs quantized response.
Article
Chemistry, Multidisciplinary
Ce Shang, Shuo Liu, Ruiwen Shao, Peng Han, Xiaoning Zang, Xiangliang Zhang, Khaled Nabil Salama, Wenlong Gao, Ching Hua Lee, Ronny Thomale, Aurelien Manchon, Shuang Zhang, Tie Jun Cui, Udo Schwingenschlogl
Summary: This study demonstrates the second-order non-Hermitian skin effect (NHSE) experimentally using a physics-graph-informed machine learning (PGIML) approach. The results reveal the sensitivity of the NHSE to boundary conditions and suggest the need for modification of topological band theory in higher dimensional non-Hermitian systems.
Article
Multidisciplinary Sciences
Kai Zhang, Zhesen Yang, Chen Fang
Summary: The authors introduce the skin effect discovered in a one-dimensional experiment and establish its universality in two and higher dimensional non-Hermitian systems. They also propose two new types of skin effect and show that systems with exceptional points exhibit the skin effect.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Subhaskar Mandal, Rimi Banerjee, Timothy C. H. Liew
Summary: This study proposes a system based on exciton-polariton elliptical micropillars that exhibits both the topological spin-Hall effect and the non-Hermitian skin effect, which have implications for polariton transport and the formation of multiply charged vortices.
Article
Multidisciplinary Sciences
Shuo Liu, Ruiwen Shao, Shaojie Ma, Lei Zhang, Oubo You, Haotian Wu, Yuan Jiang Xiang, Tie Jun Cui, Shuang Zhang
Summary: The conventional bulk-boundary correspondence fails in certain non-Hermitian systems with broken reciprocity, while a non-Bloch bulk-boundary condition based on a non-Bloch winding number can accurately predict the number of topological edge states.
Review
Physics, Multidisciplinary
Rijia Lin, Tommy Tai, Linhu Li, Ching Hua Lee
Summary: This article reviews recent developments in the non-Hermitian skin effect (NHSE), particularly focusing on its interactions with topology. It starts with an introduction to the modified bulk-boundary correspondence, the synergy between NHSE and band topology in higher dimensions, and the associated topology on the complex energy plane. It then explores emerging topics such as non-Hermitian criticality, dynamical NHSE phenomena, and the manifestation of NHSE beyond linear non-interacting crystal lattices, including its interplay with quantum many-body interactions. Finally, it surveys recent demonstrations and experimental proposals of NHSE.
FRONTIERS OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Haiping Hu, Erhai Zhao
Summary: This study explores knots tied by eigenenergy strings in one-dimensional non-Hermitian Hamiltonians, as well as their relationship with Wilson loops. An algorithm is developed to construct corresponding tight-binding non-Hermitian Hamiltonians and a scheme is proposed to probe knot structures via quantum quench.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
David-Andres Galeano, Xiao-Xiao Zhang, Jorge Mahecha
Summary: We proposed an RLC electrical circuit to theoretically analyze and simulate a new non-Hermitian SSH model with complex hoppings, showing rich physical properties such as topological winding numbers, edge states, and non-Hermitian skin phenomenon. The study demonstrates the wide-ranging topological physics inherent in electric circuits, applicable to both Hermitian and non-Hermitian systems.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Optics
Federico Roccati
Summary: A key feature of non-Hermitian tight-binding Hamiltonians is the sensitivity of spectrum and eigenstates to boundary conditions, especially leading to the non-Hermitian skin effect under open boundary conditions. A general procedure based on the Green's function method can be used to calculate the eigenstates, with applications to specific models for comparing edge states localization with bulk states.
Article
Physics, Multidisciplinary
Cem Yuce
Summary: The combination of non-Hermitian skin effect and nonlinear effects can lead to novel phenomena, which may be utilized in nonlinear structure designs. In some cases, nonlinear non-Hermitian skin effect can give rise to fractal and continuum bands at the edges. The nonlinear exceptional point may disappear in an infinitely long lattice.
Article
Physics, Multidisciplinary
Selma Franca, Viktor Koenye, Fabian Hassler, Jeroen van den Brink, Cosma Fulga
Summary: This study introduces a novel approach to exploring non-Hermitian physics involving reflection from the boundary of insulators, without the need for gain or loss. For strong topological insulators, the reflected waves exhibit non-Hermitian characteristics due to a reflection matrix exhibiting the non-Hermitian skin effect. This research expands the range of experimental platforms that can observe features associated with non-Hermitian topology.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Penghao Zhu, Xiao-Qi Sun, Taylor L. Hughes, Gaurav Bahl
Summary: In this work, the authors successfully implement a crystalline rank-2 chiral modes using non-Hermitian dynamics. They demonstrate the momentum-resolved dynamics and non-Hermitian skin effect associated with rank-2 chirality both theoretically and experimentally. This study provides a circuit-based approach to explore higher-rank chiral physics and has potential applications in systems where momentum resolution is necessary.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Guoqiang Xu, Yihao Yang, Xue Zhou, Hongsheng Chen, Andrea Alu, Cheng-Wei Qiu
Summary: This study discovers diffusion-based topological states supported by spatiotemporally modulated advections on a fluidic surface. It establishes a framework for topological diffusion and thermal edge or bulk states, potentially enabling flexible manipulation of heat and mass transfer.
Review
Optics
Hannah Price, Yidong Chong, Alexander Khanikaev, Henning Schomerus, Lukas J. Maczewsky, Mark Kremer, Matthias Heinrich, Alexander Szameit, Oded Zilberberg, Yihao Yang, Baile Zhang, Andrea Alu, Ronny Thomale, Iacopo Carusotto, Philippe St-Jean, Alberto Amo, Avik Dutt, Luqi Yuan, Shanhui Fan, Xuefan Yin, Chao Peng, Tomoki Ozawa, Andrea Blanco-Redondo
Summary: Topological photonics controls the behavior of light through the design of photonic structures, with potential applications in photonics devices. This roadmap surveys emerging areas of research within this field, with a focus on addressing fundamental scientific questions and presenting exciting opportunities for future research and developments.
JOURNAL OF PHYSICS-PHOTONICS
(2022)
Article
Chemistry, Multidisciplinary
Hao Hu, Song Han, Yihao Yang, Dongjue Liu, Haoran Xue, Gui-Geng Liu, Zheyu Cheng, Qi Jie Wang, Shuang Zhang, Baile Zhang, Yu Luo
Summary: This study extends the concept of band topology from wave systems to diffusion dynamics and experimentally observes the emergence of stable topological edge decays within the gap of bulk decays.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Tong Cai, Bin Zheng, Jing Lou, Lian Shen, Yihao Yang, Shiwei Tang, Erping Li, Chao Qian, Hongsheng Chen
Summary: Researchers have successfully developed an ultrabroadband invisibility cloak by harnessing the characteristics of material dispersion. This study provides a new approach for the development of dispersion-dominated ultrabroadband devices.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Minkyung Kim, Zihao Wang, Yihao Yang, Hau Tian Teo, Junsuk Rho, Baile Zhang
Summary: Researchers have designed and demonstrated a 3D photonic topological insulator (PTI) that exhibits self-guided topological surface states without the need for additional confinement. By removing spin-orbit coupling, this PTI opens new possibilities for manipulating photons at the outer surface of photonic bandgap materials.
NATURE COMMUNICATIONS
(2022)
Review
Chemistry, Multidisciplinary
Hengyu Lin, Yihao Yang, Yu-Chuan Hsu, Jiaqi Zhang, Claire Welton, Ibukun Afolabi, Marshal Loo, Hong-Cai Zhou
Summary: As water scarcity becomes a global issue, hygroscopic materials are seen as a significant solution. This review focuses on the recent development of hygroscopic materials, including traditional ones, crystalline frameworks, polymers, and composites. The similarities between water harvesting and carbon capture suggest a future challenge of simultaneously addressing both issues, with an emphasis on metal-organic frameworks and their water stability and uptake. Recent advances in understanding the effects of moisture on CO2 adsorption are also reviewed.
ADVANCED MATERIALS
(2023)
Article
Optics
Fujia Chen, Zhen Gao, Li Zhang, Qiaolu Chen, Qinghui Yan, Rui Xi, Liqiao Jin, Erping Li, Wenyan Yin, Hongsheng Chen, Yihao Yang
Summary: Exploiting topological ideas in modern photonics has allowed for the design of robust photonic devices. Recent theories extend topological concepts to the analysis of scattering matrices, guiding the development of complete polarization conversion. This study experimentally observes topological polarization conversion at vortex singularities of reflection coefficients and demonstrates that it covers the entire Poincare sphere using the topological nature of CPC. Furthermore, the experiment confirms that BICs lie on the critical coupling curves defining the condition for CPC. This work opens up possibilities for controlling light polarization and creating robust photonics devices by exploring topological properties in scattering matrices.
LASER & PHOTONICS REVIEWS
(2023)
Article
Physics, Multidisciplinary
Yan Meng, Shuxin Lin, Bin-jie Shi, Bin Wei, Linyun Yang, Bei Yan, Zhenxiao Zhu, Xiang Xi, Yin Wang, Yong Ge, Shou-qi Yuan, Jingming Chen, Gui-Geng Liu, Hong-xiang Sun, Hongsheng Chen, Yihao Yang, Zhen Gao
Summary: For the classification of topological phases of matter, the consideration of whether a system is spinless or spinful is important. Recently, it has been theoretically realized that the algebraic structure of symmetries can be projectively represented in the presence of gauge symmetry, which enables the switch between spinless and spinful topological phases. In this study, spinful topological phases are experimentally demonstrated in spinless acoustic crystals with projective space-time inversion symmetry. This allows for the realization of a one-dimensional topologically gapped phase characterized by a 21 winding number, with double-degenerate bands in the entire Brillouin zone and two pairs of degenerate topological boundary modes.
PHYSICAL REVIEW LETTERS
(2023)
Review
Optics
Jian Wei You, Zhihao Lan, Qian Ma, Zhen Gao, Yihao Yang, Fei Gao, Meng Xiao, Tie Jun Cui
Summary: Metasurfaces are thin films with subwavelength structures that can control the polarization, phase, and amplitude of light. Recent developments in topological photonics have greatly expanded the design possibilities for metasurfaces in novel applications. This review summarizes recent progress in the field of topological metasurfaces, covering both passive and active systems in the classical and quantum regimes. It discusses passive topological phenomena and cutting-edge studies of active topological metasurfaces, as well as their potential applications in quantum information and many-body physics.
PHOTONICS RESEARCH
(2023)
Article
Multidisciplinary Sciences
Jingyi Tian, Qi Ying Tan, Yutao Wang, Yihao Yang, Guanghui Yuan, Giorgio Adamo, Cesare Soci
Summary: The authors demonstrate a lithography-free, vertical-emitting, single-mode laser emitting in the green by using a few monolayers of perovskite quantum dots. This topological laser overcomes the limitations of low directionality and complex design requirements.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Wenhao Li, Qiaolu Chen, Yiwen Sun, Song Han, Xudong Liu, Zhijie Mei, Xuejiao Xu, Shuting Fan, Zhengfang Qian, Hongsheng Chen, Yihao Yang
Summary: Waveguide tapers are essential in silicon photonics for maximizing the coupling efficiency, but they require large footprints. A concept of taper-free waveguides is proposed, enabled by photonic topological phases, allowing efficient coupling without tapers. The experiment on an all-silicon on-chip terahertz wave platform confirms the efficacy of this concept, demonstrating its robustness against sharp corners and potential barriers. This work provides a promising solution for future compact optical/THz photonic integrated circuits.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Ke Xu, Fujia Chen, Hongsheng Chen, Ming Fang, Zhixiang Huang, Yihao Yang
Summary: By artificially creating uniform curl-free artificial gauge fields in engineered structures, we propose a mechanism to separate two counterpropagating transmission channels of a waveguide. This mechanism has been experimentally demonstrated in bilayer moire metagratings with continuously tuned synthetic gauge fields. Our work provides an alternative mechanism for designing photonic highways without the need for complicated band structure engineering and large-area bulks, which is beneficial for future ultracompact and high-density photonic integrated circuits.
Article
Multidisciplinary Sciences
Xiang Xi, Bei Yan, Linyun Yang, Yan Meng, Zhen-Xiao Zhu, Jing-Ming Chen, Ziyao Wang, Peiheng Zhou, Perry Ping Shum, Yihao Yang, Hongsheng Chen, Subhaskar Mandal, Gui-Geng Liu, Baile Zhang, Zhen Gao
Summary: The authors report the first experimental observation of topological antichiral surface states in a magnetic Weyl photonic crystal by constructing a modified Haldane model. Antichiral surface states, the two-dimensional extension of one-dimensional antichiral edge states, have never been realized in any physical system before. The unique properties of antichiral surface states, including antichiral robust propagation and a single open Fermi arc connecting two projected Weyl points, have been directly observed in this study.
NATURE COMMUNICATIONS
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Ye Dong, Xinyu Wu, Wenhao Li, Yudong Ren, Yihao Yang, Jiangtao Huangfu, Long Li, Rui Xi, Hongsheng Chen, Bin Zheng
Summary: This paper presents the design of a low profile transmitarray antenna with high polarization purity and wide operational band. It allows for adjustable beam scanning and polarization selectivity, which are crucial for radar detection and environmental adaption. By employing partially reflective surface (PRS) elements based on substrate integrated waveguide (SIW) and aperture coupling, a compact low profile transmitarray antenna with reduced element coupling is achieved. The use of SIW based phase delay enables coverage of a continuous 360 degree phase range.
2022 PHOTONICS & ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS 2022)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Wenhao Li, Rui Xi, Yudong Ren, Xinyu Wu, Yihao Yang, Jiangtao Huangfu, Zuojia Wang, Hongsheng Chen
Summary: This paper introduces a chiral coding metamirror constructed with optically transparent material to generate multiple vortex beams in different directions. The metamirror has near-perfect spin-selective absorption and can selectively generate multiple vortex beams at a designated frequency.
2022 PHOTONICS & ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS 2022)
(2022)