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arXiv 2024年

作者： Han, Ning Chen, Fujia Li, Mingzhu Zhao, Rui Li, Wenhao Chen, Qiaolu Zhang, Li Pan, Yuang Ma, Jingwen Yu, Zhi-Ming Chen, Hongsheng Yang, Yihao Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing312000 China School of Information and Electrical Engineering Hangzhou City University Hangzhou310015 China Department of Electronic Engineering The Chinese University of Hong Kong Shatin New Territories Hong Kong School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China

In topological physics, it is commonly understood that the existence of the boundary states of a topological system is inherently dictated by its bulk. A classic example is that the surface Fermi-arc states of a Weyl system are determined by the chiral charges of Weyl points within the bulk. Contrasting with this established perspective, here, we theoretically and experimentally discover a family of topological chiral bulk states extending over photonic Weyl metamaterial waveguides, solely induced by the waveguide boundaries, independently of the waveguide width. Notably, these bulk states showcase discrete momenta and function as "wormhole" tunnels that connect Fermi-arc surface states living in different two-dimensional (2D) spaces via a third dimension. Our work offers a magnetic-field-free mechanism for robust chiral bulk transport of waves and highlights the boundaries as a new degree of freedom to regulate bulk Weyl quasiparticles. Copyright © 2024, The Authors. All rights reserved.

关键词： Metamaterials

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Diffusive topological transport in spatiotemporal thermal lattices

arXiv

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arXiv 2021年

作者： Xu, Guoqiang Yang, Yihao Zhou, Xue Chen, Hongsheng Alù, Andrea Qiu, Cheng-Wei Department of Electrical and Computer Engineering National University of Singapore Kent Ridge117583 Singapore Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou China School of Computer Science and Information Engineering Chongqing Technology and Business University Chongqing400067 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou310027 China International Joint Innovation Center ZJU-UIUC Institute The Electromagnetics Academy at Zhejiang University Zhejiang University Haining314400 China Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center of the City University of New York New YorkNY10016 United States

Topological insulating phases are usually found in periodic lattices stemming from collective resonant effects, and it may thus be expected that similar features may be prohibited in thermal diffusion, given its purely dissipative and largely incoherent nature. We report the diffusion-based topological states supported by spatiotemporally-modulated advections stacked over a fluidic surface, thereby imitating a periodic propagating potential in effective thermal lattices. We observe edge and bulk states within purely nontrivial and trivial lattices, respectively. At interfaces between these two types of lattices, the diffusive system exhibits interface states, manifesting inhomogeneous thermal properties on the fluidic surface. Our findings establish a framework for topological diffusion and thermal edge/bulk states, and it may empower a distinct mechanism for flexible manipulation of robust heat and mass transfer. © 2021, CC BY.

关键词： Interface states

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Multiple Brillouin Zone Winding of Topological Chiral Edge states for Slow Light Applications

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Physical Review Letters 2024年第15期132卷 156602-156602页

作者： Fujia Chen Haoran Xue Yuang Pan Maoren Wang Yuanhang Hu Li Zhang Qiaolu Chen Song Han Gui-geng Liu Zhen Gao Peiheng Zhou Wenyan Yin Hongsheng Chen Baile Zhang Yihao Yang State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou 310027 China International Joint Innovation Center The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China Department of Physics The Chinese University of Hong Kong Shatin Hong Kong SAR China Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China Chengdu 611731 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore 637371 Singapore Centre for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen 518055 China

Photonic Chern insulators are known for their topological chiral edge states (CESs), whose absolute existence is determined by the bulk band topology, but concrete dispersion can be engineered to exhibit various properties. For example, the previous theory suggested that the edge dispersion can wind many times around the Brillouin zone to slow down light, which can potentially overcome fundamental limitations in conventional slow-light devices: narrow bandwidth and keen sensitivity to fabrication imperfection. Here, we report the first experimental demonstration of this idea, achieved by coupling CESs with resonance-induced nearly flat bands. We show that the backscattering-immune hybridized CESs are significantly slowed down over a relatively broad bandwidth. Our work thus paves an avenue to broadband topological slow-light devices.

关键词： Light propagation, transmission & absorption Metamaterials Photonic crystals Polaritons Topological materials

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Asymmetric Heat Transfer with Linear Conductive Metamaterials

arXiv

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arXiv 2022年

作者： Su, Yishu Li, Ying Qi, Minghong Guenneau, Sebastien Li, Huagen Xiong, Jian Center for Composite Materials and Structures Harbin Institute of Technology Harbin150001 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy of Zhejiang University Zhejiang University Haining314400 China UMI 2004 Abraham de Moivre-CNRS Imperial College London LondonSW7 2AZ United Kingdom Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore

Asymmetric heat transfer systems, often referred to as thermal diodes or thermal rectifiers, have garnered increasing interest due to their wide range of application possibilities. Most of those previous macroscopic thermal diodes either resort to nonlinear thermal conductivities with strong temperature dependence that may be quite limited by or fixed in natural materials or rely on active modulation that necessitated auxiliary energy payloads. Here, we establish a straightforward strategy of passively realizing asymmetric heat transfer with linear conductive materials. The strategy also introduces a new interrogative perspective on the design of asymmetric heat transfer utilizing nonlinear thermal conductivity, correcting the misconception that thermal rectification is impossible with separable nonlinear thermal conductivity. The nonlinear perturbation mode can be versatilely engineered to produce an effective and wide-ranging perturbation in the heat conduction, which imitates and bypasses intrinsic thermal nonlinearity constraints set by naturally occurring counterparts. Independent experimental characterizations of surface thermal radiation and thermal convection verified that the heat exchange between a graded linear thermal metamaterial and the ambient can be tailored to achieve macroscopic asymmetric heat transfer. Our work is envisaged to inspire conceptual models for heat transfer control, serving as a robust and convenient platform for advanced thermal management, thermal computation, and heat transport. © 2022, CC BY.

关键词： Thermal conductivity

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Photonic topological valley-locked waveguides

arXiv

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arXiv 2020年

作者： Chen, Qiaolu Zhang, Li Yan, Qinghui Xi, Rui Chen, Hongsheng Yang, Yihao Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang Zhejiang University Hangzhou310027 China International Joint Innovation Center ZJU-UIUC Institute Zhejiang University Haining314400 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore637371 Singapore Centre for Disruptive Photonic Technologies Photonics Institute Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore

Topological valley kink states have become a significant research frontier with considerable intriguing applications such as robust on-chip communications and topological lasers. Unlike guided modes with adjustable widths in most conventional waveguides, the valley kink states are usually highly confined around the domain walls and thus lack the mode width degree of freedom (DOF), posing a serious limitation to potential device applications. Here, by adding a photonic crystal (PhC) featuring a Dirac point between two valley PhCs with opposite valley-Chern numbers, we design and experimentally demonstrate topological valley-locked waveguides (TVLWs) with tunable mode widths. The photoinc TVLWs could find unique applications, such as high-energy-capacity topological channel intersections, valley-locked energy concentrators, and topological cavities with designable confinement, as verified numerically and experimentally. The TVLWs with width DOF could be beneficial to interface with the exsisting photonic waveguides and devices, and serve as a novel platform for practical use of topological lasing, field enhancement, on-chip communicaitons, and high-capacity energy transport. Copyright © 2020, The Authors. All rights reserved.

关键词： Landforms

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The RASSP Program: Origin, Concepts, and Status: An Introduction to the Issue

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Journal of VLSI Signal Processing Systems for Signal, Image, and Video technology 1997年第1-2期15卷 7-27页

作者： Richards, Mark A. Gadient, Anthony Frank, Geoffrey A. Harr, Randolph Georgia Tech. Research Institute Atlanta GA 30332-0856 United States South Carolina Research Authority Charleston SC 29464 5300 International Blvd. United States Research Triangle Institute Research Triangle Park NC P.O. Box 12194 United States Def. Adv. Research Projects Agency Electronics Technology Office Arlington VA 22203-1714 3701 N. Fairfax Drive United States Georgia Tech. United States Stanford University United States Sensors Electromagnetic Applic. Lab. Georgia Tech. Research Institute United States Signal Processing Branch SEAL's Radar Systems Division United States Georgia Tech's Sch. Elec. Comp. Eng. Georgia State of Georgia United States Atlanta Section IEEE United States University of Virginia United States Wright State University United States Carnegie Mellon University United States United States Air Force (USAF) United States AF Wright Aero. Avionics Laboratory South Carolina Research Authority Advanced Technology Group United States Intl. Electro-Tech. Commn. W. Natl. Electronics Mfg. Inititative Sch. of Elec. and Comp. Engineering Georgia Institute of Technology United States Inst. of Elec. and Electronics Eng. Association for Computing Machinery Amer. Assoc. for Artif. Intelligence United States University of North Carolina Chapel Hill NC United States Research Triangle Institute United States Electronics Technology Office United States Synopsys Corp.'s Logic Modeling Grp. United States Case Western Reserve University United States

The Rapid Prototyping of Application Specific Signal Processors (RASSP) program is a multi-year DARPA/Tri-Service initiative intended to dramatically improve the process by which complex digital systems, particularly embedded digital signal processors, are designed, manufactured, upgraded, and supported. This paper reviews the genesis of the RASSP program, considering both the problems that defined the need for the program, and the historical conditions under which it began. The RASSP program is then presented from two viewpoints. The first is programmatic, covering the goals and constraints of the program, and describing the roles of the various program participants. The second is technical, covering the major concepts upon which the developing RASSP approach to design is based and showing how the detailed technical discussions contained in the other papers in this issue of the Journal of VLSI Signal Processing relate to one another and fit into an overall development concept. The paper closes with a review of the status of the program as of this writing (Summer 1996).

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Observation of topological edge states in thermal diffusion

arXiv

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arXiv 2021年

作者： Hu, Hao Han, Song Yang, Yihao Liu, Dongjue Xue, Haoran Liu, Gui-Geng Cheng, Zheyu Wang, Qi Jie Zhang, Shuang Zhang, Baile Luo, Yu School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou310027 China International Joint Innovation Center ZJU-UIUC Institute Zhejiang University Haining314400 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore637371 Singapore Department of Physics University of Hong Kong Hong Kong Department of Electrical & Electronic Engineering University of Hong Kong China Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore637371 Singapore

The topological band theory predicts that bulk materials with nontrivial topological phases support topological edge states. This phenomenon is universal for various wave systems and has been widely observed for electromagnetic and acoustic waves. Here, we extend the notion of band topology from wave to diffusion dynamics. Unlike the wave systems that are usually Hermitian, the diffusion systems are anti-Hermitian with purely imaginary eigenvalues corresponding to decay rates. Via direct probe of the temperature diffusion, we experimentally retrieve the Hamiltonian of a thermal lattice, and observe the emergence of topological edge decays within the gap of bulk decays. Our results show that such edge states exhibit robust decay rates, which are topologically protected against disorders. This work constitutes a thermal analogue of topological insulators and paves the way to exploring defect-immune heat dissipation. Copyright © 2021, The Authors. All rights reserved.

关键词： Topology

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Breakdown of effective-medium theory by a photonic spin Hall effect

arXiv

引用

arXiv 2023年

作者： Yuan, Shuaijie Zhou, Xinxing Chen, Yu Zhong, Yuhan Sheng, Lijuan Hu, Hao Chen, Hongsheng Kaminer, Ido Lin, Xiao Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applications School of Physics and Electronics Hunan Normal University Changsha410081 China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province Institute of Microscale Optoelectronics Shenzhen University Shenzhen518060 China Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore Key Laboratory of Radar Imaging and Microwave Photonics Ministry of Education College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing211106 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing312000 China Department of Electrical Engineering Technion-Israel Institute of Technology Haifa32000 Israel

Effective-medium theory pertains to the theoretical modelling of homogenization, which aims to replace an inhomogeneous structure of subwavelength-scale constituents with a homogeneous effective medium. The effective-medium theory is fundamental to various realms, including electromagnetics and material science, since it can largely decrease the complexity in the exploration of light-matter interactions by providing simple acceptable approximation. Generally, the effective-medium theory is thought to be applicable to any all-dielectric system with deep-subwavelength constituents, under the condition that the effective medium does not have a critical angle, at which the total internal reflection occurs. Here we reveal a fundamental breakdown of the effective-medium theory that can be applied in very general conditions: showing it for deep-subwavelength all-dielectric multilayers even without critical angle. Our finding relies on an exotic photonic spin Hall effect, which is shown to be ultra-sensitive to the stacking order of deep-subwavelength dielectric layers, since the spin-orbit interaction of light is dependent on slight phase accumulations during the wave propagation. Our results indicate that the photonic spin Hall effect could provide a promising and powerful tool for measuring structural defects for all-dielectric systems even in the extreme nanometer scale. Copyright © 2023, The Authors. All rights reserved.

关键词： Spin Hall effect

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Discovery of a maximally charged Weyl point

arXiv

引用

arXiv 2022年

作者： Chen, Qiaolu Chen, Fujia Yan, Qinghui Zhang, Li Gao, Zhen Yang, Shengyuan A. Yu, Zhi-Ming Chen, Hongsheng Zhang, Baile Yang, Yihao Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center Key Lab. of Advanced Micro Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen518055 China Research Laboratory for Quantum Materials Singapore University of Technology and Design 487372 Singapore School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link 637371 Singapore Centre for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University 50 Nanyang Avenue 639798 Singapore

The hypothetical Weyl particles in high-energy physics have been discovered in three-dimensional crystals as collective quasiparticle excitations near two-fold degenerate Weyl points1-5. Such momentum-space Weyl particles carry quantized chiral charges, which can be measured by counting the number of Fermi arcs emanating from the corresponding Weyl points. It is known that merging unit-charged Weyl particles can create new ones with more charges6. However, only very recently has it been realised that there is an upper limit - the maximal charge number that a two-fold Weyl point can host is four - achievable only in crystals without spin-orbit coupling7-9. Here, we report the experimental realisation of such a maximally charged Weyl point in a three-dimensional photonic crystal. The four charges support quadruple-helicoid Fermi arcs, forming an unprecedented topology of two non-contractible loops in the surface Brillouin zone. The helicoid Fermi arcs also exhibit the long-pursued type-II van Hove singularities that can reside at arbitrary momenta. This discovery reveals a type of maximally charged Weyl particles beyond conventional topological particles in crystals. Copyright © 2022, The Authors. All rights reserved.

关键词： Topology

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Corrigendum to “Experimental study of liquid sodium flow and heat transfer characteristics along a hexagonal 7-rod bundle” [Appl. Therm. Eng. 149 (2019) 578–587.]

引用

Applied Thermal engineering 2019年 159卷

作者： Yandong Hou Liu Wang Mingjun Wang Kui Zhang Xisi Zhang Wenjun Hu Yingwei Wu Wenxi Tian Suizheng Qiu G.H. Su State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China China Institute of Atomic Energy P.O. Box 275-95 Beijing 102413 China

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