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arXiv 2023年

作者： Liu, Xin Ponomarenko, Sergey A. Wang, Fei Cai, Yangjian Liang, Chunhao Shandong Provincial Engineering and Technical Center of Light Manipulation Shandong Provincial Key Laboratory of Optics and Photonic Devices School of Physics and Electronics Shandong Normal University Jinan250014 China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal University Jinan250358 China Department of Electrical and Computer Engineering Dalhousie University HalifaxNSB3J 2X4 Canada Department of Physics and Atmospheric Science Dalhousie University HalifaxNSB3H 4R2 Canada School of Physical Science and Technology Soochow University Suzhou215006 China

In the age of information explosion, the conventional optical communication protocols are rapidly reaching the limits of their capacity, as almost all available degrees of freedom (e.g., wavelength, polarization) for division multiplexing have been explored to date. Recent advances in coherent mode division multiplexing have greatly facilitated high-speed optical communications and secure, high-capacity information storage and transfer. However, coherent mode division multiplexing is quite vulnerable to even minute environmental disturbances which can cause significant information loss. Here, we propose and experimentally demonstrate a paradigm shift to incoherent mode division multiplexing for high-security optical information encryption by harnessing the degree of coherence of structured random light beams. In contrast to the conventional techniques, our approach does not require mode orthogonality to circumnavigate unwanted mode crosstalk. In addition, our protocol has, in principle, no upper bound on its capacity. Thanks to the extreme robustness of structured random light to external perturbations, we are able to achieve highly accurate information encryption and decryption in the adverse environment. The proposed protocol opens new horizons in an array of fields, such as optical imaging, optical communications, and cryptography, and it can be relevant for information processing with acoustical, seismic, matter as well as other types of waves. © 2023, CC BY.

关键词： Cryptography

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Multi-functional metasurface architecture for amplitude, polarization and wavefront control

arXiv

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arXiv 2022年

作者： Pitilakis, A. Seckel, M. Tasolamprou, A.C. Liu, F. Deltsidis, A. Manessis, D. Ostmann, A. Kantartzis, N.V. Liaskos, C. Soukoulis, C.M. Tretyakov, S.A. Kafesaki, M. Tsilipakos, O. School of Electrical and Computer Engineering Aristotle University of Thessaloniki ThessalonikiGR-54124 Greece System Integration and Interconnection Technologies Fraunhofer IZM Berlin13355 Germany Institute of Electronic Structure and Laser Foundation for Research and Technology Hellas Crete HeraklionGR-70013 Greece Xi'an Jiaotong University School of Electronic Science and Engineering Xi'An710049 China Department of Electronics and Nanoengineering Aalto University AaltoFI-00076 Finland Department of Computer Science Engineering University of Ioannina Ioannina Greece Ames Laboratory U.S. DOE Department of Physics Astronomy Iowa State University AmesIA50011 United States Department of Materials Science and Technology University of Crete Crete HeraklionGR-70013 Greece

Metasurfaces (MSs) have been utilized to manipulate different properties of electromagnetic waves. By combining local control over the wave amplitude, phase, and polarization into a single tunable structure, a multifunctional and reconfigurable metasurface can be realized, capable of full control over incident radiation. Here, we experimentally validate a multi-functional metasurface architecture for the microwave regime, where in principle variable loads are connected behind the backplane to reconfigurably shape the complex surface impedance. As a proof-of-concept step, we fabricate several metasurface instances with static loads in different configurations (surface mount capacitors and resistors of different values in different connection topologies) to validate the approach and showcase the different achievable functionalities. Specifically, we show perfect absorption for oblique incidence (both polarizations), broadband linear polarization conversion, and beam splitting, demonstrating control over the amplitude, polarization state, and wavefront, respectively. Measurements are performed in the 4-18 GHz range inside an anechoic chamber and show good agreement with theoretically-anticipated results. Our results clearly demonstrate the practical potential of the proposed architecture for reconfigurable electromagnetic wave manipulation. © 2022, CC BY.

关键词： Electromagnetic waves

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Pressure tunable quantum anomalous Hall states in a topological antiferromagnet

arXiv

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arXiv 2023年

作者： Chong, Su Kong Lei, Chao Li, Jie Cheng, Yang Graf, David Lee, Seng Huat Tanabe, Masaki Yang, Ting-Hsun Mao, Zhiqiang MacDonald, Allan H. Wang, Kang L. Department of Electrical and Computer Engineering University of California Los AngelesCA90095 United States Department of Physics The University of Texas at Austin AustinTX78712 United States School of Materials Science and Engineering Shanghai University Shanghai200444 China National High Magnetic Field Laboratory Florida State University TallahasseeFL32310 United States 2D Crystal Consortium Materials Research Institute The Pennsylvania State University University ParkPA16802 United States Department of Physics The Pennsylvania State University University ParkPA16802 United States

Mechanical modulation of the lattice parameter can modify the electronic structure and manipulate the magnetic coupling of a material without introducing impurities. Inspired by success in pressure-controlled magnetism, we investigate the effect of hydrostatic pressure on quantized Chern states in the antiferromagnetic topological insulator MnBi2Te4, using transport as a probe. We show that pressure can enhance the robustness of quantum anomalous Hall (QAH) phases that are otherwise delicate in 7SL MnBi2Te4 and in the spin-flop (SF) state of 8SL MnBi2Te4. We explain our findings using a coupled Dirac cone model of MnBi2Te4, which identifies stronger hybridization between van der Waals layers as the driver of topological states. We further demonstrate that moderate pressures readily available in laboratory systems can provide reversible control of magnetic and topological phases. Our results reveal a strong connection between the mechanical engineering of band topology and magnetism. © 2023, CC BY.

关键词： Van der Waals forces

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Multi-mode Perturbation Modelling for Cavity Polygon and Star Modes

arXiv

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arXiv 2023年

作者： Farajollahi, Saeed Fang, Zhiwei Lin, Jintian Honari, Shahin Cheng, Ya Lu, Tao Department of Electrical and Computer Engineering University of Victoria VictoriaBCV8P 5C2 Canada XXL The Extreme Optoelectromechanics Laboratory School of Physics and Electronic Science East China Normal University Shanghai200241 China Shanghai201800 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai200062 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan030006 China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal University Jinan250358 China

Polygon and star modes enable unidirectional emission and single-frequency lasing in whispering gallery microcavities. To understand their properties and facilitate design, we have adopted both two-dimensional and three-dimensional full-wave perturbation methods to simulate these modes. Our simulation demonstrates that a tapered optical fiber can be used as a weak perturbation to coherently combine multiple whispering gallery modes into a polygon or star mode. Additionally, our simulation predicts an optical quality factor as high as 107 for the polygon modes, which is in good agreement with the experiment results. © 2023, CC BY-NC-ND.

关键词： Stars

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Mixed-Cell-Height Legalization Considering Technology and Region Constraints

Mixed-Cell-Height Legalization Considering Technology and Re...

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作者： Zhu, Ziran Chen, Jianli Zhu, Wenxing Chang, Yao-Wen Center for Discrete Mathematics and Theoretical Computer Science Fuzhou University Fuzhou China State Key Laboratory of ASIC and System Fudan University Shanghai China Department of Electrical Engineering Graduate Institute of Electronics Engineering National Taiwan University Taipei Taiwan

Mixed-cell-height circuits have become popular in advanced technologies for better power, area, routability, and performance tradeoffs. With technology and region constraints imposed by modern circuit designs, the mixed-cell-height legalization problem has become even more challenging. Additionally, an ideal legalization method should minimize both the average and maximum cell movements to preserve the quality of a given placement as much as possible. In this article, we present an effective and efficient mixed-cell-height legalization algorithm to consider technology and region constraints while minimizing the average and maximum cell movements. We first present a fence region handling technique to unify the fence regions and the default region. To obtain a desired cell assignment, we then propose a movement-aware cell reassignment method by iteratively reassigning cells in locally dense areas to their desired rows. After cell reassignment, a technology-aware legalization is presented to remove cell overlaps while satisfying the technology constraints. Finally, we propose a technology-aware refinement to further reduce the average and maximum cell movements without increasing the technology constraints violations. Compared with the champion of the 2017 CAD Contest at ICCAD and the state-of-the-art work, experimental results based on the 2017 CAD Contest at ICCAD benchmarks show that our algorithm achieves the best average and maximum cell movements and significantly fewer technology constraint violations, in a comparable runtime. The experimental results based on the modified 2015 ISPD Contest benchmarks also demonstrate the effectiveness of our algorithm in minimizing the average and maximum cell movements, compared with state-of-the-art mixed-cell-height legalizers. © 1982-2012 IEEE.

关键词： Iterative methods

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Charge trapping memory device based on the Ga2O3 films as trapping and blocking layer

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Chinese Physics B 2019年第10期28卷 101-104页

作者： Bing Bai Hong Wang Yan Li Yunxia Hao Bo Zhang Boping Wang Zihang Wang Hongqi Yang Qihang Gao Chao Lu Qingshun Zhang Xiaobing Yan Key Laboratory of Optoelectronic Information Materials of Hebei Province Key Laboratory of Digital Medical Engineering of Hebei ProvinceCollege of Electron and Information EngineeringHebei UniversityBaoding 071002China Department of Electrical and Computer Engineering Southern Illinois University CarbondaleCarbondaleIllinois 62901United States Department of Materials Science and Engineering National University of SingaporeSingapore 117576Singapore

We present a new charge trapping memory(CTM) device with the Au/Ga2O3/SiO2/Si structure, which is fabricated by using the magnetron sputtering, high-temperature annealing, and vacuum evaporation techniques. Transmission electron microscopy diagrams show that the thickness of the SiO2 tunneling layer can be controlled by the annealing *** the devices are annealed at 760℃, the measured C-V hysteresis curves exhibit a maximum 6 V memory window under a ±13 V sweeping voltage. In addition, a slight degradation of the device voltage and capacitance indicates the robust retention properties of flat-band voltage and high/low state capacitance. These distinctive advantages are attributed to oxygen vacancies and inter-diffusion layers, which play a critical role in the charge trapping process.

关键词： charge trapping memory SiO2 tunneling layer annealing temperature

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Monotonicity and Double Descent in Uncertainty Estimation with Gaussian Processes

arXiv

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arXiv 2022年

作者： Hodgkinson, Liam van der Heide, Chris Roosta, Fred Mahoney, Michael W. School of Mathematics and Statistics University of Melbourne Australia Department of Electrical and Electronic Engineering University of Melbourne Australia School of Mathematics and Physics University of Queensland Australia ARC Training Centre for Information Resilience University of Queensland Australia International Computer Science Institute United States Lawrence Berkeley National Laboratory United States Department of Statistics University of California at Berkeley United States

Despite their importance for assessing reliability of predictions, uncertainty quantification (UQ) measures for machine learning models have only recently begun to be rigorously characterized. One prominent issue is the curse of dimensionality: it is commonly believed that the marginal likelihood should be reminiscent of cross-validation metrics and that both should deteriorate with larger input dimensions. We prove that by tuning hyperparameters to maximize marginal likelihood (the empirical Bayes procedure), the performance, as measured by the marginal likelihood, improves monotonically with the input dimension. On the other hand, we prove that cross-validation metrics exhibit qualitatively different behavior that is characteristic of double descent. Cold posteriors, which have recently attracted interest due to their improved performance in certain settings, appear to exacerbate these phenomena. We verify empirically that our results hold for real data, beyond our considered assumptions, and we explore consequences involving synthetic covariates. Copyright © 2022, The Authors. All rights reserved.

关键词： Machine learning

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Outage Performance of Uplink Rate Splitting Multiple Access with Randomly Deployed Users

arXiv

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arXiv 2022年

作者： Lu, Huabing Xie, Xianzhong Shi, Zhaoyuan Lei, Hongjiang Zhao, Nan Cai, Jun The Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education Dalian University of Technology Dalian116024 China The School of Computer Science and Technology Chongqing University of Posts and Telecommunications Chongqing400065 China The Key Laboratory of Intelligent Perception and Computing of Anhui Province Anqing Normal University Anqing246011 China The School of Communication and Information Engineering Chongqing University of Posts and Telecommunications Chongqing400065 China Department of Electrical and Computer Engineering Concordia University MontrealQCH3G 1M8 Canada

With the rapid proliferation of smart devices in wireless networks, more powerful technologies are expected to fulfill the network requirements of high throughput, massive connectivity, and diversify quality of service. To this end, rate splitting multiple access (RSMA) is proposed as a promising solution to improve spectral efficiency and provide better fairness for the next-generation mobile networks. In this paper, the outage performance of uplink RSMA transmission with randomly deployed users is investigated, taking both user scheduling schemes and power allocation strategies into consideration. Specifically, the greedy user scheduling (GUS) and cumulative distribution function (CDF) based user scheduling (CUS) schemes are considered, which could maximize the rate performance and guarantee scheduling fairness, respectively. Meanwhile, we re-investigate cognitive power allocation (CPA) strategy, and propose a new rate fairness-oriented power allocation (FPA) strategy to enhance the scheduled users' rate fairness. By employing order statistics and stochastic geometry, an analytical expression of the outage probability for each scheduling scheme combining power allocation is derived to characterize the performance. To get more insights, the achieved diversity order of each scheme is also derived. Theoretical results demonstrate that both GUS and CUS schemes applying CPA or FPA strategy can achieve full diversity orders, and the application of CPA strategy in RSMA can effectively eliminate the secondary user's diversity order constraint from the primary user. Simulation results corroborate the accuracy of the analytical expressions, and show that the proposed FPA strategy can achieve excellent rate fairness performance in high signal-to-noise ratio region. Copyright © 2022, The Authors. All rights reserved.

关键词： Wireless networks

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Quantum generative training using rényi divergences

arXiv

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arXiv 2021年

作者： Kieferová, Mária Marrero, Carlos Ortiz Wiebe, Nathan Centre for Quantum Computation and Communication Technology Centre for Quantum Software and Information University of Technology Sydney Data Sciences & Analytics Group Department of Electrical & Computer Engineering Pacific Northwest National Laboratory North Carolina State University Department of Computer Science Department of Physics High Performance Computing Group University of Toronto University of Washington Pacific Northwest National Laboratory

Quantum neural networks (QNNs) are a framework for creating quantum algorithms that promises to combine the speedups of quantum computation with the widespread successes of machine learning. A major challenge in QNN development is a concentration of measure phenomenon known as a barren plateau that leads to exponentially small gradients for a range of QNNs models. In this work, we examine the assumptions that give rise to barren plateaus and show that an unbounded loss function can circumvent the existing no-go results. We propose a training algorithm that minimizes the maximal Rényi divergence of order two and present techniques for gradient computation. We compute the closed form of the gradients for Unitary QNNs and Quantum Boltzmann Machines and provide sufficient conditions for the absence of barren plateaus in these models. We demonstrate our approach in two use cases: thermal state learning and Hamiltonian learning. In our numerical experiments, we observed rapid convergence of our training loss function and frequently archived a 99% average fidelity in fewer than 100 epochs. © 2021, CC BY.

关键词： Quantum computers

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Curvature regularization to prevent distortion in graph embedding 20

Curvature regularization to prevent distortion in graph embe...

引用

Proceedings of the 34th International Conference on Neural Information Processing Systems

作者： Hongbin Pei Bingzhe Wei Kevin Chen-Chuan Chang Chunxu Zhang Bo Yang College of Computer Science and Technology Jilin University China and Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education China Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign and Department of Computer Science University of Illinois at Urbana-Champaign

ISBN: (纸本)9781713829546

Recent research on graph embedding has achieved success in various applications. Most graph embedding methods preserve the proximity in a graph into a manifold in an embedding space. We argue an important but neglected problem about this proximity-preserving strategy: Graph topology patterns, while preserved well into an embedding manifold by preserving proximity, may distort in the ambient embedding Euclidean space, and hence to detect them becomes difficult for machine learning models. To address the problem, we propose curvature regularization, to enforce flatness for embedding manifolds, thereby preventing the distortion. We present a novel angle-based sectional curvature, termed ABS curvature, and accordingly three kinds of curvature regularization to induce flat embedding manifolds during graph embedding. We integrate curvature regularization into five popular proximity-preserving embedding methods, and empirical results in two applications show significant improvements on a wide range of open graph datasets.

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