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arXiv 2019年

作者： Chaiwongkhot, Poompong Kuntz, Katanya B. Zhang, Yanbao Huang, Anqi Bourgoin, Jean-Philippe Sajeed, Shihan Lütkenhaus, Norbert Jennewein, Thomas Makarov, Vadim Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada NTT Basic Research Laboratories NTT Corporation AtsugiKanagawa Japan NTT Research Center for Theoretical Quantum Physics NTT Corporation AtsugiKanagawa Japan Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Aegis Quantum WaterlooON Canada Department of Electrical and Computer Engineering University of Toronto M5S 3G4 Canada Quantum Information Science Program Canadian Institute for Advanced Research TorontoONM5G 1Z8 Canada Russian Quantum Center Skolkovo Moscow143025 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai201315 China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia

The ability of an eavesdropper (Eve) to perform an intercept-resend attack on a free-space quantum key distribution (QKD) receiver by precisely controlling the incidence angle of an attack laser has been previously demonstrated. However, such an attack could be ineffective in the presence of atmospheric turbulence due to beam wander and spatial mode aberrations induced by the air’s varying index of refraction. We experimentally investigate the impact turbulence has on Eve’s attack on a free-space polarization-encoding QKD receiver by emulating atmospheric turbulence with a spatial light modulator. Our results identify how well Eve would need to compensate for turbulence to perform a successful attack by either reducing her distance to the receiver, or using beam wavefront correction via adaptive optics. Furthermore, we use an entanglement-breaking scheme to find a theoretical limit on the turbulence strength that hinders Eve’s attack. Copyright © 2019, The Authors. All rights reserved.

关键词： Atmospheric turbulence

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-SPECTRUM OF SELF-SIMILAR MEASURES WITH OVERLAPS IN THE ABSENCE OF SECOND-ORDER IDENTITIES

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Journal of the Australian Mathematical Society 2018年第1期106卷 56-103页

作者： SZE-MAN NGAI YUANYUAN XIE College of Mathematics and Computer Science Hunan Normal University Changsha Hunan 410081 China Department of Mathematical Sciences Georgia Southern University Statesboro GA 30460-8093 USA email smngai@georgiasouthern.edu Key Laboratory of High Performance Computing and Stochastic Information Processing (HPCSIP) (Ministry of Education of China) College of Mathematics and Computer Science Hunan Normal University Changsha Hunan 410081 PR China email xieyuanyuan198767@***

For the class of self-similar measures in $\mathbb{R}^{d}$ with overlaps that are essentially of finite type, we set up a framework for deriving a closed formula for the $L^{q}$-spectrum of the measure for $q\geq 0$. This framework allows us to include iterated function systems that have different contraction ratios and those in higher dimension. For self-similar measures with overlaps, closed formulas for the $L^{q}$-spectrum have only been obtained earlier for measures satisfying Strichartz’s second-order identities. We illustrate how to use our results to prove the differentiability of the $L^{q}$-spectrum, obtain the multifractal dimension spectrum, and compute the Hausdorff dimension of the measure.

关键词： fractal Lq-spectrum multifractal formalism self-similar measure essentially of finite type

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Discrete Graph Hashing via Affine Transformation

Discrete Graph Hashing via Affine Transformation

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Guohua Dong Xiang Zhang Long Lan Xuhui Huang Zhigang Luo College of computer National University of Defense Technology Changsha Hunan P.R. China State Key Laboratory of High Performance Computing National University of Defense Technology Changsha Hunan P.R. China Department of computer science National University of Defense Technology Changsha Hunan P.R. China

In unsupervised graph-based hashing for large-scale image retrieval, many efforts have been made to bridge the gap between the learned graph embedding and the corresponding binary codes. Relatively, few studies focus on the issue of the discrimination of graph embedding. In this paper, we firstly devise a discrete graph hashing model (DGH) that smooths graph embedding and simultaneously solving binary codes under the balanced discrete constraint, which equals a novel method of jointly learning graph embedding and spectral rotation, theoretically. To further induce discriminant graph embedding, we substitute affine transformation for spectral rotation in our DGH (abbreviated as ADGH). This is because affine transformation can accommodate both rotational angle and distance of graph embedding, while respecting the neighborhood structure among most samples. Besides, each subproblem of ADGH can yield the closed-form solution. Experiments of image retrieval on three benchmark datasets show that ADGH outperforms the representative hashing methods in quantity.

关键词： Binary codes Image retrieval Optimization Closed-form solutions Bridges Iterative methods Tuning

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Generation and detection of coherent longitudinal acoustic waves in ultrathin 1T'-MoTe2

arXiv

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arXiv 2019年

作者： Rivas, Nicolas Zhong, Shazhou Dekker, Tina Cheng, Meixin Gicala, Patrick Chen, Fangchu Luo, Xuan Sun, Yuping Petruk, Ariel A. Pichugin, Kostyantyn Tsen, Adam W. Sciaini, Germán Ultrafast Electron Imaging Lab Department of Chemistry Waterloo Institute for Nanotechnology University of Waterloo WaterlooONN2L3G1 Canada Institute for Quantum Computing Department of Physics and Astronomy Department of Electrical and Computer Engineering Department of Chemistry University of Waterloo WaterlooONN2L3G1 Canada Key Laboratory of Materials Physics Institute of Solid-State Physics Chinese Academy of Sciences Hefei230031 China University of Science and Technology of China Hefei230026 China High Magnetic Field Laboratory Chinese Academy of Sciences Hefei230031 Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China

Layered transition metal dichalcogenides have attracted substantial attention owing to their versatile functionalities and compatibility with current nanofabrication technologies. Thus, noninvasive means to determine the mechanical properties of nanometer (nm) thick specimens are of increasing importance. Here, we report on the detection of coherent longitudinal acoustic phonon modes generated by impulsive femtosecond (fs) optical excitation. Broadband fs-transient absorption experiments in 1T-f-MoTe2 flakes as a function of thickness (7 nm . 30 nm) yield a longitudinal sound speed of vl = (2990± 90) m s-1. In addition, temperature dependent measurements unveil a linear decrease of the normalized Young-fs modulus El/El,295Kwith a slope of δ(***,%' ))/δT = (.2.0± 0.1) 10-3K-1and no noticeable change caused by the Td-1T-f structural phase transition or variations in film thickness. Copyright © 2019, The Authors. All rights reserved.

关键词： Elastic moduli

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Laser Seeding Attack In Quantum Key Distribution

arXiv

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arXiv 2019年

作者： Huang, Anqi Navarrete, Álvaro Shi-Hai, Sun Chaiwongkhot, Poompong Curty, Marcos Makarov, Vadim Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada EI Telecomunicación Department of Signal Theory and Communications University of Vigo VigoE-36310 Spain School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Russian Quantum Center Skolkovo Moscow121205 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai201315 China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia

Quantum key distribution (QKD) based on the laws of quantum physics allows the secure distribution of secret keys over an insecure channel. Unfortunately, imperfect implementations of QKD compromise its information-theoretical security. Measurement-device-independent quantum key distribution (MDI-QKD) is a promising approach to remove all side channels from the measurement unit, which is regarded as the "Achilles’ heel" of QKD. An essential assumption in MDI-QKD is however that the sources are trusted. Here we experimentally demonstrate that a practical source based on a semiconductor laser diode is vulnerable to a laser seeding attack, in which light injected from the communication line into the laser results in an increase of the intensities of the prepared states. The unnoticed increase of intensity may compromise the security of QKD, as we show theoretically for the prepare-and-measure decoy-state BB84 and MDI-QKD protocols. Our theoretical security analysis is general and can be applied to any vulnerability that increases the intensity of the emitted pulses. Moreover, a laser seeding attack might be launched as well against decoy-state based quantum cryptographic protocols beyond QKD. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum cryptography

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An Extrapolation Cascadic MultigridMethod for Elliptic Problems on Reentrant Domains

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Advances in Applied Mathematics and Mechanics 2017年第6期9卷 1347-1363页

作者： Kejia Pan Dongdong He Chuanmiao Chen School of Mathematics and Statistics Central South UniversityChangshaHunan 410083China School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing(Ministry of Education of China)Hunan Normal UniversityChangshaHunan 410081China

This paper proposes an extrapolation cascadic multigrid(EXCMG)method to solve elliptic problems in domains with reentrant *** a class ofλ-graded meshes,we derive some new extrapolation formulas to construct a high-order approximation to the finite element solution on the next finer mesh using the numerical solutions on two-level of grids(current and previous grids).Then,this high-order approximation is used as the initial guess to reduce computational cost of the conjugate gradient *** application of this idea results in the EXCMG method proposed in this ***,numerical results for a crack problem and an L-shaped problem are presented to verify the efficiency and effectiveness of the proposed EXCMG method.

关键词： Richardson extrapolation Cascadicmultigrid gradedmesh elliptic problems corner singularity

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Zeolite‐Encaged Pd–Mn Nanocatalysts for CO2Hydrogenation and Formic Acid Dehydrogenation

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Angewandte Chemie 2020年第45期132卷

作者： Qiming Sun Benjamin W. J. Chen Ning Wang Qian He Albert Chang Chia‐Min Yang Hiroyuki Asakura Tsunehiro Tanaka Max J. Hülsey Chi‐Hwa Wang Jihong Yu Ning Yan NUS Environmental Research Institute (NERI) National University of Singapore 138602 Singapore Singapore Department of Chemical and Biomolecular Engineering National University of Singapore 4 Engineering Drive 4 117585 Singapore Singapore Institute of High Performance Computing Agency for Science Technology and Research 1 Fusionopolis Way #16-16 Connexis Singapore 138632 Singapore State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry International Center of Future Science Jilin University Changchun 130012 P. R. China Department of Materials Science and Engineering National University of Singapore 9 Engineering Drive 1 Singapore 117575 Singapore Department of Chemistry National Tsing Hua University Hsinchu 30013 Taiwan Department of Molecular Engineering Graduate School of Engineering Kyoto University Kyotodaigaku Katsura Nishikyo-ku Kyoto 615-8510 Japan

A CO 2 ‐mediated hydrogen storage energy cycle is a promising way to implement a hydrogen economy, but the exploration of efficient catalysts to achieve this process remains challenging. Herein, sub‐nanometer Pd–Mn clusters were encaged within silicalite‐1 (S‐1) zeolites by a ligand‐protected method under direct hydrothermal conditions. The obtained zeolite‐encaged metallic nanocatalysts exhibited extraordinary catalytic activity and durability in both CO 2 hydrogenation into formate and formic acid (FA) dehydrogenation back to CO 2 and hydrogen. Thanks to the formation of ultrasmall metal clusters and the synergic effect of bimetallic components, the PdMn 0.6 @S‐1 catalyst afforded a formate generation rate of 2151 mol formate mol Pd −1 h −1 at 353 K, and an initial turnover frequency of 6860 mol mol Pd −1 h −1 for CO‐free FA decomposition at 333 K without any additive. Both values represent the top levels among state‐of‐the‐art heterogeneous catalysts under similar conditions. This work demonstrates that zeolite‐encaged metallic catalysts hold great promise to realize CO 2 ‐mediated hydrogen energy cycles in the future that feature fast charge and release kinetics.

关键词： CO2 hydrogenation formic acid heterogeneous catalysis hydrogen storage zeolites

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Multi-granularity Hierarchical Attention Siamese Network for Visual Tracking

Multi-granularity Hierarchical Attention Siamese Network for...

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International Joint Conference on Neural Networks

作者： Xing Chen Xiang Zhang Huibin Tan Long Lan Zhigang Luo Xuhui Huang College of Computer National University of Defense Technology Changsha Hunan P.R. China State Key Laboratory of High Performance Computing National University of Defense Technology Changsha Hunan P.R. China Department of Computer Science and Technology College of Computer National University of Defense Technology Changsha Hunan P.R. China

Speed and accuracy are the two most important focuses for many visual tracking methods. Recently, siamese networks based trackers have shown very promising potentials in both aspects, which develop a twin network to measure the responses between target and hypotheses with a fully convolutional operation. However, the learned response maps are vulnerable to background clutters and scale changes as they ignore priori knowledge such as the object salience and multi-granularity cues. To explore the benefits of priori, this paper devises a multi-granularity hierarchical attention siamese network tracker (MHA-Siam) to further enhance the tracking stability without sacrificing real-time speed. Particularly, the channel-wise attention mechanism is exploited here to filter out the background while remain the salient object region;then, the response maps of the coarse-to-finer multi-layer features are fused to capture multi-granularity location information helpful for improvement in tracking stability. To make full use of them, MHA-Siam imposes the element-wise max-and-sum operation on them to induce a reliable response map for accurate location. Experiments of visual tracking on OTB benchmark shows the superiority of MHA-Siam with the competitive efficiency to its counterpart trackers.

关键词： Target tracking Visualization Task analysis Search problems Neural networks Support vector machines Network architecture

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Green wave-based virtual traffic light management scheme with VANETs

Green wave-based virtual traffic light management scheme wit...

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作者： Chou, Li-Der Shen, Tsung-Yi Tseng, Chia-Wei Chang, Yao-Jen Kuo, Yen-Wei Department of Computer Science and Information Engineering National Central University Taoyuan32001 Taiwan National Center for High-performance Computing National Applied Research Laboratories Hsinchu30076 Taiwan Department of Electronic Engineering Chung Yuan Christian University Taoyuan32023 Taiwan

Green intelligent transportation systems (GITS) have received significant attention in recent years. Traffic congestion, which is an important research topic on intelligent transportation systems (ITS), is rapidly becoming one of the most serious problems affecting urban areas. This study utilises the vehicular ad hoc networks (VANETs) technology to build a virtual traffic light (VTL) environment to reduce traffic congestion. The objective of this study is to adjust the traffic light signal time length on-demand to enable vehicles to pass through numerous intersections rapidly, thereby saving energy and reducing fuel consumption. The traffic phase combination algorithm and VTL operation mechanism are also addressed to improve the traffic congestion situation in urban areas. Simulation results indicate that the proposed scheme can increase the percentage of traffic flow and the average speed of all vehicles in all intersections, thereby saving energy. Copyright © 2017 Inderscience Enterprises Ltd.

关键词： Vehicular ad hoc networks

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Noise subtraction from KAGRA O3GK data using Independent Component Analysis

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Classical and Quantum Gravity 2023年第8期40卷 085015-085015页

作者： H Abe T Akutsu M Ando A Araya N Aritomi H Asada Y Aso S Bae Y Bae R Bajpai K Cannon Z Cao E Capocasa M Chan C Chen D Chen K Chen Y Chen C-Y Chiang Y-K Chu S Eguchi M Eisenmann Y Enomoto R Flaminio H K Fong Y Fujii Y Fujikawa Y Fujimoto I Fukunaga D Gao G-G Ge S Ha I P W Hadiputrawan S Haino W-B Han K Hasegawa K Hattori H Hayakawa K Hayama Y Himemoto N Hirata C Hirose T-C Ho B-H Hsieh H-F Hsieh C Hsiung H-Y Huang P Huang Y-C Huang Y-J Huang D C Y Hui S Ide K Inayoshi Y Inoue K Ito Y Itoh C Jeon H-B Jin K Jung P Jung K Kaihotsu T Kajita M Kakizaki M Kamiizumi N Kanda T Kato K Kawaguchi C Kim J Kim J C Kim Y-M Kim N Kimura T Kiyota Y Kobayashi K Kohri K Kokeyama A K H Kong N Koyama C Kozakai J Kume Y Kuromiya S Kuroyanagi K Kwak E Lee H W Lee R Lee M Leonardi K L Li P Li L C -C Lin C-Y Lin E T Lin F-K Lin F-L Lin H L Lin G C Liu L-W Luo M Ma’arif E Majorana Y Michimura N Mio O Miyakawa K Miyo S Miyoki Y Mori S Morisaki N Morisue Y Moriwaki K Nagano K Nakamura H Nakano M Nakano Y Nakayama T Narikawa L Naticchioni L Nguyen Quynh W-T Ni T Nishimoto A Nishizawa S Nozaki Y Obayashi W Ogaki J J Oh K Oh M Ohashi T Ohashi M Ohkawa H Ohta Y Okutani K Oohara S Oshino S Otabe K-C Pan A Parisi J Park F E Pe na Arellano S Saha Y Saito K Sakai T Sawada Y Sekiguchi L Shao Y Shikano H Shimizu K Shimode H Shinkai T Shishido A Shoda K Somiya I Song R Sugimoto J Suresh T Suzuki H Tagoshi H Takahashi R Takahashi S Takano H Takeda M Takeda K Tanaka T Tanaka S Tanioka A Taruya T Tomaru T Tomura L Trozzo T Tsang J-S Tsao S Tsuchida T Tsutsui D Tuyenbayev N Uchikata T Uchiyama A Ueda T Uehara K Ueno G Ueshima T Ushiba M H P M van Putten J Wang T Washimi C Wu H Wu T Yamada K Yamamoto T Yamamoto K Yamashita R Yamazaki Y Yang S Yeh J Yokoyama T Yokozawa T Yoshioka H Yuzurihara S Zeidler M Zhan H Zhang Y Zhao Z-H Zhu The KAGRA Collaboration Graduate School of Science Tokyo Institute of Technology Meguro-ku Tokyo 152-8551 Japan Gravitational Wave Science Project National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan Advanced Technology Center National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan Department of Physics The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Research Center for the Early Universe (RESCEU) The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Earthquake Research Institute The University of Tokyo Bunkyo-ku Tokyo 113-0032 Japan Department of Mathematics and Physics Gravitational Wave Science Project Hirosaki University Hirosaki City Aomori 036-8561 Japan Kamioka Branch National Astronomical Observatory of Japan (NAOJ) Kamioka-cho Hida City Gifu 506-1205 Japan The Graduate University for Advanced Studies (SOKENDAI) Mitaka City Tokyo 181-8588 Japan Korea Institute of Science and Technology Information (KISTI) Yuseong-gu Daejeon 34141 Republic of Korea National Institute for Mathematical Sciences Yuseong-gu Daejeon 34047 Republic of Korea School of High Energy Accelerator Science The Graduate University for Advanced Studies (SOKENDAI) Tsukuba City Ibaraki 305-0801 Japan Department of Astronomy Beijing Normal University Beijing 100875 People’s Republic of China Department of Applied Physics Fukuoka University Jonan Fukuoka City Fukuoka 814-0180 Japan Department of Physics Tamkang University Danshui Dist. New Taipei City 25137 Taiwan Department of Physics and Institute of Astronomy National Tsing Hua University Hsinchu 30013 Taiwan Department of Physics Center for High Energy and High Field Physics National Central University Zhongli District Taoyuan City 32001 Taiwan Department of Physics National Tsing Hua University Hsinchu 30013 Taiwan Institute of Physics Academia Sinica Nankang Taipei 11529 Taiwan Univ. Grenoble Alpes Laboratoire d’Annecy de Physique des Particules (LAPP) Université Savoie M

During April 7–21 2020, KAGRA conducted its first scientific observation in conjunction with the GEO600 detector. The dominant noise sources during this run were found to be suspension control noise in the low-frequency range and acoustic noise in the mid-frequency range. In this study, we show that their contributions in the observational data can be reduced by a signal processing method called independent component analysis (ICA). The model of ICA is extended from that studied in the initial KAGRA data analysis to account for frequency dependence, while the linearity and stationarity of the coupling between the interferometer and the noise sources are still assumed. We identify optimal witness sensors in the application of ICA, leading to successful mitigation of these two dominant contributions. We also analyze the stability of the transfer functions for the entire two weeks of data to investigate the applicability of the proposed subtraction method in gravitational wave searches.

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