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Quasiparticle Trapping at Vortices Producing Josephson Supercurrent Enhancement

Physical Review Letters 2022年第20期128卷 207001-207001页

作者： Yosuke Sato Kento Ueda Yuusuke Takeshige Hiroshi Kamata Kan Li Lars Samuelson H. Q. Xu Sadashige Matsuo Seigo Tarucha Department of Applied Physics University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Center for Emergent Matter Science RIKEN 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan Laboratoire de Physique de l’École Normale Supérieure ENS PSL Research University CNRS Sorbonne Université Université Paris Diderot Sorbonne Paris Cité 24 rue Lhomond 75231 Paris Cedex 05 France Beijing Key Laboratory of Quantum Devices Key Laboratory for the Physics and Chemistry of Nanodevices and School of Electronics Peking University Beijing 100871 China Division of Solid State Physics and NanoLund Lund University Box 118 SE-221 00 Lund Sweden Department of Electrical and Electronic Engineering Southern University of Science and Technology 1088 Xueyuan Blvd Nanshan Shenzhen Guangdong 518055 China Beijing Academy of Quantum Information Sciences Beijing 100193 China JST PRESTO 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan RIKEN Center for Quantum Computing RIKEN 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan

The Josephson junction of a strong spin-orbit material under a magnetic field is a promising Majorana fermion candidate. Supercurrent enhancement by a magnetic field has been observed in the InAs nanowire Josephson junctions and assigned to a topological transition. In this work we observe a similar phenomenon but discuss the nontopological origin by considering the trapping of quasiparticles by vortices that penetrate the superconductor under a finite magnetic field. This assignment is supported by the observed hysteresis of the switching current when sweeping up and down the magnetic field. Our experiment shows the importance of quasiparticles in superconducting devices with a magnetic field, which can provide important insights for the design of qubits using superconductors.

关键词： Majorana fermions Spin-orbit coupling Josephson junctions Nanowires Superconductors

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DESIGN AND IMPLEMENTATION OF THE ILLINOIS EXPRESS QUANTUM METROPOLITAN AREA NETWORK

arXiv

引用

arXiv 2022年

作者： Chung, Joaquin Eastman, Ely M. Kanter, Gregory S. Kapoor, Keshav Lauk, Nikolai Peña, Cristián Plunkett, Robert Sinclair, Neil Thomas, Jordan M. Valivarthi, Raju Xie, Si Kettimuthu, Rajkumar Kumar, Prem Spentzouris, Panagiotis Spiropulu, Maria Data Science and Learning Division Argonne National Laboratory 9700 S Cass Ave. LemontIL60439 United States The University of Chicago Consortium for Advanced Science and Engineering 924 E 57th St ChicagoIL60637 United States NuCrypt Llc 1840 Oak Ave EvanstonIL60201 United States Center for Photonic Communication and Computing Department of Electrical and Computer Engineering McCormick School of Engineering and Applied Science Northwestern University 2145 Sheridan Road EvanstonIL60208-3118 United States Division of Physics Mathematics and Astronomy California Institute of Technology 1200 E. California Blvd. PasadenaCA91125 United States California Institute of Technology 1200 E. California Blvd. PasadenaCA91125 United States Fermi National Accelerator Laboratory Kirk Rd and Pine St BataviaIL60510 United States John A. Paulson School of Engineering and Applied Sciences Harvard University 29 Oxford St. CambridgeMA02138 United States 2205 Tech Drive Suite 1-160 EvanstonIL60208 United States Department of Physics and Astronomy Northwestern University 2145 Sheridan Road EvanstonIL60208-3112 United States

The Illinois Express Quantum Network (IEQNET) is a program to realize metropolitan scale quantum networking over deployed optical fiber using currently available technology. IEQNET consists of multiple sites that are geographically dispersed in the Chicago metropolitan area. Each site has one or more quantum nodes (Q-Nodes) representing the communication parties in a quantum network. Q-Nodes generate or measure quantum signals such as entangled photons and communicate the measurement results via standard, classical signals and conventional networking processes. The entangled photons in IEQNET nodes are generated at multiple wavelengths, and are selectively distributed to the desired users via transparent optical switches. Here we describe the network architecture of IEQNET, including the Internet-inspired layered hierarchy that leverages softwaredefined networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-Nodes. Specifically, SDN decouples the control and data planes, with the control plane being entirely implemented in the classical domain. We also discuss the IEQNET processes that address issues associated with synchronization, calibration, network monitoring, and scheduling. An important goal of IEQNET is to demonstrate the extent to which the control plane classical signals can co-propagate with the data plane quantum signals in the same fiber lines (quantum-classical signal "coexistence"). This goal is furthered by the use of tunable narrow-band optical filtering at the receivers and, at least in some cases, a wide wavelength separation between the quantum and classical channels. We envision IEQNET to aid in developing robust and practical quantum networks by demonstrating metro-scale quantum communication tasks such as entanglement distribution and quantum-state teleportation. Copyright © 2022, The Authors. All rights reserved.

关键词： Network architecture

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Numerical study of heat transfer in Rayleigh-Bénard convection under rarefied gas conditions

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Physical Review E 2020年第1期102卷 013102-013102页

作者： B. Goshayeshi G. Di Staso F. Toschi H. J. H. Clercx Fluid Dynamics Laboratory and J.M. Burgers Center for Fluid Dynamics Department of Applied Physics Eindhoven University of Technology P. O. Box 513 5600 MB Eindhoven The Netherlands Centre of Analysis Scientific Computing and Applications W&I Department of Mathematics and Computer Science Eindhoven University of Technology P. O. Box 513 5600 MB Eindhoven The Netherlands Istituto per le Applicazioni del Calcolo Consiglio Nazionale delle Ricerche 00185 Rome Italy

The focus of this research is to delineate the thermal behavior of a rarefied monatomic gas confined between horizontal hot and cold walls, physically known as rarefied Rayleigh-Bénard (RB) convection. Convection in a rarefied gas appears only for high temperature differences between the horizontal boundaries, where nonlinear distributions of temperature and density make it different from the classical RB problem. Numerical simulations adopting the direct simulation Monte Carlo approach are performed to study the rarefied RB problem for a cold to hot wall temperature ratio equal to r=0.1 and different rarefaction conditions. Rarefaction is quantified by the Knudsen number, Kn. To investigate the long-time thermal behavior of the system two ways are followed to measure the heat transfer: (i) measurements of macroscopic hydrodynamic variables in the bulk of the flow and (ii) measurements at the microscopic scale based on the molecular evaluation of the energy exchange between the isothermal wall and the fluid. The measurements based on the bulk and molecular scales agreed well. Hence, both approaches are considered in evaluations of the heat transfer in terms of the Nusselt number, Nu. To characterize the flow properly, a modified Rayleigh number (Ram) is defined to take into account the nonlinear temperature and density distributions at the pure conduction state. Then the limits of instability, indicating the transition of the conduction state into a convection state, at the low and large Froude asymptotes are determined based on Ram. At the large Froude asymptote, simulations following the onset of convection showed a relatively small range for the critical Rayleigh (Ram=1770±15) that flow instability occurs at each investigated rarefaction degree. Moreover, we measured the maximum Nusselt values Numax at each investigated Kn. It was observed that for Kn≥0.02, Numax decreases linearly until the transition to conduction at Kn≈0.03, known as the rarefaction limit for

关键词： Flow instability Rarefied flows Rayleigh-Bénard convection

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Autonomous Deployment of a Solar Panel Using Elastic Origami and Distributed Shape-Memory-Polymer Actuators

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Physical Review applied 2019年第6期11卷 064069-064069页

作者： Tian Chen Osama R. Bilal Robert Lang Chiara Daraio Kristina Shea Engineering Design and Computing Laboratory Department of Mechanical and Process Engineering ETH Zurich Zurich 8092 Switzerland Division of Engineering and Applied Science California Institute of Technology Pasadena California 91125 USA Lang Origami Altadena California 91001 USA

We introduce a metamaterial-based self-deployable system with a rotational periodicity. As a demonstration, we propose an autonomous solar panel array that is programmed to self-deploy in response to changes in the surrounding temperature. We achieve shape reconfiguration and structural stability by exploiting the physical properties in the constituting material and the architecture of the wedge-shaped unit cell. The unit cell consists of one arm of the elastic “flasher” origami and a pair of scissor mechanisms. First, kinematic analysis shows the difference between the theoretical behavior and behavior considering the physical dimensions. This is used to optimize the expansion ratio. Second, the deployment mechanics are enabled through the shape-memory effect inherent in the underlying polymer. A viscoelastic constitutive model is constructed to accurately predict the self-expanding behavior. Lastly, the collapsing and deployment dynamics are discussed. Bifurcation is observed during folding, leading to two different end states, a disk or a cone. By investigating the energy landscape of the system, an apparatus is introduced to enable the disk-shaped folding. A two-stage expansion is observed during deployment. The system first rotates and then expands radially. The resulting system is three-dimensionally (3D) printed, achieves an expansion ratio of 1000% in under 40 s, and shows excellent agreement with simulation prediction both in the collapsed and expanded configurations.

关键词： Origami & Kirigami Smart materials Thermomechanical effects Elastomers Polymer glasses Shape-memory materials Solar cells Finite-element method

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Parallel Implementation of RC4 Data Encryption Method for Cloud computing

Computing Open

引用

computing Open 2023年第1期computing-open卷

作者： Arif Ullah Tanweer Alam Fawad Salam Khan Hanane Aznaoui https://***/0000-0002-7740-2206 Department of Computer Science Faculty of Computing and Artificial Intelligent Air University Islamabad Pakistan https://***/0000-0002-6350-0761 Faculty of Computer and Information Systems Islamic University of Madinah Medina Saudi Arabia https://***/0009-0005-7014-9470 Department of Creative Technology and Artificial Intelligent Air University Islamabad Pakistan https://***/0000-0002-3524-7869 Department of Computer Science Laboratory of Applied Mathematics and Computer Science Morocco

Cloud computing is an on-demand availability of computing resources. The current cloud computing environment uses different algorithms for its security; RC4 is one of them. However, due to the serial implementation of RC4 over cloud computing, the process of encryption and data transmission is badly affected by the factors of poor latency. This research is proposed to cover this factor by implementing a parallel RC4 algorithm in a cloud computing environment. The parallel RC4 model has been developed in web-based architecture relevant to the cloud computing environment. The method processed data simultaneously in four parallel pipelines encrypted through the RC4 algorithm. The proposed method used RC4 algorithms’ parallel implementation to encrypt and decrypt the data. The proposed method increases the efficiency of data encryption and decryption and transmission over a cloud environment using four pipelines at once. These four pipelines receive data and encrypt them using a key and then merge those four streams into a single cipher. These four pipelines enhance the speed of communication over cloud and solve the latency issue majorly. Data sending from node devices to cloud servers is divided into four equal streams and then encrypted using RC4 distinctly but parallel. Then after the roaming, the data are again first combined and then decrypted using the RC4 algorithm. The sample data sets are evaluated on the criteria of the starting time and ending time of the encryption and decryption of data. Results show that the proposed method is able to enhance the speed of the whole process up to average 3.7% due to the implementation of parallel technique and had reduced the time notably. The future work on this research involves enhancement of security process of RC4 algorithm since it can be breached easily.

关键词： Cloud computing RC4 algorithm encryption parallel latency

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Transformative Effects of ChatGPT on Modern Education: Emerging Era of AI Chatbots

arXiv

引用

arXiv 2023年

作者： Gill, Sukhpal Singh Xu, Minxian Patros, Panos Wu, Huaming Kaur, Rupinder Kaur, Kamalpreet Fuller, Stephanie Singh, Manmeet Arora, Priyansh Parlikad, Ajith Kumar Stankovski, Vlado Abraham, Ajith Ghosh, Soumya K. Lutfiyya, Hanan Kanhere, Salil S. Bahsoon, Rami Rana, Omer Dustdar, Schahram Sakellariou, Rizos Uhlig, Steve Buyya, Rajkumar School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen China Raygun Performance Monitoring Wellington New Zealand Center for Applied Mathematics Tianjin University Tianjin China Department of Science Kings Education London United Kingdom Cymax Group Technologies BC Canada QM Academy Queen Mary University of London London United Kingdom Jackson School of Geosciences University of Texas at Austin AustinTX United States Centre for Climate Change Research Indian Institute of Tropical Meteorology Pune India Microsoft Hyderabad India Institute for Manufacturing Department of Engineering University of Cambridge Cambridge United Kingdom Faculty of Computer and Information Science University of Ljubljana Ljubljana Slovenia Machine Intelligence Research Labs AuburnWA United States Department of Computer Science and Engineering Indian Institute of Technology Kharagpur India Department of Computer Science University of Western Ontario London Canada Sydney Australia School of Computer Science University of Birmingham United Kingdom School of Computer Science and Informatics Cardiff University Cardiff United Kingdom Distributed Systems Group Vienna University of Technology Vienna Austria Department of Computer Science University of Manchester Oxford Road Manchester United Kingdom Laboratory School of Computing and Information Systems The University of Melbourne Australia

ChatGPT, an AI-based chatbot, was released to provide coherent and useful replies based on analysis of large volumes of data. In this article, leading scientists, researchers and engineers discuss the transformative effects of ChatGPT on modern education. This research seeks to improve our knowledge of ChatGPT capabilities and its use in the education sector, identifying potential concerns and challenges. Our preliminary evaluation concludes that ChatGPT performed differently in each subject area including finance, coding and maths. While ChatGPT has the ability to help educators by creating instructional content, offering suggestions and acting as an online educator to learners by answering questions and promoting group work, there are clear drawbacks in its use, such as the possibility of producing inaccurate or false data and circumventing duplicate content (plagiarism) detectors where originality is essential. The often reported "hallucinations" within Generative AI in general, and also relevant for ChatGPT, can render its use of limited benefit where accuracy is essential. What ChatGPT lacks is a stochastic measure to help provide sincere and sensitive communication with its users. Academic regulations and evaluation practices used in educational institutions need to be updated, should ChatGPT be used as a tool in education. To address the transformative effects of ChatGPT on the learning environment, educating teachers and students alike about its capabilities and limitations will be crucial. © 2023, CC0.

关键词： Machine learning

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Provably Secure APK Redevelopment Authorization Scheme in the Standard Model

引用

Computers, Materials & Continua 2018年第9期56卷 447-465页

作者： Daofeng Li Mingxing Luo Bowen Zhao Xiangdong Che School of Computer Electrical and informationGuang Xi UniversityNanning530004China Information Security and National Computing Grid Laboratory Southwest Jiaotong UniversityChengdu610031China Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information Processing Guangxi UniversityNanning530004China School of Information Security&Applied Computing College of TechnologyEastern Michigan UniversityMichigan48197USA

The secure issues of APK are very important in Android *** order to solve potential secure problems and copyrights issues in redevelopment of APK files,in this paper we propose a new APK redevelopment mechanism(APK-SAN).By exploring sanitizable signature technology,APK-SAN allows the original developer to authorize specified modifier who can redevelop the designated source code of APK *** scheme does not require interactions between the developer and *** can reduce the communication overhead and computational overhead for ***,the signature of redeveloped APK files is valid and maintains the *** proposed APK-SAN signature can effectively protect the security of the redeveloped APK files and copyrights of the developer and modifier.

关键词： Sanitizable signature APK signature mechanism redevelopment ID-based signature scheme

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Homer’s Feasibility Analysis of a Hybrid System with a Grid Connection Option for the Mauritanian Northern Coast

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Journal of Power and Energy Engineering 2019年第2期7卷 27-42页

作者： Soukeyna Mohamed Ismail Bidjel Ramdhane Diene Ndiaye Abdel Kader Mahmoud Mohamed Elmamy Mohamed Mahmoud Menou Ahmed Mohamed Yahya Issakha Youm Applied Research Laboratory for Renewable Energies (LRAER) Université de Nouakchott Al-Aasriya (UNA) Nouakchott Mauritania Laboratory of Electronic Computing Telecommunication and Renewable Energies (LEITER) UGB Saint-Louis Senegal Laboratory of Semiconductor and Solar Energy (LASES) Faculty of Science and Technology Cheikh Anta Diop Dakar Senegal

On Mauritania’s northern coast, wind and solar resources are abundant and must be used effectively. These resources have the potential to completely or partially replace the existing or projected diesel generators. The main objective of this case study is to study the possibility of using a hybrid system (HS) of the type (diesel, wind and storage). The most important part of this case study intended for this area will be to add the solar in a first phase and then the incorporation of an interconnection with the nearby network in a second phase. This interconnection will be secured by mean of medium voltage lines of 33 kV, where the nearest point is located 35 km away. Indeed, the study of the optimization model is carried out through Homer, which was developed by National Renewable Energy laboratory [NREL]. Thus, it should be noted that the HS is analyzed on the basis of costs ($/kW) and price ($/kWh) and greenhouse gas emissions. Therefore, in order to achieve these techno-economic optimization objectives, this paper introduces a sensitivity analysis that has been proposed to determine the effect of costs on each HS configuration. In the end, HSs are needed for maximum use of renewable resources at the studied site for an uninterrupted power supply.

关键词： Homer Feasibility Analysis Hybrid System Wind Solar Grid

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Impossible meet-in-the-middle fault analysis on the LED lightweight cipher in VANETs

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Science China(Information Sciences) 2018年第3期61卷 118-130页

作者： Wei LI Vincent RIJMEN Zhi TAO Qingju WANG Hua CHEN Yunwen LIU Chaoyun LI Ya LIU School of Computer Science and Technology Donghua University imec-COSIC KU Leuven Shanghai Key Laboratory of Integrate Administration Technologies for Information Security Department of Computer Science and Engineering Shanghai Jiao Tong University Department of Applied Mathematics and Computer Science Technical University of Denmark Trusted Computing and Information Assurance Laboratory Institute of SoftwareChinese Academy of Sciences College of Science National University of Defense Technology Department of Computer Science and Engineering University of Shanghai for Science and Technology

With the expansion of wireless technology, vehicular ad-hoc networks(VANETs) are emerging as a promising approach for realizing smart cities and addressing many serious traffic problems, such as road safety, convenience, and efficiency. To avoid any possible rancorous attacks, employing lightweight ciphers is most effective for implementing encryption/decryption, message authentication, and digital signatures for the security of the VANETs. Light encryption device(LED) is a lightweight block cipher with two basic keysize variants: LED-64 and LED-128. Since its inception, many fault analysis techniques have focused on provoking faults in the last four rounds to derive the 64-bit and 128-bit secret keys. It is vital to investigate whether injecting faults into a prior round enables breakage of the LED. This study presents a novel impossible meet-in-the-middle fault analysis on a prior round. A detailed analysis of the expected number of faults is used to uniquely determine the secret key. It is based on the propagation of truncated differentials and is surprisingly reminiscent of the computation of the complexity of a rectangle attack. It shows that the impossible meet-in-the-middle fault analysis could successfully break the LED by fault injections.

关键词： VANETs LED lightweight cipher impossible meet-in-the-middle fault analysis

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Heterogeneous parallelization and acceleration of molecular dynamics simulations in GROMACS

arXiv

引用

arXiv 2020年

作者： Páll, Szilárd Zhmurov, Artem Bauer, Paul Abraham, Mark Lundborg, Magnus Gray, Alan Hess, Berk Lindahl, Erik Swedish e-Science Research Center PDC Center for High Performance Computing KTH Royal Institute of Technology Stockholm100 44 Sweden Department of Applied Physics Swedish e-Science Research Center Science for Life Laboratory KTH Royal Institute of Technology Box 1031 Solna171 21 Sweden ERCO Pharma AB Stockholm Sweden NVIDIA Corporation United Kingdom Department of Biochemistry and Biophysics Science for Life Laboratory Stockholm University Box 1031 Solna171 21 Sweden

The introduction of accelerator devices such as graphics processing units (GPUs) has had profound impact on molecular dynamics simulations and has enabled order-of-magnitude performance advances using commodity hardware. To fully reap these benefits, it has been necessary to reformulate some of the most fundamental algorithms, including the Verlet list, pair searching and cut-offs. Here, we present the heterogeneous parallelization and acceleration design of molecular dynamics implemented in the GROMACS codebase over the last decade. The setup involves a general cluster-based approach to pair lists and non-bonded pair interactions that utilizes both GPUs and CPU SIMD acceleration efficiently, including the ability to load-balance tasks between CPUs and GPUs. The algorithm work efficiency is tuned for each type of hardware, and to use accelerators more efficiently we introduce dual pair lists with rolling pruning updates. Combined with new direct GPU-GPU communication as well as GPU integration, this enables excellent performance from single GPU simulations through strong scaling across multiple GPUs and efficient multi-node parallelization. Copyright © 2020, The Authors. All rights reserved.

关键词： Computer graphics

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