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Conference on Design of Circuits and Integrated Circuits (DCIS)

作者： Binbin Yang Daniel Arumí Salvador Manich Alvaro Gómez-Pau Rosa Rodríguez-Montañés Juan Bautista Roldan Mireia Bargalló González Francesca Campabadal Liang Fang Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha China Universitat Politècnica de Catalunya Barcelona Spain Universidad de Granada (UGR) Granada Spain Institut de Microelectrònica de Barcelona-Centre Nacional de Microelectrònica Consejo Superior de Investigaciones Cientificas Bellaterra Spain

ISBN: (纸本)9781665421171

Model-based simulation is one of the effective methods of scientific research. The inherent variability of resistive switching mechanisms has been an obstacle for the massive commercial implementation of the resistive random access memory (RRAM) devices. In this work, we simulated the resistive switching behavior based on an existing RRAM Verilog-A model, in which the simulated switching parameters demonstrated a satisfactory fit with the experimental data by introducing variability into the model. Moreover, a potential application of the troublesome variability was explored in the serial configuration of two RRAM devices, a cell which had been demonstrated to generate unpredictable bits with potential applications in hardware security. Realistic simulation of RRAM based circuits is key for the future development of RRAM based applications.

关键词： Resistive RAM Switches Data models Hardware Security Integrated circuit modeling Hardware design languages

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Lattice QCD results for the topological up-quark mass contribution: too small to rescue the mu = 0 solution to the strong CP problem 38

Lattice QCD results for the topological up-quark mass contri...

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38th International Symposium on Lattice Field Theory, LATTICE 2021

作者： Alexandrou, Constantia Finkenrath, Jacob Funcke, Lena Jansen, Karl Kostrzewa, Bartosz Pittler, Ferenc Urbach, Carsten Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-Based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia2121 Cyprus Center for Theoretical Physics Co-Design Center for Quantum Advantage NSF AI Institute for Artificial Intelligence and Fundamental Interactions Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Deutsches Elektronen-Synchrotron DESY Platanenallee 6 Zeuthen15738 Germany High Performance Computing & Analytics Lab University of Bonn Friedrich-Hirzebruch-Allee 8 Bonn53115 Germany Helmholtz Institut für Strahlen- und Kernphysik University of Bonn Nussallee 14-16 Bonn53115 Germany Bethe Center for Theoretical Physics University of Bonn Nussallee 12 Bonn53115 Germany

A vanishing Yukawa coupling of the up quark could in principle solve the strong CP problem. To render this solution consistent with current algebra results, the up quark must receive an alternative mass contribution that conserves CP symmetry. Such a contribution could be provided by QCD through non-perturbative topological effects, including instantons. In this talk, we present the first direct lattice computation of this topological mass contribution, using gauge configurations generated by the Extended Twisted Mass collaboration. We use the Iwasaki gauge action, Wilson twisted mass fermions at maximal twist, and dynamical up, down, strange and charm quarks. Our result for the topological mass contribution is an order of magnitude too small to account for the phenomenologically required up-quark mass. This rules out the "massless" up-quark solution to the strong CP problem, in accordance with previous results relying on XPT fits to lattice data. The talk is based on Ref. [1], where more details can be found. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0)

关键词： Gages

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MRDRL-ROS: a Multi Robot Deep Reinforcement Learning Platform based on Robot Operating System

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Journal of Physics: Conference Series 2021年第1期2113卷

作者： Zhongxuan Cai Zhen Liang Jing Ren Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha Hunan 410073 China

Deep reinforcement learning (DRL) has greatly improved the intelligence of AI in recent years and the community has proposed several common software to facilitate the development of DRL. However, in robotics the utility of common DRL software is limited and the development is time-consuming due to the complexity of various robot software. In this paper, we propose a software engineering approach leveraging modularity to facilitate robot DRL development. The platform decouples learning environment into task, simulator and hierarchical robot modules, which in turn enables diverse environment generation using existing modules as building blocks, regardless of the underlying robot software details. Experimental results show that our platform provides composable environment building, introduces high module reuse and efficiently facilitates robot DRL.

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Load Balancing a Multi-Block Grids-based Application on Heterogeneous Platform

Load Balancing a Multi-Block Grids-based Application on Hete...

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IEEE International Conference on Computational Science and Engineering, CSE

作者： Yonggang Che Chuanfu Xu Zhenghua Wang Institute for Quantum Information & State Key Lab. of High Performance Computing College of Computer National University of Defense Technology Changsha China Science and Technology on Parallel and Distributed Processing Lab National University of Defense Technology Changsha China

ISBN: (数字)9781665403986

ISBN: (纸本)9781665403993

This paper presents a load balancing method for a multi-block grids-based CFD (Computational Fluid Dynamics) application on heterogeneous platform. This method includes an asymmetric task scheduling scheme and a load balancing model. The idea is to balance the computing speed between the CPU and the coprocessor by adjusting the workload and the numbers of threads on both sides. Optimal load balance parameters are empirically selected, guided by a performance model. performance evaluation is conducted on a computer server consists of two Intel Xeon E5-2670 v3 CPUs and two MIC coprocessors (Xeon Phi 5110P and Xeon Phi 7120P) for the simulation of turbulent combustion in a supersonic combustor. The results show that the performance is highly sensitive to the load balance parameters. With the optimal parameters, the heterogeneous computing achieves a maximum speedup of 2.30 × for a 6-block mesh, and a maximum speedup of 2.66 × for a 8-block mesh, over the CPU-only computing.

关键词： Computational modeling Computational fluid dynamics Load management Servers Task analysis Load modeling Coprocessors

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Tuning Dzyaloshinskii-Moriya interaction in ferrimagnetic GdCo: A first-principles approach

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Physical Review B 2021年第17期103卷 174414-174414页

作者： Md Golam Morshed Khoong Hong Khoo Yassine Quessab Jun-Wen Xu Robert Laskowski Prasanna V. Balachandran Andrew D. Kent Avik W. Ghosh Department of Electrical and Computer Engineering University of Virginia Charlottesville Virginia 22904 USA Institute of High Performance Computing Agency for Science Technology and Research 1 Fusionopolis Way Connexis Singapore 138632 Singapore Center for Quantum Phenomena Department of Physics New York University New York New York 10003 USA Department of Materials Science and Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Mechanical and Aerospace Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Physics University of Virginia Charlottesville Virginia 22904 USA

We present a systematic analysis of our ability to tune chiral Dzyaloshinskii-Moriya interaction (DMI) in compensated ferrimagnetic Pt/GdCo/Pt1−xWx trilayers by cap layer composition. Using first-principles calculations, we show that the DMI increases rapidly for only ∼10% W and saturates thereafter, in agreement with experiments. The calculated DMI shows a spread in values around the experimental mean, depending on the atomic configuration of the cap layer interface. The saturation is attributed to the vanishing of spin-orbit coupling energy at the cap layer and the simultaneous constancy at the bottom interface. Additionally, we predict the DMI in Pt/GdCo/X (X=Ta,W,Ir) and find that W in the cap layer favors a higher DMI than Ta and Ir that can be attributed to the difference in d-band overlap around the Fermi level. Our results open up exciting combinatorial possibilities for controlling the DMI in ferrimagnets towards nucleating and manipulating ultrasmall high-speed skyrmions.

关键词： Dzyaloshinskii-Moriya interaction Ferrimagnetism Magnetic multilayers First-principles calculations

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Characterisation of state-preparation uncertainty in quantum key distribution

arXiv

引用

arXiv 2022年

作者： Huang, Anqi Mizutani, Akihiro Lo, Hoi-Kwong Makarov, Vadim Tamaki, Kiyoshi Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha410073 China Graduate School of Engineering Science Osaka University Toyonaka Osaka560-8531 Japan Department of Electrical & Computer Engineering Department of Physics University of Toronto TorontoONM5S 3G4 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Quantum Bridge Technologies Inc. 100 College Street TorontoONM5G 1L5 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 Faculty of Engineering University of Toyama Gofuku 3190 Toyama930-8555 Japan

To achieve secure quantum key distribution, all imperfections in the source unit must be incorporated in a security proof and measured in the lab. Here we perform a proof-of-principle demonstration of the experimental techniques for characterising the source phase and intensity fluctuation in commercial quantum key distribution systems. When we apply the measured phase fluctuation intervals to the security proof that takes into account fluctuations in the state preparation, it predicts a key distribution distance of over 100 km of fiber. The measured intensity fluctuation intervals are however so large that the proof predicts zero key, indicating a source improvement may be needed. Our characterisation methods pave the way for a future certification standard. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum cryptography

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Terahertz Generation via Picosecond Spin-to-Charge Conversion in IrMn3/Ni−Fe Heterojunction

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Physical Review Applied 2021年第2期16卷 024058-024058页

作者： Cheng Li Bin Fang Like Zhang Qian Chen Xiangnan Xie Nuo Xu Zhongming Zeng Zhenyu Wang Liang Fang Tian Jiang Institute for Quantum Information & State Key Laboratory of High Performance Computing National University of Defense Technology Changsha 410073 China Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia Suzhou Institute of Nano-Tech and Nano-Bionics CAS Suzhou 215123 China College of Electronic and Information Engineering Wuxi University Wuxi 214105 China National Innovation Institute of Defense Technology Academy of Military Sciences PLA China Beijing 100010 China Beijing Academy of Quantum Information Sciences Beijing 100193 China Beijing Institute for Advanced Studies National University of Defense Technology 100010 China

Experimental investigations of ultrafast electro-optical properties in magnetic materials manifest their great potential for emerging spintronic optoelectronic devices. Here, using time-resolved terahertz emission spectroscopy, we construct a spintronic terahertz emitter consisting of an IrMn3/Ni−Fe heterojunction. A femtosecond spin current pulse is generated in the thin film of the Ni−Fe layer when it absorbs a femtosecond laser pulse, and then the spin current is converted into a transient charge current by the metallic IrMn3 layer on picosecond timescales. We timely record the terahertz emission associated with this ultrafast conversion process by means of electro-optic sampling. Besides, the spin-to-charge conversion efficiency of the IrMn3/Ni−Fe heterojunction is determined via quantitative analysis of the spin torque ferromagnetic resonance results. We have both optically verified and electrically studied the spin-to-charge conversion of the IrMn3/Ni−Fe heterojunction. Our results enlarge the material choice range of spintronic terahertz emitters, which may promote further investigations of ultrafast spin-to-charge conversion in different heterojunction materials.

关键词： Magnetization dynamics Optical sources & detectors Optoelectronics Spin current Spin-orbit coupling Ultrafast magnetic effects Magnetic multilayers Terahertz techniques

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Anharmonic Effects on the Squeezing of Axion Perturbations

arXiv

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arXiv 2023年

作者： Danieli, Valentina Kobayashi, Takeshi Bartolo, Nicola Matarrese, Sabino Viel, Matteo SISSA International School for Advanced Studies Via Bonomea 265 Trieste34136 Italy INFN - Sezione di Trieste via Valerio 2 Trieste34127 Italy IFPU Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34014 Italy Kobayashi-Maskawa Institute for the Origin of Particles the Universe Nagoya University Nagoya464-8602 Japan Dipartimento di Fisica e Astronomia "G. Galilei" Università degl Studi di Padova Via Francesco Marzolo 8 Padova35131 Italy INFN - Sezione di Padova Via Francesco Marzolo 8 Padova35131 Italy INAF - Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 Padova35122 Italy Gran Sasso Science Institute Viale F. Crispi 7 L’AquilaI-67100 Italy INAF - Osservatorio Astronomico di Trieste Via G.B. Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy

It is assumed in standard cosmology that the Universe underwent a period of inflation in its earliest phase, providing the seeds for structure formation through vacuum fluctuations of the inflaton scalar field. These fluctuations get stretched by the quasi-exponential expansion of the Universe and become squeezed. The aim of this paper is to deepen the understanding of the squeezing process, considering the effect of self-interactions. Axion-like particles can provide a useful setup to study this effect. Specifically we focus on the consequences that a non-trivial evolution of the background axion field has on the squeezing of the perturbations. We follow the evolution of the axion’s fluctuation modes from the horizon exit during inflation to the radiation-dominated epoch. We compute Bogoliubov coefficients and squeezing parameters, which are linked to the axion particle number and isocurvature perturbation. We find that the quantum mechanical particle production and the squeezing of the perturbations are enhanced, if one accounts for anharmonic effects, i.e., the effect of higher order terms in the potential. This effect becomes particularly strong towards the hilltop of the potential. Copyright © 2023, The Authors. All rights reserved.

关键词： quantum theory

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Exact Landau Level Description of Geometry and Interaction in a Flatband

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Physical Review Letters 2021年第24期127卷 246403-246403页

作者： Jie Wang Jennifer Cano Andrew J. Millis Zhao Liu Bo Yang Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA Department of Physics and Astronomy Stony Brook University Stony Brook New York 11974 USA Department of Physics Columbia University 538 W 120th Street New York New York 10027 USA Zhejiang Institute of Modern Physics Zhejiang University Hangzhou 310027 China Division of Physics and Applied Physics Nanyang Technological University 637371 Singapore Institute of High Performance Computing A*STAR 138632 Singapore

Flatbands appear in many condensed matter systems, including the two-dimensional electron gas in a high magnetic field, correlated materials, and moiré heterostructures. They are characterized by intrinsic geometric properties such as the Berry curvature and Fubini-Study metric. The influence of the band geometry on electron-electron interaction is difficult to understand analytically because the geometry is in general nonuniform in momentum space. In this work, we study the topological flatband of Chern number C=1 with a momentum-dependent but positive definite Berry curvature that fluctuates in sync with Fubini-Study metric. We derive an exact correspondence between such ideal flatbands and Landau levels and show that the band geometry fluctuation gives rise to a new type of interaction in the corresponding Landau levels that depends on the center of mass of two particles. We characterize such interactions by generalizing the usual Haldane pseudopotentials. This mapping gives exact zero-energy ground states for short-ranged repulsive generalized pseudopotentials in flatbands, in analogy to fractional quantum Hall systems. Driving the center-of-mass interactions beyond the repulsive regime leads to a dramatic reconstruction of the ground states towards gapless phases. The generalized pseudopotential could be a useful basis for future numerical studies.

关键词： Fractional quantum Hall effect Geometric & topological phases Landau levels Strong interaction Bilayer films Two-dimensional electron system Band structure methods Exact diagonalization Geometry Symmetries in condensed matter

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Faking photon number on a transition-edge sensor

arXiv

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arXiv 2021年

作者： Chaiwongkhot, Poompong Zhong, Jiaqiang Huang, Anqi Qin, Hao Shi, Sheng-Cai Makarov, Vadim Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics Faculty of Science Mahidol University Bangkok10400 Thailand Bangkok10110 Thailand Purple Mountain Observatory and Key Laboratory of Radio Astronomy Chinese Academy of Sciences 10 Yuanhua road Nanjing210033 China Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China CAS Quantum Network Co. Ltd. 99 Xiupu road Shanghai201315 China Russian Quantum Center Skolkovo Moscow121205 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale 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

We study potential security vulnerabilities of a single-photon detector based on superconducting transition-edge sensor. In a simple experiment, we show that an adversary could fake a photon number result at a certain wavelength by sending a larger number of photons at a longer wavelength. In another experiment, we show that the detector can be blinded by bright continuous-wave light and then, a controlled response simulating single-photon detection can be produced by applying a bright light pulse. We model an intercept- and-resend attack on a quantum key distribution system that exploits the latter vulnerability and, under certain assumptions, succeeds to steal the key. © 2021, CC BY.

关键词： Photons

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