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End-to-end complexity for simulating the Schwinger model on quantum computers

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arXiv 2023年

作者： Sakamoto, Kazuki Morisaki, Hayata Haruna, Junichi Itou, Etsuko Fujii, Keisuke Mitarai, Kosuke Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Toyonaka Osaka560-8531 Japan Center for Quantum Information and Quantum Biology Osaka University 560-0043 Japan Center for Gravitational Physics Yukawa Institute for Theoretical Physics Kyoto University Kitashirakawa Oiwakecho Sakyo-ku Kyoto606-8502 Japan RIKEN Wako351-0198 Japan Center for Quantum Computing RIKEN Hirosawa 2-1 Saitama Wako351-0198 Japan

The Schwinger model is one of the simplest gauge theories. It is known that a topological term of the model leads to the infamous sign problem in the classical Monte Carlo method. In contrast to this, recently, quantum computing in Hamiltonian formalism has gained attention. In this work, we estimate the resources needed for quantum computers to compute physical quantities that are challenging to compute on classical computers. Specifically, we propose an efficient implementation of block-encoding of the Schwinger model Hamiltonian. Considering the structure of the Hamiltonian, this block-encoding with a normalization factor of O(N3) can be implemented using O(N + log2(N/Ε)) T gates. As an end-to-end application, we compute the vacuum persistence amplitude. As a result, we found that for a system size N = 128 and an additive error Ε = 0.01, with an evolution time t and a lattice spacing a satisfying t/2a = 10, the vacuum persistence amplitude can be calculated using about 1013 T gates. Our results provide insights into predictions about the performance of quantum computers in the FTQC and early FTQC era, clarifying the challenges in solving meaningful problems within a realistic timeframe. © 2023, CC BY.

关键词： Hamiltonians

Size-consistency and orbital-invariance issues revealed by VQE-UCCSD calculations with the FMO scheme

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arXiv 2024年

作者： Sugisaki, Kenji Nakano, Tatsuya Mochizuki, Yuji Graduate School of Science and Technology Keio University 7-1 Shinkawasaki Saiwai-ku Kanagawa Kawasaki212-0032 Japan Quantum Computing Center Keio University 3-14-1 Hiyoshi Kohoku-ku Kanagawa Yokohama223-8522 Japan Centre for Quantum Engineering Research and Education TCG Centres for Research and Education in Science and Technology Sector V Salt Lake Kolkata700091 India Division of Medicinal Safety Science National Institute of Health Sciences 1-18-1 Kamiyoga Setagaya-ku Tokyo158-8501 Japan Department of Chemistry Research Center for Smart Molecules Faculty of Science Rikkyo University 3-34-1 Nishi-ikebukuro Toshima-ku Tokyo171-8501 Japan Institute of Industrial Science The University of Tokyo 4-6-1 KomabaMeguro-ku Tokyo153-8505 Japan

The fragment molecular orbital (FMO) scheme is one of the popular fragmentation-based methods and has the potential advantage of making the circuit flat in quantum chemical calculations on quantum computers. In this study, we used a GPU-accelerated quantum simulator (cuQuantum) to perform the electron correlation part of the FMO calculation as unitary coupled-cluster singles and doubles (UCCSD) with the variational quantum eigensolver (VQE) for hydrogen-bonded (FH)3 and (FH)2-H2O systems with the STO-3G basis set. VQE-UCCD calculations were performed using both canonical and localized MO sets, and the results were examined from the point of view of size-consistency and orbital-invariance affected by the Trotter error. It was found that the use of localized MO leads to better results, especially for (FH)2-H2O. The GPU acceleration was substantial for the simulations with larger numbers of qubits, and was about a factor of 6.7–7.7 for 18 qubit systems. Copyright © 2024, The Authors. All rights reserved.

关键词： Graphics processing unit

Public transportation network scan for rapid surveillance

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Biostatistics and Epidemiology 2023年第1期7卷

作者： Tanoue, Yuta Yoneoka, Daisuke Kawashima, Takayuki Uryu, Shinya Nomura, Shuhei Eguchi, Akifumi Makiyama, Koji Matsuura, Kentaro Institute for Business and Finance Waseda University Tokyo Japan Infectious Disease Surveillance Center National Institute of Infectious Diseases Tokyo Japan Department of Health Policy and Management School of Medicine Keio University Tokyo Japan Department of Global Health Policy Graduate School of Medicine The University of Tokyo Tokyo Japan Tokyo Foundation for Policy Research Tokyo Japan Department of Mathematical and Computing Science Tokyo Institute of Technology Tokyo Japan Center for Environmental Biology and Ecosystem Studies National Institute for Environmental Studies (NIES) Tsukuba Japan Department of Sustainable Health Science Center for Preventive Medical Sciences Chiba University Chiba Japan HOXO-M Inc Tokyo Japan Department of Management Science Graduate School of Engineering Tokyo University of Science Tokyo Japan

As people move around using public transportation networks, such as train and airplanes, it is expected that emerging infectious diseases will spread on the network. The scan statistics approach has been frequently applied to identify high-risk locations, and the results are widely used for making a clinical decisions in a timely manner. However, they are not optimally designed for modeling the spread and might not effectively work under the emergency situation where computational time is essentially important. We propose a new scan statistics approach for the public transportation network, called PTNS (Public Transportation Network Scan). PTNS utilizes the available network structure to construct potential candidates of clusters, and thus it can work well especially in situations where public transportation is the main medium of the infection spread. Further, it is designed for rapid surveillance. Lastly, PTNS is generalized to detect space-time clusters by customizing the iteration for potential clusters creation. Using the simulation data generated with a real railway network, we showed that, PTNS outperformed the conventional methods, including Circular- and Flex-scan approaches in terms of the detection performance, while the computational time is feasible. © 2022 International Biometric Society–Chinese Region.

关键词： covid-19 public transportation rapid surveillance Scan statistics spatio-temporal analysis

Characterization of State-Preparation Uncertainty in Quantum Key Distribution

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Physical Review Applied 2023年第1期19卷 014048-014048页

作者： Anqi Huang Akihiro Mizutani Hoi-Kwong Lo Vadim Makarov Kiyoshi Tamaki Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha 410073 People’s Republic of China Graduate School of Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan Department of Electrical & Computer Engineering and Department of Physics Centre for Quantum Information and Quantum Control (CQIQC) University of Toronto Toronto Ontario M5S 3G4 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Quantum Bridge Technologies Inc. 100 College Street Toronto Ontario M5G 1L5 Canada Russian Quantum Center Skolkovo Moscow 121205 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 Shanghai 201315 People’s Republic of China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow 119049 Russia Faculty of Engineering University of Toyama Gofuku 3190 Toyama 930-8555 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 characterizing 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 100km 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 characterization methods pave the way for a future certification standard.

关键词： Fluctuations & noise Optical quantum information processing Quantum cryptography Quantum engineering Quantum state engineering

Quantum Microwave Parametric Interferometer

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Physical Review Applied 2023年第2期20卷 024049-024049页

作者： F. Kronowetter F. Fesquet M. Renger K. Honasoge Y. Nojiri K. Inomata Y. Nakamura A. Marx R. Gross K.G. Fedorov Walther-Meißner-Institut Bayerische Akademie der Wissenschaften Garching 85748 Germany School of Natural Sciences Technische Universität München Garching 85748 Germany Rohde & Schwarz GmbH & Co. KG Munich 81671 Germany RIKEN Center for Quantum Computing (RQC) Wako Saitama 351-0198 Japan National Institute of Advanced Industrial Science and Technology 1-1-1 Umezono Tsukuba Ibaraki 305-8563 Japan Department of Applied Physics Graduate School of Engineering The University of Tokyo Bunkyo-ku Tokyo 113-8656 Japan Munich Center for Quantum Science and Technology (MCQST) Munich 80799 Germany

Classical interferometers are indispensable tools for the precise determination of various physical quantities. Their accuracy is bound by the standard quantum limit. This limit can be overcome by using quantum states or nonlinear quantum elements. Here, we present the experimental study of a nonlinear Josephson interferometer operating in the microwave regime. Our quantum microwave parametric interferometer (QUMPI) is based on superconducting flux-driven Josephson parametric amplifiers combined with linear microwave elements. We perform a systematic analysis of the implemented QUMPI. We find that its interferometric power exceeds the shot-noise limit and observe sub-Poissonian photon statistics in the output modes. Furthermore, we identify a low-gain operation regime of the QUMPI that is essential for optimal quantum measurements in quantum illumination protocols.

关键词： Nonlinear optics Optoelectronics Quantum metrology Superconducting quantum optics Josephson junctions Optical parametric oscillators & amplifiers Microwave techniques Optical interferometry

Controlling chaotic itinerancy in laser dynamics for reinforcement learning

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arXiv 2022年

作者： Iwami, Ryugo Mihana, Takatomo Kanno, Kazutaka Sunada, Satoshi Naruse, Makoto Uchida, Atsushi Department of Information and Computer Sciences Saitama University 255 Shimo-okubo Sakura-ku Saitama Saitama338-8570 Japan Faculty of Mechanical Engineering Institute of Science and Engineering Kanazawa University Kakuma-machi Ishikawa Kanazawa920-1192 Japan PRESTO 4-1-8 Honcho Kawaguchi Saitama332-0012 Japan Department of Information Physics and Computing Graduate School of Information Science and Technology The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan

Photonic artificial intelligence has attracted considerable interest in accelerating machine learning;however, the unique optical properties have not been fully utilized for achieving higher-order functionalities. Chaotic itinerancy, with its spontaneous transient dynamics among multiple quasi-attractors, can be employed to realize brain-like functionalities. In this paper, we propose a method for controlling the chaotic itinerancy in a multi-mode semiconductor laser to solve a machine learning task, known as the multi-armed bandit problem, which is fundamental to reinforcement learning. The proposed method utilizes ultrafast chaotic itinerant motion in mode competition dynamics controlled via optical injection. We found that the exploration mechanism is completely different from a conventional searching algorithm and is highly scalable, outperforming the conventional approaches for large-scale bandit problems. This study paves the way to utilize chaotic itinerancy for effectively solving complex machine learning tasks as photonic hardware accelerators. Copyright © 2022, The Authors. All rights reserved.

关键词： Dynamics

Numerical method for finite-size security analysis of quantum key distribution

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arXiv 2021年

作者： Zhou, Hongyi Sasaki, Toshihiko Koashi, Masato Photon Science Center Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Institute of Computing Technology Chinese Academy of Sciences Beijing100190 China Department of Applied Physics Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan

Quantum key distribution (QKD) establishes secure links between remote communication parties. As a key problem for various QKD protocols, security analysis gives the amount of secure keys regardless of the eavesdropper’s computational power, which can be done both analytically and numerically. Compared to analytical methods which tend to require techniques specific to each QKD protocol, numerical ones are more general since they can be directly applied to many QKD protocols without additional techniques. However, current numerical methods are carried out based on some assumptions such as working in asymptotic limit and collective attacks from eavesdroppers. In this work, we remove these assumptions and develop a numerical finite-size security analysis against general attacks for general QKD protocols. We also give an example of applying the method to the recent Phase-Matching QKD protocol with a simple protocol design. Our result shows that the finite-size key rate can surpass the linear key-rate bound in a realistic communication time. Copyright © 2021, The Authors. All rights reserved.

关键词： Quantum cryptography

Self-supervised approach for facial movement based optical flow

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arXiv 2021年

作者： Alkaddour, Muhannad Tariq, Usman Dhall, Abhinav Graduate Program in Mechatronics Engineering American University of Sharjah Sharjah United Arab Emirates Department of Electrical Engineering American University of Sharjah Sharjah United Arab Emirates Department of Human Centred Computing Monash University Melbourne Australia Department of Computer Science and Engineering Indian Institute of Technology Ropar Rupnagar India

computing optical flow is a fundamental problem in computer vision. However, deep learning-based optical flow techniques do not perform well for non-rigid movements such as those found in faces, primarily due to lack of the training data representing the fine facial motion. We hypothesize that learning optical flow on face motion data will improve the quality of predicted flow on faces. The aim of this work is threefold: (1) exploring self-supervised techniques to generate optical flow ground truth for face images;(2) computing baseline results on the effects of using face data to train Convolutional Neural Networks (CNN) for predicting optical flow;and (3) using the learned optical flow in micro-expression recognition to demonstrate its effectiveness. We generate optical flow ground truth using facial key-points in the BP4D-Spontaneous dataset. The generated optical flow is used to train the FlowNetS architecture to test its performance on the generated dataset. The performance of FlowNetS trained on face images surpassed that of other optical flow CNN architectures, demonstrating its usefulness. Our optical flow features are further compared with other methods using the STSTNet micro-expression classifier, and the results indicate that the optical flow obtained using this work has promising applications in facial expression analysis. © 2021, CC BY.

关键词： Optical flows

Highly reflective silver mirror enhanced by several dielectric films prepared under the low substrate temperature

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Heliyon 2024年第15期10卷 e35507页

作者： Wu, Hsing-Yu Chen, Hong-Wei Huang, Shao-Rong Hsiao, Li-Jen Cheng, Ching-Ling Yu, Guo-Yu Sun, Yung-Shin Hsu, Jin-Cherng Taiwan Space Agency Taiwan National Central University Center for Astronomical Physics and Engineering Department of Optics and Photonics Taoyuan City 320317 Taiwan National Yang Ming Chiao Tung University Institute of Space Systems Engineering Hsinchu City 300025 Taiwan Fu Jen Catholic University Department of Physics New Taipei City 242062 Taiwan Diopter Precision Taiwan Co. Ltd. Taoyuan City 324 Taiwan National United University Department of Electrical Engineering Miao-Li 36063 Taiwan Department of Engineering and Technology School of Computing and Engineering University of Huddersfield Queensgate Huddersfield HD1 3DH United Kingdom Fu Jen Catholic University Graduate Institute of Applied Science and Engineering New Taipei City 242062 Taiwan

Optical paths in telescopes frequently incorporate silver mirrors for high sensitivity. Unfortunately, silver mirrors without protective coatings are susceptible to sulfurization and oxidation, compromising their quality. Even with protective layers, insufficient adhesion between the coating and the silver film can lead to peeling, exposing the silver to external environments and affecting its quality. This study aimed to identify dielectric materials with superior adhesion to silver, rendering them ideal choices for silver coating applications. By electron gun evaporation, different dielectric layers were deposited on the top and bottom of the silver film under a substrate temperature below 150 °C. These coatings were composed of materials with desired refractive indices, including aluminum oxide (Al₂O₃), aluminum-doped silicon, magnesium fluoride (MgF₂), and other dielectrics. Following the deposition, a tape adhesion test was conducted to evaluate the bond strength of the samples. X-ray photoelectron spectroscopy (XPS) analysis was carried out to investigate the interaction between silver and its neighboring layers. The results revealed that Al₂O₃ and MgF₂ exhibited exceptional adhesion to silver. Moreover, these multilayer coatings can effectively enhance the reflectance of silver in the visible (VIS) wavelength ranges. © 2024 The Authors

关键词： Enhanced silver coating Silver adhesion Silver mirror Space optics XPS