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arXiv 2023年

作者： Hakoshima, Hideaki Endo, Suguru Yamamoto, Kaoru Matsuzaki, Yuichiro Yoshioka, Nobuyuki Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Osaka Toyonaka560-8531 Japan Center for Quantum Information and Quantum Biology Osaka University 1-2 Machikaneyama Osaka Toyonaka560-0043 Japan NTT Computer and Data Science Laboratories NTT Corporation Musashino180-8585 Japan JST PRESTO 4-1-8 Honcho Saitama Kawaguchi332-0012 Japan Department of Electrical Electronic and Communication Engineering Faculty of Science and Engineering Chuo University Bunkyo-ku 1-13-27 Kasuga Tokyo112-8551 Japan Department of Applied Physics University of Tokyo Bunkyo-ku 7-3-1 Hongo Tokyo113-8656 Japan Saitama Wako-shi351-0198 Japan

Analog and digital quantum simulators can efficiently simulate quantum many-body systems that appear in natural phenomena. However, experimental limitations of near-term devices still make it challenging to perform the entire process of quantum simulation. The purification-based quantum simulation methods can alleviate the limitations in experiments such as the cooling temperature and noise from the environment, while this method has the drawback that it requires global entangled measurement with a prohibitively large number of measurements that scales exponentially with the system size. In this Letter, we propose that we can overcome these problems by restricting the entangled measurements to the vicinity of the local observables to be measured, when the locality of the system can be exploited. We provide theoretical guarantees that the global purification operation can be replaced with local operations under some conditions, in particular for the task of cooling and error mitigation. We furthermore give a numerical verification that the localized purification is valid even when conditions are not satisfied. Our method bridges the fundamental concept of locality with quantum simulators, and therefore expected to open a path to unexplored quantum many-body phenomena. Copyright © 2023, The Authors. All rights reserved.

关键词： Purification

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Streaming-Aware Cellular Resource Allocation for UHD Video Streaming over Ultra Dense Network

Streaming-Aware Cellular Resource Allocation for UHD Video S...

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IEEE Conference on Wireless Communications and Networking

作者： Xinjing Yuan Lingjun Pu Xiaohang Xu Yuwei Xu Jingdong Xu Institute of Systems and Networks College of Computer Science Nankai University Tianjin China Tianjin Key Laboratory of Network and Data Security Technology Tianjin China State Key Laboratory of Integrated Services Networks (Xidian University) Xi’an China Purple Mountain Laboratories for Network and Communication Security China

Ultra-High-Definition (UHD) videos have absorbed great attention in recent years. However, as they are of significant size, streaming them require an extremely high bandwidth to achieve a good quality of experience, which poses a great challenge on the current cellular networks. Realizing the great potentials of coordinated multi-point joint transmission (JT-CoMP) in 5G Ultra Dense Network, we propose a novel Tuner framework for the UHD video streaming service. In this framework, we strive to design an efficient algorithm for VBS sleeping and VBS grouping to maximize the data rates of overall video users while reducing the overhead of cellular networks. To this end, we provide a comprehensive framework model and formulate a single-timescale VBS sleeping & grouping problem. We design a novel master-slave based algorithm to solve the formulated mixed-integer programming problem optimally with low complexity. In addition, we extend it to facilitate the more practical setting, i.e., two-timescale VBS sleeping & grouping. Extensive simulations validate the superior performance of our framework in various system settings.

关键词： Cellular networks Tuners 5G mobile communication Streaming media Programming Master-slave Complexity theory

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ALTERNATING ENERGY MINIMIZATION METHODS FOR MULTI-TERM MATRIX EQUATIONS

arXiv

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arXiv 2020年

作者： Kookjin, L.E.E. Elman, Howard C. Powell, Catherine E. Lee, Dongeun Extreme Scale Data Science and Analytics Department Sandia National Laboratories Department of Computer Science University of Maryland College Park United States Department of Mathematics University of Manchester United Kingdom Department of Computer Science Texas A&M University-Commerce

We develop computational methods for approximating the solution of a linear multi-term matrix equation in low rank. We follow an alternating minimization framework, where the solution is represented as a product of two matrices, and approximations to each matrix are sought by solving certain minimization problems repeatedly. The solution methods we present are based on a rank-adaptive variant of alternating energy minimization methods that builds an approximation iteratively by successively computing a rank-one solution component at each step. We also develop efficient procedures to improve the accuracy of the low-rank approximate solutions computed using these successive rank-one update techniques. We explore the use of the methods with linear multi-term matrix equations that arise from stochastic Galerkin finite element discretizations of parameterized linear elliptic PDEs, and demonstrate their effectiveness with numerical studies. Copyright © 2020, The Authors. All rights reserved.

关键词： Stochastic systems

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Social interactions affect discovery processes

arXiv

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arXiv 2022年

作者： Di Bona, Gabriele Ubaldi, Enrico Iacopini, Iacopo Monechi, Bernardo Latora, Vito Loreto, Vittorio School of Mathematical Science Queen Mary University of London LondonE1 4NS United Kingdom SONY Computer Science Laboratories Paris 6 rue Amyot Paris75005 France MindEarth Biel/Bienne2502 Switzerland Department of Network and Data Science Central European University Vienna1100 Austria Dipartimento di Fisica ed Astronomia Università di Catania INFN CataniaI-95123 Italy Complexity Science Hub Josefst äadter Strasse 39 ViennaA 1080 Austria Sapienza Univ. of Rome Physics Dept. Piazzale Aldo Moro 2 Rome00185 Italy

MSC Codes 05C81 (Primary), 91D30 (Secondary)Our network of acquaintances determines how we get exposed to ideas, products, or cultural artworks (books, music, movies, etc.). Though this principle is part of our common sense, little is known about the specific pathways through which our peers influence our discovery processes and our experience of the new. Here, we fill this gap by investigating a data set containing the whole listening histories of a large, socially connected sample of users from the online music platform ***. We demonstrate that users exhibit highly heterogeneous discovery rates of new songs and artists and that their social neighborhood significantly influences their behavior. More explorative users tend to interact with peers more prone to explore new content. We capture this phenomenology in a modeling scheme where users are represented by random walkers exploring a graph of songs or artists and interacting with each other through their social links. Even starting from a uniform population of agents (no natural differences among the individuals), our model predicts the emergence of strong heterogeneous exploration patterns, with users clustered according to their musical tastes and propensity to explore. We contend our approach can pave the way to a quantitative approach to collective discovery processes. © 2022, CC BY-NC-SA.

关键词： Music

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Quantum Error Mitigation

arXiv

引用

arXiv 2022年

作者： Cai, Zhenyu Babbush, Ryan Benjamin, Simon C. Endo, Suguru Huggins, William J. Li, Ying McClean, Jarrod R. O’Brien, Thomas E. Department of Materials University of Oxford OxfordOX1 3PH United Kingdom Quantum Motion 9 Sterling Way LondonN7 9HJ United Kingdom Google Quantum AI VeniceCA90291 United States NTT Computer and Data Science Laboratories NTT Corporation Musashino180-8585 Japan Graduate School of China Academy of Engineering Physics Beijing100193 China

For quantum computers to successfully solve real-world problems, it is necessary to tackle the challenge of noise: the errors which occur in elementary physical components due to unwanted or imperfect interactions. The theory of quantum fault tolerance can provide an answer in the long term, but in the coming era of ‘NISQ’ machines we must seek to mitigate errors rather than completely remove them. This review surveys the diverse methods that have been proposed for quantum error mitigation, assesses their in-principle efficacy, and then describes the hardware demonstrations achieved to date. We identify the commonalities and limitations among the methods, noting how mitigation methods can be chosen according to the primary type of noise present, including algorithmic errors. Open problems in the field are identified and we discuss the prospects for realising mitigation-based devices that can deliver quantum advantage with an impact on science and business. Copyright © 2022, The Authors. All rights reserved.

关键词： Fault tolerance

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Preface

Mathematics and Visualization

引用

Mathematics and Visualization 2022年 vii-x页

作者： Childs, Hank Bennett, Janine C. Garth, Christoph Computer and Information Science University of Oregon EugeneOR United States Extreme-Scale Data Science and Analytics Sandia National Laboratories LivermoreCA United States Scientific Visualization Lab University of Kaiserslautern Kaiserslautern Germany

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Fundamental limits of quantum error mitigation

arXiv

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arXiv 2021年

作者： Takagi, Ryuji Endo, Suguru Minagawa, Shintaro Gu, Mile Nanyang Quantum Hub School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore NTT Computer and Data Science Laboratories NTT Corporation Musashino Tokyo180-8585 Japan Graduate School of Informatics Nagoya University Chikusa-ku Nagoya464-8601 Japan Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 117543 Singapore

The inevitable accumulation of errors in near-future quantum devices represents a key obstacle in delivering practical quantum advantages, motivating the development of various quantum error-mitigation methods. Here, we derive fundamental bounds concerning how error-mitigation algorithms can reduce the computation error as a function of their sampling overhead. Our bounds place universal performance limits on a general error-mitigation protocol class. We use them to show (1) that the sampling overhead that ensures a certain computational accuracy for mitigating local depolarizing noise in layered circuits scales exponentially with the circuit depth for general error-mitigation protocols and (2) the optimality of probabilistic error cancellation among a wide class of strategies in mitigating the local dephasing noise on an arbitrary number of qubits. Our results provide a means to identify when a given quantum error-mitigation strategy is optimal and when there is potential room for improvement. © 2021, CC BY.

关键词： Quantum noise

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Resource-efficient generalized quantum subspace expansion

引用

Physical Review Applied 2025年第5期23卷 054021-054021页

作者： Bo Yang Nobuyuki Yoshioka Hiroyuki Harada Shigeo Hakkaku Yuuki Tokunaga Hideaki Hakoshima Kaoru Yamamoto Suguru Endo LIP6 Sorbonne Université 4 Place Jussieu 75005 Paris France Graduate School of Information Science and Technology The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan International Center for Elementary Particle Physics The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Wako-shi Saitama 351-0198 Japan JST PRESTO 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan Department of Applied Physics and Physico-Informatics Keio University Hiyoshi 3-14-1 Kohoku Yokohama 223-8522 Japan NTT Computer and Data Science Laboratories NTT Corporation 3-9-11 Midori-cho Musashino-shi Tokyo 180-8585 Japan Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Toyonaka Osaka 560-8531 Japan Center for Quantum Information and Quantum Biology Osaka University 1-2 Machikaneyama Toyonaka Osaka 560-0043 Japan

Realizing practical quantum computing requires overcoming a number of computation errors and the limitation of device size, which have intensively been tackled by quantum error mitigation. As a unified approach of noise-agnostic quantum error mitigation, generalized quantum subspace expansion (GSE) has lately been proposed to be remarkably robust regarding stochastic and coherent errors, integrating quantum subspace expansion and virtual state purification. However, the requirement in GSE to perform entangled measurements between copies of the quantum states remains a significant drawback under the current situation of quantum devices with a restricted number of qubits and their connectivity. In this work, we propose “Dual-GSE,” a resource-efficient implementation of GSE to circumvent this overhead by constructing an ansatz of error-mitigated quantum states via dual-state purification without state copies. Remarkably, the proposed method can further simulate larger quantum systems beyond the size of available quantum hardware, achieved by a suitable ansatz construction inspired by the divide-and-conquer strategy that classically reintroduces the effect of entanglement. While classically forging the entanglement comes with additional cost, the total sampling overhead can be notably reduced by reuse of the same Pauli expectation values among divided-and-conquered subsystems. We comprehensively analyze the advantages and overhead of Dual-GSE and perform numerical simulations of the eight-qubit transverse-field Ising model under various setups. Our results demonstrate that Dual-GSE estimates the ground state energy with high accuracy under gate noise with low mitigation overhead and practical sampling cost.

关键词： Qubits

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Requirements for fault-tolerant quantum computation with cavity-QED-based atom-atom gates mediated by a photon with a finite pulse length

arXiv

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arXiv 2021年

作者： Asaoka, Rui Tokunaga, Yuuki Kanamoto, Rina Goto, Hayato Aoki, Takao Computer and Data Science Laboratories NTT Corporation Musashino180-8585 Japan Department of Physics Meiji University Kanagawa Kawasaki214-8571 Japan Corporate Research and Development Center Toshiba Corporation Kanagawa Kawasaki212-8582 Japan Department of Applied Physics Waseda University Shinjuku Tokyo169-8555 Japan

We analyze the requirements for fault-tolerant quantum computation with atom-atom gates based on cavity quantum electrodynamics (cQED) mediated by a photon with a finite pulse length. For short photon pulses, the distorted shape of the reflected pulses from the cQED system is a serious error source. In the previous study by Goto and Ichimura [Phys. Rev. A 82, 032311 (2010)], only the photon loss is minimized without considering the shape distortion to optimize the system parameters. Here we show an improved optimization method to minimize the infidelity due to the shape distortion and the photon losses in a well-balanced manner for the fault-tolerant scheme using probabilistic gates [Phys. Rev. A 80, 040303(R) (2009)]. Under this optimization, we discuss the FTQC requirement for short pulses. Finally, we show that reducing the cavity length is an effective way to reduce the errors of this type of gate in the case of short photon pulses. Copyright © 2021, The Authors. All rights reserved.

关键词： Atoms

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Selective Excitation of Superconducting Qubits with a Shared Control Line through Pulse Shaping

arXiv

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arXiv 2025年

作者： Matsuda, R. Ohira, R. Sumida, T. Shiomi, H. Machino, A. Morisaka, S. Koike, K. Miyoshi, T. Kurimoto, Y. Sugita, Y. Ito, Y. Suzuki, Y. Spring, P.A. Wang, S. Tamate, S. Tabuchi, Y. Nakamura, Y. Ogawa, K. Negoro, M. Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Toyonaka Osaka560-8531 Japan QuEL Inc. Daiwaunyu Building 3F 2-9-2 Owadamachi Hachioji Tokyo192-0045 Japan Center for Quantum Information and Quantum Biology Osaka University 1-2 Machikaneyama Toyonaka Osaka560-0043 Japan e-trees.Japan Inc. Daiwaunyu Building 2F 2-9-2 Owadamachi Hachioji Tokyo192-0045 Japan NTT Computer and Data Science Laboratories NTT Corporation Musashino180-8585 Japan RIKEN Center for Quantum Computing Saitama Wako351-0198 Japan Department of Applied Physics Graduate School of Engineering University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan

In conventional architectures of superconducting quantum computers, each qubit is connected to its own control line, leading to a commensurate increase in the number of microwave lines as the system scales. Frequency-multiplexed qubit-control addresses this problem by enabling multiple qubits to share a single microwave line. However, it can cause unwanted excitation of non-target qubits, especially when the detuning between qubits is smaller than the pulse bandwidth. Here, we propose a selective-excitation-pulse (SEP) technique that suppresses unwanted excitations by shaping a drive pulse to create null points at non-target qubit frequencies. In a proof-of-concept experiment with three fixed-frequency transmon qubits, we demonstrate that the SEP technique achieves single-qubit gate fidelities comparable to those obtained with conventional Gaussian pulses while effectively suppressing unwanted excitations in non-target qubits. These results highlight the SEP technique as a promising tool for enhancing frequency-multiplexed qubit-control. © 2025, CC0.

关键词： Qubits

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