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Asynchronous Activity Detection for Cell-Free Massive MIMO: From Centralized to Distributed Algorithms

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arXiv 2022年

作者： Li, Yang Lin, Qingfeng Liu, Ya-Feng Ai, Bo Wu, Yik-Chung Shenzhen Research Institute of Big Data Shenzhen518172 China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China The Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Peng Cheng Laboratory Shenzhen518055 China Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China

Device activity detection in the emerging cell-free massive multiple-input multiple-output (MIMO) systems has been recognized as a crucial task in machine-type communications, in which multiple access points (APs) jointly identify the active devices from a large number of potential devices based on the received signals. Most of the existing works addressing this problem rely on the impractical assumption that different active devices transmit signals synchronously. However, in practice, synchronization cannot be guaranteed due to the low-cost oscillators, which brings additional discontinuous and nonconvex constraints to the detection problem. To address this challenge, this paper reveals an equivalent reformulation to the asynchronous activity detection problem, which facilitates the development of a centralized algorithm and a distributed algorithm that satisfy the highly nonconvex constraints in a gentle fashion as the iteration number increases, so that the sequence generated by the proposed algorithms can get around bad stationary points. To reduce the capacity requirements of the fronthauls, we further design a communication-efficient accelerated distributed algorithm. Simulation results demonstrate that the proposed centralized and distributed algorithms outperform state-of-the-art approaches, and the proposed accelerated distributed algorithm achieves a close detection performance to that of the centralized algorithm but with a much smaller number of bits to be transmitted on the fronthaul links. Copyright © 2022, The Authors. All rights reserved.

关键词： Internet of things

Benchmarking Noisy Intermediate Scale Quantum Error Mitigation Strategies for Ground State Preparation of the HCl Molecule

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arXiv 2023年

作者： Weaving, Tim Ralli, Alexis Kirby, William M. Love, Peter J. Succi, Sauro Coveney, Peter V. Centre for Computational Science Department of Chemistry University College London WC1H 0AJ United Kingdom Department of Physics and Astronomy Tufts University MedfordMA02155 United States Computational Science Initiative Brookhaven National Laboratory UptonNY11973 United States Center for Life Nano-Neuro Science @ La Sapienza Italian Institute of Technology Roma00161 Italy Department of Mechanical Engineering University College London WC1E 7JE United Kingdom Department of Physics Harvard University CambridgeMA02138 United States Advanced Research Computing Centre University College London WC1H 0AJ United Kingdom Informatics Institute University of Amsterdam Amsterdam1098 XH Netherlands

Due to numerous limitations including restrictive qubit topologies, short coherence times and prohibitively high noise floors, few quantum chemistry experiments performed on existing noisy intermediate-scale quantum hardware have achieved the high bar of chemical precision, namely energy errors to within 1.6 mHa of full configuration interaction. To have any hope of doing so, we must layer contemporary resource reduction techniques with best-in-class error mitigation methods;in particular, we combine the techniques of qubit tapering and the contextual subspace variational quantum eigensolver with several error mitigation strategies comprised of measurement-error mitigation, symmetry verification, zero-noise extrapolation and dual-state purification. We benchmark these strategies across a suite of eight 27-qubit IBM Falcon series quantum processors, taking preparation of the HCl molecule’s ground state as our testbed. Copyright © 2023, The Authors. All rights reserved.

关键词： Ground state

Machine-learned interatomic potentials by active learning:amorphous and liquid hafnium dioxide

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npj computational Materials 2020年第1期6卷 803-810页

作者： Ganesh Sivaraman Anand Narayanan Krishnamoorthy Matthias Baur Christian Holm Marius Stan Gábor Csányi Chris Benmore Álvaro Vázquez-Mayagoitia Leadership Computing Facility Argonne National LaboratoryArgonneIL 60439USA Institute for Computational Physics Universität StuttgartAllmandring 3Stuttgart 70569Germany Helmholtz-Institute Münster:Ionics in Energy Storage(IEK-12) Forschungszentrum Jülich GmbHCorrensstrasse 46Münster 48149Germany Applied Materials Division Argonne National LaboratoryArgonneIL 60439USA Department of Engineering University of CambridgeTrumpington StreetCambridge CB21PZUK X-ray Science Division Argonne National LaboratoryArgonneIL 60439USA Computational Science Division Argonne National LaboratoryArgonneIL 60439USA

We propose an active learning scheme for automatically sampling a minimum number of uncorrelated configurations for fitting the Gaussian Approximation Potential(GAP).Our active learning scheme consists of an unsupervised machine learning(ML)scheme coupled with a Bayesian optimization technique that evaluates the GAP *** apply this scheme to a Hafnium dioxide(HfO2)dataset generated from a“melt-quench”ab initio molecular dynamics(AIMD)*** results show that the active learning scheme,with no prior knowledge of the dataset,is able to extract a configuration that reaches the required energy fit ***,molecular dynamics(MD)simulations performed using this active learned GAP model on 6144 atom systems of amorphous and liquid state elucidate the structural properties of HfO2 with near ab initio precision and quench rates(i.e.,1.0 K/ps)not accessible via *** melt and amorphous X-ray structural factors generated from our simulation are in good agreement with *** addition,the calculated diffusion constants are in good agreement with previous ab initio studies.

关键词： amorphous dioxide scheme

Deep Variational Quantum Eigensolver: A Divide-And-Conquer Method for Solving a Larger Problem with Smaller Size Quantum Computers

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PRX Quantum 2022年第1期3卷 010346-010346页

作者： Keisuke Fujii Kaoru Mizuta Hiroshi Ueda Kosuke Mitarai Wataru Mizukami Yuya O. Nakagawa Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Toyonaka Osaka 560-8531 Japan Center for Quantum Information and Quantum Biology Institute for Open and Transdisciplinary Research Initiatives Osaka University Japan RIKEN Center for Quantum Computing (RQC) Wako Saitama 351-0198 Japan Department of Physics Kyoto University Kyoto 606-8502 Japan Computational Materials Science Research Team RIKEN Center for Computational Science (R-CCS) Kobe 650-0047 Japan JST PRESTO 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan QunaSys Inc. Aqua Hakusan Building 9F 1-13-7 Hakusan Bunkyo Tokyo 113-0001 Japan

We propose a divide-and-conquer method for the quantum-classical hybrid algorithm to solve larger problems with small-scale quantum computers. Specifically, we concatenate a variational quantum eigensolver (VQE) with a reduction in the system dimension, where the interactions between divided subsystems are taken as an effective Hamiltonian expanded by the reduced basis. Then the effective Hamiltonian is further solved by the VQE, which we call deep VQE. Deep VQE allows us to apply quantum-classical hybrid algorithms on small-scale quantum computers to large systems with strong intrasubsystem interactions and weak intersubsystem interactions, or strongly correlated spin models on large regular lattices. As proof-of-principle numerical demonstrations, we use the proposed method for quasi-one-dimensional models, including one-dimensionally coupled 12-qubit Heisenberg antiferromagnetic models on kagome lattices as well as two-dimensional Heisenberg antiferromagnetic models on square lattices. The largest problem size of 64 qubits is solved by simulating 20-qubit quantum computers with a reasonably good accuracy approximately a few %. The proposed scheme enables us to handle the problems of >1000 qubits by concatenating VQEs with a few tens of qubits. While it is unclear how accurate ground-state energy can be obtained for such a large system, our numerical results on a 64-qubit system suggest that deep VQE provides a good approximation (discrepancy within a few percent) and has room for further improvement. Therefore, deep VQE provides us a promising pathway to solve practically important problems on noisy intermediate-scale quantum computers.

关键词： Quantum algorithms Quantum computation Quantum simulation

Contextual Subspace Variational Quantum Eigensolver Calculation of the Dissociation Curve of Molecular Nitrogen on a Superconducting Quantum Computer

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arXiv 2023年

作者： Weaving, Tim Ralli, Alexis Love, Peter J. Succi, Sauro Coveney, Peter V. Centre for Computational Science Department of Chemistry University College London WC1H 0AJ United Kingdom Department of Physics and Astronomy Tufts University MedfordMA02155 United States Computational Science Initiative Brookhaven National Laboratory UptonNY11973 United States Center for Life Nano-Neuro Science @ La Sapienza Italian Institute of Technology Roma00161 Italy Department of Mechanical Engineering University College London WC1E 7JE United Kingdom Department of Physics Harvard University CambridgeMA02138 United States Advanced Research Computing Centre University College London WC1H 0AJ United Kingdom Informatics Institute University of Amsterdam Amsterdam1098 XH Netherlands

In this work we present an experimental demonstration of the Contextual Subspace Variational Quantum Eigensolver on superconducting quantum hardware. In particular, we compute the potential energy curve for molecular nitrogen, where a dominance of static correlation in the dissociation limit proves challenging for many conventional quantum chemistry techniques. Our quantum simulations retain good agreement with the full configuration interaction energy in the chosen STO-3G basis, outperforming all benchmarked single-reference wavefunction techniques in capturing the bond-breaking appropriately. Moreover, our methodology is competitive with several multiconfigurational approaches, but at a considerable saving of quantum resource, meaning larger active spaces can be treated for a fixed qubit allowance. To achieve this result we deploy an error mitigation/suppression strategy comprised of dynamical decoupling, measurement-error mitigation and zero-noise extrapolation, in addition to circuit parallelization that not only provides passive averaging of noise but improves the effective shot-yield to reduce the measurement overhead. Furthermore, we introduce a modification to previous adaptive ansatz construction algorithms that incorporates hardware-awareness into our variational circuits to minimize the transpilation cost for the target qubit topology. Copyright © 2023, The Authors. All rights reserved.

关键词： Qubits

THE LANDSCAPE OF SOFTWARE FOR TENSOR COMPUTATIONS

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arXiv 2021年

作者： Psarras, Christos Karlsson, Lars Li, Jiajia Bientinesi, Paolo Aachen Institute for Advanced Study in Computational Engineering Science RWTH AachenUniversity Aachen Germany Pacific Northwest National Laboratory Richland United States Washington and College of William & Mary WilliamsburgVA United States Department of Computing Science Umeå Universitet Umeå Sweden

Tensors (also commonly seen as multi-linear operators or as multi-dimensional arrays) are ubiquitous in scientific computing and in data science, and so are the software efforts for tensor operations. Particularly in recent years, we have observed an explosion in libraries, compilers, packages, and toolboxes;unfortunately these efforts are very much scattered among the different scientific domains, and inevitably suffer from replication, suboptimal implementations, and in many cases, limited visibility. As a first step towards countering these inefficiencies, here we survey and loosely classify software packages related to tensor computations. Our aim is to assemble a comprehensive and up-to-date snapshot of the tensor software landscape, with the intention of helping both users and developers. Aware of the difficulties inherent in any multi-discipline survey, we very much welcome the reader's help in amending and expanding our software list, which currently features 80 projects. Copyright © 2021, The Authors. All rights reserved.

关键词： Tensors

Retraction Note: Optical bio sensor based cancer cell detection using optimized machine learning model with quantum computing

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Optical and Quantum Electronics 2024年第12期56卷 1-1页

作者： Balamurugan, G. Annadurai, C. Nelson, I. Devi, K. Nirmala Oliver, A. Sheryl Gomathi, S. Department of Computing Technologies SRM Institute of Science and Technology Kattankulathur India Department of ECE Sri Sivasubramaniya Nadar College of Engineering Kalavakkam Chennai India Department of Electrical and Electronics Saveetha School of Engineering SIMATS Chennai India Department of CSE Kongu Engineering College Perundurai Erode India Department of Computational Intelligence SRM Institute of Science and Technology Kattankulathur India

Overview of couplet scoring in content-focused physics assessments

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arXiv 2023年

作者： Vignal, Michael Geschwind, Gayle Caballero, Marcos D. Lewandowski, H.J. JILA National Institute of Standards and Technology the University of Colorado BoulderCO80309 United States Department of Physics University of Colorado 390 UCB BoulderCO80309 United States Department of Physics Willamette University 900 State Street SalemOR97301 United States Department of Physics & Astronomy CREATE for STEM Institute Michigan State University East LansingMI48824 United States Department of Computational Mathematics Science & Engineering Michigan State University East LansingMI48824 United States Department of Physics Center for Computing in Science Education University of Oslo Oslo0315 Norway

Content-focused research-based assessment instruments typically use items (i.e., questions) as the unit of assessment for scoring, reporting, and validation. Couplet scoring employs an alternative unit of assessment called a couplet, which is essentially an item viewed and scored through the lens of a specific assessment objective. With couplet scoring, a single item may have more than one assessment objective and therefore more than one couplet and thus more than one score. We outline the components of traditional item scoring, discuss couplet scoring and its benefits, and use both a recently developed content research-based assessment instrument and an existing one to ground our discussion. © 2023, CC BY.

关键词： Uncertainty analysis

Cramér-rao bound optimization for joint radar-communication design

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arXiv 2021年

作者： Liu, Fan Liu, Ya-Feng Li, Ang Masouros, Christos Eldar, Yonina C. The Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen518055 China The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematicsand Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China The School of Information and Communications Engineering Faculty of Electronic and Information Engineering Xi’an Jiaotong University Xi’anShaanxi710049 China The Department of Electronic and Electrical Engineering University College London LondonWC1E 7JE United Kingdom The Faculty of Mathematics and Computer Science Weizmann Institute of Science Rehovot Israel

In this paper, we propose multi-input multi-output (MIMO) beamforming designs towards joint radar sensing and multi-user communications. We employ the Cramér-Rao bound (CRB) as a performance metric of target estimation, under both point and extended target scenarios. We then propose minimizing the CRB of radar sensing while guaranteeing a pre-defined level of signal-to-interference-plus-noise ratio (SINR) for each communication user. For the single-user scenario, we derive a closed form for the optimal solution for both cases of point and extended targets. For the multi-user scenario, we show that both problems can be relaxed into semidefinite programming by using the semidefinite relaxation approach, and prove that the global optimum can always be obtained. Finally, we demonstrate numerically that the globally optimal solutions are reachable via the proposed methods, which provide significant gains in target estimation performance over state-of-the-art benchmarks. Copyright © 2021, The Authors. All rights reserved.

关键词： Signal to noise ratio