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Photon scattering errors during stimulated Raman transitions in trapped-ion qubits

Physical Review A 2023年第3期107卷 032413-032413页

作者： I. D. Moore W. C. Campbell E. R. Hudson M. J. Boguslawski D. J. Wineland D. T. C. Allcock Department of Physics University of Oregon Eugene Oregon 97403 USA Department of Physics and Astronomy University of California Los Angeles Los Angeles California 90095 USA Center for Quantum Science and Engineering University of California Los Angeles Los Angeles California 90095 USA Challenge Institute for Quantum Computation University of California Los Angeles Los Angeles California 90095 USA

We study photon scattering errors in stimulated Raman driven quantum logic gates. For certain parameter regimes, we find that previous simplified models of the process significantly overestimate the gate error rate due to photon scattering. This overestimate is shown to be due to previous models neglecting the detuning dependence of the scattered photon frequency and Lamb-Dicke parameter, a second scattering process, interference effects on scattering rates to metastable manifolds, and the counterrotating contribution to the Raman transition rate. The resulting improved model shows that there is no fundamental limit on gate error due to photon scattering for electronic ground-state qubits in commonly used trapped-ion species when the Raman laser beams are red detuned from the main optical transition. Additionally, photon scattering errors are studied for qubits encoded in the metastable D5/2 manifold, showing that gate errors below 10−4 are achievable for all commonly used trapped ions.

关键词： Rayleigh scattering Scattering theory Spontaneous emission Ions Raman lasers

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Raman Scattering Errors in Stimulated-Raman-Induced Logic Gates in Ba+133

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Physical Review Letters 2023年第6期131卷 063001-063001页

作者： Matthew J. Boguslawski Zachary J. Wall Samuel R. Vizvary Isam Daniel Moore Michael Bareian David T. C. Allcock David J. Wineland Eric R. Hudson Wesley C. Campbell Department of Physics and Astronomy University of California Los Angeles Los Angeles 90095 California USA Challenge Institute for Quantum Computation University of California Los Angeles Los Angeles 90095 California USA Department of Physics University of Oregon Eugene 97403 Oregon USA Center for Quantum Science and Engineering University of California Los Angeles Los Angeles 90095 California USA

Ba+133 is illuminated by a laser that is far detuned from optical transitions, and the resulting spontaneous Raman scattering rate is measured. The observed scattering rate is lower than previous theoretical estimates. The majority of the discrepancy is explained by a more accurate treatment of the scattered photon density of states. This work establishes that, contrary to previous models, there is no fundamental atomic physics limit to laser-driven quantum gates from laser-induced spontaneous Raman scattering.

关键词： Quantum gates Quantum information with trapped ions Spontaneous emission Trapped ions

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HOW SOCIAL INFLUENCE AFFECTS THE WISDOM OF CROWDS IN INFLUENCE NETWORKS

arXiv

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arXiv 2022年

作者： Tian, Ye Wang, Long Bullo, Francesco Center for Systems and Control College of Engineering Peking University Beijing100871 China Mechanical Engineering Department The Center of Control Dynamical Systems and Computation University of California at Santa Barbara Santa BarbaraCA93106 United States

A long-standing debate is whether social influence improves the collective wisdom of a crowd or undermines it. This paper addresses the question based on a naïve learning setting in influence systems theory: in our models individuals evolve their estimates of an unknown truth according to the weighted-average opinion dynamics. A formal mathematization is provided with rigorous theoretical analysis. We obtain various conditions for improving, optimizing and undermining the crowd accuracy, respectively. We prove that if the wisdom of a finite-size group is improved, then the collective estimate converges to the truth as the group size increases. We show that whether social influence improves or undermines the wisdom is determined by the social power allocations in the influence system: if the influence system allocates relatively larger social power to relatively more accurate individuals, it improves the wisdom;on the contrary, if the influence system assigns less social power to more accurate individuals, it undermines the wisdom. At a population level, individuals' susceptibilities to interpersonal influence and network centralities are both crucial. To improve the wisdom, more accurate individuals should be less susceptible and have larger network centralities. Particularly, in democratic influence networks, if relatively more accurate individuals are relatively less susceptible, the wisdom is improved;if more accurate individuals are more susceptible, the wisdom is undermined, which is consistent with the reported empirical evidence. Our investigation provides a theoretical framework for understanding the role social influence plays in the emergence of collective wisdom. Copyright © 2022, The Authors. All rights reserved.

关键词： Economic and social effects

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Electroencephalogram and Event-Related Potential in Mild Cognitive Impairment: Recent Developments in Signal Processing, Machine Learning, and Deep Learning

IEEE Journal of Selected Areas in Sensors

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IEEE Journal of Selected Areas in Sensors 2025年 2卷 162-184页

作者： Azami, Hamed Mirjalili, Mina Rajji, Tarek K. Wu, Chien-Te Humeau-Heurtier, Anne Jung, Tzyy-Ping Wei, Chun-Shu Trinh, Thanh-Tung Liu, Yi-Hung University of Toronto Centre for Addiction and Mental Health TorontoONM5S 1A1 Canada University of Texas Southwestern Medical Center DallasTX75390 United States University of Florida Department of Occupational Therapy GainesvilleFL32611 United States University of Florida Center for Cognitive Aging and Memory McKnight Brain Institute GainesvilleFL32611 United States University of Angers LARIS SFR MATHSTIC AngersF-49000 France University of California Institute for Neural Computation Institute of Engineering in Medicine La Jolla CA92093 United States National Yang Ming Chiao Tung University Department of Computer Science Hsinchu City30010 Taiwan National Taipei University of Technology Graduate Institute of Manufacturing Technology College of Mechanical and Electrical Engineering Taipei10608 Taiwan Vietnam National University Department of Information and Communication Technology Faculty of Nontraditional Security HSB Hanoi720325 Viet Nam National Yang Ming Chiao Tung University Institute of Electrical and Control Engineering Hsinchu City30010 Taiwan

Mild cognitive impairment (MCI) is an early stage of non-age-related cognitive decline with an increased risk of progressing to dementia. Early detection of MCI is essential for implementing preventative strategies that can delay or prevent the onset of dementia, ultimately improving patient outcomes and reducing healthcare costs. Electroencephalograms (EEGs) and event-related potentials (ERPs) have shown significant promise in detecting MCI due to their affordability, real-time monitoring capabilities, and noninvasiveness. EEG provides continuous brain activity data, while ERPs offer insights into specific cognitive processes by analyzing brain responses to stimuli. These methods can complement each other in MCI diagnosis by providing a comprehensive view of overall brain function and detailed information on specific cognitive processes. However, EEG and ERP are susceptible to noise and interindividual variability, which can hinder their reliability. In addition, applying machine learning models on EEG or ERP for MCI detection presents challenges such as the risk of overfitting and difficulties in interpreting the underlying decision-making process. This review emphasizes recent advancements in signal processing and feature extraction methods applied to EEG and ERP data and explores the use of machine learning and deep learning techniques to enhance diagnostic accuracy and interpretative depth. By integrating these methodologies, the review highlights how EEG and ERP can contribute to a more effective understanding and monitoring of cognitive changes associated with MCI, underscoring the importance of early diagnosis for timely intervention and improved patient care. Finally, the review focuses on future research directions, including the development of advanced analytical techniques and multimodal integration approaches involving EEG and ERP to further improve diagnostic accuracy and clinical application. © 2024 IEEE.

关键词： Deep learning

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Moire-pattern-modulated electronic structures in Sb_(2)Te_(3)/graphene heterostructure

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Nano Research 2022年第2期15卷 1115-1119页

作者： Yin Yin Guanyong Wang Chen Liu Haili Huang Jiayi Chen Jiaying Liu Dandan Guan Shiyong Wang Yaoyii Li Canhua Liu Hao Zheng Jinfeng Jia Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) Shenyang National Laboratory for Materials ScienceSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Tsung-Dao Lee Institute Shanghai 200240China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

Moire superlattice has recently been found in topological insulators,which can lead to periodic modulation on the electronic *** this work,we report the low-temperature scanning tunneling microscopy study of Sb_(2)Te_(3) films grown on graphitized *** find that substrate temperature can strongly influence the rotation angles between Sb_(2)Te_(3) film and graphene *** kinds of moire patterns are observed at the first quintuple layer Sb_(2)Te_(3) film under different substrate *** shows complicated patterns with a rotation angle of nearly 0°relative to the substrate,another just exhibits simple 1 ×1 structure with a rotation angle of 30°.Other rotation angle like 8.2°is observed at higher substrate temperature as well,which is relatively *** of the d//dV curves from Sb_(2)Te_(3) films with different moire patterns indicates that the superstructure can offer degrees of freedom in tailoring electronic *** work may stimulate the further study on the moire modulation to the electronic properties of topological insulators.

关键词： moire pattern topological insulator electronic structure scanning tunneling microscopy

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Quantum Error Correction with Metastable States of Trapped Ions Using Erasure Conversion

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PRX Quantum 2023年第2期4卷 020358-020358页

作者： Mingyu Kang Wesley C. Campbell Kenneth R. Brown Duke Quantum Center Duke University Durham North Carolina 27701 USA Department of Physics Duke University Durham North Carolina 27708 USA Department of Physics and Astronomy University of California Los Angeles California 90095 USA Challenge Institute for Quantum Computation University of California Los Angeles California 90095 USA Center for Quantum Science and Engineering University of California Los Angeles California 90095 USA Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA Department of Chemistry Duke University Durham North Carolina 27708 USA

Erasures, or errors with known locations, are a more favorable type of error for quantum error-correcting codes than Pauli errors. Converting physical noise into erasures can significantly improve the performance of quantum error correction. Here, we apply the idea of performing erasure conversion by encoding qubits into metastable atomic states, proposed by Wu, Kolkowitz, Puri, and Thompson [Nat. Comm. 13, 4657 (2022)], to trapped ions. We suggest an erasure-conversion scheme for metastable trapped-ion qubits and develop a detailed model of various types of errors. We then compare the logical performance of ground and metastable qubits on the surface code under various physical constraints and conclude that metastable qubits may outperform ground qubits when the achievable laser power is higher for metastable qubits.

关键词： Quantum error correction Quantum information with trapped ions Surface code quantum computing Trapped ions

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Explicit block encodings of boundary value problems for many-body elliptic operators

arXiv

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arXiv 2024年

作者： Kharazi, Tyler Alkadri, Ahmad M. Liu, Jin-Peng Mandadapu, Kranthi K. Whaley, K. Birgitta Department of Chemistry University of California Berkeley United States Berkeley Quantum Information and Computation Center University of California Berkeley United States Department of Chemical and Biochemical Engineering University of California Berkeley United States Yau Mathematical Sciences Center Tsinghua University China Center for Theoretical Physics Massachusetts Institute of Technology United States Simons Institute Department of Mathematics University of California Berkeley United States

Simulation of physical systems is one of the most promising use cases of future digital quantum computers. In this work we systematically analyze the quantum circuit complexities of block encoding the discretized elliptic operators that arise extensively in numerical simulations for partial differential equations, including high-dimensional instances for many-body simulations. When restricted to rectangular domains with separable boundary conditions, we provide explicit circuits to block encode the many-body Laplacian with separable periodic, Dirichlet, Neumann, and Robin boundary conditions, using standard discretization techniques from low-order finite difference methods. To obtain high-precision, we introduce a scheme based on periodic extensions to solve Dirichlet and Neumann boundary value problems using a high-order finite difference method, with only a constant increase in total circuit depth and subnormalization factor. We then present a scheme to implement block encodings of differential operators acting on more arbitrary domains, inspired by Cartesian immersed boundary methods. We then block encode the many-body convective operator, which describes interacting particles experiencing a force generated by a pair-wise potential given as an inverse power law of the interparticle distance. This work provides concrete recipes that are readily translated into quantum circuits, with depth logarithmic in the total Hilbert space dimension, that block encode operators arising broadly in applications involving the quantum simulation of quantum and classical many-body mechanics. © 2024, CC BY-SA.

关键词： Quantum computers

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Comparative Analysis of GOA, WCA and PSO Tuned Fractional Order-PID controller for Cart-Inverted Pendulum

Comparative Analysis of GOA, WCA and PSO Tuned Fractional Or...

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Power and Renewable Energy Conference (IPRECON), IEEE International

作者： Neelam Verma Sudarshan K. Valluru Department of Electrical Engineering Center for Control of Dynamical Systems and Computation Delhi Technological University Delhi India

control of cart based inverted pendulum system is a classical problem of control system and is widely used to verify the effectiveness of control algorithms. In this paper, fractional order PID (FOPID) controller has been used to control the cart position and pendulum angle. Three optimization algorithms namely, particle swarm optimization (PSO), water cycle algorithm (WCA) and grasshopper optimization algorithm (GOA) has been used to tune the parameters of the FOPID controller for underline problem. Results shows that, FOPID controller was able to control both cart position and pendulum angle effectively. Further, it has also been shown that GOA tuned FOPID controller performs better as compared to WCA and PSO tuned FOPID controller. The entire system was simulated using MATLAB2018a.

关键词： Renewable energy sources Software packages control systems Particle swarm optimization Optimization Matlab

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Photon scattering rates in trapped ion qubits

Photon scattering rates in trapped ion qubits

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Quantum 2.0, QUANTUM 2022

作者： Quinn, A.D. Moore, I.D. Campbell, W.C. Hudson, E.R. Brudney, S.J. Lesak, A.A. Metzner, J.M. Wineland, D.J. Allcock, D.T.C. Department of Physics University of Oregon EugeneOR United States Department of Physics and Astronomy University of California Los Angeles Los AngelesCA United States Center for Quantum Science and Engineering University of California Los Angeles Los AngelesCA United States Challenge Institute for Quantum Computation University of California Los Angeles Los AngelesCA United States

We describe a new model for two-photon stimulated Raman transitions and our efforts to test this model in40Ca+ ions. Compared to previous models, our model predicts lower scattering at certain Raman beam detunings. &#... 详细信息

ISBN: (纸本)9781957171111

关键词： Trapped ions

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PDMATLAB2D: A Peridynamics MATLAB Two-dimensional Code

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Journal of Peridynamics and Nonlocal Modeling 2024年第1期6卷 149-205页

作者： Seleson, Pablo Pasetto, Marco John, Yohan Trageser, Jeremy Reeve, Samuel Temple Computer Science and Mathematics Division Oak Ridge National Laboratory P.O. Box 2008 MS-6013 Oak Ridge 37831-6013 TN United States Department of Mechanical and Aerospace Engineering University of California San Diego 9500 Gilman Drive La Jolla 92093 CA United States George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 801 Ferst Dr Atlanta 30332 GA United States Center for Control Dynamical Systems and Computation University of California at Santa Barbara Harold Frank Hall Room 5119 Santa Barbara 93106 CA United States Engineering Sciences Center Sandia National Laboratories P.O. Box 5800 MS-1322 Albuquerque 87185-1322 NM United States Computational Sciences and Engineering Division Oak Ridge National Laboratory P.O. Box 2008 MS-6085 Oak Ridge 37831-6085 TN United States

PDMATLAB2D is a meshfree peridynamics implementation in MATLAB suitable for simulation of two-dimensional fracture problems. The purpose of this code is twofold. First, it provides an entry-level peridynamics computational tool for educational and training purposes. Second, it serves as an accessible and easily modifiable computational tool for peridynamics researchers who would like to adapt the code for a multitude of peridynamics simulation scenarios. The current version of the code implements a bond-based brittle elastic peridynamic model and a critical stretch criterion for bond breaking. However, the code is designed to be extendable for other peridynamic models and computational features. In this paper, we provide an overview of the code structure and functions with illustrative examples. Due to the integrated computation and postprocessing MATLAB capabilities, PDMATLAB2D can serve as an effective testbed for testing new constitutive models and advanced numerical features for peridynamics computations. © UT-Battelle, LLC, under exclusive licence to Springer Nature Switzerland AG 2024. corrected publication 2024.

关键词： Fracture Meshfree Peridynamics Two-dimensional

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