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Experimental demonstration of topological bounds in quantum metrology

National Science Review 2024年第10期11卷 254-262页

作者： Min Yu Xiangbei Li Yaoming Chu Bruno Mera F.Nur ünal Pengcheng Yang Yu Liu Nathan Goldman Jianming Cai School of Physics Hubei Key Laboratory of Gravitation and Quantum Physics Institute for Quantum Science and Engineering Huazhong University of Science and Technology International Joint Laboratory on Quantum Sensing and Quantum Metrology Huazhong University of Science and Technology Advanced Institute for Materials Research (WPI-AIMR) Tohoku University TCM Group Cavendish Laboratory University of Cambridge Institut für Theoretische Physik and IQST Universit?t Ulm Center for Nonlinear Phenomena and Complex Systems Université Libre de Bruxelles Laboratoire Kastler Brossel Collège de France Shanghai Key Laboratory of Magnetic Resonance East China Normal University

Quantum metrology is deeply connected to quantum geometry, through the fundamental notion of quantum Fisher information. Inspired by advances in topological matter, it was recently suggested that the Berry curvature and Chern numbers of band structures can dictate strict lower bounds on metrological properties, hence establishing a strong connection between topology and quantum metrology. In this work,we provide a first experimental verification of such topological bounds, by performing optimal quantum multi-parameter estimation and achieving the best possible measurement precision. By emulating the band structure of a Chern insulator, we experimentally determine the metrological potential across a topological phase transition, and demonstrate strong enhancement in the topologically non-trivial regime. Our work opens the door to metrological applications empowered by topology, with potential implications for quantum many-body systems.

关键词： quantum metrology multi-parameter estimation topological bounds Berry curvature Chern number topological phase transition

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Two-parameter estimation with three-mode NOON state in a symmetric triple-well potential

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Communications in Theoretical Physics 2022年第4期74卷 52-60页

作者： Fei Yao Yi-Mu Du Haijun Xing Libin Fu Graduate School of China Academy of Engineering Physics Beijing 100193China

We propose a scheme to realize two-parameter estimation via Bose–Einstein condensates confined in a symmetric triple-well *** three-mode NOON state is prepared adiabatically as the initial *** two parameters to be estimated are the phase differences between the *** sensitivity of this estimation scheme is studied by comparing quantum and classical Fisher information *** a result,we find an optimal particle number measurement ***,the precision of this estimation scheme means that the Heisenberg scaling behaves under the optimal measurement.

关键词： multi-parameter estimation Heisenberg scaling precision three-mode NOON state symmetric triple-well potential

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Demagnetization Fault Diagnosis for PMSM Drive System with Dual Extended Kalman Filter

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WORLD ELECTRIC VEHICLE JOURNAL 2025年第2期16卷 112-112页

作者： Wang, Jiahan Li, Chen Zhou, Zhanqing Tiangong Univ Tianjin Key Lab Intelligent Control Elect Equipmen Tianjin 300387 Peoples R China Zhejiang Univ Zhejiang Univ Adv Elect Equipment Innovat Ctr Hangzhou 311107 Peoples R China

Aiming at the irreversible demagnetization of permanent magnet synchronous motors (PMSMs) under extreme working conditions, a fault diagnosis method for permanent magnet demagnetization based on multi-parameter estimation is proposed in this paper. This scheme aims to provide technical support for enhancing the safety and reliability of permanent magnet motor drive systems. In the proposed scheme, multiple operating states of the motor are acquired by injecting sinusoidal current signals into the d-axis, ensuring that the parameter estimation equation satisfies the full rank condition. Furthermore, the accurate dq-axis inductance parameters are obtained based on a recursive least square method. Subsequently, a dual extended Kalman filter is employed to acquire real-time permanent magnet flux linkage data of PMSMs, and the estimation data between the two algorithms are transferred to each other to eliminate the bias of permanent magnet flux estimation caused by a parameter mismatch. Finally, accurate evaluation of the remanence level of the rotor permanent magnet and demagnetization fault diagnosis can be achieved based on the obtained permanent magnet flux linkage parameters. The experimental results show that the relative estimation errors of the dq-axis inductance and permanent magnet flux linkage are within 5%, which can realize the effective diagnosis of demagnetization fault and high-precision condition monitoring of a permanent magnet health.

关键词： demagnetization fault permanent magnet synchronous motor fault diagnosis multi-parameter estimation recursive least square dual extended Kalman filter

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Research on compound control strategy of sensorless permanent magnet synchronous motor

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INTERNATIONAL JOURNAL OF ELECTRIC AND HYBRID VEHICLES 2023年第2期15卷 200-216页

作者： Zhou, Kai Harbin Univ Sci & Technol Minist Educ Engn Res Ctr Automot Elect Dr Control & Syst Integ 52 Xuefu Rd Harbin 150080 Heilongjiang Peoples R China

The parameters of permanent magnet synchronous motor (PMSM) change from time to time at low speeds, leading to unstable operations. Aiming at this shortcoming, this paper proposes a control method of sensorless PMSM feedforward voltage estimation combined with multi-parameter estimation, and the parameters required for the feedforward voltage control (FFVC) are given through the multi-parameter estimation model. The FFVC is used to dynamically control the current of the stator voltage in the inner loop, and the sliding mode controller is added to improve the sensitivity and stability of the parameter change at the low speeds of the PMSM. This method improves the dynamic stability of the motor control system and eliminates the transient oscillation in the speed estimation. Through software simulation and experimental verification on the hardware platform of a 2-kW PMSM, it is shown that the proposed control strategy can make the PMSM run stably at low speeds.

关键词： feedforward voltage estimation multi-parameter estimation permanent magnet synchronous motor PMSM sliding mode controller

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Enhancing quantum metrology for multiple frequencies of oscillating magnetic fields by quantum control

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Chinese Physics B 2024年第6期33卷 177-187页

作者：雷昕范静怡庞盛世 School of Physics Sun Yat-sen UniversityGuangzhou 510275China

Quantum multi-parameter estimation has recently attracted increased attention due to its wide applications, with a primary goal of designing high-precision measurement schemes for unknown parameters. While existing research has predominantly concentrated on time-independent Hamiltonians, little has been known about quantum multi-parameter estimation for time-dependent Hamiltonians due to the complexity of quantum dynamics. This work bridges the gap by investigating the precision limit of multi-parameter quantum estimation for a qubit in an oscillating magnetic field model with multiple unknown frequencies. As the well-known quantum Cramer–Rao bound is generally unattainable due to the potential incompatibility between the optimal measurements for different parameters, we use the most informative bound instead which is always attainable and equivalent to the Holevo bound in the asymptotic limit. Moreover, we apply additional Hamiltonian to the system to engineer the dynamics of the qubit. By utilizing the quasi-Newton method, we explore the optimal schemes to attain the highest precision for the unknown frequencies of the magnetic field, including the simultaneous optimization of initial state preparation, the control Hamiltonian and the final measurement. The results indicate that the optimization can yield much higher precisions for the field frequencies than those without the optimizations. Finally,we study the robustness of the optimal control scheme with respect to the fluctuation of the interested frequencies, and the optimized scheme exhibits superior robustness to the scenario without any optimization.

关键词： quantum metrology multi-parameter estimation quantum control

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Experimental 3D super-localization with Laguerre–Gaussian modes

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Quantum Frontiers 2023年第1期2卷 1-8页

作者： Hu, Chenyu Xu, Liang Wang, Ben Li, Zhiwen Zhang, Yipeng Zhang, Yong Zhang, Lijian National Laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and Manipulation College of Engineering and Applied Sciences School of Physics and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Research Center for Quantum Sensing Zhejiang Lab Hangzhou 310000 China

Improving three-dimensional (3D) localization precision is of paramount importance for super-resolution imaging. By properly engineering the point spread function (PSF), such as utilizing Laguerre–Gaussian (LG) modes and their superposition, the ultimate limits of 3D localization precision can be enhanced. However, achieving these limits is challenging, as it often involves complicated detection strategies and practical limitations. In this work, we rigorously derive the ultimate 3D localization limits of LG modes and their superposition, specifically rotation modes, in the multi-parameter estimation framework. Our findings reveal that a significant portion of the information required for achieving 3D super-localization of LG modes can be obtained through feasible intensity detection. Moreover, the 3D ultimate precision can be achieved when the azimuthal index l is zero. To provide a proof-of-principle demonstration, we develop an iterative maximum likelihood estimation (MLE) algorithm that converges to the 3D position of a point source, considering the pixelation and detector noise. The experimental implementation exhibits an improvement of up to two-fold in lateral localization precision and up to twenty-fold in axial localization precision when using LG modes compared to Gaussian mode. We also showcase the superior axial localization capability of the rotation mode within the near-focus region, effectively overcoming the limitations encountered by single LG modes. Notably, in the presence of realistic aberration, the algorithm robustly achieves the Cramér-Rao lower bound. Our findings provide valuable insights for evaluating and optimizing the achievable 3D localization precision, which will facilitate the advancements in super-resolution microscopy. © The Author(s) 2023.

关键词： 3D localization Laguerre–Gaussian modes Maximum likelihood estimate multi-parameter estimation Quantum Fisher information

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Two-parameter estimation in a matter-wave Sagnac interferometer

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Communications in Theoretical Physics 2020年第9期72卷 39-48页

作者： Xu Yu Hong-Bin Liang Xiao-Guang Wang Zhejiang Institute of Modem Physics Department of PhysicsZhejiang UniversityHangzhou 310027China Graduate School of China Academy of Engineering Physics Beijing 100193China

We explore the general characteristics of a matter-wave Sagnac interferometer in a two-parameter estimation scheme. We find that the measurement precisions of both parameters cannot reach the Heisenberg limit(HL) simultaneously when the input state is maximally entangled. Only one of the parameters' uncertainties can approach the HL while the other is scaled by the standard quantum *** provide the conditions with which the measurement precision of the specific parameter can reach the HL. We also discuss and figure out the concrete expressions of the constraint conditions for saturating the quantum Cramér–Rao bound. To satisfy these constraint conditions, the evolution time has to be a series of discrete values. Additionally, we calculate the variances of the parameters through some examples under these constraint conditions. The results provided in our work show some intrinsic features of the matter-wave Sagnac interferometer for the two-parameter estimation, which can be valuable in actual experiments.

关键词： multi-parameter estimation matter wave Sagnac interferometer Heisenberg limit

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Quantum sensing networks for the estimation of linear functions

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JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL 2020年第34期53卷 1-28页

作者： Rubio, Jesus Knott, Paul A. Proctor, Timothy J. Dunningham, Jacob A. Univ Exeter Dept Phys & Astron Stocker Rd Exeter EX4 4QL Devon England Univ Nottingham Sch Math Sci Ctr Math & Theoret Phys Quantum Nonequilibrium Sy Univ Pk Nottingham NG7 2RD England Sandia Natl Labs Livermore CA 94550 USA Univ Sussex Dept Phys & Astron Brighton BN1 9QH E Sussex England

The theoretical framework for networked quantum sensing has been developed to a great extent in the past few years, but there are still a number of open questions. Among these, a problem of great significance, both fundamentally and for constructing efficient sensing networks, is that of the role of inter-sensor correlations in thesimultaneousestimation of multiple linear functions, where the latter are taken over a collection local parameters and can thus be seen as global properties. In this work we provide a solution to this when each node is a qubit and the state of the network is sensor-symmetric. First we derive a general expression linking the amount of inter-sensor correlations and the geometry of the vectors associated with the functions, such that the asymptotic error is optimal. Using this we show that if the vectors are clustered around two special subspaces, then the optimum is achieved when the correlation strength approaches its extreme values, while there is a monotonic transition between such extremes for any other geometry. Furthermore, we demonstrate that entanglement can be detrimental for estimating non-trivial global properties, and that sometimes it is in fact irrelevant. Finally, we perform a non-asymptotic analysis of these results using a Bayesian approach, finding that the amount of correlations needed to enhance the precision crucially depends on the number of measurement data. Our results will serve as a basis to investigate how to harness correlations in networks of quantum sensors operating both in and out of the asymptotic regime.

关键词： quantum sensing networks multi-parameter estimation quantum metrology quantum correlations

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Improving crop modeling to better simulate maize yield variability under different irrigation managements

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AGRICULTURAL WATER MANAGEMENT 2022年第0期262卷 107429-107429页

作者： Abimbola, Olufemi P. Franz, Trenton E. Rudnick, Daran Heeren, Derek Yang, Haishun Wolf, Adam Katimbo, Abia Nakabuye, Hope N. Amori, Anthony Univ Nebraska Sch Nat Resources 101 Hardin Hall3310 Holdrege St Lincoln NE 68583 USA Univ Nebraska Dept Biol Syst Engn 223L W Chase Hall Lincoln NE 68583 USA Univ Nebraska Dept Agron & Hort POB 830915 Lincoln NE 68583 USA Arable Labs Inc 51 Fed StSuite 301 San Francisco CA 94107 USA

Crop models have been used for investigating crop responses to environmental stresses for decades. The study objectives were to (i) calibrate and validate a simple crop model (Hybrid-Maize) using in-situ measured data from sixteen uniquely managed treatments as part of the University of Nebraska-Lincoln Testing Ag Performance Solutions (TAPS) program in North Platte, NE, and (ii) carry out sensitivity analysis and parameter estimation using a multi-parameter optimization approach. Sixteen Arable Mark 1 sensors and thirty two Mark 2 sensors (Arable Labs Inc., San Francisco, CA) collecting hourly and daily weather and crop information in 2019 and 2020 respectively, were installed in the TAPS subsurface drip irrigation experimental plots which were planted with maize and subjected to different irrigation and nitrogen practices. Hybrid-Maize was used for simulating maize yield on the sixteen treatments in 2019 and 2020. Sensitivity analysis showed that initial light use efficiency (LUE), potential kernel filling rate (G5), potential number of kernels per ear (G2), growth respiration coefficient of grain (GRG), empirical parameter determining the relative contribution of a soil layer to water uptake (SLW), and maximum photosynthetic rate (MPR) were the most sensitive parameters to yield. A novel multi-parameter optimization (MPO) approach based on kriging was used for calibrating these six parameters, and the best parameter sets which were later used for model validation. Calibration results showed that there seemed to be strong linear relationships between total water received (WR) and some of the parameters. By using each year's MPO averages of the six parameters instead of default values, ME, MAE, RMSE, uRMSE, and nRMSE were all reduced by about 69%, 66%, 60%, 27%, and 61% respectively for validation treatments. The advantage of using in-situ sensors, coupled with the suitability of the calibrated model for simulating maize yield under different irrigation management,

关键词： Yield prediction Irrigation Hybrid-Maize multi-parameter estimation In-situ sensors

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One from many: estimating a function of many parameters

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JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL 2021年第1期54卷 014001-014001页

作者： Gross, Jonathan A. Caves, Carlton M. Univ New Mexico Ctr Quantum Informat & Control Albuquerque NM 87131 USA Univ Queensland Ctr Engn Quantum Syst Sch Math & Phys St Lucia Qld 4072 Australia Univ Sherbrooke Inst Quant Sherbrooke PQ J1K 2R1 Canada Univ Sherbrooke Dept Phys Sherbrooke PQ J1K 2R1 Canada

Difficult it is to formulate achievable sensitivity bounds for quantum multiparameter estimation. Consider a special case, one parameter from many: many parameters of a process are unknown;estimate a specific linear combination of these parameters without having the ability to control any of the parameters. Superficially similar to single-parameter estimation, the problem retains genuinely multiparameter aspects. Geometric reasoning demonstrates the conditions, necessary and sufficient, for saturating the fundamental and attainable quantum-process bound in this context.

关键词： quantum metrology multi-parameter estimation Fisher information Cramer– Rao bound process norm

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