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Security of quantum key distribution with virtual mutually unbiased bases

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 13-21页

作者： Hong-Wei Li Chen-Peng Hao Zhi-Jiang Chen Li Gong Yi-Fei Lu Yang Wang Jia-Ji Li Chun-Mei Zhang Rong Wang Zhen-Qiang Yin Qing-Yu Cai Henan Key Laboratory of quantum Information and Cryptography SSF IEUZhengzhou 450000China institute of quantum Information and Technology Nanjing University of Posts and TelecommunicationsNanjing 210003China Department of Physics University of Hong KongHong Kong 999077China Key Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China School of Information and Communication Engineering Hainan UniversityHaikou 570228China

In a perfect quantum key distribution(QKD)protocol,quantum states should be prepared and measured with mutually unbiased bases(MUBs).However,in a practical QKD system,quantum states are generally prepared and measured with imperfect MUBs using imperfect devices,possibly reducing the secret key rate and transmission *** analyze the security of a QKD system with imperfect MUBs,we propose virtual MUBs to characterize the quantum channel against collective attack,and analyze the corresponding secret key rate under imperfect state preparation and measurement *** generally,we apply the advantage distillation method for analyzing the security of QKD with imperfect MUBs,where the error tolerance and transmission distance can be sharply *** analysis method can be applied to benchmark and standardize a practical QKD system,elucidating the security analysis of different QKD protocols with imperfect devices.

关键词： quantum key distribution mutually unbiased bases advantage distillation

Electric field dependence of spin qubit in a Si-MOS quantum dot

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Chinese Physics B 2024年第6期33卷 248-253页

作者：马荣龙倪铭周雨晨孔真真王桂磊刘頔罗刚曹刚李海欧郭国平 CAS Key Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in quantum Information and quantum Physics University of Science and Technology of ChinaHefei 230026China Key Laboratory of Microelectronics Devices and Integrated Technology Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029China Beijing Superstring Academy of Memory Technology Beijing 100176China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Origin quantum Computing Company Limited Hefei 230026China

Valley, the intrinsic feature of silicon, is an inescapable subject in silicon-based quantum computing. At the spin–valley hotspot, both Rabi frequency and state relaxation rate are significantly enhanced. With protection against charge noise, the valley degree of freedom is also conceived to encode a qubit to realize noise-resistant quantum ***, based on the spin qubit composed of one or three electrons, we characterize the intrinsic properties of valley in an isotopically enriched silicon quantum dot(QD) device. For one-electron qubit, we measure two electric-dipole spin resonance(EDSR) signals which are attributed to partial occupation of two valley states. The resonance frequencies of two EDSR signals have opposite electric field dependences. Moreover, we characterize the electric field dependence of the upper valley state based on three-electron qubit experiments. The difference of electric field dependences of the two valleys is 52.02 MHz/V, which is beneficial for tuning qubit frequency to meet different experimental requirements. As an extension of electrical control spin qubits, the opposite electric field dependence is crucial for qubit addressability,individual single-qubit control and two-qubit gate approaches in scalable quantum computing.

关键词： silicon-based quantum computing valley electric-dipole spin resonance

Enhanced Sensing Mechanism Based on Shifting an Exceptional Point

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Research 2024年第3期6卷 285-292页

作者： Xuan Mao Guo-Qing Qin Hao Zhang Bo-Yang Wang Dan Long Gui-Qin Li Gui-Lu Long Department of Physics State Key Laboratory of Low-Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China Beijing institute of Radio Measurement The Second Academy of China Aerospace Science and Industry Corporation(CASIC)Beijing 100854China Purple Mountain Laboratories Nanjing 21111China Frontier Science Center for quantum Information Beijing 100084China Beijing Academy of quantum Information Sciences Beijing 100193China

Non-Hermitian systems associated with exceptional points (EPs) are expected to demonstrate a giant response enhancement for various sensors. The widely investigated enhancement mechanism based on diverging from an EP should destroy the EP and further limits its applications for multiple sensing scenarios in a time sequence. To break the above limit, here, we proposed a new enhanced sensing mechanism based on shifting an EP. Different from the mechanism of diverging from an EP, our scheme is an EP nondemolition and the giant enhancement of response is acquired by a slight shift of the EP along the parameter axis induced by perturbation. The new sensing mechanism can promise the most effective response enhancement for all sensors in the case of multiple sensing in a time sequence. To verify our sensing mechanism, we construct a mass sensor and a gyroscope with concrete physical implementations. Our work will deepen the understanding of EP-based sensing and inspire designing various high-sensitivity sensors in different physical systems.

关键词： mechanism shifting exceptional

A novel matrix topology-based analysis method of thermal circuits for reliability optimization of HSER

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Chinese Journal of Aeronautics 2024年第4期37卷 479-492页

作者： Huimin LIANG Bo LI Jiaxin YOU Shan JIANG Mengtong ZHU Aobo WANG Department of Electrical Engineering Harbin Institute of TechnologyHarbin 150001China Nanjing Research institute of electronics Technology Nanjing 210008China

Hermetically Sealed Electromagnetic Relay(HSER), used in aviation and aerospace,demands high reliability due to its critical applications. Given its complex operating conditions, efficient thermal analysis is essential for optimizing reliability. The commonly used Finite Element Method(FEM) is often time-consuming and may not be efficient or adaptable for complex multi-dimensional system calculations and design processes. This paper introduces an analysis method for thermal networks based on matrix perspective technology, encompassing matrix transformation, backpropagation of the heat path model, temperature rise calculation, solution comparison, and product implementation. Using the similarity theory of heat circuits, a basic thermal unit is established. Based on the fundamental connection between key components, a thermal network for a typical HSER is designed. An experimental system is set up, and the thermal network model's accuracy is confirmed using test data. Employing the topology analysis method, the topology of the thermal network is analyzed under both coil-energized and de-energized states. Potential thermal paths are identified, leading to optimized solutions for the HSER. Utilizing these solutions, the thermal path matrix topology model is backpropagated to the thermal path for temperature rise calculations. When compared to prototype HSER test data, the efficiency and accuracy of this matrix topology-based analysis method are confirmed.

关键词： Thermal networks HSER(Hermetically Sealed Electromagnetic Relay) Heat-circuit topology model Heat-circuit matrix Optimization design

Neural network based adaptive nonsingular practical predefined-time fault-tolerant control for hypersonic morphing aircraft

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Chinese Journal of Aeronautics 2024年第4期37卷 421-435页

作者： Shihao XU Changzhu WEI Litao ZHANG Rongjun MU School of Astronautics Harbin Institute of TechnologyHarbin 150001China Beijing institute of Control&electronics Technology Beijing 100038China

This paper develops a novel Neural Network(NN)-based adaptive nonsingular practical predefined-time controller for the hypersonic morphing aircraft subject to actuator faults. Firstly, a novel Lyapunov criterion of practical predefined-time stability is established. Following the proposed criterion, a tangent function based nonsingular predefined-time sliding manifold and the control strategy are developed. Secondly, the radial basis function NN with a low-complexity adaptation mechanism is incorporated into the controller to tackle the actuator faults and uncertainties. Thirdly, rigorous theoretical proof reveals that the attitude tracking errors can converge to a small region around the origin within a predefined time, while all signals in the closed-loop system remain bounded. Finally, numerical simulation results are presented to verify the effectiveness and improved performance of the proposed control scheme.

关键词： Hypersonic morphing aircraft(HMA) Neural network(NN) Adaptive control Practical predefined-time control Fault-tolerant control

Purification of copper foils driven by single crystallization

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Chinese Physics B 2024年第2期33卷 506-511页

作者：寇金宗赵孟泽李兴光何梦林杨方友刘科海成庆秋任云龙刘灿付莹吴慕鸿刘开辉王恩哥 Songshan Lake Materials Laboratory Dongguan 523808China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Guangdong Provincial Key Laboratory of quantum Engineering and quantum Materials School of PhysicsSouth China Normal UniversityGuangzhou 510006China Guangdong–Hong Kong Joint Laboratory of quantum Matter Frontier Research Institute for PhysicsSouth China Normal UniversityGuangzhou 510006China State Key Laboratory for Mesoscopic Physics Frontiers Science Center for Nano-optoelectronicsSchool of PhysicsPeking UniversityBeijing 100871China Key Laboratory of quantum State Construction and Manipulation(Ministry of Education) Department of PhysicsRenmin University of ChinaBeijing 100872China International Center for quantum Materials Collaborative Innovation Center of Quantum MatterPeking UniversityBeijing 100871China School of Physics Liaoning UniversityShenyang 110036China

High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of *** success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor *** purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.

关键词： purification copper foil thermal annealing technique single crystallization

Topological magnetoelectric response in ferromagnetic axion insulators

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National Science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen institute for quantum Science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

quantum advantages for image filtering on images with efficient encoding and lower-bounded signal-to-noise ratio

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 2-12页

作者： Zidong Cui Shan Jin Akira Sone Xiaoting Wang institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610051China Key Laboratory of quantum Physics and Photonic quantum Information Ministry of EducationUniversity of Electronic Science and Technology of ChinaChengdu 611731China Department of Physics University of MassachusettsBoston 02125USA

quantum image processing has long been a fascinating field,but establishing the existence of quantum speedup for all images remains *** this study,we aim to identify a subset of images for which a quantum algorithm can be developed with a guaranteed ***,we present a quantum image filtering algorithm that exhibits an exponential speedup for efficiently encoded images with a lower-bounded signal-to-noise *** approach relies on a fixed-point Grover's search to emulate the effect of Hadamard multiplication with the filtering *** demonstrate its effectiveness,we apply our method to three typical filtering ***,we emphasize the significance of the efficient-encoding assumption by illustrating that the quantum speedup may diminish for images lacking efficient *** work underscores the importance of exploring image types and features to realize potential quantum advantages in image processing.

关键词： quantum computing quantum image filtering quantum speedup

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Merger estimates for a disformal Kerr black hole in quadratic degenerate higher-order scalar-tensor theories

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Chinese Physics C 2024年第5期48卷 284-292页

作者：蒋洪鑫杜欣怡潘启沅陈松柏荆继良 Key Laboratory of Low Dimensional quantum Structures and quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applicationsand Department of PhysicsHunan Normal UniversityChangsha 410081China institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We investigate the main features of a disformal Kerr black hole merger in quadratic degenerate higher-order scalar-tensor *** the ringdown stage of the black hole merger,for the prograde orbit,the real part of the quasinormal modes decreases with an increase in the disformal parameter,and the imaginary part also decreases,except in the Kerr case for a large spin ***,for the retrograde orbit,the real part increases with an increase in the disformal parameter,and the imaginary part always decreases with *** the approximate final spin,regardless of an equal spin,unequal spin,or generic spin configuration merger,the final black hole spin always increases with an increase in the disformal *** results show that the disformal parameter in the disformal Kerr solution and the MOG parameter in the Kerr-MOG case have obviously different effects on the black hole merger,which suggests the differences between these two spacetime structures.

关键词： black hole merger quasinormal modes final black hole spin disformal Kerr black hole quadratic degenerate higher-order scalar-tensor(DHOST)theory