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Enhancing quantum temporal steering via frequency modulation

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Chinese Physics B 2024年第5期33卷 239-245页

作者：吴孟凯程维文 Institute of signal processing & Transmission Nanjing University of Posts and TelecommunicationNanjing 210003China

Various strategies have been proposed to harness and protect space-like quantum correlations in different models under ***,little attention has been given to temporal-like correlations,such as quantum temporal steering(TS),in this *** this work,we investigate TS in a frequency-modulated two-level system coupled to a zero-temperature reservoir in both the weak and strong coupling *** analyze the impact of various frequency-modulated parameters on the behavior of TS and *** results demonstrate that appropriate frequency-modulated parameters can enhance the TS of the two-level system,regardless of whether the system is experiencing Markovian or non-Markovian ***,a suitable ratio between modulation strength and frequency(i.e.,all zeroes of the 0th Bessel function J_(0)(δ/?))can significantly enhance TS in the strong coupling *** findings indicate that efficient and effective manipulation of quantum TS can be achieved through a frequency-modulated approach.

关键词： quantum temporal steering frequency modulation decoherence

Self-attention Guidance Based Crowd Localization and Counting

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Machine Intelligence Research 2024年第5期21卷 966-982页

作者： Zhouzhou Ma Guanghua Gu Wenrui Zhao School of Information Science and Engineering Yanshan UniversityQinhuangdao066000China Hebei Key laboratory of Information Transmission and signal processing Qinhuangdao066000China

Most existing studies on crowd analysis are limited to the level of counting,which cannot provide the exact location of *** paper proposes a self-attention guidance based crowd localization and counting network(SA-CLCN),which can simultaneously locate and count *** take the form of object detection,using the original point annotations of crowd datasets as supervision to train the ***,the center point coordinate of each head as well as the number of crowds are ***,to cope with the spatial and positional variations of the crowd,the proposed method introduces transformer to construct a globallocal feature extractor(GLFE)together with the convolutional *** establishes the near-to-far dependency between elements so that the global context and local detail features of the crowd image can be extracted ***,this paper designs a pyramid feature fusion module(PFFM)to fuse the global and local information from high level to low level to obtain a multiscale feature *** downstream tasks,this paper predicts candidate point offsets and confidence scores by a simple regression header and classification *** addition,the Hungarian algorithm is used to match the predicted point set and the labelled point set to facilitate the calculation of *** proposed network avoids the errors or higher costs associated with using traditional density maps or bounding box ***,we have conducted extensive experiments on several crowd datasets,and the proposed method has produced competitive results in both counting and localization.

关键词： Crowd localization crowd counting transformer point supervision object detection

On Isodual Double Toeplitz Codes

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Journal of Systems Science & Complexity 2024年第5期37卷 2196-2206页

作者： SHI Minjia XU Li SOLé Patrick Key laboratory of Intelligent Computing and signal processing Ministry of Education School of Mathematical Sciences Anhui University State Key laboratory of Information Security Institute of Information Engineering Chinese Academy of Sciences CNRS University of Aix Marseille Centrale Marseille

Double Toeplitz（shortly DT） codes are introduced here as a generalization of double circulant codes. The authors show that such a code is isodual, hence formally self-dual（FSD）. FSD codes form a far-reaching generalization of self-dual codes, the most important class of codes of rate one-half. Self-dual DT codes are characterized as double circulant or double negacirculant. Likewise, even binary DT codes are characterized as double circulant. Numerical examples obtained by exhaustive search show that the codes constructed have best-known minimum distance, up to one unit, amongst formally self-dual codes, and sometimes improve on the known values. For q = 2, the authors find four improvements on the best-known values of the minimum distance of FSD codes. Over F4an explicit construction of DT codes, based on quadratic residues in a prime field, performs equally well. The authors show that DT codes are asymptotically good over Fq. Specifically, the authors construct DT codes arbitrarily close to the asymptotic Varshamov-Gilbert bound for codes of rate one half.

关键词： Double circulant codes double Toeplitz codes formally self-dual codes isodual codes

Gray code based gradient-free optimization algorithm for parameterized quantum circuit

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Chinese Physics B 2024年第2期33卷 189-194页

作者：张安琪武春辉赵生妹 Institute of signal processing and Transmission Nanjing University of Posts and TelecommunicationsNanjing 210003China Key laboratory of Broadband Wireless Communication and Sensor Network Technology(Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China

A Gray code based gradient-free optimization(GCO)algorithm is proposed to update the parameters of parameterized quantum circuits(PQCs)in this *** parameter of PQCs is encoded as a binary string,named as a gene,and a genetic-based method is adopted to select the *** individuals in the offspring are decoded in Gray code way to keep Hamming distance,and then are evaluated to obtain the best one with the lowest cost value in each *** algorithm is performed iteratively for all parameters one by one until the cost value satisfies the stop condition or the number of iterations is *** GCO algorithm is demonstrated for classification tasks in Iris and MNIST datasets,and their performance are compared by those with the Bayesian optimization algorithm and binary code based optimization *** simulation results show that the GCO algorithm can reach high accuracies steadily for quantum classification ***,the GCO algorithm has a robust performance in the noise environment.

关键词： gradient-free optimization Gray code genetic-based method

High-Precision DOA Estimation Method Based on Synthetic Aperture Technique

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Journal of Beijing Institute of Technology 2024年第2期33卷 111-118页

作者： Yongjia Dou Guangcai Sun Yuqi Wang Mengdao Xing National Key laboratory of Radar signal processing Xidian UniversityXi’an 710071China School of Communication and Information Engineering Xi’an University of Science and TechnologyXi’an 710054China

The existing direction-of-arrival(DOA)estimation methods only utilize the current received signals,which are susceptible to *** this paper,a method for DOA estimation based on a motion platform is proposed to achieve high-precision DOA estimation by utilizing past and present *** concept of synthetic aperture is introduced to construct a linear DOA estima-tion model.A DOA fine-tuning method based on the linear model is proposed to eliminate the lin-ear DOA variation,achieving a non-coherent accumulation of DOA ***,the baseband modulation and the phase modulation caused by the range history are compensated to achieve the coherent accumulation of all the DOA *** results show that the proposed method can significantly improve the DOA estimated accuracy at low signal-to-noise ratios(SNR).

关键词： synthetic aperture direction-of-arrival(DOA)estimation coherent accumulation

Diffraction deep neural network-based classification for vector vortex beams

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Chinese Physics B 2024年第3期33卷 387-392页

作者：彭怡翔陈兵王乐赵生妹 Institute of signal processing and Transmission Nanjing University of Posts and Telecommunications (NJUPT)Nanjing 210003China Key laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of EducationNanjing 210003China National laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

The vector vortex beam(VVB)has attracted significant attention due to its intrinsic diversity of information and has found great applications in both classical and quantum ***,a VVB is unavoidably affected by atmospheric turbulence(AT)when it propagates through the free-space optical communication environment,which results in detection errors at the *** this paper,we propose a VVB classification scheme to detect VVBs with continuously changing polarization states under AT,where a diffractive deep neural network(DDNN)is designed and trained to classify the intensity distribution of the input distorted VVBs,and the horizontal direction of polarization of the input distorted beam is adopted as the feature for the classification through the *** numerical simulations and experimental results demonstrate that the proposed scheme has high accuracy in classification *** energy distribution percentage remains above 95%from weak to medium AT,and the classification accuracy can remain above 95%for various strengths of *** has a faster convergence and better accuracy than that based on a convolutional neural network.

关键词： vector vortex beam diffractive deep neural network classification atmospheric turbulence

Anisotropic spin transport and photoresponse characteristics detected by tip movement in magnetic single-molecule junction

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Chinese Physics B 2024年第4期33卷 640-648页

作者：陈登辉羊志付新宇秦申奥严岩王传奎李宗良邱帅 Shandong Key laboratory of Medical Physics and Image processing&Shandong Provincial Engineering and Technical Center of Light Manipulations School of Physics and ElectronicsShandong Normal UniversityJinan 250358China

Orientation-dependent transport properties induced by anisotropic molecules are enticing in single-molecule ***,using the first-principles method,we theoretically investigate spin transport properties and photoresponse characteristics in trimesic acid magnetic single-molecule junctions with different molecular adsorption orientations and electrode contact *** transport calculations indicate that a single-molecule switch and a significant enhancement of spin transport and photoresponse can be achieved when the molecular adsorption orientation changes from planar geometry to upright *** maximum spin polarization of current and photocurrent in upright molecular junctions exceeds 90%.Moreover,as the Ni tip electrode moves,the tunneling magnetoresistance of upright molecular junctions can be increased to 70%.The analysis of the spin-dependent PDOS elucidates that the spinterfaces between organic molecule and ferromagnetic electrodes are modulated by molecular adsorption orientation,where the molecule in upright molecular junctions yields higher spin *** theoretical work paves the way for designing spintronic devices and optoelectronic devices with anisotropic functionality base on anisotropic molecules.

关键词： molecular spintronics spin polarization tunneling magnetoresistance photocurrent single-molecule junctions

Effects of mixed aerosol on the path loss of NLOS UV communication system

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Optoelectronics Letters 2024年第9期20卷 549-559页

作者： MA Yuzhao ZHOU Jingyi Tianjin Key laboratory for Advanced signal processing Civil Aviation University of ChinaTianjin 300300China College of Electronic Information and Automation Civil Aviation University of ChinaTianjin 300300China

Performance of non-line-of-sight(NLOS)ultraviolet(UV)communication is closely related with the communication range,system geometry and the atmosphere aerosol *** this paper,we investigate the path loss of the NLOS UV ... 详细信息

关键词： communication properties. NLOS

Track-before-detect for bistatic radar based on pseudo-spectrum

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Chinese Journal of Aeronautics 2024年第1期37卷 236-246页

作者： Tao HAN Gongjian ZHOU School of electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China Key laboratory of Marine Environmental Monitoring and Information processing Ministry of Industry and Information TechnologyHarbin 150001China

Track-Before-Detect(TBD) is an efficient method to detect dim targets for radars. Conventional TBD usually follows an approximate motion model of the target, which may cause an inaccurate integration of the target energy. A TBD technique on basis of pseudo-spectrum in mixed coordinates adopting an accurate motion model for bistatic radar system is developed in this *** predicted position in bistatic polar plane is derived according to a nonlinear function that exactly describes the constant Cartesian velocity motion. Then around the predicted position, a pseudo-spectrum is formulated and its samples are accumulated to the integration frame for energy integration. The evolution of the state and the procedure of accumulation of the target energy are derived elaborately. The superior performance of the proposed method is demonstrated by some simulations.

关键词： Weak target detection Bistatic radar Track-before-detect Pseudo-spectrum Multiframe integration