An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing ab...An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing abundant quantum resources for measurement-based quantum computation,and multi-user quantum networks.We propose and generate cluster quantum microcombs within an on-chip optical microresonator driven by multi-frequency lasers.Through resonantly enhanced four-wave mixing processes,continuous-variable cluster states with 60 qumodes are deterministically created.The graph structures can be programmed into one-and two-dimensional lattices by adjusting the configurations of the pump lines,which are confirmed inseparable based on the measured covariance matrices.Our work demonstrates the largest-scale cluster states with unprecedented raw squeezing levels from a photonic chip,offering a compact and scalable platform for computational and communicational tasks with quantum advantages.展开更多
Aimed at solving the distance and vetocity decoupling problems of a moving target in LFMCW radar signal processing, a multiple repetition frequency waveform is adopted and a Doppler frequency duster algorithm is propo...Aimed at solving the distance and vetocity decoupling problems of a moving target in LFMCW radar signal processing, a multiple repetition frequency waveform is adopted and a Doppler frequency duster algorithm is proposed, which is capable of recovering true velocity form the coupled velocity estimation directly. For the resolution of multiple targets, a match algorithm based on mean square error is also proposed. The combination of the above two methods realizes distance and velocity decoupling of multiple moving targets. The result of simulation verifies the effectiveness of the methods, the velocity estimation performance of DFS algorithm is improved by 2.5 dB compared with Chinese remiander theorem.展开更多
This paper presents another necessary condition about the optimum parti-tion on a finite set of samples. From this condition, a corresponding generalized sequential hao f k-means (GSHKM) clustering algorithm is built ...This paper presents another necessary condition about the optimum parti-tion on a finite set of samples. From this condition, a corresponding generalized sequential hao f k-means (GSHKM) clustering algorithm is built and many well-known clustering algorithms are found to be included in it. Under some assumptions the well-known MacQueen's SHKM (Sequential Hard K-Means)algorithm, FSCL (Frequency Sensitive Competitive Learning) algorithm and RPCL (Rival Penalized Competitive Learning) algorithm are derived. It is shown that FSCL in fact still belongs to the kind of GSHKM clustering algth rithm and is more suitable for producing means of K-partition of sample data,which is illustrated by numerical experiment. Meanwhile, some improvements on these algorithms are also given.展开更多
基金supported by the National Key R&D Plan of China(Grant No.2021ZD0301500)Beijing Natural Science Foundation(Z210004,Z240007)+2 种基金National Natural Science Foundation of China(92150108,62222515,12125402,12174438)the High-performance Computing Platform of Peking Universitysupported by the Micro/nano Fabrication Laboratory of Synergetic Extreme Condition User Facility(SECUF).
文摘An optical frequency comb comprises a cluster of equally spaced,phase-locked spectral lines.Replacing these classical components with correlated quantum light gives rise to cluster quantum frequency combs,providing abundant quantum resources for measurement-based quantum computation,and multi-user quantum networks.We propose and generate cluster quantum microcombs within an on-chip optical microresonator driven by multi-frequency lasers.Through resonantly enhanced four-wave mixing processes,continuous-variable cluster states with 60 qumodes are deterministically created.The graph structures can be programmed into one-and two-dimensional lattices by adjusting the configurations of the pump lines,which are confirmed inseparable based on the measured covariance matrices.Our work demonstrates the largest-scale cluster states with unprecedented raw squeezing levels from a photonic chip,offering a compact and scalable platform for computational and communicational tasks with quantum advantages.
文摘Aimed at solving the distance and vetocity decoupling problems of a moving target in LFMCW radar signal processing, a multiple repetition frequency waveform is adopted and a Doppler frequency duster algorithm is proposed, which is capable of recovering true velocity form the coupled velocity estimation directly. For the resolution of multiple targets, a match algorithm based on mean square error is also proposed. The combination of the above two methods realizes distance and velocity decoupling of multiple moving targets. The result of simulation verifies the effectiveness of the methods, the velocity estimation performance of DFS algorithm is improved by 2.5 dB compared with Chinese remiander theorem.
文摘This paper presents another necessary condition about the optimum parti-tion on a finite set of samples. From this condition, a corresponding generalized sequential hao f k-means (GSHKM) clustering algorithm is built and many well-known clustering algorithms are found to be included in it. Under some assumptions the well-known MacQueen's SHKM (Sequential Hard K-Means)algorithm, FSCL (Frequency Sensitive Competitive Learning) algorithm and RPCL (Rival Penalized Competitive Learning) algorithm are derived. It is shown that FSCL in fact still belongs to the kind of GSHKM clustering algth rithm and is more suitable for producing means of K-partition of sample data,which is illustrated by numerical experiment. Meanwhile, some improvements on these algorithms are also given.
