We designed the experimental generation system of the optical GHZ-like and cluster-like quadripartite entangled states for continuous variables.We theoretically demonstrated that the two different types of quadriparti...We designed the experimental generation system of the optical GHZ-like and cluster-like quadripartite entangled states for continuous variables.We theoretically demonstrated that the two different types of quadripartite entangled states can be obtained by the linearly optical transformation of four amplitude-quadrature and phase-quadrature squeezed states produced from a pair of nondegenerate optical parametric amplifiers under appropriate phase relations.The criteria for full inseparability of quadripartite cluster-like state were deduced,and the dependency of the quadripartite entanglement on the initial squeezing degree,the transmission efficiencies of the system and the detection efficiency of homodyne detection were numerically calculated.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.10674088 and 60608012)Program for Changjiang Scholars andInnovative Research Team in University(Grant No.IRT0516)
文摘We designed the experimental generation system of the optical GHZ-like and cluster-like quadripartite entangled states for continuous variables.We theoretically demonstrated that the two different types of quadripartite entangled states can be obtained by the linearly optical transformation of four amplitude-quadrature and phase-quadrature squeezed states produced from a pair of nondegenerate optical parametric amplifiers under appropriate phase relations.The criteria for full inseparability of quadripartite cluster-like state were deduced,and the dependency of the quadripartite entanglement on the initial squeezing degree,the transmission efficiencies of the system and the detection efficiency of homodyne detection were numerically calculated.
文摘针对去蜂窝大规模多输入多输出(Cell-Free massive Multiple Input Multiple Output,CF-mMIMO)系统多用户场景下导频污染抑制所涉及的优化目标维度高的问题,提出基于K-Means分簇和用户优先级的导频分配方案。该方法基于指数态聚类误差平方和(Sum of the Squared Error,SSE)确定最佳K值,再基于大尺度衰落进行簇心初始化,以此改进K-Means方法实现用户分簇;然后根据分簇结果先基于类高斯距离对簇交界处高优先级用户分配导频,再对每个簇内低优先级用户依据最大误差最小化独立分配导频。这种方法可以显著降低导频污染抑制问题维度,改善导频分配机制。仿真结果表明,所提方法可以有效抑制多用户场景下的导频污染,提高吞吐量,并降低干扰抑制问题的维度。
