基于量子纠缠对的二阶相关星地时钟同步研究

Research on Clock Synchronization between Satellite and Ground Station Based on Second-order Correlation of the Quantum Entangled Photons

在卫星导航系统中,常用的时间同步方法可以提供纳s级同步精度,为突破经典无线电理论的测量精度而利用纠缠光子对的量子测量方法可提供fs级测量精度。基于量子光学的二阶相关函数定义,对自发参量下转换过程产生量子纠缠光子对的二阶相关函数在晶体范围内进行柱面积分,代入波矢量的一阶展开,积分结果得到二阶相关函数与测量时间差的关系。基于二阶相关函数的时间相关性,提出一种星地时钟同步测量方案。仿真表明:在理想情况下二阶相关函数反映时间精度达70fs,文中设计方案同步测量精度可达140fs。

The time synchronization accuracy on the order of nanoseconds can be provided using the conventional methods of time synchronization,a higher measurement accuracy on the order of femto-seconds can be reached by quantum measurement which employs entangled photon pairs in order to break the limit of measurement accuracy of conventional methods.The second-order correlation function of the entangled photon pairs which produced in a spontaneous type-Ⅱ parametric down-conversion is investigated by integral transforming in the nonlinear crystal and substituting the first order expand of the wave vector.The relation between the second-order correlation function and temporal difference.A quantum method in clock synchronization between satellite and ground station is proposed based on the temporal correlation.The simulation indicates that the measurement accuracy provided by the second-order correlation function can be 70 femto-seconds and the synchronization accuracy in the scheme can be 140 femto-seconds in the ideal case.