镱原子光晶格钟二阶Zeeman频移的测量

Measurement of the Second-order Zeeman Shift in Ytterbium Lattice Clock

背景磁场的精确标定对于原子钟的闭环运转以及不确定度评估有着重要的影响。在中性原子光晶格钟的不确定度的评估中,背景磁场引入的二阶Zeeman频移是重要的贡献项之一。本文提出利用自比对的方法,测量不同背景磁场条件下镱原子钟跃迁~1S_(0)→~3P_(0)两个π跃迁谱线对应的Zeeman分裂频率间距差值,得到Zeeman分裂频率间距差与相应背景磁场线圈电流的对应关系,最终标定出最小Zeeman分裂间距差在三个维度上对应的补偿磁场线圈驱动电流值。在此基础上,分别调节偏置磁场处于高低磁场强度条件下,测量了剩余背景磁场对钟跃迁频率产生的二阶Zeeman频移。结果显示二阶塞曼频移系数-0.0655(3) Hz/G~2,对应的二阶Zeeman频移不确定度5.7×10^(-17)。这项工作的开展为镱原子光晶格钟不确定度总体评估奠定了基础。

The background magnetic field has an important influence on the long-term closed-loop operation and the uncertainty evaluation for atomic optical clocks.The second-order Zeeman shift introduced by the background magnetic field is one of the important terms to be considered.In this paper,we firstly measure the spacing difference of the Zeeman splitting corresponding to the two π transitions of ytterbium clock transition ~1S_(0)→~3P_(0) along with the different background magnetic field.Secondly,the spacing difference of the Zeeman splitting along with the driven current of the shielding magnetic field is obtained.Finally,the driven current of the shielding magnetic field used to generate the minimum the spacing difference of the Zeeman splitting is derived in three dimensions.Based on the measurement,the second-order Zeeman shift can be obtained by tuning the polarizing magnetic field in high and low modes by self-comparison method.The result shows the coefficient of the second-order Zeeman shift is-0.065 5(3) Hz/G~2 and the uncertainty due to the second-order Zeeman shift is 5.7×10^(-17).This work will contribute to the total uncertainty budget of our ytterbium lattice clock in the future.