Margolis H S, Barwood G P, Huang G, Klein H A, Lea S N, Szymaniec K, Gill P
National Physical Laboratory (NPL), Teddington, Middlesex TW11 0LW, UK.
Science. 2004 Nov 19;306(5700):1355-8. doi: 10.1126/science.1105497.
The frequency of the 5s 2S(1/2)-4d 2D(5/2) electric quadrupole clock transition in a single, trapped, laser-cooled 88Sr+ ion has been measured by using an optical frequency comb referenced to a cesium fountain primary frequency standard. The frequency of the transition is measured as 444,779,044,095,484.6 (1.5) hertz, with a fractional uncertainty within a factor of 3 of that of the cesium standard. Improvements required to obtain a cesium-limited frequency measurement are described and are expected to lead to a 88Sr+ optical clock with stability and reproducibility exceeding that of the primary cesium standard.
利用一台以铯喷泉基准频率标准为参考的光学频率梳，测量了单个囚禁的、激光冷却的88Sr+离子中5s 2S(1/2)-4d 2D(5/2)电四极矩时钟跃迁的频率。测得该跃迁频率为444779044095484.6（1.5）赫兹，其分数不确定度在铯标准的三分之一以内。文中描述了获得受铯限制的频率测量所需的改进措施，预计将得到一台稳定性和复现性超过基准铯标准的88Sr+光学时钟。
