摘要
本文报道了中国科学院武汉物理与数学研究所基于单个囚禁冷却钙离子精密光谱实验进展. 采用微型射频阱(Paul阱)囚禁单个钙离子, 实现囚禁离子的激光冷却, 冷却离子被囚禁在Lamb-Dicke区域, 囚禁时间长达2个月以上. 用于钙离子4s^2S_(1/2)-3d^2D_(5/2)钟跃迁探测的729 nm激光的线宽压窄到1 Hz以下, 并实现连续1个月的稳定运行. 为了实现频率比对, 搭建了两台相似的钙离子光频标. 通过对系统误差的细致评估, 两台钙离子光频标的频率相对不确定度均小于6′10^(-17). 通过42 d的独立比对实验, 两台钙离子光频标的频差为3′10^(-17), 不确定度为5.5′10^(-17). 通过3 d的连续频率比对, 两台钙离子光频标的阿伦偏差为1×10^(-14)τ^(-1/2), 2×10~4 s稳定度达到了7′10^(-17). 同时, 利用基于全球定位系统(GPS)朔源到世界标准时(SI)的光频测量系统, 再次测量了钙离子钟跃迁4s^2S_(1/2)-3d^2D_(5/2)的绝对频率值, 其结果为(411042129776401.7±1.1) Hz. 在此基础上完成了两个基于单个囚禁冷却钙离子的精密光谱实验. 一是钙离子钟跃迁魔幻波长的测量, λ_(|mj|=1/2_=(395.7992±7) nm和λ_(|mj|=3/2)=(395.7990±7) nm,与Tang等人的理论预言相符合. 二是钙离子3d^2D_(5/2)态寿命测量, 其结果(1174±10) ms与牛津大学和Innsbruck大学新近在线型阱中基于单个囚禁离子的测量结果相符合, 并与Sahoo的最新理论结果相符合.
The experimental study at Wuhan Institute of Physics and Mathematics （WIPM）, Chinese Academy of Scienses （CAS） on the precision spetroscopy based on single trapped Ca^＋ ion is described in this paper. A single Ca^＋ ion is trapped in a miniature Paul trap and laser cooled to Lamb-Dicke regime, and the ion can be trapped more than 2 months. The linewidth of the 729 nm laser for probing the Ca^＋4s^2S1/2-3d^2D5/2 clock transition is reduced to lessthan 1 Hz by locked to a super cavity, and the 729 nm laser can be locked more than 1 month continuously. Two similar Ca^＋ ion optical frequency standards are set up for frequency comparison. The systematic uncertainty is evaluated to be 〈6× 10^-17 for both ftrquency standards. The frequency difference of two frequency standards is measured to be 3.0 （5.5）× 10^-17 within 42 d. The Allan deviation for a single clock is measured to be 1 × 10^-14τ^-1/2 with a 3-d-continuous comparison, the stability for a reaches 7× 10^-17 at an averaging time of 20000 s. Meanwhile, the absolute frequency of the Ca^＋4s^2S1/2-3d^2D5/2 clock transition is measured to be 41104212977640 1.7（1.1） Hz with respect to the SI second through the Global Positioning System （GPSx）. The precision spectroscopy experiments are carried out based on the single Ca^＋ ion system. The magic wavelengths for the Ca＋ optical frequency standardare measured to be λ｜mj｜=1/2=395.7992（7） nm and λ｜mj｜=3/2=395.7990（7） nm, which agrees with theoretical calculation made by Tang et al. The lifetime of the 3aeD5/2 is measured to be 1174（10） ms, which is agree with the experimental measurement made by University of Oxford and University of Innsbruck and the recent theoretical calculation made by Sahoo.
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2016年第7期52-73,共22页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家重点基础研究发展规划(编号:2012CB821301,2005CB724502)
国家自然科学基金(编号:11474318,91336211,11034009,11304363)资助项目
关键词
频标
精密测量
钙离子
寿命测量
魔幻波长
optical frequency standard, precision spectroscopy, Ca^＋ ion, lifetime measurement, magic wavelength
