囚禁离子光频标的比对实验

The optical frequency standards have been rapidly developed in the past two decades, the best optical frequency standard developed has better performance than the Cs fountain clock. It can be predicted that the optical frequency standard will be further developed to understand the physical world, also can meet the needs of the country, and openning up a new era. Our research group is being developing an optical frequency standard based on a sigle trapped calcium ion over the past decade. In order to reach a better performance, we have to find which part is limiting us. Therefore, based on the first calcium ion optical clock already realized, this project will improve the second ion trapping system, achieving ion trapping for very long time; and the probe laser will be improved with better performace and a <20 Hz linewidth of the clock transiton can be achieved; after that we will run the two optical clocks for the same time and a comparison stabilty of 10^-16 level will be measured at an averaging time of 10000 s; by comparing the two clocks the systematic shifts including shifts caused by motions, ac Stark shifts caused by laser powers will be further evaluated, eventually reduce the systematic uncertainty of the calcium ion optical clock.

近二十年来光频标得到了飞速发展，国际上最好的光频标在性能指标上已经超过了Cs喷泉钟。可以预见，光频标还会得到进一步的发展，从而在认识客观物理世界和满足国家重大需求等方面开创新的时代。我们小组近十多年来坚持开展了囚禁冷却钙离子光频标的实验工作。为了进一步提高性能，找到限制钙离子光频标稳定度及不确定度的瓶颈所在，本项目拟在一台已经实现锁定的钙离子光钟基础上，对已搭建的第二套离子阱进行优化，实现第二套离子阱系统的长时间离子囚禁；提高钟跃迁探测激光器的稳定性，得到线宽小于20Hz的钟跃迁探测谱线；实现两台钙离子光频标的同时锁定，比对10000秒稳定度进入10^-16量级；在此基础上对运动效应引起的频移、激光强度引起的ac Stark频移等系统误差进行进一步研究和评估，减小钙离子光频标的系统不确定度。

近二十年来光频标得到了飞速发展，从而在认识客观物理世界和满足国家重大需求等方面开创新的时代。我们小组近十多年来坚持开展了囚禁冷却钙离子光频标的实验工作。为了进一步提高性能，找到限制钙离子光频标稳定度及不确定度的瓶颈所在，通过本项目三年来的实施，按照计划我们完成的相关工作如下：实现了新系统上单个40Ca+的稳定囚禁；同时完善了第一套40Ca+离子阱系统。将729nm钟跃迁激光锁定到ULE腔上，通过优化腔及相关光路的隔声及温控系统，改善了腔及相关光路的稳定性，同时减小了剩余幅度调制，获得了得到线宽 <1Hz，频率稳定度 <2E-15(1~100s) 的729nm钟跃迁探测激光。完成了比对装置的搭建，进行了两个离子钟跃迁频率的比对实验。通过进一步抑制系统误差，40Ca＋离子光频标的不确定度和稳定度均进入E-17量级。利用基于GPS 朔源到SI 秒定义的方法测量了40Ca＋钟跃迁绝对频率，40Ca＋离子光频率测量值两次被国际时间频率咨询委员会会议（CCFT20）所采纳。