可搬运铷喷泉原子钟量子化轴磁场的设计与优化  

Design and Optimization of Quantized Axial Magnetic Field for Transportable Rubidium Fountain Atomic Clock

作　　者：程鹤楠 邓思敏达 张镇 项静峰 任伟[1] 吉经纬 刘亮[1] 吕德胜[1,2] Cheng Henan;Deng Siminda;Zhang Zhen;Xiang Jingfeng;Ren Wei;Ji Jingwei;Liu Liang;Lii Desheng(Key Laboratory of Quantum Optics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;College of Materials Science and Opto-Electronic Technology,University of Chinese Academy of Sciences,Beijing 100000,China)

机构地区：[1]中国科学院上海光学精密机械研究所量子光学重点实验室,上海201800 [2]中国科学院大学材料科学与光电技术学院,北京100000

出　　处：《光学学报》2021年第19期45-51,共7页Acta Optica Sinica

基　　金：国家自然科学基金(12004401);科技部重大仪器专项(2013YQ09094304)。

摘　　要：喷泉钟量子化轴磁场的空间均匀性和时间稳定性是制约原子钟输出频率稳定度和不确定度的重要因素。从外磁场屏蔽、磁场线圈设计、线圈电流源稳定性等方面考虑,构建并优化设计了一套可搬运铷喷泉原子钟量子化轴磁场系统。为了消除环境磁场对量子化轴磁场的影响,使用5层坡莫合金磁屏蔽进行外磁场的屏蔽;利用4组对称的补偿线圈,通过计算给予合适的电流,获得喷泉钟内部30 cm原子自由飞行尺度内磁场波动小于1 nT;通过改善C场供电电流方式,从而优化量子化轴磁场的时间稳定性,磁场随时间的波动小于0.1 nT。优化后喷泉钟长期频率稳定度达2.9×10^(-16),磁场空间分布不均匀性带来的二阶塞曼频移不确定度为3.4×10^(-19),由磁场随时间波动带来的二阶塞曼频移的不确定度为5.1×10^(-17)。The spatial homogeneity and temporal stability of a fountain clock’s quantized axial magnetic field are essential factors that govern frequency stability and uncertainty. In this study, the quantized axial magnetic field system of a transportable rubidium fountain atomic clock is constructed and optimally designed considering several aspects, such as external magnetic field shielding, magnetic field coil design, and coil current source stability. A five-layer permalloy magnetic shield is used to shield the external magnetic field to eliminate the influence of the ambient magnetic field on the quantized axial magnetic field. The appropriate current is obtained through simulation using four groups of symmetrical compensation coils. The fluctuation of magnetic field less than 1 nT is obtained in a 30-cm free flight trajectory of the cold atoms cloud. The temporal stability of the quantized axial magnetic field is optimized by improving the C-field supply current method, and the fluctuation of the field over time is less than 0.1 nT. After optimization, the long-term frequency stability of the fountain clock reaches 2.9×10^(-6), and the uncertainty of the second-order Zeeman frequency shift caused by the inhomogeneity of the magnetic field spatial distribution is less than 3.4×10^(-9). Additionally, the uncertainty of the second-order Zeeman frequency shift caused by the fluctuation of the magnetic field with time is approximately 5.1×10^(-7).

关 键 词：原子与分子物理学 塞曼效应 超精细结构 原子钟 磁敏跃迁法 

分 类 号：O562[理学—原子与分子物理]