基于二维磁光阱的增强型^(199)Hg冷原子团制备  

Enhanced production of ~(199)Hg cold atoms based on two-dimensional magneto-optical trap

作　　者：余泽鑫 刘琪鑫 孙剑芳[1] 徐震[1,2] Yu Ze-Xin;Liu Qi-Xin;Sun Jian-Fang;Xu Zhen(Key Laboratory of Quantum Optics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,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,北京100049

出　　处：《物理学报》2024年第1期140-148,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11874371,91436105,12104474);中国科学院战略性先导科技专项(批准号:XDB21030200);上海市科技计划(批准号:22ZR1471000)资助的课题。

摘　　要：在精密测量领域中,高效地制备冷原子团具有重要的意义.在光晶格钟里,缩短冷原子团的制备时间可以降低Dick噪声,从而提高光晶格钟的稳定性.本文采用二维磁光阱加推送光的构型提高了三维磁光阱在超高真空环境中的装载率,并通过压缩磁光阱技术降低了原子团温度,实现了用于^(199)Hg光晶格钟的增强型冷原子团制备.实验上通过优化三维和二维磁光阱的失谐量和磁场梯度以及推送光的失谐量和功率等参数,将三维磁光阱的^(199)Hg冷原子装载率增强了51倍,提升至3.1×10^(5)s^(–1),然后使用压缩磁光阱技术将^(199)Hg冷原子团的温度降低至45μK,低于多普勒冷却理论温度.这种基于二维磁光阱的增强型冷原子团制备可在超真空环境下实现对三维磁光阱装载率的高增益,有效地缩短了冷原子团的制备时间,同时也降低了原子团的温度,有利于提高光晶格的转移效率,为其他冷原子实验中冷汞原子团制备提供了有效方案.Efficient preparation of cold atoms plays an important role in realizing precision measurement including optical lattice clocks(OLCs).Fast preparation of cold atoms reduces Dick noise by shortening dead time in a clock interrogation cycle,which improves the stability of OLCs.Here,we increase the loading rate of the threedimensional magneto-optical trap(3D-MOT) in the ultra-high vacuum environment by utilizing the twodimensional magneto-optical trap(2D-MOT) with a push beam,reduce the temperature of cold atoms with the compression-MOT technique which is implemented by reducing the detuning of 3D-MOT rapidly at the end of atom preparation,and realize the enhanced production of cold atoms for ~(199)Hg OLCs.To achieve 3D-MOT and 2D-MOT of mercury atoms,a deep ultraviolet laser(DUVL) system composed of three DUVLs is developed with one working in lower power for frequency locking and the other two in high power for laser cooling.Such a configuration improves the long-term frequency stability and shows greater robustness than our previous system consisting of two DUVLs.To maximize the 3D-MOT loading rate,we orderly optimize the detuning and the magnetic field gradient of 3D-MOT and those of 2D-MOT as well as the detuning and the power of the push beam.After all parameters are optimized,we measure the maximum loading rate of 3D-MOT to be 3.1×10~5 s~(–1) and prepare cold atoms of 1.8×10~6 in 9 s.The loading rate is greatly enhanced by a factor of 51 by using 2DMOT and the push beam.In order to improve the efficiency of transferring cold atoms from 3D-MOT to optical lattice,we use compression-MOT technique to reduce the temperature of cold atoms and produce cold ~(199)Hg atoms which are about 45 μK,lower than the expected temperature of Doppler cooling theory.By achieving the high gain of the 3D-MOT loading rate under the ultra-high vacuum and reducing the temperature of cold atoms,this enhanced preparation of cold atoms based on 2D-MOT effectively shortens the preparation time of cold atoms and improves the transfer

关 键 词：汞原子 光晶格钟 激光冷却 二维磁光阱 

分 类 号：O562[理学—原子与分子物理] TN24[理学—物理]