集成2D MOT式横向冷却的小型化塞曼减速装置  

A Compact Zeeman Decelerator with Integrated 2D Magneto-optical Trap for Transverse Cooling

作　　者：王德众 刘晓勇 李杰 贾志鹏[1,2] 张雨辰 戴汉宁 WANG De-zhong;LIU Xiao-yong;LI Jie;JIA Zhi-peng;Zhang Yu-chen;Dai Han-ning(Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences,University of Science and Technology of China,Hefei 230026,China;Shanghai Research Center for Quantum Sciences and CAS Center for Excellence in Quantum Information and Quantum Physics,University of Science and Technology of China,Shanghai 201315,China;Hefei National Laboratory,University of Science and Technology of China,Hefei 230088,China)

机构地区：[1]中国科学技术大学合肥微尺度物质科学国家研究中心,安徽合肥230026 [2]中国科学技术大学中国科学院量子信息与量子科技创新研究院,上海量子科学研究中心,上海201315 [3]合肥国家实验室,安徽合肥230088

出　　处：《量子光学学报》2024年第4期68-77,共10页Journal of Quantum Optics

基　　金：国家自然科学基金(12074367);上海市市级科技重大专项(2019SHZDZX01);中国科学院B类先导专项(XDB35020200);科技创新2030—“量子通信与量子计算机”重大项目(2021ZD0300106)。

摘　　要：在锶原子光钟系统中,从原子炉喷出的锶原子气体需要经过塞曼减速器进行预冷却,由于径向速度较大的原子会脱离塞曼减速光作用区域,因此还需要对原子进行横向冷却。为实现塞曼减速器和横向冷却装置的小型化、集成化,并降低系统功耗,设计了总长度为95 mm的永磁体阵列塞曼减速器,可在67 mm的减速区域内将轴向速度260 m/s的原子减速至50 m/s,由40个小磁体固定在支架上构成减速磁场。横向冷却基于二维磁光阱原理,径向梯度磁场由塞曼减速器提供,位于轴向磁场零点处,σ^(+)-σ^(-)的光场通过集成到塞曼减速器内的折叠光学实现。根据原子束流轴向速度分布的测量结果,对集成横向冷却的塞曼减速装置进行了性能评估:从410℃的原子炉喷出的高温锶原子气体,速度在50 m/s以下的低速原子占比为0.5%,经过塞曼减速光减速后,低速原子比例提高到2.4%,横向冷却可将低速原子比例进一步提高到4.8%。在560 ms的装载时间内,一级冷却阶段俘获了8.0×10^(5)的87Sr原子,为实现高性能的小型化锶原子光钟提供了参考。Objective In strontium atomic optical clock experiments,hot atoms emitted from the Sr oven need to undergo precooling by a Zeeman decelerator and a transverse cooling device, which often results in a larger size for the optical clocksystem. To reduce the size of the optical clock system, we have integrated the Zeeman decelerator and transverse cooling deviceon the basis of ensuring the precooling effect.Methods Previously, we utilized 40 small magnets to design a permanent magnet array Zeeman decelerator with an overall lengthof 95 mm. By mounting three reflecting mirrors on the frame of the Zeeman decelerator, beam of 461 nm laser can create twopairs of mutually perpendicular transverse cooling beams across the cross-section of the decelerator, thereby achieving the integrationof transverse cooling and the Zeeman decelerator. Furthermore, it was observed that at the axial magnetic field null pointof the Zeeman decelerator, there exists a radial gradient magnetic field of approximately 27 G/cm. By installing reflecting mirrorsat this location, a transverse cooling device based on a two-dimensional magneto-optical trap (2D MOT) can be constructed.Results and Discussions To ensure the performance of the Zeeman deceleration, we simulated the motion of atoms within theZeeman decelerator, calculated the proportion of low-speed atoms below 50 m/s, and compared it with experimental results.According to the simulation, transverse cooling can increase the proportion of low-speed atoms by a factor of 2.56. In the experiment,for hot atoms ejected from a Sr oven at 410 ℃, the proportion of low-speed atoms was 0.5%. After the Zeeman decelerationprocess without transverse cooling, the proportion of low-speed atoms increased to 2.4%. Furthermore, after undergoing bothZeeman deceleration and transverse cooling processes, the proportion of low-speed atoms was further increased to 4.8%. Thisdemonstrates that the 2D MOT-style transverse cooling device integrated within the decelerator can significantly enhance theeffect of Zeeman

关 键 词：锶原子光钟 小型化原子源 塞曼减速器 横向冷却 

分 类 号：O562[理学—原子与分子物理]