锶玻色子的“魔术”波长光晶格装载实验研究  

Experimental research on loading strontium bosons into the optical lattice operating at the“magic”wavelength

作　　者：田晓[1,2] 王叶兵[1] 卢本全[1,2] 刘辉[1,2] 徐琴芳[1] 任洁[1] 尹默娟 孔德欢[1] 常宏[1] 张首刚[1] 

机构地区：[1]中国科学院国家授时中心时间频率基准重点实验室,西安710600 [2]中国科学院大学,北京100049

出　　处：《物理学报》2015年第13期40-47,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61127901,11474282)资助的课题~~

摘　　要：光晶格中性原子光钟的不确定度已达到10-18量级.本文介绍了碱土金属锶原子玻色子88Sr在"魔术"波长处的一维光晶格装载,实现冷锶原子的囚禁并使锶原子的钟跃迁能级(5s2)1S0—(5s5p)3P0在此波长处的交流斯塔克光频移一致.实验中半导体激光器产生"魔术"光波长(813 nm),通过实验搭建光学驻波场并获得晶格激光聚焦光束,束腰半径为38μm.经过一级冷却和二级冷却后温度约为2μK的冷锶原子被此"魔术"波长光晶格囚禁.通过实验测量得到锶原子玻色子88Sr光晶格寿命为270 ms,数目约为1.2×105,温度在3.5μK左右,此外研究了晶格光功率对晶格囚禁原子数目及温度的影响作用.原子的光晶格装载为后续的钟跃迁提供了长的探测时间,为进一步的光钟闭环提供了实验基础.The optical lattice clock with neutral atoms occupies an outstanding position in the research field of atomic clocks, demonstrating the great potential of its performance （like the uncertainty and the stability）. At present, the optical lattice clock has realized a 10？18 level of its uncertainty. In this paper, we present the realization of loading bosonic atoms 88Sr （strontium, alkaline-earth metals） into a one-dimensional （1D） optical lattice in our laboratory. The optical lattice where the atoms are trapped can make the energy level shift, called Stark shift. But there is the special optical lattice operating at the“magic”wavelength for clock transitions （5s2） 1S0—（5s5p） 3P0, which can make the same Stark light-shift for both of them, indicating a zero light-shift relative to the clock. In our experiment, Sr atoms are cooled in a two-stage cooling and its temperature can be as low as 2 μK. Then these cold atoms are confined in the Lamb-Dicke region by the lattice laser output from an amplified diode laser operating at the “magic” wavelength, 813 nm. Experimentally, it is straightforward to provide 850 mW of lattice power focused to a 38 μm beam radius. After the cold atoms have trapped in the optical lattice, the lifetime of atoms in 1D optical lattice is measured to be 270 ms. The temperature and the number are about 3.5 μK and 1.2 × 105 respectively. Besides, effects of the power of the lattice laser on both the number and temperature are analyzed. The number changes linearly with the laser power, while there is no obvious influence on the temperature by the power. This original and special approach for atoms trapped in the optical lattice can provide a long interrogation time for probing the clock transition. Furthermore, it may be the foundation for developing our optical lattice clock of strontium atoms.

关 键 词：光钟 冷原子 魔术波长 光晶格 

分 类 号：O562[理学—原子与分子物理]