【作者】 王强；

【导师】 方占军；

【作者基本信息】 中国计量科学研究院 ， 测试计量技术与仪器， 2010， 硕士

【摘要】 基于激光冷却和囚禁的铯原子喷泉钟是目前准确度最高的时间频率基准,其频率不确定度已经进入10-16量级。而激光冷却中性原子或单离子光钟有潜力实现10-18的量级,比目前最好的喷泉钟高100倍以上。2006年第17届CCTF会议将锶原子的5s21S1-5s5p3P0作为时间频率的次级秒定义之一。在不远的将来,有可能代替铯原子频率标准成为更加先进的时间频率秒定义。锶原子的冷却和囚禁是锶光钟研究中最基础也是最重要的一步。实验中,用锶原子单重态1S0-1P1的跃迁作为初级冷却,跃迁线宽约32 MHz,所对应激光为波长461nm的蓝光。利用原子的激光冷却和囚禁技术,用自旋翻转型塞曼减速器成功将大量锶原子从速度400 m／s以上冷却到速度50 m／s以下,并用磁光阱囚禁了锶原子,形成蓝MOT原子团。再加入二维准直、重泵浦激光后MOT中囚禁的原子数有10倍以上的增加。经过实验测量得到蓝MOT中的原子寿命为355 ms,原子数为108,温度为2-3mK。在461 nm激光冷却和囚禁的基础上,成功实现锶原子689 nm激光的红冷却,形成红MOT,并用吸收成像法拍照；初步估计原子从蓝MOT向红MOT的转移效率为20%；用荧光的飞行时间图像法初步测量红MOT原子团的温度为18μK。更多还原

【Abstract】 Laser cooling and trapping Cs fountain clock with a frequency uncertainty of 10"15 is cuurently the most accurate primary frequency standard. Optical clock has the potential to reach an uncertainty of 10-18, more than 100 times better. In the 17th CCTF, the 5s2 1S1-5s5p 3P0 transition of Strontium atom was recommended to be one of the secondary definition of the SI base unit "second". Most possibly, the Cs fountain clock time and frequency standard will be re-defined with the optical clock in the near future.This thesis summarizes our preliminary experiments about laser cooling and trapping of Strontium atoms, which are very important steps for the study of strontium optical lattice clock. The 1S0-1P1 transition which is used to pre-cool the strontium atoms has a natural linewidth of about 32 MHz, and the wavelenth is about 461 nm. The atoms beam is slowed down from 400 m/s to less than 50 m/s with a spin-flip Zeeman slower. The slow atoms are trapped in the blue Magneto-Optical Trap (blue MOT), and the atoms number in the trap is 10 times more with 2D collimation laser and repumping lasers. There are more than 108 atoms in the trap with a lifetime about 355 ms. The temperature measured with Time-Of-Fight (TOF) method is about 2-3 mK. About 20% atoms in the blue MOT are transferred to the red MOT with 689 nm laser. The atom cloud images are taken by a normal CCD with absorption imaging method and by an EMCCD with fluorescence imaging method. The TOF method is used to calculate the temperature of the atoms in the red Mot, the approximate temperature is about 18μK.更多还原