光晶格中镱原子的拉曼边带冷却

Raman Sideband Cooling of Ytterbium Atom in Optical Lattice

为了对光晶格中的镱(Yb)原子进一步降温,系统地介绍拉曼边带冷却的原理和方法;为了有效评估边带冷却的效果,利用边带谱来获得原子温度信息;171Yb原子被囚禁在一维光晶格中后,利用波长分别为578、1388、556nm的冷却光、回泵光、极化光3束激光同时作用在原子上来实现原子振动能态的降低,利用578nm的钟激光探询原子的1s0→3p0跃迁,通过扫描钟激光的频率得到运动边带谱,并通过拟合边带谱得到原子温度。结果表明:经过拉曼边带冷却后,晶格中原子的温度从24μK降到了10μK;原子温度的降低可以抑制原子间的碰撞频移,有利于获得赫兹量级的超窄钟跃迁谱。

To decrease the temperature of ytterbium (Yb) atom trapped in optical lattice,the principle and method of Raman sideband cooling were introduced.The temperature of atoms was decreased from sideband spectrum to evaluate the effect of sideband cooling.After the 171 Yb fermion isotope atoms were loaded into the lattice,three different laser beams of clock laser,polarization laser,and repumping laser at 578,1 388,556 nm were used to proceed the sideband cooling process,so that the vibrational state was further degraded.The motional sideband spectrum with the typical carrier-sideband structure was obtained with the interrogation of 1s 0→ 3p 0 clock transition with 578 nm clock laser.The atomic temperature was decreased from the sideband spectrum.The results show the atomic temperature decreases from 24 μK to 10 μK after sideband cooling.The even lower temperature of the cold atom is of great benefit for depressing the collision shift and Hertz level clock transition spectrum.