摘要
Λ增强型灰色黏团冷却技术(Λ gray molasses cooling,Λ-GMC)已被广泛用于制备低于亚多普勒温度极限的冷原子样品实验中.本文设计搭建了宽范围、快速调谐的激光系统,其调谐范围最高可达600 MHz.基于该激光系统,于光学微腔中心通过铯原子D2 线Λ-GMC冷却辅助腰斑大小为 15 μm的交叉偶极阱中原子的装载,相比于传统的偏振梯度冷却辅助装载,原子数增加了约 4倍,原子温度由 25 μK 降低至8μK.该实验对超冷原子样品实验制备和单原子阵列俘获等研究具有重要借鉴意义.
Abstract
Λ-enhanced gray molasses cooling(Λ-GMC)technique has been widely used in experiments to prepare cold atomic samples below the sub-Doppler temperature limit.To meet the experimental requirements of cavity quantum electrodynamics systems,we design and construct a wide-range,fast-tuning laser system by integrating tapered amplifiers,fiber phase modulators,etalon,injection locking amplification techniques etc.This laser system achieves a maximum tuning range of 600 MHz and a frequency tuning speed of 5 ns.Based on this laser system,loading atom in a crossed dipole trap assisted by cesium D2 line Λ-GMC cooling in the center of the optical microcavity is studied,and various factors affecting the atom loading are mainly as follows:laser duration τ,three-dimensional magnetic fieldτ(Bx,By,Bz),single-photon detuning ∆,two-photon detuning,δ ratio of cooling beam power to repumping beam power Icool/Irep,and cooling beam power Icooling.The optimal parameters in this system are follows:τ=7 ms,δ=0.2 MHz,∆=5Γ,Icool/Irep=3,and Icool=1.2Isat.Comparing with traditional PGC-assisted loading,the number of atoms is increased about 4 times,and the atomic temperature decreases from 25 μK to 8 μK.This experiment provides important insights for preparing ultracold atomic samples and capturing single atom arrays.
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