基于超冷原子分子的高精密频梳光谱研究

The research of high-precision frequency comb spectroscopy is very important in fields of laser precision spectroscopy, trace-gas detection and quantum control. Based on ultracold cesuim atoms and moleculs, the high resoltion frequency comb spectroscopy of high excited ultracold cesium atoms will be obtained by two-photon transition. The non-coherent processes among atoms will be suppressed and coherent population of high excited states will be realized by control femtosecond frequency comb parameters such as interval between two pulses, pulse phase offset and number of pluses. The absolute frequencies of corresponding hyperfine transition of atom will be measured. The narrow-band Raman transition between molecular Rovibrational level will be realized by action of coherent pump-dump ultrashort pulse chain on weak bound state molecule which formed by photoassociation.The dynamic processes of ultracold molecules will be coherently controlled with aim to form deeply bound, ultracold molecules. The coherent control ultrofast of ultracold molecules and the high resolution, non-linear resonance excitement techniques of molecules in both time and frequency domains will be developed. The new mechanisms of quantum information based on interaction between femtosecond frequency comb and ultracold atoms and molecules will be explored.

高精密频梳光谱的研究对于激光精密光谱学、痕量气体探测和量子操控方面等具有很重要的意义。本课题旨在超冷铯原子分子系统上，一方面利用双光子跃迁获取高分辨的超冷原子高激发态频梳光谱。通过控制飞秒光学频率梳的脉冲间隔、相位、脉冲数等参数实现对原子非相干过程的抑制，实现冷原子在高激发态的相干布居，计算对应超精细跃迁的绝对频率。另一方面利用光学整形后的相干pump-dump超短脉冲链作用在光缔合制备的弱束缚态分子上，实现分子振转能级间的窄带拉曼跃迁，相干操控超冷分子动力学过程，制备深束缚态的超冷分子，获取基态分子的高精密频梳光谱。通过相干操控超冷分子超快过程，发展时域和频域高分辨的分子非线性共振激发的技术。探索飞秒光学频率梳和超冷原子分子相互作用在量子信息处理上的新机制。

本项目建立了一套运行稳定、并能实现高分辨探测的实验系统，在此系统中开展了超冷原子分子制备及其精密光谱的研究。理论上利用半经典理论建立超冷原子分子系统的量子相干模型，解决不同激发态相干布居、不同原子态（原子态和分子态）之间量子相干和飞秒激光脉冲常数的关系。实验上通过飞秒光学频率梳和超冷原子相互作用，利用双光子跃迁获取高分辨的超冷原子频梳光谱，得到了铷原子高激发态超精细结构常数及超精细跃迁的绝对频率。利用光学整形后飞秒脉冲链和弱束缚态的超冷分子相互作用，制备振转能级可控的强束缚态超冷分子，实现超冷分子动力学过程的操控，获取超冷分子的高精密光谱。本课题的相关研究成果对于精密光谱、痕量气体探测和量子操控方面等具有很重要的意义。