Improvement of the short-term stability of atomic fountain clock with state preparation by two-laser optical pumping

• Published in: Chinese physics B 2021-05, Vol.30 (5), p.50602-310
• Main Authors: Han, Lei, Fang, Fang, Chen, Wei-Liang, Liu, Kun, Dai, Shao-Yang, Zuo, Ya-Ni, Li, Tian-Chu
• Format: Article
• Language: English
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/abe22a

To improve the signal to noise ratio (SNR) and the short-term stability of cesium atomic fountain clocks, the work of two-laser optical pumping is presented theoretically and experimentally. The short-term stability of the NIM6 fountain clock has been improved by preparing more cold atoms in the | F = 4, m F = 0〉 clock state with a shortened cycle time. Two π -polarized laser beams overlapped in the horizontal plane have been applied after launching, one is resonant with | F = 4〉 → | F ′ = 4〉 transition and the other is resonant with | F = 3〉 → | F ′ = 4〉 transition. With optical pumping, the population accumulated in the | m F = 0〉 clock state is improved from 11% to 63%, and the detection signal is increased by a factor of 4.2, the SNR of the clock transition probability and the short-term stability are also improved accordingly.