Optical state selection process with optical pumping in a cesium atomic fountain clock

• Published in: Chinese physics B Vol. 30; no. 8; pp. 80602 - 308
• Main Authors: Han, Lei, Fang, Fang, Chen, Wei-Liang, Liu, Kun, Zuo, Ya-Ni, Zheng, Fa-Song, Dai, Shao-Yang, Li, Tian-Chu
• Format: Journal Article
• Language: English
• Published: Key Laboratory of Time and Frequency Standards,National Institute of Metrology (NIM),Beijing 100029,China 01.07.2021; School of Optics and Photonics,Beijing Institute of Technology,Beijing 100081,China%Key Laboratory of Time and Frequency Standards,National Institute of Metrology (NIM),Beijing 100029,China%School of Optics and Photonics,Beijing Institute of Technology,Beijing 100081,China
• Subjects: atomic fountain clock; spin polarization; optical state selection; optical pumping
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/ac0698

We propose and realize a new optical state selection method on a cesium atomic fountain clock by applying a two-laser 3–3′ optical pumping configuration to spin polarize atoms. The atoms are prepared in | F = 3, m F = 0〉 clock state with optical pumping directly after being launched up, followed by a pushing beam to push away the atoms remaining in the | F = 4〉 state. With a state selection efficiency exceeding 92%, this optical method can substitute the traditional microwave state selection, and helps to develop a more compact physical package. A Ramsey fringe has been achieved with this optical state selection method, and a contrast of 90% is obtained with a full width half maximum of 0.92 Hz. The short-term frequency stability of 6.8 × 10 −14 ( τ / s ) −1/2 is acquired. In addition, the number of detected atoms is increased by a factor of 1.7 with the optical state selection.