An Evaluation of the Zeeman Shift of the ⁸⁷Sr Optical Lattice Clock at the National Time Service Center

• Main Authors: Xiaotong Lu, Mojuan Yin, Ting Li, Yebing Wang, Hong Chang
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Applied Sciences
• Subjects: zeeman shift; optical lattice clocks; strontium atoms; optical lattices; laser cooling and trapping
• Online Access: https://www.mdpi.com/2076-3417/10/4/1440
• ISSN: 2076-3417

The Zeeman shift plays an important role in the evaluation of optical lattice clocks since a strong bias magnetic field is applied for departing Zeeman sublevels and defining a quantization axis. We demonstrated the frequency correction and uncertainty evaluation due to Zeeman shift in the ⁸⁷Sr optical lattice clock at the National Time Service Center. The first-order Zeeman shift was almost completely removed by stabilizing the clock laser to the average frequency of the two Zeeman components of <i>m</i>_F = &#177;9/2. The residual first-order Zeeman shift arose from the magnetic field drift between measurements of the two stretched-state center frequencies; the upper bound was inferred as 4(5) &#215; 10^&#8722;18. The quadratic Zeeman shift coefficient was experimentally determined as &#8722;23.0(4) MHz/T² and the final Zeeman shift was evaluated as 9.20(7) &#215; 10^&#8722;17. The evaluation of the Zeeman shift is a foundation for overall evaluation of the uncertainty of an optical lattice clock. This measurement can provide more references for the determination of the quadratic coefficient of ⁸⁷Sr.