Chinese Science Bulletin

, Volume 58, Issue 8, pp 853–863 | Cite as

Optical frequency standard based on a single 40Ca+

  • KeLin GaoEmail author
Open Access
Invited Article Atomic & Molecular Physics


Research on the development of the optical frequency standard based on trapped and cold 40Ca+ with the 4s 2S1/2-3d 2D5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10−16. The absolute frequency of the clock transition was measured at 10−15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.


optical frequency standard single calcium ion systematic uncertainty absolute frequency measurement 


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© The Author(s) 2013

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors and Affiliations

  1. 1.State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Atomic Frequency Standards, Wuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhanChina

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