A Liquid-Nitrogen-Cooled Ca+ Ion Optical Clock with a Systematic Uncertainty of 4.4E-19
Abstract
We report a single-ion optical clock based on the 4S_1/2-3D_5/2 transition of the 40Ca+ ion, operated in a liquid nitrogen cryogenic environment,achieving a total systematic uncertainty of 4.4E-19. We employ a refined temperature evaluation scheme to reduce the frequency uncertainty due to blackbody radiation (BBR), and the 3D sideband cooling has been implemented to minimize the second-order Doppler shift. We have precisely determined the average Zeeman coefficient of the 40Ca+ clock transition to be 14.345(40) Hz/mT^2, thereby significantly reducing the quadratic Zeeman shift uncertainty. Moreover, the cryogenic environment enables the lowest reported heating rate due to ambient electric field noise in trapped-ion optical clocks.
Keywords
Cite
@article{arxiv.2506.17423,
title = {A Liquid-Nitrogen-Cooled Ca+ Ion Optical Clock with a Systematic Uncertainty of 4.4E-19},
author = {Baolin Zhang and Zixiao Ma and Yao Huang and Huili Han and Ruming Hu and Yuzhuo Wang and Huaqing Zhang and Liyan Tang and Tingyun Shi and Hua Guan and Kelin Gao},
journal= {arXiv preprint arXiv:2506.17423},
year = {2025}
}
Comments
12 pages, 14 figures