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A single-atom optical clock with high accuracy

Published

Author(s)

Windell Oskay, Scott A. Diddams, Elizabeth A. Donley, Tara M. Fortier, Thomas P. Heavner, Leo W. Hollberg, Wayne M. Itano, Steven R. Jefferts, M J. Jensen, Kyoungsik Kim, F Levi, Thomas E. Parker, James C. Bergquist

Abstract

For the past fifty years, atomic frequency standards based on the cesium ground-state hyperfine splitting have been the most accurate timepieces in the world. One of the most accurate, current-generation, cesium standards is the NIST-F1 fountain, which has recently been evaluated with an inaccuracy of about 4×10−16. However, it has long been recognized that a frequency standard based upon an atomic optical transition has the potential for both accuracy and stability substantially better than that of a cesium standard. We now report a comparison between NIST-F1 and our optical frequency standard based on an ultraviolet transition in a single, laser-cooled, trapped mercury ion. In this comparison, the fractional systematic frequency uncertainty of the mercury standard was below 1.2×10−16 and the absolute frequency of the transition was measured versus cesium to be 1 064 721 609 899 144.94 (97) Hz, with a statistically limited total fractional uncertainty of 9.1×10−16. This result is not only the most accurate absolute measurement of an optical frequency to date, but also demonstrates conclusively that frequency control in the mercury-ion system is possible at a level superior to that of the best present-day cesium frequency standards.
Citation
Physical Review Letters
Volume
97

Keywords

atomic clock, cesium fountain, femtosecond laser frequency comb, mercury-ion frequency standard, optical frequency standard, single-ion frequency standard, trapped ions
Created July 14, 2006, Updated January 27, 2020