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Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place



Till P. Rosenband, David Hume, P. O. Schmidt, Chin-Wen Chou, Anders Brusch, Luca Lorini, Windell Oskay, Robert E. Drullinger, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Nathan R. Newbury, W Swann, Wayne M. Itano, David J. Wineland, James C. Bergquist


We report the frequency ratio of the two most accurate and stable atomic clocks with a total fractional uncertainty of 5.2 X 10-17 . This frequency ratio is the best-known physical constant that is not a simple integer. Repeated measurements during the past year yield a preliminary constraint on the temporal variation of the fine-structure constant α of α-dot / α = (1.4{= or -}1.7)X 10-17/year. The ratio of aluminum and mercury optical clock frequencies ŅAl+Hg+ is 1.052 871 833 148 990 48(6), where the uncertainty comprises a statistical measurement uncertainty of 4.3 X 10-17, and systematic uncertainties of 1.6 X 10-17 and 2.4 X 10-17 in the mercury and aluminum frequency standards respectively.


atom trapping and cooling, quantum computation:quantum information processing, quantum superpositions, quantum-state engineering, trapped ions


Rosenband, T. , Hume, D. , Schmidt, P. , Chou, C. , Brusch, A. , Lorini, L. , Oskay, W. , Drullinger, R. , Fortier, T. , Stalnaker, J. , Diddams, S. , Newbury, N. , Swann, W. , Itano, W. , Wineland, D. and Bergquist, J. (2008), Frequency ratio of Al<sup>+</sup> and Hg<sup>+</sup> single-ion optical clocks; metrology at the 17th decimal place, Science, [online], (Accessed May 30, 2024)


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Created March 6, 2008, Updated January 27, 2020