Alpha-Dot or Not: Comparison of Two Single Atom Optical Clocks

Published

October 5, 2008

Author(s)

Till P. Rosenband, David Hume, Chin-Wen Chou, J.C. Koelemeij, A. Brusch, Sarah Bickman, Windell Oskay, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Nathan R. Newbury, William C. Swann, Wayne M. Itano, David J. Wineland, James C. Bergquist

Abstract

Repeated measurements of the frequency ratio of Hg⁺ and Al⁺ single-atom optical clocks over the course of a year yield a constraint on the possible temporal variation of the fine-structure constant a. The time variation of the measured ratio corresponds to a time variation in the fine structure constant of α-dot/α=(-1.6 ± 2.3) × 10^-17, which is consistent with no change. The frequency ratio of these clocks was measured with a fractional uncertainty of 5.2 × 10^-17. Stability simulations for optical clocks whose probe time is limited by 1/f-noise in the laser local oscillator yield an estimate of the optimal probe time, as well as a modified expression for the theoretical clock stability.

Proceedings Title

Proc. 2008 Symposium on Frequency Standards and Metrology

Conference Dates

October 5-11, 2008

Conference Location

Pacific Grove, CA

Pub Type

Conferences

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Keywords

optical clocks, atomic clocks, trapped ions

Citation

Rosenband, T. , Hume, D. , Chou, C. , Koelemeij, J. , Brusch, A. , Bickman, S. , Oskay, W. , Fortier, T. , Stalnaker, J. , Diddams, S. , Newbury, N. , Swann, W. , Itano, W. , Wineland, D. and Bergquist, J. (2008), Alpha-Dot or Not: Comparison of Two Single Atom Optical Clocks, Proc. 2008 Symposium on Frequency Standards and Metrology, Pacific Grove, CA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=901534 (Accessed October 20, 2025)