Author Affiliations

J.E. Stalnaker,¹ S.A. Diddams,¹ T.M. Fortier,^1,2 V. Gerginov,¹ Y. Le Coq,¹ V. Mbele,^1,3 C.W. Oates,¹ D. Ortega,⁴ C.E. Tanner,⁵ and L. Hollberg¹

¹National Institute of Standards and Technology, Time and Frequency Division MS 847, 325 Broadway, Boulder, CO 80305

²Los Alamos National Laboratory, P-23 Physics Division MS H803, Los Alamos, NM 87545

³CSIR, NML, P.O. Box 395, Pretoria, ZA-0001, South Africa; School of Physics, University of the Witwatersrand, Johannesburg, ZA-2050, South Africa

⁴Gleb Wataghin Physics Institute, State University of Campinas (UNICAMP) C.P. 6165 Campinas, SP 13083-970 Brazil

⁵University of Notre Dame, Department of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556-5670