Comptes Rendus
The optical calcium frequency standards of PTB and NIST
Comptes Rendus. Physique, Volume 5 (2004) no. 8, pp. 845-855.

We describe the current status of the Ca optical frequency standards with laser-cooled neutral atoms realized in two different laboratories for the purpose of developing a possible future optical atomic clock. Frequency measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST) make the frequency of the clock transition of 40Ca one of the best known optical frequencies (relative uncertainty 1.2×10−14) and the measurements of this frequency in both laboratories agree to well within their respective uncertainties. Prospects for improvement by orders of magnitude in the relative uncertainty of the standard look feasible.

Nous décrivons le présent état de l'art des étalons de fréquence optique avec des atomes neutres de Ca refroidis par laser, réalisés dans deux différents laboratoires, dans le but de développer éventuellement une future horloge atomique dans le domaine optique. Les mesures de fréquences réalisées à la Physikalisch-Technische Bundesanstalt (PTB) et au National Institute of Standards and Technology (NIST) ont permis d'établir la fréquence d'horloge du 40Ca parmi les fréquences optiques les mieux connues (avec une exactitude relative de 1.2×10−14), ces mesures de fréquence étant en bon accord dans les deux laboratoires dans la limite de leur incertitude respective. Potentiellement, une amélioration par plusieurs ordres de grandeur de l'exactitude relative de l'étalon semble possible.

Published online:
DOI: 10.1016/j.crhy.2004.08.005
Keywords: Optical frequency standard, Atomic clock, Laser spectroscopy
Mot clés : Étalons de fréquence optique, Horloge atomique, Spectroscopie laser

U. Sterr 1; C. Degenhardt 1; H. Stoehr 2; Ch. Lisdat 2; H. Schnatz 1; J. Helmcke 1; F. Riehle 1; G. Wilpers 3; Ch. Oates 3; L. Hollberg 3

1 Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
2 Institut für Quantenoptik, Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
3 National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
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U. Sterr; C. Degenhardt; H. Stoehr; Ch. Lisdat; H. Schnatz; J. Helmcke; F. Riehle; G. Wilpers; Ch. Oates; L. Hollberg. The optical calcium frequency standards of PTB and NIST. Comptes Rendus. Physique, Volume 5 (2004) no. 8, pp. 845-855. doi : 10.1016/j.crhy.2004.08.005.

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