Measurement of the Hydrogen <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi mathvariant="italic">S</mi></math></span>- <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi mathvariant="italic">S</mi></math></span> Transition Frequency by Phase Coherent Comparison with a Microwave Cesium Fountain Clock

M. Niering; R. Holzwarth; J. Reichert; P. Pokasov; Th. Udem; M. Weitz; T. W. Hänsch; P. Lemonde; G. Santarelli; M. Abgrall; P. Laurent; C. Salomon; A. Clairon

doi:10.1103/PhysRevLett.84.5496

Measurement of the Hydrogen $1 S$ - $2 S$ Transition Frequency by Phase Coherent Comparison with a Microwave Cesium Fountain Clock

M. Niering, R. Holzwarth, J. Reichert, P. Pokasov, Th. Udem, M. Weitz, T. W. Hänsch, P. Lemonde, G. Santarelli, M. Abgrall, P. Laurent, C. Salomon, and A. Clairon

Phys. Rev. Lett. 84, 5496 – Published 12 June 2000

Abstract

We report on an absolute frequency measurement of the hydrogen $1 S - 2 S$ two-photon transition in a cold atomic beam with an accuracy of 1.8 parts in $10^{14}$ . Our experimental result of 2 466 061 413 187 103(46) Hz has been obtained by phase coherent comparison of the hydrogen transition frequency with an atomic cesium fountain clock. Both frequencies are linked with a comb of laser frequencies emitted by a mode locked laser.

Received 6 March 2000

DOI:https://doi.org/10.1103/PhysRevLett.84.5496

Authors & Affiliations

M. Niering, R. Holzwarth, J. Reichert, P. Pokasov^*, Th. Udem, M. Weitz, and T. W. Hänsch

Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany

P. Lemonde¹, G. Santarelli¹, M. Abgrall¹, P. Laurent¹, C. Salomon², and A. Clairon¹

¹BNM-LPTF, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France
²Laboratoire Kastler Brossel, ENS, 24 rue Lhomond, 75005 Paris, France