Cold atom clocks and applications

Sébastien Bize (1, 2, 3, 4) , Philippe Laurent (1, 2, 3, 4) , Michel Abgrall (1, 2, 3, 4) , Harold Marion (1, 2, 3, 4) , Ivan Maksimovic (1, 2, 3, 4) , Luigi Cacciapuoti (1, 2, 3, 4) , Jan Grünert (1, 2, 3, 4) , Céline Vian (1, 2, 3, 4) , Franck Pereira dos Santos (1, 2, 3, 4) , Peter Rosenbusch (1, 2, 3, 4) , Pierre Lemonde (1, 2, 3, 4) , Giorgio Santarelli (1, 2, 3, 4) , Peter Wolf (1, 2, 3, 4) , André Clairon (1, 2, 3, 4) , André N. Luiten (5) , Michael E. Tobar (5) , Christophe Salomon (6)

1 SYRTE - Systèmes de Référence Temps Espace
2 Métrologie des fréquences optiques
3 Références micro-ondes et échelles de temps
4 Théorie et métrologie
5 School of Physics, University of Western Australia
6 LKB (Lhomond) - Laboratoire Kastler Brossel

This paper describes advances in microwave frequency standards using laser-cooled atoms at BNM-SYRTE. First, recent improvements of the ¹³³Cs and ⁸⁷Rb atomic fountains are described. Thanks to the routine use of a cryogenic sapphire oscillator as an ultra-stable local frequency reference, a fountain frequency instability of 1.6 × 10^-14 tau^-1/2 where tau is the measurement time in seconds is measured. The second advance is a powerful method to control the frequency shift due to cold collisions. These two advances lead to a frequency stability of 2 × 10^-16 at 50 000 s for the first time for primary standards. In addition, these clocks realize the SI second with an accuracy of 7 × 10^-16, one order of magnitude below that of uncooled devices. In a second part, we describe tests of possible variations of fundamental constants using ⁸⁷Rb and ¹³³Cs fountains. Finally we give an update on the cold atom space clock PHARAO developed in collaboration with CNES. This clock is one of the main instruments of the ACES/ESA mission which is scheduled to fly on board the International Space Station in 2008, enabling a new generation of relativity tests.

Domaines: Astrophysique [astro-ph]

Sébastien Bize, Philippe Laurent, Michel Abgrall, Harold Marion, Ivan Maksimovic, et al.. Cold atom clocks and applications. Journal of Physics B: Atomic, Molecular and Optical Physics, 2005, 38, pp.449. ⟨10.1088/0953-4075/38/9/002⟩. ⟨hal-03732879⟩