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A: Atomphysik
A 11: Ultrakalte Atomphysik III
A 11.1: Vortrag
Mittwoch, 15. März 2006, 10:40–10:55, H6
Atomic fountain clocks: recent results — •P. Rosenbusch1, S. Bize1, F. Chapelet1, Ph. Laurent1, H. Marion1, C. Vian1, Ch. Salomon2, and A. Clairon1 — 1SYRTE, Observatoire de Paris, FRANCE — 2LKB, ENS, Paris, FRANCE
In 1967 the second was defined through the hyperfine transition of 133Cs. Since then much effort has been spend on realising a macroscopic, usable clock signal. The best approach today are atomic fountain clocks, regularly serving as primary standards. About 109 atoms are laser cooled to 1µK and launched up vertically. On their way up and down the atoms pass through a microwave cavity, where they interact with a reference microwave signal for about 12 ms. The duration between the two interactions is typically 0.5 s. This Ramsey interrogation leads to a 1 Hz FWHM of the central fringe [1].
In this conference we will present recent improvements on the 3 fountains operated by SYRTE and discuss their clock performances. We will demonstrate a relative clock stability of near to 1· 10−14 at 1 s and an accuracy of a few 10−16. We give details on the first direct comparison between two fountain clocks having a stability of 6·10−14 at 1 s [2]. Clock comparisons between Cs and Rb test the possible variation of fundamentals constants such as α. We find no variation of α above 7· 10−17/year [1,3].
[1] S. Bize et al., C. R. Physique 5, 829 (2004); S. Bize et al., J. Phys. B: At. Mol. Opt. Phys. 38, S449 (2005)
[2] C. Vian et al., IEEE Trans. Instrum. Meas. 54, 833 (2005)
[3] H. Marion et al., Phys. Rev. Lett. 90, 150801 (2003)