2005/02/22 by S. Bize, Ph. Laurent, P. Laurent +21 · 230 citations
Engineering · Physics and Astronomy · #Advanced Frequency and Time Standards #Aerospace engineering #Atomic and Subatomic Physics Research #Atomic clock #Atomic physics #Cold Atom Physics and Bose-Einstein Condensates #Electrical engineering #Engineering #Frequency standard #International Space Station #Microwave #Optics #Physics #Quantum #Quantum mechanics #Ultracold atom #physics.atom-ph
paper · pdf · doi:10.1088/0953-4075/38/9/002
published in Journal of Physics B Atomic Molecular and Optical Physics 38(9), S449-S468 (IOP Publishing) · 30 pages, 11 figures
arxiv created 2005/02/22 · openalex publication_date 2005/04/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
This paper describes advances in microwave frequency standards using laser-cooled atoms at BNM-SYRTE. First, recent improvements of the 133 Cs and 87 Rb 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 τ −1/2 where τ 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 87 Rb and 133 Cs 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.