TY - JOUR

T1 - Advances in atomic fountains

AU - Bize, S.

AU - Laurent, P.

AU - Abgrall, M.

AU - Marion, H.

AU - Maksimovic, I.

AU - Cacciapuoti, L.

AU - Grunert, J.

AU - Vian, C.

AU - Pereira Dos Santos, F.

AU - Rosenbusch, P.

AU - Lemonde, P.

AU - Santarelli, G.

AU - Wolf, P.

AU - Clairon, A.

AU - Luiten, Andre

AU - Tobar, Michael

AU - Salomon, C.

PY - 2004

Y1 - 2004

N2 - This article describes the work performed at BNM-SYRTE (Observatoire de Paris) in the past few years, toward the improvement and the use of microwave frequency standards using laser-cooled atoms. First, recent improvements of the Cs-133 and Rb-87 atomic fountains are described. An important advance is the achievement of a fractional frequency instability of 1.6 x 10(-14)tau(-1/2) where tau is the measurement time in seconds, thanks to the routine use of a cryogenic sapphire oscillator as an ultra-stable local frequency reference. The second advance is a powerful method to control the frequency shift due to cold collisions. These two advances lead to a fractional frequency in stability of 2 x 10(-16) at 50000 s between two independent primary standards. In addition, these clocks realize the SI second with an accuracy of 7 x 10(-16), one order of magnitude below that of uncooled devices. Tests of fundamental physical laws constitute an important field of application for highly accurate atomic clocks. In a second part, we describe tests of possible variations of fundamental constants using Rb-87 and Cs-133 fountains. The third part is 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 will fly on board the International Space Station in 2007-2008, enabling a new generation of relativity tests. (c) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

AB - This article describes the work performed at BNM-SYRTE (Observatoire de Paris) in the past few years, toward the improvement and the use of microwave frequency standards using laser-cooled atoms. First, recent improvements of the Cs-133 and Rb-87 atomic fountains are described. An important advance is the achievement of a fractional frequency instability of 1.6 x 10(-14)tau(-1/2) where tau is the measurement time in seconds, thanks to the routine use of a cryogenic sapphire oscillator as an ultra-stable local frequency reference. The second advance is a powerful method to control the frequency shift due to cold collisions. These two advances lead to a fractional frequency in stability of 2 x 10(-16) at 50000 s between two independent primary standards. In addition, these clocks realize the SI second with an accuracy of 7 x 10(-16), one order of magnitude below that of uncooled devices. Tests of fundamental physical laws constitute an important field of application for highly accurate atomic clocks. In a second part, we describe tests of possible variations of fundamental constants using Rb-87 and Cs-133 fountains. The third part is 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 will fly on board the International Space Station in 2007-2008, enabling a new generation of relativity tests. (c) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

U2 - 10.1016/j.crhy.2004.09.003

DO - 10.1016/j.crhy.2004.09.003

M3 - Article

VL - 5

SP - 829

EP - 843

JO - Comptes Rendus Physique

JF - Comptes Rendus Physique

SN - 1296-2147

IS - 8

ER -