Search for variations of fundamental constants using atomic fountain clocks.
Over five years, we have compared the hyperfine frequencies of 133Cs and 87Rb atoms in their electronic ground state using several laser-cooled 133Cs and 87Rb atomic fountains with an accuracy of approximately 10(-15). These measurements set a stringent upper bound to a possible fractional time variation of the ratio between the two frequencies: d/dt ln([(nu(Rb))/(nu(Cs))]=(0.2+/-7.0)x 10(-16) yr(-1) (1sigma uncertainty). The same limit applies to a possible variation of the quantity (mu(Rb)/mu(Cs))alpha(-0.44), which involves the ratio of nuclear magnetic moments and the fine structure constant.
Marion
H
H
BNM-SYRTE, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France.
Pereira Dos Santos
F
F
Abgrall
M
M
Zhang
S
S
Sortais
Y
Y
Bize
S
S
Maksimovic
I
I
Calonico
D
D
Grünert
J
J
Mandache
C
C
Lemonde
P
P
Santarelli
G
G
Laurent
Ph
P
Clairon
A
A
Salomon
C
C