Frequency comparison of two high-accuracy Al+ optical clocks.
We have constructed an optical clock with a fractional frequency inaccuracy of 8.6x10{-18}, based on quantum logic spectroscopy of an Al+ ion. A simultaneously trapped Mg+ ion serves to sympathetically laser cool the Al+ ion and detect its quantum state. The frequency of the {1}S{0}<-->{3}P{0} clock transition is compared to that of a previously constructed Al+ optical clock with a statistical measurement uncertainty of 7.0x10{-18}. The two clocks exhibit a relative stability of 2.8x10{-15}tau{-1/2}, and a fractional frequency difference of -1.8x10{-17}, consistent with the accuracy limit of the older clock.
Chou
C W
CW
Time and Frequency Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA. chinwen@nist.gov
Hume
D B
DB
Koelemeij
J C J
JC
Wineland
D J
DJ
Rosenband
T
T