title: Accurate measurement of the 12.6 GHz "clock" transition in trapped (171)Yb(+) ions.
abstract: We have measured the frequency of the (171)Yb(+) 12.6 GHz M(F)=0-->0 ground state hyperfine "clock" transition in buffer gas-cooled ion clouds confined in two similar, but not identical, linear Paul traps. After correction for the known differences between the two ion traps, including significantly different second-order Doppler shifts, the frequencies agree within an uncertainty of less than 2 parts in 10(13). Our best value, based on an analytic model for the second-order Doppler shift, for the frequency of the clock transition of an isolated ion at zero temperature, velocity, electric field and magnetic field, is 12642812118.466+0.002 Hz.
authors.affiliation: Nat. Meas. Lab., CSIRO, Lindfield, NSW.
authors.forename: P H
authors.initials: PH
authors.lastname: Fisk
authors.forename: M J
authors.initials: MJ
authors.lastname: Sellars
authors.forename: M A
authors.initials: MA
authors.lastname: Lawn
authors.forename: G
authors.initials: G
authors.lastname: Coles