8 research outputs found
Linear Paul trap design for an optical clock with Coulomb crystals
We report on the design of a segmented linear Paul trap for optical clock
applications using trapped ion Coulomb crystals. For an optical clock with an
improved short-term stability and a fractional frequency uncertainty of 10^-18,
we propose 115In+ ions sympathetically cooled by 172Yb+. We discuss the
systematic frequency shifts of such a frequency standard. In particular, we
elaborate on high precision calculations of the electric radiofrequency field
of the ion trap using the finite element method. These calculations are used to
find a scalable design with minimized excess micromotion of the ions at a level
at which the corresponding second- order Doppler shift contributes less than
10^-18 to the relative uncertainty of the frequency standard
Absolute frequency measurement of the In clock transition with a mode-locked laser
The absolute frequency of the In -
clock transition at 237 nm was measured with an accuracy of 1.8 parts in
. Using a phase-coherent frequency chain, we compared the
- transition with a methane-stabilized He-Ne laser at 3.39 m
which was calibrated against an atomic cesium fountain clock. A frequency gap
of 37 THz at the fourth harmonic of the He-Ne standard was bridged by a
frequency comb generated by a mode-locked femtosecond laser. The frequency of
the In clock transition was found to be
kHz, the accuracy being limited by the uncertainty of the He-Ne laser
reference. This represents an improvement in accuracy of more than 2 orders of
magnitude on previous measurements of the line and now stands as the most
accurate measurement of an optical transition in a single ion.Comment: 3 pages, 2 figures. accepted for publication in Opt. Let