Physical Review A
Kilohertz-resolution spectroscopy of the 2S1/2−2F7/2 electric octupole transition in a single 171Yb+ ion
Stephen A. Webster, Philip H. Taylor, M. Roberts, G. P. Barwood, Patrick Robert Gill
Abstract
Spectroscopy has been performed on $\mathrm{the}{}^{2}{S}_{1/2}(F=0,{m}_{F}{=0)\ensuremath{-}}^{2}{F}_{7/2}{(F=3,m}_{F}=0)$ electric octupole transition in ${}^{171}{\mathrm{Yb}}^{+}$ with kilohertz resolution. A quantum jump rate of more than one per second has been achieved, a factor of 100 improvement on previous work. Spectra including the sidebands at the trap secular frequency show the ion to be in the Lambe-Dicke regime and hence the Doppler effect has been eliminated to first order. The dynamic Stark shift is a significant perturbation to the frequency because of the high intensity required to drive the octupole transition. It has been measured as ${42}_{\ensuremath{-}10}^{+12} \ensuremath{\mu}\mathrm{Hz}{\mathrm{W}}^{\ensuremath{-}1}{\mathrm{m}}^{2}$ and with further reduction in the probe laser linewidth, it should be possible to reduce the relative uncertainty in this shift to the parts in ${10}^{18}$ level. The transition is free from the Zeeman effect to first order and has a measured second-order shift of $1.9(3) \mathrm{mHz}(\ensuremath{\mu}\mathrm{T}{)}^{\ensuremath{-}2}.$ It should be possible to reduce the relative uncertainty in this shift to below the part in ${10}^{18}$ level. The electric quadrupole shift may be the limiting systematic effect, but cannot yet be observed with the current resolution on the transition.