Cs-Based Frequency Measurement of a Single, Trapped Ion Transition in the Visible Region of the Spectrum

Abstract

An optical frequency chain referenced to a Cs atomic clock has been used to measure directly the frequency of the electric quadrupole allowed $5s{}_{}{}^2{}_{}{}^{}S_{1/2}^{}{}_{}{}^{}-4d{}_{}{}^2{}_{}{}^{}D_{5/2}^{}{}_{}{}^{}$ transition at 445 THz in a single, trapped, and laser cooled ${}^{88}{\mathrm{Sr}}^{+}$ ion. A transition frequency, $f_{S-D}=444\mathrm{}779044095.4\mathrm{kHz}$ with an estimated standard uncertainty of 0.2 kHz has been determined. Intrinsic offsets of the probed ion transition in the current experiment are calculated to be at the ${10}^{-15\mathrm{}}$ level.