Speaker
Description
We report on a transportable and user-friendly optical clock that uses the electric quadrupole transition ($\phantom{}^2S_{1/2}-\phantom{}^2D_{3/2}$) of a single trapped $\phantom{}^{171}$Yb$^+$ ion at 436~nm as the reference. The clock has been developed in an industry-lead collaboration (Opticlock) and is set up in two 19" racks. The main advantages of the system are its ability to robustly operate continuously over weeks and that it provides transportability. As a first step towards remote comparisons, Opticlock will travel to Finland in August 2024 to be compared with the $\phantom{}^{88}$Sr$^+$ clock at VTT MIKES. For this proof of concept campaign, Opticlock is aimed to demonstrate a short-term frequency instability below $5\times10^{-15}\sqrt{\tau}$ and a systematic uncertainty below $5\times10^{-18}$. The frequency instability of Opticlock has been improved by reducing the dead time required for magnetic field decay and its systematic uncertainty reduced by direct measurements of AC magnetic field and improved knowledge of the shift resulting from thermal radiation. Furthermore, a frequency comb generator is set up and integrated into the system. Prior to the remote measurement, the optical clock performance is assessed by local test transportation that identifies weak links in the system. The results pave the way for future key comparisons of high-performance optical clocks using transportable standards as an alternative to satellite-based techniques and optical fiber links.
