Absolute frequency measurement of a Lu$^+$ $(^{3}\rm D_1)$ optical frequency standard via link to international atomic time

TL;DR

This paper reports the first absolute frequency measurement of a Lu$^+$ optical standard, linking it to international atomic time with high precision, based on three months of intermittent operation of a single-ion standard.

Contribution

It provides the first absolute frequency value for a Lu$^+$ ($^{3} m D_1$) optical frequency standard, establishing traceability to SI units via remote link to IAT.

Findings

Measured frequency: 353,638,794,073,800.35 Hz

Fractional uncertainty: 9.2 x 10^{-16}

Operational over 3 months with 162 hours of uptime

Abstract

We report on an absolute frequency measurement of the ${\rm Lu}^{+}\,(^{3}\rm D_1)$ standard frequency which is defined as the hyperfine-average of $^{1}\rm S_0$ to $^{3}\rm D_1$ optical clock transitions in $^{176}{\rm Lu}^{+}$. The measurement result of $353\,638\,794\,073\,800.35(33)$Hz with a fractional uncertainty of $9.2 \times 10^{-16}$ was obtained by operating a single-ion $^{176}{\rm Lu}^{+}$ frequency standard intermittently over 3 months with a total uptime of 162 hours. Traceability to the International System of Units (SI) is realized by remote link to International Atomic Time. This is the first reported absolute frequency value for a ${\rm Lu}^{+}\,(^{3}\rm D_1)$ optical frequency standard.