Frequency ratio of an $^{115}$In$^+$ ion clock and a $^{87}$Sr optical lattice clock

TL;DR

This paper reports the first measurement of the frequency ratio between an $^{115}$In$^+$ ion clock and a $^{87}$Sr optical lattice clock, achieving high precision and establishing a new link in optical clock frequency networks.

Contribution

It presents the first frequency ratio measurement between an $^{115}$In$^+$ ion clock and a $^{87}$Sr optical lattice clock with unprecedented accuracy.

Findings

Frequency ratio determined as 2.9527487498748634(21)

Measurement duration exceeded 90,000 seconds

Achieved relative uncertainty of 7.0 x 10^{-16}

Abstract

We report on the first frequency ratio measurement of an $^{115}$In+ single ion clock and a $^{87}$Sr optical lattice clock. A hydrogen maser serves as a reference oscillator to measure the ratio by independent optical combs. Over more than 90 000 seconds of measurement time, the frequency ratio $f_{\rm{In^+}}/f_{\rm{Sr}}$ is determined to be 2.952 748 749 874 863 4(21) with relative uncertainty of $7.0 \times 10^{-16}$. The measurement creates a new connection in the network of frequency ratios of optical clocks.