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Absolute frequency measurement of the $^{176}$Lu$^+\,(^{3}\mathrm{D}_1)$ standard against the NRC-FCs2 fountain with $2.6\times10^{-16}$ uncertainty

arXiv Physics Thursday 09 July 2026, 06:01 UTC By K. J. Arnold, Bin Jian, Zhao Zhang, Qi Zhao, Qin Qichen, N. Jayjong, M. D. K. Lee, Scott Beattie, M. D. Barrett 1 min read
Key Points

Announce Type: new Abstract: We report an improved absolute frequency measurement of the $^{176}$Lu$^+\,(^{3}\mathrm{D}_1)$ optical frequency standard, evaluated via a remote link to the NRC-FCs2 caesium fountain primary frequency standard. Operating a single ion clock with 94.2% uptime over 10 days, and using an ambiguity-resolved precise point positioning (PPP-AR) link over the Global Positioning System (GPS), we determine an absolute frequency of $353\,638\,794\,073\,800.33(9)\,$Hz at a...

arXiv:2607.07044v1 Announce Type: new Abstract: We report an improved absolute frequency measurement of the $^{176}$Lu$^+\,(^{3}\mathrm{D}_1)$ optical frequency standard, evaluated via a remote link to the NRC-FCs2 caesium fountain primary frequency standard. Operating a single ion clock with 94.2% uptime over 10 days, and using an ambiguity-resolved precise point positioning (PPP-AR) link over the Global Positioning System (GPS), we determine an absolute frequency of $353\,638\,794\,073\,800.33(9)\,$Hz at a fractional uncertainty of $2.6 \times 10^{-16}$. This agrees with our previous result, which underpins the CIPM recommended frequency value, and reduces the uncertainty by a factor of 3.6.
NRC (ORG) PPP-AR (ORG) the Global Positioning System (ORG) CIPM (ORG)
Originally published by arXiv Physics Read original →

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