The number of optical ion clocks in Finland doubled for a short period in the fall of 2024 as VTT MIKES was hosting PTB's Opticlock for a comparison campaign!
The aim of the two-month comparison campaign was to check if our optical atomic clock ticks in perfect sync with Opticlock, a state-of-the-art transportable ytterbium ion optical clock from PTB (Physikalisch-Technische Bundesanstalt) in Germany.
In the comparison campaign the frequency ratio between the Opticlock, which uses a single 171Yb+ ion, and our optical clock based on a single 88Sr+ ion was measured. A first inspection of over 670 hours of good quality measurement data indicates proper operation of both clocks and will allow the team to determine the frequency ratio with a statistical uncertainty below 10–17. Moreover, the results will allow us to determine the consistency of our 88Sr+ laboratory clock and PTB’s 171Yb+ and 88Sr+ laboratory clocks. This successful clock comparison campaign was the first in the European Partnership on Metrology project Transportable optical clocks for key comparisons (TOCK) (1
The results show that comparing distant clocks using transportable standards is a viable alternative to satellite-based technologies and fibre links for future key comparisons of high-performance optical clocks. Moreover, the results will make a significant contribution to the milestones towards the redefinition of the SI second. Such a redefinition is considered, because optical atomic clocks now provide about 100 times better performance than the best caesium atomic clocks, the current primary standard for time and frequency.
Further information on the optical atomic clocks: Opticlock and Optical atomic clock at VTT MIKES.
PHOTO: The team of PTB’s and VTT’s researchers involved in the action, from left: Anders Wallin (VTT), Thomas Fordell (VTT), Saaswath Jeyalathaa Karthikeyan (PTB), Thomas Lindvall (VTT), Nils Huntemann (PTB) and Kalle Hanhijärvi (VTT).
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The project (22IEM01 TOCK) has received funding from the European Partnership on Metrology, co-financed from the European Union’s Horizon Europe Research and Innovation Programme and by the Participating States.
