News

Optical clock comparison shows new high accuracy, resulting in a Nature paper

Hourglass, an early timekeeping device

A recently completed EMPIR project confirms unprecedented ultra-low deviation between two independent single-ion optical clocks

The project 'Optical clocks with 1E-18 uncertainty' (15SIB03, OC18) compared two optical clocks, based on single ytterbium ions, for more than 1000 hours. The relative deviation between the "tick" rates of the clocks was found to be less than 3×10-18, in agreement with the previously estimated accuracy. This means that after approximately ten billion years these clocks would deviate from each other by one second.

The current definition of the SI second is based on energy levels in the caesium-133 atom, and the best atomic clocks that realise this definition achieve uncertainties in the range of 2×10-16. Even though this accuracy is far superior to that of all the other SI units, it needs to be improved further in order to address many of the scientific challenges emerging in modern physics.

One of those challenges is at the focus of a Nature publication that reports the ytterbium clock comparison experiment in the EMPIR project.

This new measurement not only has implications on plans to redefine the SI second but will also aid those working in fields where such very high accuracy is needed – including satellite navigation, geodetic height measurement, radio astronomy, and in some exciting quests into fundamental physics.


This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.

Want to hear more about EURAMET?
Sign up for EURAMET newsletters and other information

Follow us on LinkedIn and Twitter

 

Select your area of interest
EMPIR project on renewable gas flow measurements commissions new test benches
2021-12-02

Investigating renewable gas flow meter accuracy for compliance with the EU Measuring Instruments Directive more

Results of EMPIR project receives international recognition
2021-11-29

A new digital communication format developed by an EMPIR project is expected to be the future for the communication of metrology data more

European Partnership on Metrology successfully passed Parliament and Council
2021-11-22

The Metrology Partnership enters next stage after adoption more

Protecting European citizens from the risks of ionising radiation
2021-11-12

Introducing the new European Metrology Network for Radiation Protection more

Page 1 of 176.