National Physical Laboratory

NPL's atomic clock revealed to be the world's most accurate

NPL's caesium fountain atomic clock has been revealed to be the most accurate long-term timekeeper in the world.

The NPL-CsF2 atomic clock
The NPL-CsF2 atomic clock

The clock, known as 'NPL-CsF2', is used as the primary frequency standard for the measurement of time in the UK and contributes to International Atomic Time and Universal Coordinated Time - the worldwide timescales used for global communications, satellite navigation and time stamping of financial transactions.

NPL scientists and partners from Pennsylvania State University, USA, evaluated the clock with physical measurements and mathematical models and have published their results in the scientific journal Metrologia.

The new models and calculations have reduced the uncertainties associated with effects that occur inside atomic clocks, such as interactions between individual atoms and with external fields.

Krzysztof Szymaniec, the leader of the project at NPL, said:

"Together with other improvements of the caesium fountain, these models and numerical calculations have improved the accuracy of the UK's caesium fountain clock, NPL-CsF2, by reducing the uncertainty to 2.3 × 10-16 - the lowest value for any primary national standard so far."

The methods used to improve the NPL clock can also be used to evaluate the caesium fountain clocks of other countries at other laboratories, substantially improving the world's most accurate methods of keeping time.

"The first atomic clock was demonstrated at NPL and we have led research into providing ever more accurate time keeping," Szymaniec said. "Combining our own measurement expertise with that of our colleagues at Penn State, we have shown that timekeeping at NPL continues to be some of the most advanced in the world."

Find out more about NPL's work on Time and Frequency

Fore more information, please contact: Krzysztof Szymaniec

Last Updated: 2 May 2012
Created: 26 Aug 2011

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