Sundials, egg timers, or the stopwatch on your phone – what’s the most accurate way to measure a second?
16 January 2026
Sundials, egg timers, or the stopwatch on your phone – what’s the most accurate way to measure a second?
In a review article published in Optica, our researchers explore how time is measured at the highest level of precision – and what it takes to count hundreds of trillions of atomic ticks per second.
Until recently, the most accurate atomic clocks rely on extremely stable caesium atoms that deliver billions of ticks per second.
This approach is currently being surpassed by a new generation of even more precise atomic clocks. These use optical signals that tick much faster – around a hundred trillion ticks per second.
The only way to work with these atoms is to use a sophisticated tool called an optical frequency comb – this makes these ticks comprehensible by normal electronics.
The challenge is that combs and clocks are still large, complex, and fragile.
At our Centre, we’re working to make the atomic clock + optical frequency comb a powerful frontrunner combination for measuring the second as accurately as possible – by transforming bulky frequency combs into compact, robust microcombs.
Congratulations to Tara Fortier from the National Institute of Standards and Technology (NIST), Helen Margolis from the National Physical Laboratory (NPL), and our Chief Investigator Andre Luiten on this timely review article.
Read the full review article in Optica here: https://opg.optica.org/optica/fulltext.cfm?uri=optica-13-1-143