The blue cloud of strontium atoms trapped in lasers that powers the clock.
(Credit: The Ye group and Brad Baxley, JILA)
An experimental clock has set the records for both accuracy and stability, being able to keep time for longer than the Earth has been in existence.
There has never, in the history of clockmaking, been a 100 per cent accurate clock. Even the most exclusive pieces of haute horlogerie lose, at the very least, a few seconds per year.
The strontium atomic clock is now the most accurate clock ever made, which will neither lose nor gain a single second for five billion years. To put that in perspective, the Earth is only an estimated 4.5 billion years old — and the previous record holder, NIST's Quantum Logic Clock, was only accurate to 3.7 billion years.
The clock's stability — that is, the uniformity of its ticks — is also second to none, matching NIST's ytterbium atomic clock unveiled in August last year.
The strontium clock works by trapping strontium atoms in a lattice of laser light. These atoms are bathed in a very stable red laser light at the exact frequency that prompts the switch between energy levels — and it's this switch that forms that clock's ticking.
"We already have plans to push the performance even more," said NIST/JILA Fellow and group leader Jun Ye. "So in this sense, even this new Nature paper represents only a 'mid-term' report. You can expect more new breakthroughs in our clocks in the next 5 to 10 years."
The strontium clock is the first clock to hold both records since the caesium fountain atomic clocks of the 1990s.
The full results of the experiment can be read in a paper titled "An optical lattice clock with accuracy and stability at the 10−18 level", published in the journal Nature.