Precision timing: This atomic clock won’t go wrong for next 15 BILLION years



By NewsGram Staff Writer

In a showcase of the remarkable precision of physicists, an atomic clock has been fine-tuned to the point where it won’t lose or gain a second in 15 billion years — longer than the universe has existed.

According to reports made by developers in the journal Nature, the optical lattice clock, which uses strontium atoms, is now three times more accurate than a year ago when it set the previous world record.

The advancement  is significant as it brings science a step closer to replacing the current gold standard in timekeeping: the caesium fountain clock that is used to set Coordinated Universal Time (UTC), the official world time.

The clock in the latest study, developed by scientists at the National Institute of Standards and Technology (NIST) and the University of Colorado in Boulder, measures time by detecting the natural vibrations or ticks of strontium atoms in red laser light, said the team.

An NIST statement said that the clock’s stability — how closely each tick matches every other tick, has been improved by almost 50 percent, another world record.

This enhanced stability brings optical lattice clocks closer to the point of replacing the current standard of measurement, the caesium fountain clock, said a Nature press summary.

Currently, international time is set through the caesium fountain clock, which has improved significantly over the decades and can keep time to within one second over 100 million years.

But new, experimental optical clocks that work with strontium atoms at optical frequencies much higher than the microwave frequencies used in caesium clocks, have been shown in recent years to be even more accurate.

The clock is also sensitive enough, the researchers said, to measure tiny changes in the passage of time at different altitudes — a phenomenon predicted by Albert Einstein a century ago and studied ever since.

Study co-author Jun Ye said, “Our performance means that we can measure the gravitational shift when you raise the clock just two centimetres (0.78 inches) on the Earth’s surface.

This is actually one of the strongest points of our approach, in that we can operate the clock in a simple and normal configuration”,  said Ye.

The team had built a radiation shield around the atom chamber of their clock, which means it can be operated at room temperature rather than in cryogenic conditions.

Since 1967 the world’s official unit of time, the second, has been determined by the vibration frequency of an atom of the metallic element Caesium 133 — a method of measurement similar to monitoring the pendulum swings of a grandfather clock.

The study authors say that precise and accurate optical atomic clocks have the potential to transform global timekeeping.

Satellite navigation systems, mobile telephones and digital TV, among other applications, and  research fields such as quantum science require accurate timekeeping.