Giant Sapphire Clock sets new pace

Reposted From: ABC Science, full article below.

An Australian scientist has developed a clock so accurate it is expected to lead to a new standard for defining time.

The new clock is so stable over short time periods, it is equivalent to a clock that loses or gains only one second every 40 million years.

“All clocks are based on some repetitive element, like the swing of a pendulum in a grandfather clock,” says the University of Western Australia‘s Dr Andre Luiten, whose work has just won him an international science award.

Since 1967, global time-keeping has been determined by so-called “atomic clocks” – with the repetitive phenomenon being the natural oscillation of a particular frequency of radiation emitted by atoms of caesium.

But Dr Luiten’s new clock is based on the repetitive bouncing of microwaves pumped inside a crystal of sapphire.

The fist-sized crystals – grown artificially in the United States and worth around $10,000 each – are kept at minus 267 degrees celcius and have very special properties.

So long as their temperature is held constant to within one ten millionth of a degree, the number of times the microwaves bounce back and forth inside the crystal stays remarkably constant, making them ideal for accurate time keeping.

Dr Luiten’s team is one of three around the world which have been working on developing these “microwave clocks”, which are 10,000 times more accurate than atomic clocks over short time periods (less than a day).

But his selection as Young Scientist of the Year, awarded by the Union Radio-Scientifique Internationale, recognised Australia’s cutting edge role, Dr Luiten told The Lab.

The WA team’s clock is better than any other in the world at defining time over short periods.

While a modified version of the technology was already being applied in radar and communication systems, the most accurate version was still a research tool. But one with huge potential.

Already the European Space Agency has invited Dr Luiten to build one of six clocks to be sent into orbit on the International Space Station, where it would play a role in research aimed at testing if “universal constants” like the speed of light, really are constant in time and space. The orbiting clock would also help define a new international standard for time.

“Being able to align the world’s clocks to a billionth of a second might sound esoteric, but it has enormous implications in telecommunications,” Dr Luiten said. “You need to be able to time the exchange of information very precisely.”

Because microwave clocks are most accurate over short time periods, they may produce the best results when combined with atomic clocks, which are most accurate over longer time periods.

A combination sapphire and caesium clock, built by Dr Luiten’s team in collaboration with the Laboratoire Primaire du Temps et des Fréquences (LPTF), has already yielded a world record for time keeping with an accuracy equivalent to one second in 50 million years.