Japanese scientists develop atomic clock with improved accuracy

April 4th, 2011 - 5:57 pm ICT by ANI  

Melbourne, Apr 4 (ANI): Japanese scientists have developed a new type of atomic clock, which has the potential to dramatically improve GPS accuracy and test the laws of physics.

The highly accurate “optical lattice” atomic clock, developed by Professor Hidetoshi Katori and his team at the University of Tokyo, could also become a useful tool in developing relativistic geodesy and the search for minerals and hydrocarbons.

Atomic clocks are highly accurate time and frequency standards, and are used to define the International Atomic Time (TAI) and the Universal Time Coordinated (UTC).

But atomic clocks gradually lose accuracy and it is common for atomic clock to be used to adjust another.

Atomic clocks rely on the frequency of microwaves emitted by electrons inside each atom as they oscillate between two energy states.

Since 1967, the International System of Units has defined the second as 9,192,631,770 oscillations of the caesium-133 atom. This definition determines other physical quantities, like the volt and the metre.

Current optical lattice clocks are limited by the “Dick effect” - a source of unwanted noise associated with the laser used to read out the frequency of the clock.

The optical lattice clock of Katori and colleagues avoids this boundary, allowing it to achieve much higher stability.

Professor Victor Flambaum, of the University of New South Wales, worked with Katori on an earlier phase of the research. He says optical lattice clock differs from current “ion” clocks.

“Instead of measuring ions which are trapped in an oscillation electric field … they suggested a completely different type of clock where atoms are trapped into nodes of an optical lattice produced by a laser field,” ABC Science quoted him as saying.

He describes the electromagnetic field as being like an egg carton with atoms placed in the hollows.

“An ion clock normally works with a single atom and you need to work this for a long time to achieve accuracy,” Flambaum said.

“In this latest clock you can manipulate thousands of atoms, so you can achieve a result much faster,” he stated.

According to the researchers, the clock is extremely stable and accurate, and will enable global positioning systems to detect height differences of around 10 centimetres, in tens of minutes.

“As a result of this work we can measure frequency of atomic clocks to 17 digits accuracy. It is so accurate that they can even feel differences in the gravitational potential of the Earth,” Flambaum said.

“In gravity fields time ticks slower so the ticking of the clock depends on how strong the gravitational potential of a body is,” he explained.

Flambaum says one of the applications of the optical lattice clock would be oil exploration.

“Because oil is a low density liquid, so gravitational potential of oil is lower than the rocks around,” he said.

“You could search for minerals; and global positioning system on all levels, from cars to aircraft and spacecraft, what they call real-time relativistic geodesy,” he revealed.

The research has been published in Nature Photonics. (ANI)

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