Now, an 'ultra-cold atomic clock'! | india | Hindustan Times
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Now, an 'ultra-cold atomic clock'!

india Updated: Dec 08, 2006 20:22 IST
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French Nobel laureate Prof Claude Cohen–Tannoudji on Friday disclosed that there were plans to set up a kind of a global time keeper or clock in space.

In an exclusive interview with the Hindustan Times he said, there are plans to have an "ultra-cold atomic clock" in a space station to synchronise and give precise common time reference to all the clocks in the world. 

He said ultra cold atomic clocks were so precise that they would go off by less than a second in 300 million years.   

Ultra cold atomic clocks have been developed as an offshoot of the work done by Prof Cohen-Tannoudji to cool atoms .

He received his Nobel Prize in 1997 alongwith Steven Chu and William Daniel Phillips for the development of methods to cool and trap atoms with laser light. 

Seventy three year old Prof Cohen-Tannoudji explained that his work is primarily concerned with controlling the motion of atoms with light. 

He said atoms and molecules generally moved around the room at room temperature at a speed of about one kilometer per second. However, when laser light was put on the atoms their velocity was slowed down by the pressure of photons in the laser ray. This pressure of light is called "radiation pressure",he added. 

As temperature depends on the velocity of atoms, slowing down of atoms led to lowering of the temperature. 

Shining laser light can thus bring down the temperature to millionths of a Kelvin (on the Kelvin scale the freezing point of water is 273) to have "cold atoms" .

Instead of the usual one kilometer per second velocity these "cold atoms" move at one centimeter per second. By trapping these cold atoms in a vaccum and using magnetic field and light, temperatures could be reduced further to nano Kelvin levels or billionths of Kelvin,he added. 

The cold atoms because of their slow movement remain for longer period in the observable  zone which help in making extremely precise scientific measurements. One of the major application for cold atoms is in making better atomic clocks which depend on the natural atomic frequency of cesium or rubidium atom to keep precise time, he said.

Ultra cold atomic clocks would improve GPS system further, besides improving high speed communication, gyrometers, he added. 

The recent discovery in the USA of a Bose-Einstein condensation of ultra cold atoms have now led to work on Atom lasers where light would be replaced by a beam of matter, he added. 

"Curiosity has always driven me and I feel we must never forget the fundamental side of physics for getting new ideas and breakthrough in technology, even though politicians have a short term view and its difficult to get funds for fundamental research," he added.

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