World's most accurate clock unveiled improve the accuracy of navigation around the world.

Experimental design based on a single mercury ion which is better than 1 second in 400 million years,

The most accurate atomic clock of its kind is unveiled today, marking a new leap forward in efforts to synchronise telecom networks and deep-space communications, as well improve the accuracy of navigation around the world.

JILA's strontium atomic clock is now the world's most accurate clock based on neutral atoms
The new clock is based on a few thousand strontium atoms trapped in grids of laser light and is twice as accurate the current US time standard based on a "fountain" of caesium atoms.

This clock tops previous records for accuracy in clocks based on atoms. Although not as accurate as an experimental design based on a single mercury ion (a charged mercury atom), which is better than 1 second in 400 million years, technology to interconnect so called "neutral atom" clocks, such as the strontium one, into a "clock of clocks" promises to make them the most precise of all.

Ultra cold atoms are the "pendulums" for atomic clocks because they only absorb highly precise frequencies of light and, because a frequency is the number of oscillations per second, they can be used to measure the passing of time.

Because the strontium atoms absorb higher frequency light than earlier clocks, which rely on longer microwaves, these optical clocks have shorter and more accurate "ticks" - 430 trillion per second.

The next-generation atomic clock is reported today in the journal Science by Dr Jun Ye and colleagues at JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

The team could link the new clock with existing clocks, using a special fibre optic link, which is crucial if the new clock is to be used as a timekeeping standard, since that has to depend on polling the ticks of lots of clocks.

The JILA and NIST are home to optical clocks based on a variety of atoms, including strontium, calcium, mercury, aluminum, and ytterbium, each offering different advantages
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