Monday, June 04, 2007

Great technology: weazl bets however that it won't be soon available for civilian use

Record distance set in quantum communication

A quantum communication has been sent across a record 144 kilometres (90 miles) using a process which can one day be tapped to send messages across space with absolute secrecy the monthly Nature Physics said Sunday.

The procedure exploits the quantum properties of particles, such as photons, to become entangled, behaving like psychic twins, an article said.

And even if they are far apart, a disturbance to one affects the other -- an oddity called entanglement which Albert Einstein himself lyrically dubbed "spooky interaction."

This method "could be an important step towards future satellite-based quantum-communication networks," Nature said.

In the experiment, polarisation-entangled photon pairs were generated on Roque de los Muchachos mountain on the island of La Palma in Spain's Canary Islands.

While one photon stayed in La Palma, its twin was sent over an optical free-space link to Tenerife about 144 kilometres away, where the Optical Ground Station of the European Space Agency acted as a receiver, a marked improvement over the 13-kilometre distance achieved earlier in a similar experiment.

The researchers from Austria, Britain, Germany, Italy and the Netherlands were able to generate a quantum cryptographic key over 144 kilometres.

Researchers said the experiment "is an essential first step towards future satellite-based quantum communication and experiments on quantum physics in space."

Original article posted here

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