Quantum cryptography takes to the skies

[Udhay Shankar N]

http://www.newscientist.com/news/news.jsp?id=ns99992875

Quantum cryptography takes to the skies

19:00 02 October 02

NewScientist.com news service


Quantum cryptography keys encoded in photons of light have been transmitted 
more than 23 kilometres through air, British researchers have announced. 
They say the breakthrough is an important step towards a global 
communications system that is completely secure.

Earlier in 2002 a Swiss company managed to send quantum keys over 60 
kilometres. But this was through optical fibres, which limits the 
technology to ground-based transmission.

"Our experiment paves the way for the development of a secure global 
key-distribution network based on optical links to low-Earth-orbit 
satellites," says John Rarity, at QinetiQ, the public arm of the UK's 
defence research agency.

Rarity acknowledges that the 23 kilometres is still a long way short of the 
1000 kilometres needed to reach all LEO satellites, but he believes that 
improvements in filtering out ambient light could make this feasible soon. 
"I think I will have a system design to do that by March 2003," he says.

Another obstacle to be overcome is to engineer signals that, unlike the 
visible light used, will not be absorbed by clouds.

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-- 
((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))


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