Enigma variations: Economist

Kobal

Jul 10th 2008
From The Economist print edition
A device that counts photons will secure optical data networks from prying eyes

REMOVE the outer coating from a strand of optical fibre, bend it and attach a sensor to detect the tiny amount of light that will leak out. Hacking into an optical network like this is the modern equivalent of a wire tap. But now a laboratory in Cambridge, England, has found a way to turn a hacker's screen instantly blank if he infiltrates the network. This is because the data are being encrypted in a new and probably unbreakable way with one of the first practical devices to be developed for quantum information technology.

The idea of using the more arcane aspects of quantum theory to do things that standard information technology cannot manage has been around for a while. One branch of the field is quantum computing. This, if it can be made to work routinely, promises machines that can do lots of calculations in parallel instead of one at a time, and thus solve problems existing computers cannot manage. The other branch is quantum cryptography, which promises unbreakable codes for messages.

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