Perfect secrecy has come a step closer with the launch of the world's first computer network protected by unbreakable quantum encryption at a scientific conference in Vienna.

Quantum cryptography is completely different from the kinds of security schemes used on computer networks today.

These are typically based on complex mathematical procedures which are extremely hard for outsiders to crack but not impossible given sufficient computing resources or time.

But quantum systems use the laws of quantum theory, which have been shown to be inherently unbreakable

All quantum security schemes are based on the Heisenberg Uncertainty Principle, on the fact that you cannot measure quantum information without disturbing it," .

"Because of that, one can have a communications channel between two users on which it's impossible to eavesdrop without creating a disturbance. An eavesdropper would create a mark on it. That was the key idea."

In practice this means using the ultimate quantum objects: photons, the "atoms of light". Incredibly faint beams of light equating to single photons fired a million times a second raced between the nodes.


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