ONE of the great things about quantum cryptography is that it promises to tip you off if an eavesdropper has intercepted your communications. But there’s a catch: messages transmitted this way can only be sent over short distances.
This week, however, researchers at Toshiba’s European laboratory in Cambridge, UK, revealed a device that could extend the technique’s range indefinitely.
Quantum cryptography systems work by checking the polarisation of a pair of entangled photons to ensure that a key has not been intercepted. If the polarisations do not match, someone is listening in. This has been made to work over short…
