Photon counter lets quantum messages go the distance

2019-03-02 09:06:00

By Paul Marks 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,