The fibre-optic cables that carry Internet traffic can also be used for a powerful form of the strange phenomenon known as quantum teleportation.
According to quantum mechanics, two particles can become ‘entangled’, meaning that the quantum properties of one are tightly linked to the properties of the other, no matter how far apart the particles. Quantum teleportation enlists a pair of entangled particles to transmit information about a third particle, such as a photon, from a sender to a receiver.
In continuous-variable quantum teleportation, entangled particles help to transmit a stream of information comprising numerical values that can range widely, such as the amplitudes of a laser’s light waves. But until now, this form of teleportation has been achieved only over very short distances in the lab.
Xiaojun Jia and his colleagues at Shanxi University in Taiyuan, China, used common optical fibre to carry out continuous-variable teleportation of laser-light values across a distance of 6 kilometres. The information was replicated at the receiving location with a higher accuracy than would have been possible using classical physics.
This approach could allow optical fibre to be used for powerful forms of quantum computing.