Researchers from the Universities of Glasgow, Stanford, Tokyo and Würzburg describe how they have implemented a novel tool for a long-distance telecommunication link which is impossible for hackers to breach.

Published in the journal Nature Communications, the technique could also underpin the creation of a new form of 'quantum internet'. Scientists have previously used the phenomenon of quantum entanglement, also known as 'spooky action at a distance',  to allow the exchange of information over short distances.

Entanglement allows particles which are physically separated to share properties, for example, the direction of one electron's spin will be related to the direction of spin of its entangled partner. This process of entanglement also allows scientists to encode information in quantum particles, similar to the way in which the ones and zeroes (known as bits) of digital communication are used to encode all kinds of data.

"The physics behind quantum communication, by their very nature, make data transfer utterly secure – any tampering with either side of the communication will be immediately apparent because it will affect the quantum correlations," Natarajan said. The paper is titled 'Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits'.