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Quantum breakthrough signals tighter telecoms security

Tue 24 Nov 2015

Quantum networking

Researchers have outlined a new quantum technology breakthrough which could improve the encryption of data and its secure exchange over long distance telecommunications networks.

In a paper [PDF] published in the Nature Communications journal, scientists from the Universities of Glasgow, Stanford, Tokyo and Würzburg describe how quantum entanglement can allow separated particles to share properties. This process has enabled information to be encoded in quantum particles, in the same fashion as conventional binary bits – ones and zeros.

The researchers argue that quantum information shared between two computers is more secure, as any disruption from an unauthorised third party will change the properties of the quantum correlations and immediately become detectable, as well as making the information impossible to copy. This means that only the two parties involved in the transfer, through the entangled particles, will have access to the data.

Quantum networking with time-bin encoding and an entangled photon-pair source at midpoint for the entanglement distribution over long distances

Quantum networking with time-bin encoding and an entangled photon-pair source at midpoint for the entanglement distribution over long distances

In this recent study the team, demonstrating what could be developed into a ‘quantum internet’, achieved a world-first by transferring a quantum bit (qubit) over a 2km length of standard fibre optic cable.

Lead researcher Dr Chandra Mouli Natarajan, an electrical engineer at Glasgow University explained that this effect was created by building correlations between the spin of an electron inside a crystal of semiconducting material called a ‘quantum dot’ and a photon passing down the optic cable. By using the quantum dot to generate the photon, the team was able to control the spin and entangle it with the trapped electron.

“Quantum dots are commonly used to generate individual photons. However, these types of photons can’t travel very far in the standard fibre optic network used in the telecommunications industry because they tend to leak out along the way,” explained Natarajan.

“Quantum dots are also capable of trapping electrons, and previously our research group had shown that entanglement can be created between the trapped electron and a photon generated by the quantum dot.”

Natarajan continued that for the first time the team was able to establish a long-distance correlation between the trapped electron and the photon passing through the telecommunications band.

“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 concluded that the work is “an important step towards creating architectures for the future hybrid quantum internet.”


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