【The Australian】Quantum leap to catch hackers on the hop 2017-06-16

Scientists say unhackable communication networks could be as little as five years away, after they smashed the distance record for the transmission of subatomic particles in a special “quantum” state.

In separate breakthroughs reported yesterday, two research teams have beamed “entangled” light particles from space without breaking their other-worldly connections.

The advances, outlined in the journals Science and Optica, could overcome a major barrier in the development of communications safeguarded by ultra-secure “quantum keys” rather than mathematical algorithms.

Experts believe the algorithms used to encrypt online messages will be useless in a decade or two, as computers become powerful enough to crack them. An alternative is to tag messages with light particles entangled with each other through the weird properties of quantum physics.

Atoms and subatomic particles can become bound to each other over vast distances, in such a way that any attempt to interfere with one affects the other. If an eavesdropper tries to measure one of the particles, it destroys the entanglement and blows the hacker’s cover.

However, until now, physicists have succeeded in transmitting entangled particles only about 100km. Over longer distances, light leaches out of the optical ­fibres used for ground-based telecommunications, which degrades the quantum signal.

Now, the two teams have overcome this problem using lasers and satellites. Chinese researchers managed to transmit entangled photons to three separate ground stations, each about 1200km apart, by splitting a laser signal from a purpose-built satellite orbiting a few hundred kilometres above the Earth.

Meanwhile, a German team in the Canary Islands succeeded in measuring quantum-entangled particles beamed to the Earth from a European satellite circling far higher, about 38,000km up.

“This satellite-based technology opens up bright prospects for both practical quantum communications and fundamental experiments at distances previously inaccessible on the ground,” said the University of Science and Technology of China, which led the first study.

The Max Planck Institute for the Science of Light, which led the German study, said its findings demonstrated the feasibility of “quantum communication networks” based on satellites rather than fibre optics.

“Light travelling down to Earth is very well suited to be operated as a quantum key distribution network,” said lead researcher Christoph Marquardt. “This greatly cuts down on development time, meaning it could be possible to have such a system as soon as five years from now.”

The Australian, 2017-06-16, Source: http://www.theaustralian.com.au/higher-education/quantum-leap-to-catch-hackers-on-the-hop/news-story/832de51eb173f6f2165672d2fa1fe029



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