Quantum-encrypted communication satellites could be a reality within five years – Wired.co.uk

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A laser in space has measured quantum states on Earth, 38,000km away, for the first time.

This means a network of satellites communicating through quantum encryption could become a reality within five years, according to researchers behind the breakthrough experiment.

"We were quite surprised by how well the quantum states survived traveling through the atmospheric turbulence to a ground station," said Christoph Marquardt from the Max Planck Institute for the Science of Light, Germany, and lead author of the new paper.

Cracking quantum measurements at long distance is crucial to developing a network for quantum-encrypted communication.

Quantum-encrypted communication would be much more secure than the mathematical algorithms used currently. This is because of the properties of quantum mechanics called Heisenbergs uncertainty principle.

Currently, information can be encrypted with techniques based on mathematical algorithms. It is difficult to figure out the exact algorithm used to encrypt a piece of data, making the approach largely safe for now.

However, experts anticipate computers powerful enough to crack the codes will surface in the next 10 to 20 years. This development would mean current encryption methods would be redundant as they could easily be broken.

Last year, researchers at Chatham House's International Security Department said satellites and other space communications technology are at significant risk from hackers and cyber attacks.

But there is a potential solution - and this is where quantum mechanics comes into it.

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Heisenbergs uncertainty principle means the act of observing a particle creates certain changes in its behaviour. Specifically, it means we cannot know both the momentum and position of a particle to the same degree of certainty at once.

Quantum encryption uses this to create encoded data in the form of light that, if intercepted, will change its behaviour. This can alert the people communicating that the security key is not safe to use.

The problem comes when sending data over long distances. Researchers have been moving towards satellite-based systems because previous attempts at using optical fibres have proven difficult due to signal losses.

Marquardt and his team measured quantum states encoded in a laser beam sent from one of the satellites already in space, working with satellite telecommunications company Tesat-Spacecom GmbH and the German Space Administration.

The satellites had been designed for laser communication, but was not ideally suited for the task.

"From our measurements, we could deduce that the light traveling down to Earth is very well suited to be operated as a quantum key distribution network," Marquardt said. "We were surprised because the system was not built for this. The engineers had done an excellent job at optimizing the entire system."

The team created quantum states in a range the satellite normally does not operate, and were able to make quantum-limited measurements from the ground.

Based on the results, Marquardt says we could see quantum-encrypted communications via satellites within five to ten years.

"The paper demonstrates that technology on satellites, already space-proof against severe environmental tests, can be used to achieve quantum-limited measurements, thus making a satellite quantum communication network possible. This greatly cuts down on development time, meaning it could be possible to have such a system as soon as five years from now."

But there is much work left to do, he added. "There is serious interest from the space industry and other organizations to implement our scientific findings," said Marquardt.

"We, as fundamental scientists, are now working with engineers to create the best system and ensure no detail is overlooked."

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