Two world firsts as researchers hack an unhackable quantum network

As we saw during the recent 2016 US election, protecting traditional computer systems and electoral systems, which have now been classified as Critical National Infrastructure (CNI), which use ones and zeros, from hackers isn't a perfect science, nor is it likely to ever be. But now consider the complex world of quantum computing, where bits of information can simultaneously exist in multiple states at the same time and the threat becomes even harder to tackle.

Now researchers at the University of Ottawa have uncovered clues that could help companies protect quantum computing networks from external attacks , and if you, like everyone else, including the experts, just raised an eyebrow because you thought quantum networks were completely secure then join the club. Surprise! They're not as it turns out - and that might come as a bitter pill for many, especially the Chinese who recently spent vast sums of money deploying their own "unhackable" quantum communications satellite and network.

However, in order to find ways to protect quantum networks from hacking first the team had to hack one so it's handy that they had their very own quantum network, one of the largest in the world, to play around with.

"Our team has built the first high-dimensional quantum cloning machine capable of performing quantum hacking to intercept a secure quantum message," said University of Ottawa Department of Physics professor Ebrahim Karimi, who holds the Canada Research Chair in Structured Light, "once we were able to analyze the results, we discovered some very important clues to help protect quantum computing networks against potential hacking threats."

The new breakthrough, and the ability to clone photons has, and will, come as a shock to many in the community who thought quantum systems were perfectly secure, and that's understandable. Because until now no one has been able to clone the photons that are used to carry the quantum information and even if they had been able to it was thought that the cloned photon would exist in a deteriorated state, changing the information it held and thereby defeating the purpose of the initial hack.

Traditional computing on the other hand allows a hacker to simply copy and paste information and replicate it exactly, but this doesn't hold true in the quantum computing world, where attempts to copy quantum information, or qubits, result in what Karimi refers to as "bad" copies.

Oh how things change...

Professor Karimi's team were able to clone the photons that transmit information, namely the single carriers of light known as qubits, as well as quantum theory allows, meaning that the clones were almost exact replicas of the original information. However, in addition to undermining what was previously thought to be a perfect way of securely transmitting information, the researchers' analysis revealed promising clues into how to protect against such hacking.

"What we found was that when larger amounts of quantum information are encoded on a single photon, the copies will get worse and hacking even simpler to detect," said Frédéric Bouchard, a University of Ottawa doctoral student, "we were also able to show that cloning attacks introduce specific, observable noises in a secure quantum communication channel. Ensuring photons contain the largest amount of information possible and monitoring these noises in a secure channel should help strengthen quantum computing networks against potential hacking threats."

Karimi and his team hope that their quantum hacking efforts could be used to study quantum communication systems, or more generally to study how quantum information travels across quantum computer networks. To read their paper, visit the Science Advances website.