Quantum leap on the horizon?


Cambridge researchers are devising new methods to keep sensitive information out of the hands of hackers. They launched the UK’s first ‘unhackable’ network – made safe by the “laws of physics” – in 2018.

It’s really important to get this right as it’s our first chance to start doing very detailed studies and see how these systems really work in the field.
- Ian White

When buying an item online, we voluntarily hand over our credit card information. But how do we know that it’s safe? Most sensitive information sent over the internet is secured through encryption, a process that converts information into a code that can only be unlocked by those with the encryption key. Currently, encryption keys are essentially impossible to break with conventional computing equipment – it would simply take too long and too much computing power to do the mathematical calculations that could reveal the key.

But in the coming decades, all that could change. Google, IBM and many other companies are all working to build a quantum computer that would outperform contemporary computers by taking advantage of the ability of subatomic particles to exist in more than one state at a time. A quantum computer could enable us to make calculations and solve problems that are well out of reach of even the most powerful supercomputers, but in the wrong hands, they could also crack encryption keys with relative ease.

So how can individuals, corporations and governments keep information safe in the face of this potential threat?

A group of researchers in Cambridge’s Department of Engineering are working to defend against the security threats posed by quantum computers by developing ‘unhackable’ encryption keys hidden inside particles of light, or photons, and sent over optical fibres.

Quantum keys are generated randomly through quantum mechanics, taking advantage of a property of photons that prevents them being cloned. The real strength of quantum links, however, is that if an attacker attempts to intercept the key, the quantum state of the photons changes and they cannot be used as part of the key, rendering the information carried by the stolen photons worthless.

“This means that we can send single photons over our networks and end up with keys at each end which are fundamentally secure,” says Professor Ian White, Head of the Photonics group in Cambridge’s Department of Engineering.

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Reproduced courtesy of the University of Cambridge


The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.

University of Cambridge (cam.ac.uk)