Researchers at Melbourne University are growing diamond particles on optical fibres to transmit information they say will be impossible to hack. The diamonds, just 1/1000 of a millimetre in size, send information through a single photon of light instead of the billions of photons found in an ordinary light beam.

Research fellow James Rabeau compares the technology to flicking a torch to send a message to a friend across a room.

Light from the torch can be seen by others in the room, because there are billions of photons, and the message can be de-coded.

But if the light was a single photon beam, others in the room could not see it, and the two friends would also know instantly if it had been intercepted.

“If it’s intercepted, no useable information is gleaned,” Dr Rabeau said.

At the moment, when information is sent electronically, such as credit card details, it is encrypted and then decoded at the other end, but the information can be stolen along the way.

“They’re stealing a coded message and then if they have very powerful computers they can start to try to crack the code,” he said.

“Computers are getting faster and faster so codes have to get better.

“But our technique exploits quantum mechanics. This allows you to communicate in total secrecy, with unhackable codes.”

The quantum cryptography project has been given $3.3 million by the Victorian Government to allow researchers to develop a prototype and make it commercially available.

Dr Rabeau said two companies were already selling a similar system for about $80,000, that simply “turned down” the light.

“They don’t reliably produce single particles of light,” he said.

“It’s pretty secure, but it’s still not absolutely secure.”

The diamond particles are produced in a 1500 watt microwave reactor, using gases containing carbon to grow tiny crystals of diamond over the tip of the optic fibre, which itself is only the size of a hair.

Dr Rabeau said the technology did have limitations and slowed down the speed at which a message was sent, at this stage to about 120km/h.

Nevertheless, demand was expected to be high, he said.

“There are huge military and national security implications if we can do this,” Dr Rabeau said.

“I think there’s a lot of potential for spin-off technologies, this is a very unique device.”

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