News in Science

Nothing helps create pure randomness

Counting on nothing Quantum fluctuations within a vacuum are helping Australian researchers create billions of random numbers.

The random number generator, created by Professor Ping Koy Lam, Dr Thomas Symul and Dr Syed Assad from the Australian National University (ANU), uses highly sensitive light detectors to 'listen' to an empty space.

Until recently a vacuum was thought to be completely empty. But modern quantum theory now suggests that it is filled with virtual sub-atomic particles spontaneously appearing and disappearing, creating random noise.

This 'vacuum noise' may affect, and ultimately pose a limit to, the performance of fibre optic communication, radio broadcasts and computer operation.

"While it has always been thought to be an annoyance that engineers and scientists would like to circumvent, we instead exploited this vacuum noise and used it to generate random numbers," says Lam, who is part of the ANU's ARC Centre of Excellence for Quantum Computation and Communication Technology.

"Random number generation has many uses in information technology. Global climate prediction, air traffic control, electronic gaming, encryption, and various types of computer modelling all rely on the availability of unbiased, truly random numbers."

Currently, random number generators use computer algorithms. But if these algorithms are known, it is relatively easy to predict their output meaning the numbers are not truly random.

"To overcome this issue, random number generators relying on inherently random physical processes, such as radioactive decay and chaotic behaviour in circuits, have been developed," says Lam.

Their work first appeared in Applied Physics Letters.

According to the researchers the device is now able to create 5.7 billion random digits every second, examples of which are published online.

"We can easily push this technology even faster, but currently we have already reached the capacity of our internet connection," says Assad.

In 2010, a team based at the University of Toronto achieved 500 million random digits per second using similar technology. Researchers at Oxford University created a string of 42 randomly generated digits, which could be used in quantum encryption, using quantum entanglement - where two particles exhibit identical characteristics no matter how far apart they are separated.

The ANU group is now working with a private company to commercialise the technology and aims to miniaturise it to the size of a thumb drive.