Scientists have made the world's smallest diamond ring, which could play a role in the future of computing.

At just 5 micrometres across and 300 nanometres thick, the ring is unlikely to fit on anyone's finger, say the Australian researchers who made it.

The University of Melbourne researchers hope the tiny loop will let them manipulate single photons, the smallest 'packet' of light.

They hope the ring, which was carved from a slither of diamond, will help researchers build powerful computers that use the properties of quantum physics.

"For quantum information processing, diamonds have some truly unique possibilities," says Professor Steven Prawer, whose team presented images of the ring at an American Physical Society meeting this month in New Orleans.

Scientists know in theory how quantum computers could take advantage of the rules of physics to carry out enormous numbers of processes at the same time.

But building such a computer in the real world has been an enormous challenge.