Super computer harnesses power of quantum mechanics

OPTICAL CHIP:THE WORLD of computing is about to change with a super-fast computer that works using light. More importantly, the security of the data it contains will be "guaranteed by the laws of physics".

We have long awaited the arrival of the “quantum computer”, one that uses technology based on quantum mechanics. The immense technological demands were thought so difficult that it would take another 25 years to deliver a working quantum computer.

This timeline may have changed given the development of an optical chip that offers a new route to quantum computing. Details of the chip were revealed yesterday at the science festival with simultaneous publication in the journal Science.

The chip uses the smallest pieces of light possible, photons, to make it work. It is an approach that could deliver a quantum computer in as little as five years, said Prof Jeremy O’Brien, research leader and director of the Centre for Quantum Photonics at the University of Bristol.

The chip is a fraction of the size of a penny, yet it has the attributes expected of a quantum device, said Bristol researcher Dr Jonathan Matthews.

The phenomenon of superposition and entanglement, where photons share the same space at exactly the same time enabling them to be directly connected to one another even if separated by a great distance, are the hallmarks of a quantum computer, Prof O’Brien explained.

The two photons are sent into the chip to do what is known as a “quantum walk”, following minute channels as they pass through. The channels “act like light pipes to guide the photons”, Prof O’Brien said. This allows them to become entangled before they exit the chip.

This approach quickly opens the way to developing a computer that is massively more powerful than anything available today.

“Each time we add a photon, the complexity of the problem we are able to solve increases exponentially,” Prof O’Brien said. Two photons gives 10 outcomes, three gives 100, four gives 1,000 and so on. The result is a computer that can never be hacked and is always safe from interference, “security that is guaranteed by the laws of physics”, he adds.