Optical chip enables new approach to quantum computing

An international research group led by scientists from the University of Bristol has developed a new approach to quantum computing that could soon be used to perform complex calculations that cannot be done by today's computers.

Scientists from Bristol's Centre for Quantum Photonics have developed a silicon chip that could be used to perform complex calculations and simulations using quantum particles in the near future. The researchers believe that their device represents a new route to a quantum computer – a powerful type of computer that uses quantum bits (qubits) rather than the conventional bits used in today's computers.

Unlike conventional bits or transistors, which can be in one of only two states at any one time (1 or 0), a qubit can be in several states at the same time and can therefore be used to hold and process a much larger amount of information at a greater rate.

"Our technique could improve our understanding of such important processes and help, for example, in the development of more efficient solar cells," adds Prof O'Brien. Other applications include the development of ultra-fast and efficient search engines, designing high-tech materials and new pharmaceuticals.

The leap from using one photon to two photons is not trivial because the two particles need to be identical in every way and because of the way these particles interfere, or interact, with each other. There is no direct analogue of this interaction outside of quantum physics.

"Now that we can directly realize and observe two-photon quantum walks, the move to a three-photon, or multi-photon, device is relatively straightforward, but the results will be just as exciting" says Prof O'Brien. "Each time we add a photon, the complexity of the problem we are able to solve increases exponentially, so if a one-photon quantum walk has 10 outcomes, a two-photon system can give 100 outcomes and a three-photon system 1000 solutions and so on."

The group, which includes researchers from Tohoku University, Japan, the Weizmann Institute in Israel and the University of Twente in the Netherlands, now plans to use the chip to perform quantum mechanical simulations. The researchers are also planning to increase the complexity of their experiment not only by adding more photons but also by using larger circuits. ###

Contact: Aliya Mughal

*Aliya.Mughal@bristol.ac.uk*WEB:

*University of Bristol*