Bristol researchers get two photons to do the quantum walk
1 min read
An international research group led by scientists from the University of Bristol's Centre for Quantum Photonics have developed a chip that could be used to perform complex calculations and simulations using quantum particles. The researchers believe that their device represents a new route to a quantum computer.
"It is widely believed that a quantum computer will not become a reality for at least another 25 years," said Professor Jeremy O'Brien, Director of the Centre for Quantum Photonics. "However, we believe, using our new technique, a quantum computer could, in less than 10 years, be performing calculations that are outside the capabilities of conventional computers."
The technique developed in Bristol uses two identical photons moving along a network of circuits in a silicon chip to perform what is known as a quantum walk. Quantum walk experiments using one photon have been done before and can be modelled exactly by classical wave physics. However, this is the first time a quantum walk has been performed with two particles and the implications are said to be far reaching.
"Using a two photon system, we can perform calculations that are exponentially more complex than before," said Prof O'Brien. "This is very much the beginning of a new field in quantum information science and will pave the way to quantum computers that will help us understand the most complex scientific problems."
In the short term, the team expect to apply their new results immediately for developing new simulation tools in their own lab. In the longer term, a quantum computer based on a multiphoton quantum walk could be used to simulate processes which themselves are governed by quantum mechanics, such as superconductivity and photosynthesis.
The leap from using one to two photons is not trivial because the two particles need to be identical in every way and because of the way the particles interact with each other. "Now we can directly realise and observe two photon quantum walks, the move to a three photon or multiphoton device is relatively straightforward," said 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, 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.
