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Research Fellows Directory

John Rarity

Professor John Rarity

Research Fellow


University of Bristol

Research summary

Advances in technology now make it routine for us to isolate and detect individual particles of light (photons), to test their quantum properties and illustrate Einstein’s paradoxes. Key experiments show light behaves like a particle and a wave within the same apparatus and that the properties of separate photons can be strongly correlated even when they are separated by large distances (commonly known as entanglement). To build up entanglement between many photons we need to manipulate photons individually and control the interactions between them. If we could do this between many separate photons we could build a novel information processor, a quantum computer. Here in Bristol we are building the fundamental gates of such a machine. We are doing this by developing various optical and solid state based elements suitable for creating and manipulating single and multi-photon states. In particular we are developing quantum gates where a bit carried on a single photon can be used to control the value of a bit carried on another single photon. Recently we have succeeded in demonstrating such quantum gates in the laboratory using miniature optical circuits analogous to electronic ‘chips’. However such devices are not efficient enough yet to make a large scale quantum computer. In our theoretical studies we have made significant progress towards designing a high efficiency gate. To achieve this we are modeling and engineering optical devices at the scale of the wavelength of light and below. Such devices will allow us to create photons and guide them to regions where they can interact strongly thus forming efficient quantum gates.

Grants awarded

The nano-optical quantum information toolbox.

Scheme: Wolfson Research Merit Awards

Dates: Apr 2006 - Mar 2011

Value: £75,000