Quantum route to more powerful computers

University scientists have taken a major step forward in developing a powerful new type of computer which could process information much faster than conventional computers. Dr Jonathan Jones (pictured left), at the Oxford Centre for Molecular Sciences, and colleagues at the University's Clarendon Laboratory and Mathematical Institute are working on a new computer based on quantum mechanics. The potential of quantum computers was first observed by the American physicist Professor Richard Feynman in 1982. Three years later, Dr David Deutsch at the University's Department of Astrophysics showed that, in principle, quantum computers could be built. Dr Jones said: `Since then, there has been extensive research in this field, but although the theory is fairly well understood, actually building a quantum computer has proved extremely difficult.' A conventional computer tackles a search problem by trying each possible answer in turn until it has a solution which meets the criteria it is searching for. According to the theory, a quantum system reaches a destination taking not just one path at a time, but taking every possible path simultaneously. Thus, it is argued, a computer based on quantum properties will perform all the calculations simultaneously, and so find the solution very much more quickly than a conventional computer. The Oxford team has built a small quantum computer based on the molecule cytosine, a naturally occurring component of DNA, and are using nuclear magnetic resonance (NMR)—a technique widely used in modern chemistry and one of the most powerful tools available for analysing molecular structures—to implement computational operations. Dr Jones added: `Using this computer with two component parts or qubits, we have solved a simple problem faster than could be achieved on a classical computer, but this is by no means the limit of what can be achieved. Preliminary studies have been made of systems containing three qubits and it should be possible to build even larger, and thus more powerful NMR quantum computers, to tackle more complex problems.'