The future of computing -- carbon nanotubes and superconductors to replace the si...( The future of computing is under the...)

The future of computing is under the spotlight at the Institute of Physics Condensed Matter and Materials Physics conference at the Royal Holloway College of the University of London on 26-28 March.

The silicon chip, which has supplied several decades worth of remarkable increases in computing power and speed, looks unlikely to be capable of sustaining this pace for more than another decade in fact, in a plenary talk at the conference, Suman Datta of Pennsylvania State University, USA, gives the conventional silicon chip no longer than four years left to run.

As silicon computer circuitry gets ever smaller in the quest to pack more components into smaller areas on a chip, eventually the miniaturized electronic devices are undermined by fundamental physical limits. They start to become leaky, making them incapable of holding onto digital information. So if the steady increases in computing capability that we have come to take for granted are to continue, some new technology will have to take over from silicon.

At the conference, researchers at Leeds University in the UK will report an important step towards one prospective replacement. Carbon nanotubes, discovered in 1991, are tubes of pure carbon just a few nanometres wide about the width of a typical protein molecule, and tens of thousands of times thinner than a human hair. Because they conduct electricity, they have been proposed as ready-made molecular-scale wires for making electronic circuitry.

Some nanotubes behave as semiconductors, like silicon; others carry electric currents like metal wires. Already, fundamental elements of computer circuits such as transistors have been made from individual carbon nanotubes.

But the problem is arranging nanotubes into circuit patterns. One particular difficulty is that they are typically made as mixtures of metallic a
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