Strange ideas can come from ordinary places. This one came from Texas. In 1981, John A. Wheeler, the father of the black hole and a theoretical physicist at the University of Texas in Austin, threw a party. The guests were all young physicists with a common interest in the foundations of computing, a topic that Wheeler believed--correctly--would become increasingly important in the years to come.
It was at this party that a conversation with Charles Bennett, an IBM physicist, sparked an idea in the mind of Oxford University researcher David Deutsch. It struck him that computer theory was based on Newton's laws, not the more fundamental description of the universe provided by quantum theory.
At the time, the computer industry was beginning to fret over the future of microchips. How many calculations per second would be ultimately possible, how much heat would this produce, and could silicon survive the constant baking? To help them, computer scientists turned to the theory developed in the 1930s by the pioneer of their field, Alan Turing. But at Wheeler's party, said Deutsch, "I could see immediately that using the laws [of quantum mechanics] would give a different answer."
Deutsch began work on a paper that is now generally regarded as a classic in the field. Published in 1985, it describes how a computer might run using the strange rules of quantum mechanics and why such a computer differs fundamentally from ordinary computers.
Fifteen years later, the revolution that Deutsch started has reached global proportions. Quantum computers are no longer seen as weird curiosities but as the powerful future of the computer industry, and the debate is shifting from whether they will ever become a reality to when they will do so. The excitement is not due to their power, although they undoubtedly will be more powerful than today's models. Their big selling point, the killer app if you like, is that they can solve problems and carry out simulations that are basically impossible on conventional computers.
Such is the potential of these devices that the list of companies funding research programs sounds like a roll call of the world's biggest telecommunications and computer businesses. They include IBM, Hewlett-Packard, Lucent Technologies, AT&T, and Microsoft. There is even a New York Citybased start-up called MagiQ Technologies that hopes to make money by developing intellectual property in this field.
One of the strongest forces driving the development of quantum computers is the fear they will crack with ease secret codes that are impervious to other computers. The alarm bells started ringing in 1994, when Peter Shor of AT&T's Bell Laboratories in New Jersey showed that quantum computers were far faster than their ordinary brethren at factoring numbers.
Finding the factors of large numbers is so difficult for conventional computers that code-makers rely on this weakness of theirs to protect sensitive data. With the development of quantum computers, these codes will be obsolete. As soon as the first modest-sized quantum computer is switched on, governments and their militaries will be forced to concede that many of their codes are unsafe. Understandably, they are keen to find out just what quantum computers can do, and various national laboratories have begun substantial programs, in particular the U.S. National Institute of Standards and Technology in Boulder, Colo.; Los Alamos National Laboratory in New Mexico; and the United Kingdom equivalent, the Defence Evaluation and Research Agency in Malvern.
Aside from its promise for espionage there is the new physics unveiled almost daily by scientists trying to understand quantum information and how to control it. Quantum computers are becoming tiny laboratories in which scientists can test the theories of quantum mechanics with greater precision than ever before. Arguably the strongest team in the world making such discoveries is at the University of Oxford. Smaller groups exist at places such as MIT, Caltech, and a group of Australian universities, with influential individuals scattered throughout the United States, Europe, and Israel. After a late start, Japan has begun a concerted effort to catch up.