Coming Not So Soon To A Galaxynear You: The Quantum Computer

Try, try again. That's the way computers crack a secret code. Searching through billions of trillions of possible keys takes so long that codes with many digits are, practically speaking, unbreakable. But mathematician Peter W. Shor of AT&t Bell Laboratories has conceived of a shortcut: If at first you don't succeed, go quantum. Shor envisions a computer based on the rules of quantum physics. In the quantum world, a single photon exists in many places at the same time. In Shor's computer, many different computational paths would exist at the same time. The interference of those paths with each other would filter out the answer almost instantaneously.

Don't go shopping for a quantum computer at Circuit City. Shor's work still is just a theory, building on earlier work by such scholars as David Deutsch of Oxford University and Umesh V. Vazirani of the University of California at Berkeley. Says Shor: "The real challenge would be getting the quantum mechanical behavior working with enough precision to allow you to compute things accurately." And when might that be? "On the order of decades, I expect."

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