Researchers cast wary eye on atomic-level computing.

• Author: Pappalardo, Joe
• Position: Up Front

Government researchers have spent a decade investigating computers that use the principles of quantum mechanics to process information much faster than currently possible. The promise of quantum computers is enormous, but experts within the U.S. military research community disagree on the scope and utility of this technology.

Experts point out that quantum computers could execute calculations several millions of times faster than conventional systems, but that the technology still is years away from becoming truly functional.

Interest in quantum computing is growing. Since 1994, the government's annual funding of quantum computing programs has gone from near-zero to $80 million a year, noted Henry Everitt, chief scientist for the Army Research Office.

Everitt manages one of the nation's largest programs in quantum computing. Other key players are the Defense Advanced Research Projects Agency, the National Security Agency and the Advanced Research and Development Activity.

Twice a year, since 1999, Everitt has chaired a meeting with the dozen or so federal agencies currently researching quantum computing. "My collaborative agencies are asking if one could be built," Everitt said in an interview. "Frankly, I have my doubts."

Everitt's effort is aimed at determining if the laws of physics would allow a quantum computer to exist. On that front, at least, things look hopeful. "So far the physics seem to be accommodating," Everitt noted.

If quantum computing seems esoteric, that's because it makes little sense to those who aren't particle physicists. Quantum mechanics is the study of matter at the atomic level, where the "normal" rules of physics don't apply.

Traditional computers encode information in a series of bits, and manipulate them in a specific order. They can do these manipulations very quickly. But a quantum computer could do a lot more at the same time, taking advantage of the oddities found at the atomic level.

Quantum objects can exist in multiple states simultaneously. By taking advantage of this phenomenon, quantum computers could perform simultaneous Factoring. Bringing that theory to a workable reality, however, is still a daunting challenge.

One problem facing scientists is the inability to keep the inner workings of a quantum computer stable. Quantum bits are like little tops spinning about an externally applied magnetic field at a known frequency (for example, 500 million revolutions a second.) If the spin rate changes even...