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p2p news / p2pnet: A computer that’s not running but still finds answers?
"It sounds absurd," says a Nature story. "But Onur Hosten of the University of Illinois at Urbana-Champaign and colleagues have shown that it works. The have created a kind of quantum computer using light beams, and find that it can find a particular item in a database without actually looking for it.
"This is bizarre even by the weird standards of quantum mechanics, which is notorious for counterintuitive effects. Hosten and colleagues call it ‘counterfactual’ quantum computation: a way of probing the outcome of an event by looking at situations in which it didn’t actually happen."
Err, Yes.
"Some people like to think of this as two different universes", computer scientist Richard Josza of Bristol University in England is quoted as saying. "In one universe the computer runs, while in a parallel universe it doesn’t. One might say then that the computer does actually run, but in a ‘parallel universe’. "So you wouldn’t be charged for the cost of running it," says Josza.
But Hosten and his colleagues say it’s more than a mere exercise in quantum weirdness, says the story, adding, "they think it might help in making useful quantum computers. So far, such devices constructed from light beams or trapped atoms are mere toys, which have far too little computing power to solve really hard problems.
"One of the obstacles to scaling up such model computers is that it is very hard to prevent quantum information from leaking away into the surroundings. This leakage is largely due to the way that quantum bits interact with their environment as the computation proceeds. But if the computation isn’t actually run at all, this leakage might be much smaller, making quantum computation less error-prone."
Also See:
Nature - The computer that works when it’s idle, February 22, 2006
