The quantum computer

By Hugh McKellar, KMWorld editor in chief

Talk about one of those long-pondered academic theories definitely not for the layperson. For me, it's one of those things I've heard and read some about, but for the life of me, don't really understand—sort of like the mathematical concept of "phi." Ancient scholars called phi the golden ratio of antiquity, a number (1.6180339887 ... ) that never ended. It was so admired for its universal harmony, 16th century scholars dubbed it "the divine proportion," and subsequent devotees have related it to such things as the breeding patterns of rabbits, the shape of the galaxy and the petal arrangements of roses. That's what they tell me, anyway.

Now to quantum computers, which have been in the academic realm for decades, but they are now emerging into the domain of practicality. Physicists from Purdue and Duke universities report that these powerful computers, based on quantum mechanics, are much closer to development because of some recent scientific breakthroughs. In fact, DARPA (the Defense Advanced Research Projects Agency, which gave us the now-defunct Total Information Awareness office), is reportedly ready to drop a few million bucks into quantum computer research.

The Purdue News Service reports that the Duke and Purdue physicists joined "a pair of tiny 'puddles' of a few dozen electrons sandwiched inside a semiconductor," thereby allowing the two "quantum dots" to become parts of a transistor, the key switching elements in chips. The scientists speculate that computers using a large number of quantum dots switches working together would significantly outperform conventional machines because of both the smaller transistor size and astounding increases in computing speed.

What seems especially intriguing is that as these circuits become increasing smaller—chips the size of molecules, perhaps—the laws of quantum physics replace those of traditional physics. Albert Chang, co-author of the Purdue report with lead author Jen-Chung Chen, explains, "An electron, for example, can behave like a particle or a wave at times, and it has the odd ability to seemingly be in two different states at once. Physicists need a different set of words and concepts to describe the behavior of objects that can do such counterintuitive things. One concept we use is the 'spin' of an electron, which we loosely imagine as being similar to the way the Earth spins each day on its axis.

"But it also describes a sort of ordering electrons must obey in one another's presence: When two electrons occupy the same space, they must pair with opposite spins, one electron with 'up' spin, the other 'down.' " They add that spin is one property that physicists seek to harness for memory storage. So, what we can look forward to in quantum computers is truly astronomical increases in computing speed and capability.

Perhaps they can help us understand, as well, the breeding patterns of rabbits, petal arrangements of roses and how to use my voicemail system

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