The physics of very small objects has features that make uncanny things possible. One of these is that outcomes of interactions are not clearly one or another, but a probability of each of different possible ways. A particle within a nucleus, for instance, has a probability of being outside the nucleus as well, which is why radioactivity is possible. The undisturbed state of the particle, in fact, is both within and outside, till a measurement is made. This quality, of things being in more than one state at once, unlike the usual condition of one or the other, suggests a new mechanism that can consider different possible values of the same variables in a calculation and a number of computations, all at once.
It was the legendary Richard Feynman who, as early as in 1982, had the insight to think of such a device. The idea was of using an object, like an electron, which could have a spin “up” or “down”, in the same way as an electronic gate, which could be “open” or “shut”, to represent the digits “0” or “1” of binary arithmetic. The idea held promise as the electron could be in both states at once, unlike the electronic device, but for many years there was no method to actually use this property for computation.
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