Quantum Mechanics

The essence of Quantum Mechanics concerned with Quantum computing is fairly straightforwards: all possiblities simultaneously exist.

Huh?

Think of a parallel universe to this one. In this parallel universe, your hair is a different color to now. Everything else is the same, only your hair is different. Now, think of several parallel universes existing at the same time. In each, your hair is a different color.

Now do it with every conceivable color you can think of: pink, red, green, blue, lilac, black, white, grey ...

Each of these possibilities exist right now. The quantum box is closed. Your hair color is 'superpositioned'.

Now decide what color it is.

So it is with everything within a closed Quantum system.

Translated to computing ... current computers work on a binary system; ones and zeros. It is either on (one) or off (zero). To arrive at any solution, computers basically number crunch until they arrive at the answer through a set of predetermined instructions.

Quantum computing is different. There is a third state: both on and off. Once measured, it is either on or off (one or zero). Prior to that, the answer has already been calculated but without the number crunching, since every possible binary outcome already exists. The difficulty has always been arriving at the correct answer.

Not any more. The final hurdles have been tentatively crossed and strides are being made. Todays most sophisticated supercomputer will one day seem like an abacus.