So what’s happening to quantum computing ?

I remember the hype: soon we would have quantum computers – computers powerful enough to solve their way through most known encryptions, and other NP-complete problems. This would be a way to break Moore’s law in the other direction for those problems.

In quantum computers the zeroes and ones are electron spins. But nothing’s ever that definite in quantum physics: electrons have a probability to be in any one state – so you effectively have one, zero, and all the values in between. No bits, but qubits.

The second quantumphysical, er, feature, used in quantum computing would be quantum entanglement. When two particles are entangled, acting on one particle would have an effect on both particles simultaneously – this bugged Einstein, since we’re talking about faster-than-light transmission.

So how is all that used for processing ? You can’t even properly measure an electron state, so you have to repeat the processing several times to have an idea of the probability function. I would suggest you read this Wikepedia entry if you’re interested. All i can say is, shore up your braincells: time for higher maths.

Anyway, last article i read about an actual implementation talked about a 16 qubit prototype, which is not that much. And the article didn’t actually say that it worked.

Most of the techniques you read about talk about major cooling (for superconduction), high precision lasers, spin incoherence and other niceties.

All this makes me think we won’t be carrying a candy-sized supercomputer in our pocket any time soon.

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