Okay, here is how I think it might work - I am not a quantum computer programmer, so take my ideas with lots of salt.

Imagine a completely classical world. Imagine a bit (e.g. a coin faceup or facedown) inside of a container (e.g. a cup). Imagine a fundamental physical operation something like shaking the cup. If you don't know whether the bit is faceup or facedown, then you might imagine that inside the cup are two superimposed worlds. That is, you can imagine that the world is one possibility thin where you are, and then bubbles out to be two possibilities thin inside the cup.

When you shake the cup and then open the cup, one way to describe what happens is that the superimposed worlds "collapse", nondeterministically, into one of the possibilities. This is something like popping the bubble. Another way to describe what happens is that the bubble expands through you, splitting you, and one of the copies sees one of the possibilities, and the other copy sees the other possibility.

We can model entanglement in this classical world - imagine taking the cup-coin combination, and passing it through a duplicator. You still don' t know whether the coin is heads or tails, but "collapsing" one will also "magically" collapse the other.

This is all well and good, you say - but it isn't quantum computation.

My understanding here is fuzzier. As I understand it, there's an additional "imaginary" dimension in the quantum computation than there is in the classical possibility-worlds that we've been talking about. Sometimes, the bubble or stack of possible worlds, when viewed from the outside, can have constructive or destructive interference, as if the different worlds were transparencies that one can stack and look through.

To the QC novices - does that make sense? To the QC experts - is that even roughly true?