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You would find prime factors.

What else would you expect to happen?

Let me be a little more specific: how would the performance of finding prime factors using Shor's algorithm running on libquantum compare to classical factoring algorithms? I know it would be less efficient, but by how much? How many digits could I reasonably expect to factor in non-geologic time this way? How big a task would it be to code? Is this a reasonable experiment to try to do?

I'm pretty sure it would end up being slower, if only for the overhead. But don't take my word for it, go ahead and run it.

I know it's not too hard to write gates for testing with QCViewer [https://github.com/aparent/QCViewer], (Linux only for the moment, I'm just going to be improving and possibly porting it to OSX)

It would be exponentially less efficient, as the simulation algorithm used represents and operates on all 2^n possible quantum states of n qubits.

If you know nothing about QM, imagine the classical analogue: a classical CPU simulator with exactly one (say) 32-bit register, which, instead of being represented as 32 bits, is represented as 2^32 bits, exactly one of which is set to 1; the only way to determine which bit this is is to scan the entire array.

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