But the guy who made that bet doesn't think physics prevents a quantum computer. "Many people assumed I was a QC skeptic, and was offering the prize because I hoped to spur research aimed at disproving QC. Which is actually an interesting misreading" http://www.scottaaronson.com/blog/?p=902

Yeah I was just pointing out that there is disagreement. I think of it like time travel - nobody has proved that it is impossible, but a lot of people suspect that a "sensible" universe wouldn't allow it.

the rate of progress seems in fact astoundingly slow. if gene sequencing is outstripping moore's law, quantum computing is underperforming it by a mile. this quantum computer did the same 3 x 5 = 15 factorization that was done ~15 years ago. and has added just one special q-bit over its predecessors. albeit this is a more "fair" factorization technique than the early experiments, which have been likened to loaded dice.