Unless D-Wave has changed their direction in the last 5 years (the last time I checked in with their progress), nothing they are doing actually constitutes a "real quantum computer". When I say "real," I mean one of those quantum computers that actually leverages quantum interference to solve problems, which could be used to break not just Bitcoin cryptography, but all the cryptography on which the internet is based. If this was a real problem, you can be sure that alarm bells would be ringing around the world, and for much more than just Bitcoin.
Real quantum computers aren't just faster -- they solve problems differently. Shor's algorithm takes integer factorization from O(ecuberoot(N)) on a classical computer to O(N2) on a quantum computer. This isn't just faster -- this makes a whole class of essentially-unsolvable problems, solvable (including the discrete logarithm problem on which Bitcoin crypto is based).
Yes, you can get a speedup on pure-guessing problems using Grover's algorithm -- from O(2N) to O(2N/2). That's a unique capability that QCs can exploit, but the least interesting in terms of breaking cryptosystems. Most crypto systems use key sizes big enough that even if you halved the keysize, it would still be secure. And the defense is to just double your keysizes, once, and the problem goes away. But not with Shor's algorithm -- the whole class of problems is compromised.
D-Wave has always been a joke in the world of QCs. What they are doing is cool, and they may be developing technology that is somewhat related to QCs, but they shouldn't be using the phrase "Quantum Computing" in their product name, because that terms is reserved for a whole new class of computing systems, not classical computers that use quantum bits to do things classically faster.
etotheipi, an article I just ran into that reflects your comments here :
http://www.scottaaronson.com/blog/?p=1400It's true that when you cross over into the commercial arena, you typically encounter disjoints between promises and reality. Whenever you get enough public interest in some scientific idea, eg. Quantum Computing, someone will claim to be delivering it despite it being impossible.
There are projects being advertised right here in this forum, that claim even to be Open Source, that don't even come close to living up to the claims made about it.
because once one slices through all the layers of ugh—the rigged comparisons, the “dramatic announcements” that mean nothing, the lazy journalists cherry-picking what they want to hear and ignoring the inconvenient bits
sounds a lot like a project I know...
