Linked by Thom Holwerda on Fri 9th Feb 2007 22:12 UTC
A Canadian start-up says it will demonstrate a working commercial quantum computer in Mountain View next week, years ahead of many experts' predictions. Venture capital-funded to the tune of USD 20m, Vancouver-based D-Wave says it has built a quantum computer with 16 qubits - the quantum world's version of a digital bit, but which simultaneously encodes 1 and 0, so can carry more information and solve problems more quickly.
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Member since:
2005-10-13
Basically, each "bit" can store more than just a 1 or a 0 at the same time. The physics involved are way over my head, but basically it is a non-deterministic machine. It can be in multiple states at the same time. So while a normal 16-bit cpu can have one of 64K different possible values in a register, a 16-qubit cpu can have 64K different values in the register at the same time and operate on all of them simultaneously.
Anyway, the practical result is this: they can do quadratic algorithms in linear time. Currently there are a lot of problems that simply take forever to calculate on a normal cpu, and by giving them a quadratic speedup these problems can actually be done. Check out the NP class of problems for some examples (non-deterministic polynomial time). Breaking encryption keys is one example. The traveling salesman problem is one you might be familiar with from school. Search algorithms can be drastically sped up.
And is there any merit in using them instead of normal processors?
Well, they seem to be very low power and they may end up scaling better than traditional cpus, but then again they may not. For the foreseeable future they're going to be a lot slower at most computations and probably a heck of a lot more expensive. They should be fantastic at certain things like simulations and AI, so it is possible we may eventually see an add on card like the physics one out now, but that seems like it will be quite a ways in the future.
But most calculations right now are already designed to run in linear time on a normal cpu (or they would be too slow) and so they wouldn't get any speed up from a quantum computer. One way to think about it is to say this cpu is like a 64K core cpu, with each core doing the same set of calculations at the same time - obviously each core is going to be pretty slow compared to current technology and if you only utilize 1 of them there's not much point.
Edited 2007-02-10 09:43