A Working Quantum Computer in 3 Years?

prostoalex writes "Vancouver, BC-based D-Wave Systems got $17.5 mln from Draper Fisher Jurvetson to work on a preliminary version of a quantum computer, Technology Review reports. Delivery date? Within three years: 'It won't be a fully functional quantum computer of the sort long envisioned; but D-Wave is on track to produce a special-purpose, "noisy" piece of quantum hardware that could solve many of the physical-simulation problems that stump today's computers, says David Meyer, a mathematician working on quantum algorithms at the University of California, San Diego.'"

Comments

Mathematician

[TorKlingberg]

says David Meyer, a mathematician working on quantum algorithms at the University of California, San Diego.

I will believe this when it comes from an experimental physicist.

Re:Mathematician

[TorKlingberg]

Judging from the reaction of the mods, I think I should explain myself.

I have nothing against mathematicians. I just don't think they are the right ones to predict when we will have _working_ quantum computers.

Quantum is just another buzzword

[Dancin_Santa]

The whole mania behind this technology is that somehow we will be able to pull correct data out of thin air using the magical properties of quantum units. Somehow eigenvalues will just instantaneously pop into existence by the careful selection of input parameters.

Too bad that's not how it works. These computers will still have to process data the same as any other processor and all the threat behind magically decoding 128-bit encryption is pure fluff. We are talking about another way of computing, for sure, but it is just another step in the evolution of computing systems rather than a brand new magic bullet for encryption maniacs.

It is also unclear why people want to build a "quantum computer" when it seems that simply putting it on a peripheral board and using it as a separate calculation machine seems to be a much more straightforward application of the device than trying to cram a whole computer with these chips.

Re:Quantum is just another buzzword

[Stalyn]

Yeah... quantum was a buzzword in 1905. But now it's actual science and proven. Quantum mechanics and QFT are two of the most successful theories to date. Yes there are conflicts with GR. And yes QM and QFT are most likely incomplete. However for a quantum computer there is no need for a theory that will supersede QM/QFT. The domain for quantum computing is well within the reach of QM itself.

Actually things like superdense coding and quantum teleportation have been verfied in the lab. So this stuff isn't exactly nonsense.

Re:Quantum is just another buzzword

[ettlz]

Good points. There are few "good" uses for quantum computers --- mainly, breaking public keys by factorising the product of two large primes (which may prove unrealisable in practise: I don't know how long one could keep an O(100) qbit state coherent), QM simulations (i.e., designable software experiments), and searching databases more quickly than classically possible. There will always be a need for classical computers.

Re:Quantum is just another buzzword

[Deanalator]

Yes, the pressing desire to read the mail of those people who haven't switched algorithms. Obviously this is worth spending billions on.

Or how about being able to solve the hardest math problems we have ever been able to think up as a species in mere seconds?

Shor's algorithm is great because we have been working on trying to understand the primes since the dawn of mathematics. You also dont seem to understand that once this takes hold, there will be no more public key algorithms. PKE is based on the idea that some math problems are harder to solve than to verify. Given a large enough quantum computer, that really is no longer the case.

It is my opinion that being able to harness the computational power of the universe as our own personal calculators is well worth the billions being invested.

Vaporware Award goes to....

[NoSuchGuy]

The 2006, 2007, 2008 Vaporware Award goes to D-Wave Systems.

Wow, a Quantum Computer that only exist in a "Powerpoint Universe ©".

got my hopes up

[n0rr1s]

... but it's not a proper quantum computer. It's based on tunneling, not entanglement. The latter is what everyone understands by the term 'quantum computer'. Their computer just requires knowledge of quantum theory to build it. Well, so do conventional computers...

Decoherence! It simply won't work.

[exp(pi*sqrt(163))]

I am yet to see a description of a quantum computer that isn't plagued by decoherence problems. Basically, if you perturb a quantum computer by a small amount, e, then the wave function will diverge away from the idea state by exp(ket) for some constant k. So basically quantum computers will very rapidly start producing garbage. There are countless papers describing error correction but all this does is replace exp(ket) by exp(k'et) where k' is a bit smaller than k. Tthat exponential will still rapidly swallow the correction and give you decoherence before you can actually run anything. Some papers claim to get k right down to zero. But whenever you look you find they always make some assumtion about the system (ie. about various off diagonal terms in the Hamiltonian, the bits that give rise to these exponentials) and relaxing those assumptions ever so slightly (as is inevitable in the real world) brings back the exponential decay into decoherence.

One or two bit at a time quantum computers - sure, we can build those. My hunch, however, is that to build an N bit quantum computer is exp(N) hard. I expect we will eventually have non-trivial quantum computers, but unfortunately the amount of effort to make them will be as much as the effort to build a classical machine that can simulate them. This isn't just nay-saying, unlike the claims that driving at over 30mph would kill humans, my claims are backed up by many physicists, in particular those that don't have a financial interest in quantum computers.

On the other hand, quantum computer science is very interesting as a branch of mathematics and Shor's algorithm for factoring, for example, is a thing of beauty. So I don't blame people bluffing in order to get grant money. And I suppose I don't really hold it against researchers trying to get money out of venture capitalists this way either. Just as long as that money isn't coming out of any funds I'm investing in...