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Test: Quantum Or Not, Controversial Computer No Faster Than Normal
sciencehabit writes The D-Wave computer, marketed as a groundbreaking quantum machine that runs circles around conventional computers, solves problems no faster than an ordinary rival, a new test shows. Some researchers call the test of the controversial device, described in Science, the fairest comparison yet. "...to test D-Wave’s machine, Matthias Troyer, a physicist at the Swiss Federal Institute of Technology, Zurich, and colleagues didn't just race it against an ordinary computer. Instead, they measured how the time needed to solve a problem increases with the problem's size. That's key because the whole idea behind quantum computing is that the time will grow much more slowly for a quantum computer than for an ordinary one. In particular, a full-fledged 'universal' quantum computer should be able to factor huge numbers ever faster than an ordinary computer as the size of the numbers grow." D-Wave argues that the computations used in the study were too easy to show what its novel chips can do.
Is this a case where D-Wave was fraudulently trying to pass something off as quantum when they knew it wasn't, or did they really and truly not know. How could they not know?
Because the machine costs ten million dollars and the people selling it are obviously not going to publish information that portrays their machine in a bad light. Very few people have access to these, and those who do often have a vested interest in convincing people the machine is worthwhile.
Originally I meant to bet with Matthias Troyer if the D-Wave machine was truly a quantum annealer. At the time Matthias wrote me:
""Actually, we can't bet anymore since I know the results that we're going to publish and we'll say yes to quantum :-). We should have done the bet a year ago."
So we decided to bet if the current crop of D-Wave machines can already beat conventional computing.
Obviously I lost that bet, but not by much.
It will be interesting to see how the next chip generation will fare, there is still lots of room for higher qubit integration. In comparison to conventional CMOS the D-Wave chip structures are huge.
Conventional chip design doesn't have lots of room at the bottom any more. D-Wave on the other hand still has plenty of room at the bottom.
That's why I will continue to bet on them.
That's been the big question with D-Wave all along. What does it really do, how does it really work, what's it good for, is it real?
Everybody knows what a universal quantum computer is good for - running Shor's algorithm to do factoring and totally wrecking public-key cryptography, plus whatever other problems people care about in the real world. But general-purpose quantum computers so far can't keep enough qbits entangled together to factor numbers bigger than 21 = 3x7, and if anybody's figured out how to do significantly bigger than that, they're keeping it Really Well Hidden (either because they're a government, or because a government will want them to do stuff, or because a government will want them killed.)
Meanwhile, D-Wave has 512 qbits that they claim they'll be able to do something with, and maybe it'll have a chance of being cool or useful. And maybe if you kick in enough megabucks to get a non-disclosure agreement, you'll be able to get some information beyond vague quantumy handwaving. They are the only game in town, after all.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
It is not gate based universal quantum computing but special purpose quantum annealing.
If you accept this as a valid approach to quantum computing has certainly been the subject of much debate.
.... maybe the slahdot stub should have had a link to hear from the horse's mouth?
In this interview Matthias Troyer puts his team's results into the correct context.
But the makers of the computer can't find a single problem it solves well. Why is that?
Aside from profit, why is that question even relevant? It took a century for the geocentric model to give more accurate results than the old heliocentric model. Here we appear to have quite a few independent observers who know quantum annealing when they see it, I am not one of them. Sure it could be a scam but so far I have seen zero evidence supporting that hypothesis.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
What we need to know about is the existence or non-existence of unfair comparisons, i.e., problems that favor the putatively "quantum" computer.
Since I don't expect a quantum computer to be faster at everything, then finding a bunch of solutions to problems that aren't any faster on the "quantum computer" doesn't prove anything, even if the problems look like the kind of problems you'd hope would be quantum-computery. There's not much more you can do than point to the absence of evidence when the burden of proof isn't on you.
The burden of proof is on the vendor here, and standard of "proof" is conceptually simple at least: demonstrate that for some task this device offers any practical advantage whatsoever over the best available conventional technology. That could be in absolute performance against the best available tech(e.g. ASICs and supercomputers), in relative performance over similarly priced systems, or in some practical measure other than performance, such as power consumption. Any clearly identifiable and verifiable advantage counts as positive proof the vendor has something worth paying attention to.
Of course even comparable performance by a novel architecture on some class of problems is interesting, because of the huge advantages a mature technology enjoys. Performance of a new design even in the same ballpark as a mature design suggests future improvements might be in the works. But it's only a suggestion.
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