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Test: Quantum Or Not, Controversial Computer No Faster Than Normal 119

Posted by samzenpus
from the you're-doing-it-wrong dept.
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.
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Test: Quantum Or Not, Controversial Computer No Faster Than Normal

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  • by vux984 (928602) on Thursday June 19, 2014 @08:29PM (#47277893)

    No. They are trying to measure the growth of the problem. So its not important which one is absolutely faster, but which one takes relatively more time as the problem becomes more difficult.

    The conventional computer should take exponentially longer as the problem becomes mroe difficult. The quantum one should not.

    In this test, both took exponentially longer. So either the d-wave doesn't work, or as the manufacturer has claimed, the problems were not setup to demonstrate the class of problems where the d-wave will show better performance relative to problem complexity growth than a conventional computer.

    Seems odd to me though that they can't provide easily verified sample problem spaces where their device works better than a conventional PC as the problem gets 'bigger'.

  • by K. S. Kyosuke (729550) on Thursday June 19, 2014 @08:42PM (#47277983)
    Wow. So quantum, very scam, much dollars.
  • by Ken_g6 (775014) on Thursday June 19, 2014 @08:49PM (#47278031) Homepage

    This could mean that D-Wave isn't quantum. Or it could mean that quantum computing in general isn't faster than normal computing. I seem to recall some physicist making a bet that quantum computing would be proved equivalent to classical computing.

  • by Anonymous Coward on Thursday June 19, 2014 @09:02PM (#47278111)

    I've been surprised time and again that D-Wave has kept afloat as long as it has. It *will* fail in the end, the only question is how much of that investment money Geordie Rose got safely stashed before the collapse. Their approach is fundamentally not quantum computing.

  • by radish (98371) on Thursday June 19, 2014 @09:56PM (#47278391) Homepage

    Which in turn would mean that for the problem space it's capable of operating within it's no faster than a normal computer. Which reduces down to "it's no faster than a normal computer".

  • by Anonymous Coward on Thursday June 19, 2014 @10:12PM (#47278477)

    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.

  • by bill_mcgonigle (4333) * on Thursday June 19, 2014 @11:29PM (#47278831) Homepage Journal

    Which reduces down to "it's no faster than a normal computer".

    I'm not sure I get this argument. The guys selling this stuff have said for a while that their device is fast enough at quantum annealing to be useful for learning to program quantum computers, and that when their manufacturing ramps up they'll have many more qubits, and I think the implication is that the speed doesn't scale linearly. They were telling the Googles and the Lockheeds, 'look you need to invest in our product and services so you can be ready in the quantum computing space when the better hardware emerges'.

    That it's not absolutely faster than a conventional computer at this point is interesting, academically, but not terribly relevant to their sales pitch, unless we can show that the problem at hand fits inside their limited qubit space and the types of algorithms its supposed to be able to handle at this point, and still does not do what's expected of it.

    Also: did a tiny Canadian computer company produce a computer that's as fast (within the problem space) as a modern Xeon on their slim budget? That would almost seem revolutionary - AMD can't even do that with GlobalFoundary's fab on their side.

    Maybe it is a scam, but this kind of analysis seems somewhat orthogonal to their claims. By all means, pop one open and find the i7 inside, and there won't be any question, but that's not really where we are today.

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