from Hacker News

Performance of quantum computer no better than ordinary PC, say analysts

by aasarava on 6/19/14, 8:12 PM with 42 comments

  • by Xcelerate on 6/19/14, 8:34 PM

    The title of the article "Performance of quantum computer no better than ordinary PC" is just flat out wrong. The real issue that physicists are concerned about is whether the D-wave machine is a quantum computer or not. The issue is not whether quantum computers are "better" than classical ones.

    Assuming the correctness of quantum mechanics, a quantum computer WILL be faster than classical computers for specific classes of problems, exponentially faster in some cases. This has been mathematically proven. (EDIT: No it hasn't apparently. See Michael Nielsen's response below.)

  • by dm2 on 6/19/14, 8:47 PM

    Here is another article today bashing the D-Wave Two computers: http://www.wired.com/2013/06/d-wave-quantum-computer-usc/

    These machines are testing a completely new computing concept. We're trying to learn how they work so that we can apply that to building machines that can actually outperform traditional computers, and once that's achieved then the potential benefit will be enormous.

    According to http://www.dwavesys.com/d-wave-two-system as you scale up qubits the power demands do not increase. That alone has huge potential.

    Maybe new materials need to be developed to see the full potential of these computers, lots of research needs to be done. Why are all of these articles so pessimistic?

    NASA, Lockheed, and Google purchasing these multi-million dollar machines should indicate that there is at-least some potential and value in the D-Wave computers, even if in the end they just learn what D-Wave did wrong.

    https://www.youtube.com/watch?v=CMdHDHEuOUE

    "We don't know the best questions to ask the quantum computers, that's what we're trying to find out now."

  • by icegreentea on 6/19/14, 8:48 PM

    This is the paper in question: http://www.sciencemag.org/content/early/2014/06/18/science.1...

    Which appears (I can't tell, paywalled) to be an update or this one: http://arxiv.org/abs/1401.2910

    I don't have to time to read the article properly right now, but doesn't look like they did anything ridiculous in their choice of testing algorithm.

  • by robgibbons on 6/19/14, 9:05 PM

    Firstly, this is the first of a new class of computers, so I am not surprised it may be slow at first. Secondly, this machine uses a relatively small number of bits, compared to a classical computer. Lastly, they're throwing classical problems at a quantum processor and wondering why it's not magically faster. I would like to see how an optimized quantum algorithm performs.

  • by bwy on 6/19/14, 11:57 PM

    A few other comments have pointed it out already, but how does this comparison actually mean anything? For example, multiplication with the first hole-punch computers was no faster than multiplying by hand and paper (probably slower), but look where we are now!

  • by mpthrapp on 6/19/14, 8:25 PM

    The title is slightly misleading. This article is only talking about the performance of one specific quantum computer. (The D-Wave Two).

  • by yellowapple on 6/19/14, 10:57 PM

    What's the definition of "ordinary PC" being used? Not finding an answer to that in the article, which makes it difficult to get an idea of what the researchers are comparing this thing to.

  • by ColinWright on 6/19/14, 8:48 PM

  • by owenversteeg on 6/19/14, 9:07 PM

  • by MrBuddyCasino on 6/19/14, 9:56 PM

  • by michaelochurch on 6/19/14, 10:52 PM

    Weird title. If someone built a quantum computer that performed remotely as well as a 2014-era classical machine, that would be huge news. Quantum computers are really hard to build.