Reexamining classical and quantum models for the D-Wave One processor

More science on data from the D-Wave One system at USC.

Reexamining classical and quantum models for the D-Wave One processor

We revisit the evidence for quantum annealing in the D-Wave One device (DW1) based on the study of random Ising instances. Using the probability distributions of finding the ground states of such instances, previous work found agreement with both simulated quantum annealing (SQA) and a classical rotor model. Thus the DW1 ground state success probabilities are consistent with both models, and a different measure is needed to distinguish the data and the models. Here we consider measures that account for ground state degeneracy and the distributions of excited states, and present evidence that for these new measures neither SQA nor the classical rotor model correlate perfectly with the DW1 experiments. We thus provide evidence that SQA and the classical rotor model, both of which are classically efficient algorithms, do not satisfactorily explain all the DW1 data. A complete model for the DW1 remains an open problem. Using the same criteria we find that, on the other hand, SQA and the classical rotor model correlate closely with each other. To explain this we show that the rotor model can be derived as the semiclassical limit of the spin-coherent states path integral. We also find differences in which set of ground states is found by each method, though this feature is sensitive to calibration errors of the DW1 device and to simulation parameters.

7 thoughts on “Reexamining classical and quantum models for the D-Wave One processor

  1. Hi Geordie,

    I follow your blog because I want to write about quantum computing and because D-Wave seems to be on the leading edge of commercializing such a product. And even though I am a writer who has worked for tech companies in Silicon Valley for more than a decade, I am not a physicist. Which makes posts like this very difficult to decipher. Perhaps I am not your intended audience. But it seems to me that the best way to get your story told more broadly would be to include some more posts that explain what you are doing in plain english, for the rest of us. I personally think that quantum computing is the next big thing in tech. I also think it is controversial. Two reasons this story will be around for awhile.

    What I would like to be able to do is write about is why it matters. I know, for example, that Google is using D-Wave in its labs. It would be great to know more about that and the practical applications of quantum computers.

    All the best,
    Diana

      • Hello Diana,
        Hello Diana, I am also a long time follower of D-wave technology and I understand how things can be complicated in this field. Most of the post here are indeed scientific and quite technical, but don’t be intimidated, I think the comprehension is completely within reach by a lay person, like me for example😉 With a little bit of background research I think you will be able to follow eventually. You don’t have to know everything but the general knowledge will help you interpret the articles on the issues that matter to you.

        For some background knowledge I recommend the D-wave website which has a chock-full of great explanations for beginners, check out this primer for example: http://dwavesys.com/tutorials/background-reading-series/quantum-computing-primer

        Another site that may help is Henning Dekant’s blog – wavewatching.net. I think his blog is excellent! He’s not a physicist either but knows D-wave stuff very well.

        Just one disclaimer, once you delve into the world of D-Wave technology, saga, and controversy it can be pretty addicting😉 Good luck.

      • @Ramsey, thank you so much for your recommendations and support! Even though I know a fair amount about computing (mostly UNIX and SPARC) I get lost in the physics and have been trying to teach myself about the basics. So thank you for these links! Very helpful!

        All the best,
        Diana

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