Visiting D-Wave Systems

So I spent last week hanging out at D-Wave systems which was awesome. For anyone not in the know, they are (to the best of my knowledge) the only company pursuing the ambitious goal of building a large scale quantum computer.

Their architecture consists of superconducting flux qubits implemented in the framework of Adiabatic Quantum Computing (AQC). Most people think of the gate model when they envisage quantum computing, which consists of applying unitary evolution operators (rotations in the Bloch sphere) to single qubits and to entangled states of multiple qubits. AQC works a little differently, by slowly evolving the Hamiltonian of the system (slow in order to keep it in the ground state) from an initial Hamiltonian (where the ground state is easily prepared) to one where the ground state would encode the solution to a hard problem.

To compare, the gate model involves moving between states, and taking the system to higher energy levels. Remaining in the ground state means that you are always protected from sources of decoherence (i.e. nearby states) by an energy gap, which is a minimum at the point where the energies of the two Hamiltonians would classically intersect. However at this point the quantum mechanical explanation predicts an anticrossing of these states, and thus the appearance of the energy gap (hope I got that correct). I’m from an experimental gate model background, be kind 😀

They really are a unique company, and their experimental effort was impressive. (Of course so too was the theoretical side, but coming from an experimental background I could relate more to the cool kit and the data). I met some really fantastic people whilst I was there. Not to mention the fact that Vancouver is one of the most beautiful cities I have visited. Combine immense yet aesthetically pleasing skyscrapers, modern city living, a picturesque harbour with a mountain range backdrop, stunning forests and parks, beaches, amazing coffee, numerous outdoor sports opportunities and more seafood restaurants than you could possibly dream of, and the picture begins to take shape. They also have nutella ice-cream… Just thought I’d mention that.

To check out more about the company, you can read Geordie’s blog (he’s the CTO of D-Wave and a really cool guy) or visit the company link above.

Some recent papers can be found here, here and here.

Hopefully I’ll be able to report more on this topic in the future!

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10 thoughts on “Visiting D-Wave Systems

  1. rrtucci says:

    Susan, I read from your About page that you are both an artist and a physicist. I am too…sort of. Here is my D-wave art:

  2. We had a visit from Herb Martin and Mohammad Amin a few months ago, and I have to admit, it didn’t do anything to easy my skepticism. As an experimentalist yourself, how do you rate their progress?

  3. physicsandcake says:

    @rrtucci: Somehow, I already saw that picture 🙂 Yeah, it’s hard work being an artist and a physicist – I don’t have any time left over!

  4. physicsandcake says:

    @Joe: IMO, the experimental side of things was all good. They are performing several fundamental experiments to show qubit behaviour, as illustrated in the recent arxiv paper. It’s just a case of whether or not the architecture will scale, although I’m not so hot on the theory side of that. I guess it’s a case of wait and see 🙂

  5. Ian Durham says:

    So what’s your take on their claim to have developed a 16 qubit quantum computer? Did they really do it? I mean, I understand not wanting to show off your architecture if you’re commercial enterprise, but at the recent QIS Gordon Conference Dorit Aharanov asked the very insightful and somewhat rhetorical question: how will we know if it worked the way it is supposed to even if it truly is a quantum computer? In other words, how can we verify its “quantumness” or, rather, the “quantumness” of any result it calculates?

  6. Geordie says:

    Hi Ian: Ultimately the answer to this question relates to the reason for building these machines in the first place. Quantum computers are just a means to an end, with the end being the capability of running new sorts of algorithms with better scaling than is possible classically. Computational scaling is empirically extractable from experiment. If the experimental scaling agrees with the predictions of the behavior of quantum adiabatic algorithms, and is better than possible classically, then there remains no question.

  7. quantummoxie says:

    Geordie, thanks for your reply. I guess I disagree with you philosophically on that, at least in part, but then I’m a theorist. In other words, I think to ultimately prove the “quantumness” of it we need a new theory that is outside of QM. And, on a more practical note, if it is as simple as you say, you wouldn’t have as many critics in the QIS community. Nonetheless, I applaud your efforts and I don’t mean these comments as taking anything away from your work. You have to realize I’m trained as a mathematician and thus have a very high standard for proof.

  8. quantummoxie says:

    One more thing: The Quantum Times (newsletter for APS Topical Group on QI in case you’re not a member and don’t know what I’m talking about) would welcome an article on D-Wave. Perhaps Suz could write something for an upcoming issue? Pictures might ease some folks’ minds.

  9. physicsandcake says:

    It would be cool to be involved with the Quantum Times (I am a reader of the newsletter) although perhaps someone at D-Wave could write a better, more in-depth article, as I only stayed long enough to get an overview 🙂

  10. quantummoxie says:

    Well, I think the reason it might be better to have you or someone like you (i.e. a visitor) write it is that it would at least appear to be a bit more objective.

    I’m glad to hear you’re a reader! The next issue should be out soon and includes a picture of one of Barry Sanders’ grad students lecturing on quantum mechanics in nothing but a sarong… 😉

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