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Scientists Dubious of Quantum Computing Claims

Posted by Zonk on Fri Feb 16, 2007 05:35 PM
from the little-salt-with-your-quantum dept.
Science Technology
Dollaz wrote with a link to the International Business Times, which questions the authenticity of D-Wave's Quantum computing. We discussed the 'Sudoku playing' computer yesterday, but scientists in the field have expressed a lot of distrust of the company's findings. The machine was not available for inspection during or after the demo, and even if the technology was working as intended there is some doubt that it can be scaled. The article points out that "notwithstanding lofty claims in the company's press release about creating the world's first commercial quantum computer, D-Wave Chief Executive Herb Martin emphasized that the machine is not a true quantum computer and is instead a kind of special-purpose machine that uses some quantum mechanics to solve problems." Good to see people in the field questioning 'breakthroughs'.
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[+] Technology: Quantum Computer Demoed, Plays Sudoku 309 comments
prostoalex writes "Canadian company D-Wave Systems is getting some technology press buzz after successfully demonstrating their quantum computer (discussed here earlier) that the company plans to rent out. Scientific American has a more technical description of how the quantum computer works, as well as possible areas of application: 'The quantum computer was given three problems to solve: searching for molecular structures that match a target molecule, creating a complicated seating plan, and filling in Sudoku puzzles.' Another attendee provides some videos from the demo." Anyone want to guess how long before "qubit" gets compressed to "quit" (as "bigit" became "bit" in the last century)?
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  • I Knew It! (Score:2, Funny)

    by Anonymous Coward
    I knew something was up when it got stuck on a level four Sudoku.

    And then when it coughed and 'had to take a smoke break.' I knew there was a reason no one could look at it.

    • Reply button missing (Score:5, Interesting)

      by dangitman (862676) on Friday February 16 2007, @07:54PM (#18046714)

      Good to see people in the field questioning 'breakthroughs'.

      This is an odd statement, because that's generally what people "in the field" do. The author says this as though it's unusual to see anybody questioning lofty claims. In fact, it's very common. The first slashdot article about this was met mostly with skepticism.

      Note: Replying to this post, because I am not getting a "reply" button for the story itself. Anybody else experiencing this bug?

      • Re: (Score:3, Informative)

        by orkysoft (93727)
        There's a Reply link in the floating thingy.
      • The author says this as though it's unusual to see anybody questioning lofty claims.

        That wasn't the author, that was Zonk. In a summary, anything not in blockquote tags was written by the posting "editor". Apart from that, I agree, that's the way it's supposed to work - someone makes a claim, experts in the field scrutinise and challenge it. The claim is either upheld, or refuted. That's science. Duh.

  • Well DUH (Score:5, Funny)

    by UbuntuDupe (970646) * on Friday February 16 2007, @05:39PM (#18045408) Journal
    The machine was not available for inspection during or after the demo, ...

    Yes ... that's how a quantum mechanical system works -- you look at it, you change it. I can imagine these guys in peer review, "Look, this double-slit [wikipedia.org] experiment of yours is really interesting and all, but we can't publish your results unless you record the photons going through EACH slot, on EACH time, otherwise, how do we know you're faking it?"

    I kid, I kid. I think...

    • Re:Well DUH (Score:5, Funny)

      by idontgno (624372) on Friday February 16 2007, @05:49PM (#18045540) Journal
      That's the real problem. Until they look, the computer is in a superpositon of being and not being a quantum processor. They're afraid to look, lest its probability field collapse into an eigenstate of "just marketing hype."
      • ...but looking once collapses it, but you can look again and it'll collapse a different way, right? For instance, electrons -- look once and it's in one place, look again and it's somewhere else.

        So, can't they just put together "just marketing hype", then turn their backs, close their eyes, and shoot the marketers who actually understand the hype, so it'll uncollapse into a probability field again, then turn around and have a chance of it being finished?

        You know, kind of like how the finite probability driv

        • Re:Well DUH (Score:4, Informative)

          by pclminion (145572) on Friday February 16 2007, @06:49PM (#18046150)

          Don't confuse the uncertainty of quantum collapse with the uncertainty of the Uncertainty Principle. They are two different concepts. The uncertainty principle derives from a mathematical truth (it would be true even if the world was not governed by quantum physics), whereas the uncertainty associated with wavefunction collapse is a true quantum effect unrelated to the Heisenberg uncertainty principle.

          (The Uncertainty Principle is a consequence of the fact that momentum and position are dual-spaces of each other -- similar "uncertainty" principles arise, for the same reasons, in more mundane fields such as signal processing)

    • Re:Well DUH (Score:5, Funny)

      by Profane MuthaFucka (574406) <busheatskok@gmail.com> on Friday February 16 2007, @06:02PM (#18045690) Homepage Journal
      There is a universe somewhere in which you did not make that joke. And some luckier copy of me gets to live in that universe.

  • Thats my problem with the press release, too: (Score:4, Informative)

    by imsabbel (611519) on Friday February 16 2007, @05:39PM (#18045424)
    "instead a kind of special-purpose machine that uses some quantum mechanics to solve problems."

    Well, _any_ mosfet based transitor uses quantum mechanics to solve problems (you get real problems explaining band-formation and the influence of substrate doting classically). That statement is trimmed down to be as slippery as possible.

  • How would you?

    I'm legitimately curious. Such a device has never been built, how do these guys prove they have one? They say themselves they aren't certain if it's quantum-ing up the sudoku.

  • Uncertainty? (Score:5, Funny)

    by Quila (201335) on Friday February 16 2007, @05:44PM (#18045486)

    He said all the evidence the company has indicates that the device is performing quantum computations, but he acknowledged there is some uncertainty.

    Time to check the cat.
  • He kind of has a point in that, even if it isn't a "true" quantum computer and it simply uses some quantum processes, it doesn't matter a whole lot to the people interested in buying it. They're more interested in the power to do stuff they can't right now. That being said, the fact that they aren't willing to show the machine to scientists makes me question whether this machine actually uses quantum processes.

    • They're more interested in the power to do stuff they can't right now.

      They should get the Sudoku books with the easier puzzles!

    • Re:He kind of has a point... (Score:5, Interesting)

      by Sam Nitzberg (242911) on Friday February 16 2007, @07:26PM (#18046496)
      Direct test for a quantum computer:
      Solve any problem polynomially reducable to SAT/3-SAT (http://en.wikipedia.org/wiki/Boolean_satisfiabili ty_problem)
      without the use of heuristic algorithms. Further, show it being done in polynomial-time with respect to the problem size.

      Naturally, the machine and program would also have to be subject to inspection to show that it wasn't just spitting out a canned response to a problem already worked on and answered by a team of supercomputers elsewhere....

      Fortunately, checking the result won't take too long. The check should be calculable on a conventional computer in polynomial-time.

      • Solve any problem polynomially reducable to SAT/3-SAT

        You have your reducibility direction mixed up: even really easy problems (like sorting, or outputting "2") are reducible to SAT. It's the hard problems that SAT reduces to.

        Not that this matters, because quantum computing is very unlikely to be able to solve NP-complete problems. It does seem to help with very structured problems like factoring, though. No, factoring is (almost definitely) not NP-complete.

        Further, show it being done in polynomial-time with respect to the problem size.

        Polynomial-time is an asymptotic notion. It can't be verified for a particular problem size (or finite set of problem sizes). It is purely an analytical concept, not an experimental/testable one.

    • Re:He kind of has a point... (Score:5, Informative)

      by TMacPhail (519256) on Friday February 16 2007, @07:51PM (#18046692)

      I went to the Vancouver demo of this yesterday and it is pretty clear why they couldn't have it available for inspection at an event like this. It is located in a specially shielded room in their lab to reduce signal noise with a cooling system that cools a portion of the computer down to 4mK (extremely close to absolute zero).

      Besides, even if I or anyone else there was able to inspect it, do you really think that we could look at it and say "hey, I don't see any quantum effects"

  • Uncertainty? (Score:4, Funny)

    by nonpareility (822891) on Friday February 16 2007, @05:46PM (#18045512)

    He said all the evidence the company has indicates that the device is performing quantum computations, but he acknowledged there is some uncertainty.
    Sounds like a joke that flew over the reporter's head.

  • Good blog responses (Score:5, Interesting)

    by Ambitwistor (1041236) on Friday February 16 2007, @05:51PM (#18045570)
    Quantum computing researcher Scott Aaronson wrote some good anti-hype pieces about the D-Wave PR here [scottaaronson.com] and here [scottaaronson.com], focusing on their incorrect marketing claims to be able to solve NP-complete problems in polynomial time. The first link also has an update with comments from Lawrence Ip of Google, who clarifies what the D-Wave people are really claiming.

    • They didn't do what they said they did (Score:5, Insightful)

      by QEDog (610238) on Friday February 16 2007, @07:10PM (#18046372)
      There are several things to note about the announcement. First, the emphasis was on selling that this computer can solve NP-Complete problems, something that it is, to say the least, not right. An adiabatic quantum computer, such as the one they claim they had, cannot "solve" NP-complete problems. It can at most give a quadratic improvement, at most. They didn't even showed that the did this. Solving a particular instance of an NP-complete problem (such as the 9x9 sudoku) does NOT mean that you can solve an NP-comp problem. Either they lied, or there were intenionally using language that was not very precise to give the wrong impression. So the things that they said they can do cannot be done.

      What did they do? Nobody knows. They were very careful to evade the important question: what did they actually accomplish? They never mentioned qubit decoherence times, fidelity, nothing. These are things they can claim without compromising the trade secrets. They gave a lot of emphasis to saying that the computer is part a classical computer, and part a quantum computer, something that nobody really cares about. What is important is to spell out exactly what was the part of the problem the quantum computer solved.

      The CTO has a blog, and he sounds very competent in it. I'm guessing that he just had a lot or pressure from the investors to show *something*. It was just a big show to get some Venture Capitals. Pretty graphics and tech demos are cool for getting fans for videogame consoles and getting VC only, not so much as to make scientific claims.
      • I thought that NP-Complete problems can be generalised to one-another, so if a solution can be found for one NP-Complete problem then it can be generalised for all. Doesn't this mean that other NP-Complete problems can be generalised to Sudoku?
        • It's that a given limited Sudoku doesn't demonstrate the ability to solve an arbitrarily large Sudoku in finite time, not that Sudoku as a problem isn't equivalent to other problems computationally.

      • Misconceptions about NP-Completeness (Score:5, Interesting)

        by et764 (837202) on Saturday February 17 2007, @12:13AM (#18048222)
        Depending on what you mean by "solve," I think you are a little mistaken on what it means for a problem to be NP-Complete. NP-Complete problems are actually relatively easy to solve. For example, take 3SAT, were you have a bunch of boolean variables, x[1] through x[n], and then a bunch of string of clauses ANDed together, as in (x[1] OR x[2] OR NOT x[3]) AND (x[24] OR NOT x[37] OR x[42]) ... To solve 3SAT you just have to tell me whether there exists some combination of variables such that the expression is true. You can just enumerate all 2^n possible combinations of variable assignments and see if any of them work out to be true. The problem is, it doesn't take very large values of n before it will take you longer than the time civilization has been around to try all the combinations. 3SAT is easy to solve, if you just want an answer. What's still an open question is whether we can come up with an algorithm that can solve it efficiently, where efficiently means in O(n^k) time for some k, rather than O(2^n).

        For a problem that actually can't be solved, try the Halting Problem.

        Now, the cool thing about NP-Complete problems is that any other problem that's known to be in NP (meaning we can solve them, just some instances will take a ridiculous amount of time to do so) can be efficiently transormed, meaning transformed in polynomial time, into an NP-Complete problem. This means if you can really solve general instances of Sudoku in polynomial time, you can take an instance of the 3SAT problem, efficiently transform it into an instance of Sudoku, then efficiently solve the Sudoku problem and then transform the answer into a solution to the 3SAT problem. If they have really built such a machine, this is a big deal.

  • Marketing department at work... (Score:3, Interesting)

    by viking2000 (954894) on Friday February 16 2007, @05:52PM (#18045594)
    Let me guess: It is a regular computer that solves a regular problem the regular way. One function needed is a number generator.

    You could pick any device that returns different numbers at different times. It could be a microphone, a geiger counter, a clock og a quantum device

    Now pick the quantum device, and call the whole device a "Quantum computer"

    This is normal in marketing departments. The only unusual thing here is that they got the engineering department to go with them.

  • Maybe, but... (Score:4, Insightful)

    by Flimzy (657419) on Friday February 16 2007, @05:54PM (#18045612)
    Maybe it's not a true quantum "computer", but is that bad? The first electronic "problem solving machines" weren't true computers, either. That doesn't mean that this "custom" quantum machine isn't a useful step in the right direction...
  • I heard Pamela Jones was last seen with the Quantum Computer.
  • I've never liked the use of dubious to denote a state of mind. If this is correct

    The claims were dubious...
    what the heck is this supposed to mean?

    The scientists were dubious...
    Merriam-Webster approves the use, but I would avoid it. How about "Scientists Skeptical of Quantum Computing Claims"?

    Hey, if you're not anal retentive, you have no business being a programmer.
    • Seems as though it's one of those wonderful English portmanteaus. The OED has no problems with it being used to refer to the claims themselves and the scientists' views of those claims. At least it's not a nonstandard English flutzpah.
      • At least it's not a nonstandard English flutzpah.

              In fact, it's a perfectly cromulent word.
    • The claims were questionable or suspect as to true nature or quality (1b)

      The scientists were unsettled in opinion (2)

      http://www.m-w.com/dictionary/dubious [m-w.com]

  • I've been saying for ages it's a scam (Score:5, Interesting)

    by exp(pi*sqrt(163)) (613870) on Friday February 16 2007, @06:11PM (#18045790) Journal
    It's the electronic equivalent of using soap bubbles to solve the traveling salesman problem. For simple problems you really can use soap bubbles because soap bubbles like to form minimal surfaces. This 'quantum' computer does something similar - it uses a form of annealing to find the minimum of some function with the energy representing the function you're trying to minimise. Cool the system and you find what that minimum energy is. But soap bubbles don't scale.

    So the first part of the scam is this: even if this device wasn't a quantum device at all it would still work to some extent because when you allow systems to cool they fall into lower energy states. If the 'quantum' aspect of things works then it might find that state faster, but without careful monitoring there's no way of telling if the 'quantumness' had anything to do with what it did. In fact, for large systems we know that it won't be very 'quantum' at all because it will interact with its environment and decohere. But it's a perfect strategy for designing a machine that you can claim is quantum, when it isn't. It stinks of scam.

    Secondly: suppose you want to solve a challenging problem with this device. For example you want to search some space for a miniumum of some sort. For this machine to be effective the state space must be pretty large or else you could use a regular classical computer. Consider a billion state problem (quite small really for combinatorial problems). You have to be able to get a system to settle into the minimum energy state despite the fact that there are a billion states nearby all of which have almost the same energy. Just the tiniest input of energy and it'll jump up from that minimum. There is absolutely no way that they can search a large enough state space and still have the minimum energy state sufficiently far from other states.

    BTW This device is quite different from what is conventionally meant by a 'quantum computer', it's more like a quantum, analog computer.

    Real and useful 'digital' quantum computers are a long way off. I expect that the size of quantum computers will grow by a bit or so per year at the most. (When I say 'bit' I mean total memory, not the size of the bus.)

  • I thought they already had a conventional algorithm that could solve Sudoku without utilizing quantum effects?

    I'm very skeptical about the whole concept of utilizing quantum effects to solve problems. It's an interesting idea, utilizing the structure of the universe to tell us what we want to know, but it may not be at all practical. Nature doesn't seem to have utilized the method, and since it evolves molecule-sized structures it ought to be in the position to do so.

    I think that, when we're done playing

    • Re: (Score:2, Interesting)

      by austior (1063772)

      I thought they already had a conventional algorithm that could solve Sudoku without utilizing quantum effects?

      Quantum computers can only solve problems that conventional algorithms can solve. Potentially, they could solve them faster.

      Nature doesn't seem to have utilized the method

      There are a lot of useful things nature hasn't discovered, like wheels (macro sized) and transistors. The nervous system doesn't take advantage of ANY molecular scale computation, so how could it build a quantum computer?

    • You're right. I have two friends who have written Sudoku solvers for the hell of it. One in Java, one in (gack!) Matlab. I don't think it's a good demo application of a quantum computer, unless it's a fake quantum computer created by the marketing department. ("It has Transistors, which use QM effects! Take that, FTC!")
  • Scientists are skeptical because it hasn't been submitted for peer review. Yes, but that's true for any new scientific discovery. It's not entirely fair to spin that into "this quantum computer might not really work".
    Also, while the article claims it might not be a "true quantum computer", it never really says how that's different from a "computer that uses quantum mechanics to solve certain problems", and given its audience, can't possibly expect its readers to know. To me, this just sounds like journal

  • So, is this the right place.... (Score:4, Informative)

    by FooAtWFU (699187) on Friday February 16 2007, @06:29PM (#18045978) Homepage
    Is this the right place to plug my animated JavaScript sudoku solver [fennecfoxen.org]? Guaranteed 100% Non-Vaporware! Inspect it all you like!

    :)

  • The media is always trying to spice things up. Statements like "we are attempting to build a quantum computer" and "we ran 100 tests and had 1 good result, which could've been chance" get warped into "quamtum computer built" and "quantum computer shows promise, produces results". The media as a whole isn't biased left or right, but they are biased towards sensationalism. There doesn't seem to be any easy way to introduce a little more restraint and fact checking into their reporting that doesn't just mak
    • Sorry to rain on your damn-the-media parade, but these exact claims were made by the company, presentations and all. In this case the media really wasn't hyping anything, the examples D-wave showed during their presentation however did seem more like a PR-stunt than scientific research. Could be wrong though, IANAQCS.


      Anything for the VC.

  • Good to see people in the field questioning 'breakthroughs'.

    Well, have there been any peer reviewed papers published in journals with good reputation? If not, we have here the number one sign of bogus science [chronicle.com]: The discoverer pitches his claim directly to the media and questioning is the only reasonable attitude. For me, they lost it when they announced that the presentation was going to be remote, that the actual machine would not be in the room where the presentation was held. Yeah, so you haven't actually

  • They didn't hire me so they must know something (Score:4, Interesting)

    by Jay 78 (1065226) on Saturday February 17 2007, @12:48AM (#18048416)
    I actually interviewed with these guys a few months back. I can tell you I was quite impressed with the facility and they came off as very bright. I also got a tour of the facility so I'll share what I know. The chip core is stored in a large tank roughly 2m tall and cooled to very very near absolute zero. That is then held inside what is in essence a very large faraday cage. All the refrigeration and electronic equipment is kept outside with only passive sensors allowed in the room wherever possible. Apparently electrical noise and stray heat has been a huge hurdle. From what I understood they saw themselves as building chips that would be housed on site and used remotely so it doesn't surprise me that they didn't have a setup that was available for public viewing. The company culture was essentially work till you drop and hope the stock options make you rich.

    • Re: (Score:3, Interesting)

      by Mock (29603)
      I was at the Vancouver showing.
      I've done a lot of smoke and mirror shows myself, and this demo did not smell funny at all.

      The headline "Scientists Dubious of Quantum Claims" is rather sensationalist for what they're actually saying in the article.
      Can you really fault them for not wanting to move a computer that has to be housed in a special chamber, cooled to near absolute zero, and be havily shielded from any outside interference?
      Besides, judging by the questions people asked, not a single person in the au

    • Re: (Score:3, Insightful)

      by imsabbel (611519)
      Well, the thing is, a _real_ quantum computer would also be to fragile to move. Thats a reality in ultra-low-temperature equipment of the needed sensitivity.

      And still, even if they were on-site, if they wanted to cheat, how would you check that its really the QC that does the calculations? Even if there is a cable going into it, who says the real data didnt elsewhere? Or somebody put a laptop somewhere inside the QC?

      There is simply no way to verify the claim without taking the whole assembly apart, which of

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