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Comments: 132 +-   Programmable Quantum Computer Created on Thursday November 26, @11:41AM

Posted by Soulskill on Thursday November 26, @11:41AM
from the four-out-of-five-ain't-bad dept.
science
technology
An anonymous reader writes "A team at NIST (the National Institute of Standards and Technology) used berylium ions, lasers and electrodes to develop a quantum system that performed 160 randomly chosen routines. Other quantum systems to date have only been able to perform single, prescribed tasks. Other researchers say the system could be scaled up. 'The researchers ran each program 900 times. On average, the quantum computer operated accurately 79 percent of the time, the team reported in their paper.'"
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  • The researchers ran each program 900 times. On average, the quantum computer operated accurately 79 percent of the time, the team reported in their paper.

    20% of the time it got it wrong, and 1% of the time, someone looked in the box and it wasn't there. 79% accurate. That's pretty useless. I've got a pair of dice that can do just as badly.

    • Re: (Score:2, Funny)

      by Anonymous Coward

      My dice are 100% accurate. I ask them for a random number, and every time that is what they return.

      • Re: (Score:2)

        by Fizzl (209397)

        int rand()
        { return 3; } //Chosen with a fair dice roll

        (Old joke, yeah.)

      • My dice are 100% accurate. I ask them for a random number, and every time that is what they return.

        I can fix that for you with a bit of sandpaper (dice that are slightly sanded on one or more faces are called"flats [metal-express.net]", and come up non-random).

    • Re:79% accuracy ... (Score:5, Insightful)

      by Timothy Brownawell (627747) <tbrownaw@prjek.net> on Thursday November 26, @12:12PM (#30238042) Journal

      79% accurate. That's pretty useless.

      Not useless at all, just have it solve the same problem 5 or 15 times and go with the answer that it gives most often. Plus, for some problems it's much easier to verify an answer than to come up with it -- for those problems, just pair it with a normal computer to check the answers, and keep trying until it says the answer is right.

      • Re: (Score:3, Informative)

        by Frequency Domain (601421)

        79% accurate. That's pretty useless.

        Not useless at all, just have it solve the same problem 5 or 15 times and go with the answer that it gives most often. Plus, for some problems it's much easier to verify an answer than to come up with it -- for those problems, just pair it with a normal computer to check the answers, and keep trying until it says the answer is right.

        One of the classic examples of that last one is prime factorization. In general it's very hard to come up with the two primes that were multiplied to create a very large number, but if the quantum computer coughs up a candidate it's downright trivial to check whether that's a solution.

      • There's still room for error there though, and that is simply unacceptable based upon how we use our computers today.

        This means that quantum-based processor will either become useful for a certain niche (something that doesn't require precise results) or we'll find a way to make them useful for everyday stuff... like outfitting classical processor technology with quantum capabilities to solve specific types of problems more efficiently.

        • There's still room for error there though, and that is simply unacceptable based upon how we use our computers today.

          This is why everybody uses only ECC memory in their desktop machines and all filesystems in common use support checksumming for data integrity.

      • The programmable quantum computer is 100% accurate all the time, it always prints 42.

        • Re:79% accuracy ... (Score:5, Funny)

          by Jahava (946858) on Thursday November 26, @12:52PM (#30238324)

          That's TOTALLY moronic. That's like saying "get 5 or 15 people to guess your birthday and go with the answer that it gives most often."

          Are people accurate 79% of the time? In the examples you gave? Then no, it's not like that at all.

          How stupid can you get?

          Many thanks for demonstrating!

          • There were examples where people had the same (lousy) accuracy as this. Try reading the links instead of just looking at the portions I quoted for brevity.

              • Note the article - hundreds of different functions were tested, with an overall accuracy of 79%. How are you intending to build more than a trivial piece of code when you have 79% accuracy from each function, on average? The fact is, the more function calls you add, and the more functions you add, the more likely that at least one will be wrong - and then the errors will, of course, cascade, since now you already have bad data for the next fuction, and it's highly unlikely you'll get just the right error

        • Re:79% accuracy ... (Score:5, Informative)

          by chhamilton (264664) on Thursday November 26, @01:01PM (#30238398)

          No, it's actually a perfectly reasonable idea. Consider running the device (n+m) times. The probability of it being right n times and wrong m times is given by:

          P(n,m) = (n+m)!/n!/m! 0.79^n 0.21^m

          Now consider the probability of it being right (majority has the right answer) out of 2n+1 trials. This is the given by:

          S(n) = sum( P(n+1+i,n-i), i=0..n )

          This can be simplied to a closed form using Legendre and gamma functions, but that's kind of messy and it's far easier to just plug in values and do the summation. As it turns out, doing the experiment 15 times and taking the majority (plugging 7 into S(n)) will give you the correct answer 99.4% of the time. Doing things 35 times gets you to five nines of accuracy... completely reasonable in my books.

            • You can't ever have 100% accuracy, ever. Nothing you do can ever change that.

              This isn't talking about " 2+2 = 3.9999999999882 on average after 100 runs". The given algorithm is 2+2 = 4, with 99.99999999% confidence, determined after 100 runs. Which is what you ALREADY get with non-quantum computers, because nothing is 100%.

              Quantum computing is not like floating-point computing. It gets an exact answer, with any individual run having potentially shitty accuracy, but accuracy can be fixed. The errors and

              • The problem is you want to look at the accuracy of the entire system, not just one line. In a 100,000 line program, making multiple recursive calls to many functions, 21% errors in each function will mean you'll pretty much never get the same answer twice between runs, whereas conventional hardware is pretty darned deterministic.

                It's not like FP arithmetic, but the errors still do accumulate, because bad output from one step becomes bad input for the next - the errors accumulate aggressively.

        • 79% accurate. That's pretty useless.

          Not useless at all, just have it solve the same problem 5 or 15 times and go with the answer that it gives most often.

          That's TOTALLY moronic. That's like saying "get 5 or 15 people to guess your birthday and go with the answer that it gives most often."

          That would actually be quite impressive, I don't know of a computer that can guess a random value, such as a birthday, with 79% accuracy. And everything else in your post, though I've heard most of it before, just makes me feel sad for the condition of the USA.

          • His entire post was based on a satire article. The fact that so many people took it seriously makes me happy I'm better than those elitists! Wait...

            • My point is simple - we laugh at the American citizens who think the United States is a foreign country and can't find it on the map, but we take :quantum computing" seriously when it has equally laughable results. Until it's accurate, the "computing" part should be removed. It might be quantum, but it ain't computing, because it simply doesn't compute (pun intended :-).

              Next buzzword bingo article - "Cloud quantum computing at the LHC makes baguette disappear 50% of the time! Latest theory is toast! Ph

          • Your assumption is TOTALLY moronic. Creating an emotional argument has ALWAYS been the most effective tactic in trolling.

          • Think about it - the posters' premise was that take a sample of 5 to 15 times, and go with the majority answer. I pointed out some of the hazards of that. There are many more, all obvious to anyone who wants to think for a few minutes.

            Let's say we do a calculation, 2+2. We do it 5 times. If it's only right 79% of the time, every once in a while, we'll get a sample of 5 where the majority is not 4 ... So, if we have a condition like if (2+2 == 4), it will fail once in a while, in a non-predictable way

              • And if you have code that is non-trivial, then you're going to have more than one function call. Say you have code that executes a few billion function calls (not too hard to imagine - your computer does it every day just surfing the web and drawing pretty icons on-screen). Your 4/10000 error for each function call after picking the median of 5 iterations means that we can pretty much guarantee that every run of the overall program for the rest of your life will be in error. So, you say, increase the nu

          • Now imagine that the problem that this computer solves is extremely difficult, and would take billions of years to solve on a conventional computer.

            Suddenly it doesn't sound so stupid anymore, eh?

            Problems have a way of falling down a lot quicker than you'd think. When they started sequencing the human genome, they thought it would take 100 years. Gee, how time flies - it sure didn't seem like it took 100 years.

            There's almost always a better algorithm if you look at a problem long enough.

          • If this is the way these systems work, and since they're so tiny, wouldn't it make sense to build them as triple-redundant (or more) all running the same exact routines, and take the majority answer? Or perhaps have a cluster of them running in parallel the same routine X number of times and take the majority answer from that?

    • 79% accurate. That's pretty useless. I've got a pair of dice that can do just as badly.

      You may be interested in purchasing this chip I have here. It has a very nice fdiv routine. Since we're so good friends, I'll give you a 100.00001353% discount.

    • >>79% accurate. That's pretty useless. I've got a pair of dice that can do just as badly.

      79% accurate? That's good enough for government work!

    • A factoring algorithm that gives the correct answer with 50% probability (in a short enough time) would be very useful.
      Since you can check the answer with a single multiply, you keep trying until you have the correct answer.

      This is one of a set of problems labeled "NP" - a characteristic is that you can verify an possible answer in polynomial time.
      Any of these problems can be solved with a polynomial time algorithm that gives the correct answer 50% of the time.

    • Re: (Score:3, Informative)

      by xZgf6xHx2uhoAj9D (1160707)
      Actually quantum computing is, by design, probabilistic. Every specifically quantum algorithm (even Shor's infamous factoring algorithm) gives incorrect results by design for the simple reason that it's really not possible to have quantum algorithms which succeed all the time (unless you forgeo their quantum properties). So long as the probability of a correct answer is strictly greater than 0.5, however, one only has to repeat the computation a constant number of times to get the probability of success arb

  • Could be worse... (Score:3, Funny)

    by Shivinski (1053538) on Thursday November 26, @11:54AM (#30237898) Homepage

    On average, the quantum computer operated accurately 79 percent of the time,

    Well, its better then anything Microsoft can come up with...I'll take 10!

  • Since it's a Quantum Computer, shouldn't reading the results actually mess up the results? Or at least that's what I understood from that Futurama racing joke.

  • In some alternate universe, there's a guy who is riding a bus, a thought pops into his head, "Pick a number between 1 and 100. Now, add 3. Now, divide by 13...". 99% of the time, he does the problem in his head, 79% of the time he finishes it. 1% of the time, he says, "Screw it". 100% of the time, he wonders where the hell these things are coming from and decides to check himself into the nearest mental ward.

    Quantum computing is screwing up someone's day.

  • How do they know? (Score:3, Insightful)

    by jpmorgan (517966) on Thursday November 26, @12:26PM (#30238150) Homepage

    I'm curious how they could possibly know that it operated correctly 79% of the time, since the underlying quantum state isn't observable. You could say it produced the 'correct' results 79% of the time, but that's not the same as saying it operated correctly 79% of the time; it's very possible for a quantum computer to operate incorrectly and still produce the right result, through sheer random chance.

    I suppose I could read the paper.

  • Ha ha (Score:2, Insightful)

    by cefek (148764)

    Can you imagine the accuracy of a Beowulf cluster of that?

      • Or, you get more combinations of right, wrong, and other as answers. Now, what happens when one unit in the cluster suddenly starts throw the right answer 100%?

        Or, goes 100% wrong?

        Or, goes 100% OTHER?

        What if it taps something we cannot comprehend?

        What if it hits "other" just once. And as a result, somewhere in the timeless Eternity, God freezes, bends over, and monkeys fly out of His ass?

      • Re: (Score:3, Funny)

        by dem0n1 (1170795)

        Again 79%. size does not matter

        That's what she sighed as she patted him on the knee and then walked out of his life never to be seen again.

  • Experimental physicist Boris Blinov says that one of the most exciting things about the new study is that the quantum computer may be scaled up. “What’s most impressive and important is that they did it in the way that can be applied to a larger-scale system,” says Blinov, of the University of Washington in Seattle. “The very same techniques they’ve used for two qubits can be applied to much larger systems.”

    Pretty soon they will be able to calculate the US budget with accuracy heretofore unmatched by any recent administration.

    • You don't need two quantum states for that, one will suffice.

      In The Red, until the end of the universe (where I hear there's a very nice restaurant).

  • First infinite loop.... (Score:5, Funny)

    by Temujin_12 (832986) on Thursday November 26, @01:28PM (#30238608)

    do {
        solveProblem();
    } until (getPhotonPosition() && getPhotonVelocity());

  • The old 80-20 rule. The other 21% of failures caused the first 79% to be correct.

  • You know what they say... 79% of the time, it's correct every time.

  • Get out into the Beyond [wikipedia.org], and you can reasonably expect 100% efficiency out of your quantum computers. Keep going into the Transcend, and you can reasonably expect better than 100% efficiency -- or at least that's what it looks like to merely-human minds.

    Just don't open any unsigned JAR files.

  • Can it run Linux?

    • Re:correct and incorrect? (Score:5, Funny)

      by NoYob (1630681) on Thursday November 26, @11:53AM (#30237888)

      So is that 21% of the time is was both correct and incorrect ?

      That's correct and the other 79% of the time the cat died.

    • The actual state of the machine is "all possibilities at once", it is the act of observing the result that actually collapses the waveform and causes the answer to settle into a specific state.

      So obviously, in the 21% cases, the operator just looked at the computer "in a funny way".

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