Programmable Quantum Computer Created

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Programmable Quantum Computer Created

Posted by Soulskill on Thursday November 26, 2009 @04:41AM from the four-out-of-five-ain't-bad dept.

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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79% accuracy ... by tomhudson · 2009-11-26 04:44 · Score: 1

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.
1. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 04:50 · Score: 2, Funny
  
  My dice are 100% accurate. I ask them for a random number, and every time that is what they return.
2. Re:79% accuracy ... by Fizzl · 2009-11-26 04:53 · Score: 1
  
  int rand()
  { return 3; } //Chosen with a fair dice roll
  (Old joke, yeah.)
  
  --
  Bot Assisted Blogging
3. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 04:57 · Score: 1, Funny
  
  Someone will put linux on it, and it will be able to crack RSA, but people won't be able to figure out how to get their printers to work with ti.
4. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 05:03 · Score: 1, Funny
  
  Someone will put linux on it, and it will be able to crack RSA, but people won't be able to figure out how to get their printers to work with ti.
  ...Or their keyboards.
5. Re:79% accuracy ... by Timothy+Brownawell · 2009-11-26 05:12 · Score: 4, Insightful
  
  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.
6. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 05:32 · Score: 0
  
  What do you mean "useless". It's already surpassed slashdot.
7. Re:79% accuracy ... by tomhudson · 2009-11-26 05:40 · Score: 1
  
  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", and come up non-random).
8. Re:79% accuracy ... by billakay · 2009-11-26 05:48 · Score: 1
  
  You might want to look up the randomized computational complexity class BPP. There is 2/3 - 1/3 split on when it answers correctly. I believe that it answers correctly 2/3 of the time, and the other 1/3 time is indeterminate. All you need to do is run it a few times (these algorithms are very fast, and average the results. The summation of these attempts very quickly approach many nines of accuracy after a relatively short number of attempts. In fact, before the (relatively) recent discovery that primality testing is in P (the discovery of a deterministic poly-time algorithm for testing whether a number is prime), the best algorithm was in BPP, and in fact, that is the algorithm that is mostly used today because of it's speed.
9. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 05:50 · Score: 0, Insightful
  
  you noticed that the article you are quoting is satire right?
10. Re:79% accuracy ... by Jahava · 2009-11-26 05:52 · Score: 5, Funny
  
  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!
11. Re:79% accuracy ... by dem0n1 · 2009-11-26 05:53 · Score: 0, Offtopic
  
  So, according to your "go-with-the-flow" theory, the capital of the US is Minneapolis-St. Paul.
  Does that mean Al Franken is the President then?
  
  --
  Why save your soul when you can sell it for a profit?
12. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 06:00 · Score: 0
  
  How stupid can you get?
  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?
13. Re:79% accuracy ... by chhamilton · 2009-11-26 06:01 · Score: 4, Informative
  
  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.
14. Re:79% accuracy ... by WCguru42 · 2009-11-26 06:06 · Score: 1
  
  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.
  
  --
  "Educate the mind but never at the expense of the soul."~Blessed Basil Moreau
15. Re:79% accuracy ... by ShakaUVM · 2009-11-26 06:14 · Score: 1
  
  >>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!
16. Re:79% accuracy ... by tolkienfan · 2009-11-26 06:15 · Score: 1
  
  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.
17. Re:79% accuracy ... by Frequency+Domain · 2009-11-26 06:27 · Score: 2, Informative
  
  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.
18. Re:79% accuracy ... by RudeIota · 2009-11-26 06:35 · Score: 1
  
  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.
  
  --
  Fact: Everything I say is fiction.
19. Re:79% accuracy ... by Captain+Segfault · 2009-11-26 06:44 · Score: 1
  
  That's TOTALLY moronic.
  I've been seeing this a lot lately.
  Is responding to objectively correct posts with a combination of insults and an invalid argument the current fashion in troll-land, or has slashdot been invaded by twelve year old non-nerds? In good faith I'll assume the latter, leaving me with a stupid question: how did a twelve year old get a five digit UID?
20. Re:79% accuracy ... by xZgf6xHx2uhoAj9D · 2009-11-26 06:48 · Score: 2, Informative
  
  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 arbitrarily close to 1.
21. Re:79% accuracy ... by LKM · 2009-11-26 06:54 · Score: 1
  
  There's still room for error there though, and that is simply unacceptable based upon how we use our computers today.
  Well, no. Computers can always be wrong. Repeat the calculation often enough, and you'll be better than your average PC. Besides, as RudeIota notes, sometimes the calculation is hard, but verifying the result is trivial (that is often the case in cryptography, for example). In those cases, you can just repeat the calculation until it's correct.
22. Re:79% accuracy ... by roguetrick · 2009-11-26 07:03 · Score: 1
  
  I hope because of that his post is satire.
  
  --
  -The world would be a better place if everyone had a hoverboard
23. Re:79% accuracy ... by roguetrick · 2009-11-26 07:06 · Score: 1
  
  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...
  
  --
  -The world would be a better place if everyone had a hoverboard
24. Re:79% accuracy ... by roguetrick · 2009-11-26 07:08 · Score: 1
  
  Your assumption is TOTALLY moronic. Creating an emotional argument has ALWAYS been the most effective tactic in trolling.
  
  --
  -The world would be a better place if everyone had a hoverboard
25. Re:79% accuracy ... by mugurel · 2009-11-26 07:14 · Score: 1
  
  So I guess in the near future we will be seeing things like:
  >>> 1 + 1
  2 (p < .001)
26. Re:79% accuracy ... by Timothy+Brownawell · 2009-11-26 07:23 · Score: 1
  
  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.
27. Re:79% accuracy ... by tomhudson · 2009-11-26 07:47 · Score: 1
  
  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.
28. Re:79% accuracy ... by tomhudson · 2009-11-26 07:51 · Score: 0, Troll
  
  I want 1005 accuracy. I don't want 2+2 = 3.9999999999882 on average after 100 runs, then having it fail every time when I do an if(2+2) == 4).
  Sure, I could use a delta, and then make sure it's under that, but then you have the accumulation of errors and tolerances.
  Take a barrel of shit, add a cup of wine, you still have a barrel of shit.
  Take a barrel of wine, add a cup of shit, you have a barrel of shit.
  A failure rate of 21% is bad business. Ask Microsoft wrt the XBox RRofD
29. Re:79% accuracy ... by tomhudson · 2009-11-26 07:57 · Score: 1
  
  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! Physicists blame the French. EU demands youtube videos be removed because they make fun of scientists!"
30. Re:79% accuracy ... by tomhudson · 2009-11-26 08:16 · Score: 1
  
  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. So now, instead of having just a 79% accuracy, you have a cascade of inaccuracies. If every line of your code has a 1 in 5 chance of failing, anything more complicated than trivial programs like "goodbye, world!" will fail more than they will succeed.
  Think of it - if you have 100 lines of code, with a chance of 1% error every time any one line was run, your program will almost always give wrong output.
  It's like in the old days of tube computers - sure, a tube might last 10,000 hours - but with 10,000 tubes, you'd better make sure your program didn't require a week to run - on average, at least one tube would burn out long before then.
31. Re:79% accuracy ... by tomhudson · 2009-11-26 08:19 · Score: 0, Flamebait
  
  ... you notice that it's backed up by similar interviews on video all over the net? Americans who think that the US invaded Israel, who point to Australia and think it's Iraq, etc...
  Just because it's satire doesn't mean it isn't true - satire is used to expose truth, not hide it.
32. Re:79% accuracy ... by tomhudson · 2009-11-26 08:22 · Score: 1
  
  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.
33. Re:79% accuracy ... by Device666 · 2009-11-26 08:24 · Score: 1
  
  The programmable quantum computer is 100% accurate all the time, it always prints 42.
34. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 08:31 · Score: 1
  
  Your links is interesting in one sense but completely irrelevant to the issue at hand. And, frankly, the birthday thing was YOUR example, and it was completely wrong, so maybe you shouldn't have made that your example? You can't possibly castigate somebody for not inventing an argument you didn't make, especially a bad one, based on an irrelevant link you provided.
  From looking at the link, it's more like asking 6-17 people what country is the world's largest consumer of oil, and going with the most common answer. Which is an effective tactic that is likely to be right. For birthdays? No amount of guessing is going to help, because your chances of selecting each wrong answer are equal to your chances of selecting the right answer. These statistics only work when the chances of getting the answer right are higher than the chances of choosing any particular wrong answer, but then they DO work.
  At 79% accuracy, repeating independent trials 5 times and taking the most common answer gives you >90% accuracy (you have to be wrong 3 times to no longer guarantee accuracy, and that's 21% cubed, or 0.009261%, times 5 choose 3, or 10, + a bit for being wrong 4 or 5 times -- and if the incorrect answers don't match you're still getting the right answer, so the accuracy is a bit better than that on anything but a binomial question). Repeating 15 times brings the error down to ~2%, and again, if the "wrong" answers are evenly distributed among a large number of alternatives, then the error is now a very, VERY small number, far lower than 1%. Eventually, repeated trials make the chances of error in a traditional computer from phenomena like spontaneous bit-flipping and self-interference even in binomial cases.
35. Re:79% accuracy ... by kheldan · 2009-11-26 08:31 · Score: 1
  
  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?
  
  --
  Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
36. Re:79% accuracy ... by Your.Master · 2009-11-26 08:35 · Score: 1
  
  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 tolerances don't accumulate; it's confidence that accumulates with this sort of algorithm.
37. Re:79% accuracy ... by tomhudson · 2009-11-26 08:43 · Score: 1
  
  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 to cancel it out.
  The more complex the program, the more likely that you'll never get the same answer twice over n runs ... it's still useless at this point - the only quantum computing device that has the necessary power to correct for bad inputs is your brain, and that's because it doesn't need to find "the right" answer - just one good enough to survive.
38. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 08:56 · Score: 0
  
  I don't think you understand what 79 percent accuracy means.
  79 percent accuracy means that 21% of the time, the answer is wrong. But if you do the same answer 5 times, then the percentage of the answer being wrong gets much smaller. This is simple probability stuff.
  0.21 * 0.21 * 0.21 * 0.21 * 0.21 = 0.0004084101. That's 4 hundreths of a percent chance of it being inaccurate. This number gets hugely smaller with an increasing sample size. For example 15 tries gets you a 0.000000000068. I don't know, but that seems pretty darn good, to me.
  -XcepticZP
39. Re:79% accuracy ... by tomhudson · 2009-11-26 09:05 · Score: 1
  
  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.
40. Re:79% accuracy ... by tomhudson · 2009-11-26 09:16 · Score: 1
  
  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 number of iterations at each step. The problem is, the number of iterations needed to keep the overall error rate down increases rapidly with each new function call because errors do accumulate for non-trivial programs.
41. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 09:19 · Score: 0
  
  Still, we're not talking about a comercial device. Not yet, at least. When transistors were first conceived, you can be damn sure that no one could make a completely accurate numerical computer out of it. So it's just a matter of time.
42. Re:79% accuracy ... by tomhudson · 2009-11-26 09:37 · Score: 1
  
  Still, we're not talking about a comercial device. Not yet, at least. When transistors were first conceived, you can be damn sure that no one could make a completely accurate numerical computer out of it. So it's just a matter of time.
  
  Transistor radios were out 5 years (1952) after the transistor was invented (1947). Between 1955 and 1957 several companies were selling fully-transistorized calculators and computing devices.
  I doubt we'll be seeing fully-quantized computers in 10 years.
43. Re:79% accuracy ... by tlhIngan · 2009-11-26 10:12 · Score: 1
  
  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.
  Or uses floating-point hardware. Regardless of how many bits you use, floating-point computations are always approximate (mostly because the range of numbers that can be represented is larger than the number of possible numbers a given bit length can represent).
  Hell, these computers might be more accurate, since there's a number of floating point operations you can do where the precision drops sharply because of the way it works.
44. Re:79% accuracy ... by wumingzi · 2009-11-26 10:20 · Score: 1
  
  .. you notice that it's backed up by similar interviews on video all over the net? Americans who think that the US invaded Israel, who point to Australia and think it's Iraq, etc...
  I'm not going to stand up for Americans' knowledge of the world beyond their borders (of their country or their county), but remember that the interviews you often see on the net are the result of hours of interviews cooked down to the 4 minutes which are the funniest and most outrageous.
  The reality IS bad, don't get me wrong, but it's not THAT bad!
45. Re:79% accuracy ... by Bloodoflethe · 2009-11-26 10:34 · Score: 1
  
  You are acting like they will only make one calculation and go with it. You keep talking about this 21%, when the accuracy measurements, (until they find a way to make it more accurate) would require confidence testing on the numbers before input into as an answer into your program. Not that I think they'll be happy with doing it that way. But for now, it'll give you the accuracy necessary to get the job done right.
  
  --
  "Little is much when little you need."
46. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 10:56 · Score: 0
  
  That second link, for the huffingtonpost article. I guess you missed this at the top:
  "Editor's note: This post is a satire."
  This makes your accuracy 50%, still not as good as the quantum computer. Better luck next time.
47. Re:79% accuracy ... by Imrik · 2009-11-26 11:38 · Score: 1
  
  These aren't new problems like the human genome sequencing was, we've been looking at these problems for quite a while now. While we occasionally do get a slightly better algorithm it's still the same order of complexity.
48. Re:79% accuracy ... by volpe · 2009-11-26 11:42 · Score: 1
  
  Plus, for some problems it's much easier to verify an answer than to come up with it
  Yes. They're called "NP Complete" problems.
49. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 12:55 · Score: 0
  
  Yes. I already knew that.
50. Re:79% accuracy ... by ae1294 · 2009-11-26 13:04 · Score: 1
  
  how did a twelve year old get a five digit UID?
  I've been watching eBay for a low cost 4 digit UID...
51. Re:79% accuracy ... by Dunbal · 2009-11-26 13:06 · Score: 1
  
  Hmmm? The result sets are independent of each other. Just like the probability of throwing a die and saying that "6" is the "wrong" number, you have a 1/6 chance of getting it "wrong" EACH TIME you throw the dice. It doesn't matter how often you've thrown it before, this time, your chance is 1/6. And next time, you chance is 1/6. This is why people lose money in casinos. The dice don't have to listen to you, they don't HAVE to eventually give the number you want, etc.
  
  --
  Seven puppies were harmed during the making of this post.
52. Re:79% accuracy ... by amazingxkcd · 2009-11-26 13:26 · Score: 1
  
  how can it always say 42 unless it knows the question? if the question is known, then we cease to exsist since the question and the answer cannot be known in the same universe at the same time... unless someone else in a parrallel universe knows the question, then the programmable quantum computer is a space time travelling machine, for which would be epic!
53. Re:79% accuracy ... by Timothy+Brownawell · 2009-11-26 13:36 · Score: 1
  
  Plus, for some problems it's much easier to verify an answer than to come up with it
  Yes. They're called "NP Complete" problems.
  Maybe:
  
  If f is a one-way function, then the inversion of f would be a problem whose output is hard to compute (by definition) but easy to check (just by computing f on it). Thus, the existence of a one-way function implies that P != NP. However, it is not known whether P != NP implies the existence of one-way functions.
  
  I'm not certain exactly what this means, but part of it seems to be that "one-way" != "NP-complete" (because that would result in a much shorter explanation). But it does at least seem to mean that one-way functions would be a subset of NP problems, which I wasn't certain of when I posted that.
54. Re:79% accuracy ... by Anonymous Coward · 2009-11-26 13:44 · Score: 1, Informative
  
  It's actually 4;
  --
  And then I notice I have finished my sentence with a semicolon. Am I going crazy?yes:no;
55. Re:79% accuracy ... by mdwh2 · 2009-11-26 13:49 · Score: 1
  
  I want 1005 accuracy. I don't want 2+2 = 3.9999999999882 on average after 100 runs, then having it fail every time when I do an if(2+2) == 4).
  Sure, I could use a delta, and then make sure it's under that, but then you have the accumulation of errors and tolerances.
  I take it you've never done programming, or not with floating points, anyway. Because that's exactly how it is, already.
56. Re:79% accuracy ... by smoker2 · 2009-11-26 14:58 · Score: 1
  
  I didn't see the part where the accuracy mentioned was that generated by the computation, only the computer. If your liquid helium boils off, or you have a short, or , or ,or. None of those are relevant to the mathematical accuracy, only the reliability of a concept machine. So they're not Sony yet - big deal.
57. Re:79% accuracy ... by mesterha · 2009-11-26 15:13 · Score: 1
  
  They never claimed each statement or function call had a 79% chance of success, they said the program had a 79% of success. This is fine for a randomized algorithm. Check out http://en.wikipedia.org/wiki/Monte_Carlo_algorithm for more information.
  
  --
  
  Chris Mesterharm
58. Re:79% accuracy ... by Captain+Segfault · 2009-11-26 17:19 · Score: 1
  
  The problem is, the number of iterations needed to keep the overall error rate down increases rapidly with each new function call because errors do accumulate for non-trivial programs.
  No it doesn't; adding extra repetitions decreases the error rate exponentially; you only need repetitions logarithmic in the length of the program.
  In practice it would be foolish to write something like a web browser on a quantum computer with a nontrivial error rate -- but this is just an early prototype. After a while the error rate will be much lower than 21%. (Consider the error rate on a modern CPU!)
59. Re:79% accuracy ... by mhelander · 2009-11-26 17:54 · Score: 1
  
  "The result sets are independent of each other."
  Yes, that's why he could just multiply them like that.
60. Re:79% accuracy ... by Captain+Segfault · 2009-11-26 18:00 · Score: 1
  
  I pointed out some of the hazards of that.
  My issue is not that, but that you felt the need to insult the OP in the process. Yes, the idea has hazards. Yes, it doesn't work if the error rate is 20% per operation. That doesn't make the idea moronic.
  
  Think of it - if you have 100 lines of code, with a chance of 1% error every time any one line was run, your program will almost always give wrong output.
  The reasoning is actually exactly the same. Given a sufficiently low error rate and some reasonable bounds on the types of errors you can implement an error correcting code to detect and eliminate those errors. (oversimplifying, you need an error rate sufficiently low to be able to detect errors in your error detection.) 1% is probably good enough, at least working in a model like "boolean logic circuits" rather than "lines of code." 20% almost certainly isn't.
  The same general idea applies to quantum "logic circuits".
  This error correction logic obviously isn't free; it adds a logarithmic factor to the cost/length/whatever of your program. That's not such a big deal if you're running an algorithm which is exponentially faster than it's classical counterpart.
61. Re:79% accuracy ... by jonadab · 2009-11-27 00:40 · Score: 1
  
  > 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.
  
  If it were a standard electronic computer, you'd return it for a refund and never buy anything from that manufacturer again.
  
  Five nines sounds good, because for an *uptime* figure, it is good.
  
  But for computational accuracy, that's abysmal. At a speed of only 1 GHz, which isn't exactly a screaming speed demon these days, your computer would be making ten thousand mistakes per second. For traditional computing applications, that makes it so much useless scrap. If our computers make one computational error per *hour*, we complain about how horribly buggy the software is, because we have come to expect that our hardware won't do that to us.
  
  The other poster's suggestion, of using the quantum computer to suggest candidate answers and a traditional electronic computer to check them, makes much better sense. There are whole categories of computing problems where checking the answers is trivial, if you can in the first place get a candidate answer that's at all likely to be correct.
  
  That, and obviously this is a research prototype and the accuracy could potentially be improved in the future, just as we expect that the performance level will be improved by further research.
  
  --
  Cut that out, or I will ship you to Norilsk in a box.
62. Re:79% accuracy ... by Zaiff+Urgulbunger · 2009-11-27 03:34 · Score: 1
  
  /me stirs berylium ions and tastes...
  /me announces "needs more cats!"
63. Re:79% accuracy ... by chhamilton · 2009-11-27 06:14 · Score: 1
  
  Why do things at a level of granularity of 100,000 lines? Why not get the quantum computer to do the 'repeat x times and pick the most common answer' at each instruction? It'll introduce exactly the same slow down factor, and vastly reduce the chance of error propagation.
  Conventional computers already have a certain amount of error that creeps in. Suppose during a single tick of the clock cycle there is some chance P of an error occurring. Find the 'repetition factor' n such that the quantum computer guarantees you no more than the same amount of error P, and you've got a quantum computer that gives you exact answers (over arbitrarily long programs) with the same chance of error as a conventional computer having run the same number of arguments. It becomes more an issue of speed, rather than errors.
  Having to repeat each fundamental step some large number of times slows down the computer. (To get 1/10^40 chance of error, repeat the calculation ~400 times given any individual calculation has a 21% chance of failure.) However, this will disappear as the underlying hardware is improved, which it invariably will be (given more years of development time, I'm sure errors will be reduced from 21% to far below 1%).
  Many real world problems are already built around this notion, whereby we only know the answer to be correct with a high degree of confidence (see 'Monte Carlo algorithms'). The underlying process only needs to be correct more often than it's wrong (it could be 50% + epsilon versus 50% - epsilon) and we can just keep repeating the calculation until we get any arbitrary accuracy we wish.
64. Re:79% accuracy ... by steve_bryan · 2009-11-27 15:34 · Score: 1
  
  Please, stop embarrassing yourself. There is nothing wrong with being uninformed, but it should not be a point of pride.
65. Re:79% accuracy ... by CTachyon · 2009-11-28 17:14 · Score: 1
  
  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 arbitrarily close to 1.
  Nitpick: though this is true for the most familiar quantum algorithms, i.e. the ones in BQP (Bounded-error Quantum Polynomial-time), there are also some quantum algorithms that give exact answers with 100% certainty, such as EQP (Exact Quantum Polynomial-time).
  
  --
  Range Voting: preference intensity matters
66. Re:79% accuracy ... by Anonymous Coward · 2009-11-30 07:42 · Score: 0
  
  You should probably try reading your own links. Half your argument (the huffington post article) is a satire. Meaning not real.
correct and incorrect? by bongey · 2009-11-26 04:45 · Score: 1

So is that 21% of the time is was both correct and incorrect ?
1. Re:correct and incorrect? by NoYob · 2009-11-26 04:53 · Score: 5, Funny
  
  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.
  
  --
  It's NOT me! It's the meds! I'm on 1000mg of Fukitol.
2. Re:correct and incorrect? by Bottles · 2009-11-26 04:53 · Score: 0
  
  Well, yes and no.
3. Re:correct and incorrect? by electricbern · 2009-11-26 05:08 · Score: 1
  
  Yes, although there is a 21% chance that my answer is wrong.
  
  --
  alias possession='chmod 666 satan && ls /dev > il && tail daemon.log'
4. Re:correct and incorrect? by Anonymous Coward · 2009-11-26 05:18 · Score: 0
  
  Depends if you look at it or not
5. Re:correct and incorrect? by V!NCENT · 2009-11-26 05:35 · Score: 2, Funny
  
  So in the other universe 21% of the time cats die. I knew this universe was violent!
  
  --
  Here be signatures
6. Re:correct and incorrect? by daveime · 2009-11-26 06:38 · Score: 1
  
  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".
7. Re:correct and incorrect? by Anonymous Coward · 2009-11-26 10:21 · Score: 0
  
  I don't believe a quantum computer can not operate accurately. However, it can be observed inaccurately! Perhaps they should replace the observer and try again.
wait by jaggeh · 2009-11-26 04:52 · Score: 1

79% of the time they work every time

--
I would give everything i own for a little bit more.
Think of the cats! by jeffshoaf · 2009-11-26 04:53 · Score: 1

Were any cats harmed in the running of the programs?

--
Putting the "anal" back into "analyst"...
1. Re:Think of the cats! by V!NCENT · 2009-11-26 05:37 · Score: 1
  
  $cat BoxInside.sh ...
  Oh crap!
  
  --
  Here be signatures
2. Re:Think of the cats! by Dunbal · 2009-11-26 12:53 · Score: 1
  
  Screw the cats.... I want to know about puppies.
  
  --
  Seven puppies were harmed during the making of this post.
Could be worse... by Shivinski · 2009-11-26 04:54 · Score: 3, Funny

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!
1. Re:Could be worse... by DiegoBravo · 2009-11-26 06:24 · Score: 0, Flamebait
  
  And is better than the probability of total Linux hardware support for any random pc/laptop!
2. Re:Could be worse... by Anonymous Coward · 2009-11-26 06:37 · Score: 0
  
  You meant windows 7, right? Linux got far better than it in drivers lately...
Accurate only 79% of the time? by Yvan256 · 2009-11-26 05:03 · Score: 1

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 by WED+Fan · 2009-11-26 05:11 · Score: 5, Funny

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.

--
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
1. Re:In Some Alternate Universe by StripedCow · 2009-11-26 06:07 · Score: 1
  
  And that's by having only one quantum computer in a single universe... now imagine what would happen if all the other universes would start inventing such computers!
  
  --
  If Pandora's box is destined to be opened, *I* want to be the one to open it.
2. Re:In Some Alternate Universe by StripedCow · 2009-11-26 06:08 · Score: 1
  
  By the way, who would be able to claim the invention when the universes merge? Hmm, intriguing concept, prior art in a parallel universe...
  
  --
  If Pandora's box is destined to be opened, *I* want to be the one to open it.
3. Re:In Some Alternate Universe by WED+Fan · 2009-11-26 09:59 · Score: 1
  
  I've already patented "A Quantum Method for Parralel Copyright, Trademark, and Patent Registration".
  (Note: I assert that this comment is now prior art in all Universes and proof of my ownership of said patent, including Universes that contain no processes or concepts of copyright, trademark, or patent.)
  
  --
  Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
4. Re:In Some Alternate Universe by Anonymous Coward · 2009-11-26 10:12 · Score: 0
  
  By the way, who would be able to claim the invention when the universes merge? Hmm, intriguing concept, prior art in a parallel universe...
  Oh, just get the other guy's patent lawyer declared Anathem :)
Obligatory Anchorman quote by spineboy · 2009-11-26 05:15 · Score: 1

Loosely paraphrased here
79% of the time it is 100% accurate

--
..........FULL STOP.
Improving on the 79% accuracy by jonaskoelker · 2009-11-26 05:20 · Score: 2, Funny

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.
How do they know? by jpmorgan · 2009-11-26 05:26 · Score: 2, Insightful

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.
1. Re:How do they know? by palegray.net · 2009-11-26 05:35 · Score: 5, Funny
  
  I suppose I could read the paper.
  I think you might be on to something here.
  
  --
  512 MB RAM, 20 GB disk, 200 GB transfer, five datacenters. $19.95/month.
2. Re:How do they know? by Anonymous Coward · 2009-11-26 06:25 · Score: 0
  
  It's possible, but I'd bet that the odds of getting the correct answer after a failure are negligible (millions to one?) and so wouldn't significantly alter their claim that it was working correctly 79% of the time.
3. Re:How do they know? by FarFromUnique · 2009-11-26 06:33 · Score: 1
  
  +5 Accurate! If only I had actual mod points...
4. Re:How do they know? by Anonymous Coward · 2009-11-26 10:19 · Score: 0
  
  I suppose I could read the paper.
  I think you might be on to something here.
  Dude, that kind of speak could undermine the entire slashdot-commenting community.
5. Re:How do they know? by ultracool · 2009-11-26 18:12 · Score: 1
  
  The underlying quantum state *is* observable. Why wouldn't it be?
  If you RTFA (and not even the paper is necessary for this), you will see that they are limited by the fidelity of their setup, ie. signal to noise. Hence, when they improve their apparatus, they will get more accurate results.
Ha ha by cefek · 2009-11-26 05:30 · Score: 2, Insightful

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

--
Plain old sigh.
1. Re:Ha ha by OricAtmos48K · 2009-11-26 05:34 · Score: 1
  
  Again 79%. size does not matter
2. Re:Ha ha by Anonymous Coward · 2009-11-26 05:55 · Score: 1, Informative
  
  not if they are parallel. computations that are done on each node where the majority of the answer is the right answer (as long as it's accurate past 50%). won't increase speed but will increase accuracy.
3. Re:Ha ha by dem0n1 · 2009-11-26 05:57 · Score: 3, Funny
  
  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.
  
  --
  Why save your soul when you can sell it for a profit?
4. Re:Ha ha by Sulphur · 2009-11-26 06:18 · Score: 1
  
  21% of the time Beowulf accidentally shakes Grendel's hand.
Why is the result Right or Wrong? by WED+Fan · 2009-11-26 05:50 · Score: 1

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?

--
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
Bye-bye encryption? by orkysoft · 2009-11-26 05:59 · Score: 1

How long until they get it to factor huge numbers?

--

I suffer from attention surplus disorder.
1. Re:Bye-bye encryption? by u38cg · 2009-11-26 06:41 · Score: 1
  
  Conditioning on the NSA? A negative number, I'd suspect.
  
  --
  [FUCK BETA]
Bring it on, save the nation by hwyhobo · 2009-11-26 06:11 · Score: 1

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.

--
End anonymous moderation and posting on /.
1. Re:Bring it on, save the nation by daveime · 2009-11-26 06:41 · Score: 1
  
  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).
2. Re:Bring it on, save the nation by hwyhobo · 2009-11-26 09:59 · Score: 1
  
  You don't need two quantum states for that, one will suffice.
  Funny +1
  
  In The Red, until the end of the universe
  Insightful +1
  Too bad I cannot moderate in the same thread I post in.
  
  --
  End anonymous moderation and posting on /.
Make more and check correlation by Anonymous Coward · 2009-11-26 06:16 · Score: 0

Put them all in a cold vacuum chamber and check whether there is any correlation in errors. Maybe you could detect some wobbles in space time.
First infinite loop.... by Temujin_12 · 2009-11-26 06:28 · Score: 4, Funny

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

--
Faith is a willingness to accept something w/o complete proof and to act on it. Reason allows you to correct that faith.
1. Re:First infinite loop.... by Anonymous Coward · 2009-11-26 08:10 · Score: 0
  
  Something tells me that it might know the photon's velocity...
2. Re:First infinite loop.... by jandoedel · 2009-11-26 12:03 · Score: 1
  
  actually that's not an infinite loop. you can actually get both position and velocity of a particle.
  the result of getPhotonPosition() and getPhotonVelocity() just has to be a function, not a single number...
  
  So you could get for example two gaussian functions as result. And then you use some fuzzy logic.
  
  PS: the velocity of a photon is often the speed of light (in vacuüm)
3. Re:First infinite loop.... by inflame · 2009-11-26 13:17 · Score: 1
  
  i think you meant electron
4. Re:First infinite loop.... by BlueParrot · 2009-11-26 15:53 · Score: 1
  
  do {
  solveProblem();
  } until (getPhotonPosition() && getPhotonVelocity());
  In vacuum Photon Velocity will be a rather famous constant.
  The photon momentum, on the other hand, depends on the photon's energy ( i.e the colour ). Thus you can't break the uncertainty principle using photons, even though their velocity is always the same.
  Now in before some smartass points out it is gluons that have colour.
5. Re:First infinite loop.... by FreakyGreenLeaky · 2009-11-26 19:34 · Score: 1
  
  No.
  foreach (@mind_numbing_question) {
  $answer = solveProblem($_);
  say $answer;
  }
  42
  42
  42 ...
6. Re:First infinite loop.... by naam00 · 2009-11-26 21:21 · Score: 1
  
  Velocity is a vector, you can only be somewhat sure its length will be c.
Ahh... by Cytlid · 2009-11-26 06:50 · Score: 1

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

--
FLR
Well by mewsenews · 2009-11-26 06:58 · Score: 1

You know what they say... 79% of the time, it's correct every time.
Who cares? by drej · 2009-11-26 07:13 · Score: 1

That's all well and good, but the important thing is: Will it be able to run Crysis 2?
1. Re:Who cares? by amazingxkcd · 2009-11-26 14:03 · Score: 1
  
  u mean Crysis Quantum?
the 21% it was also correct by Anonymous Coward · 2009-11-26 07:26 · Score: 0

but on a different quantum space, of course.
79% is the best you can expect in the Slow Zone. by jeffb+(2.718) · 2009-11-26 07:42 · Score: 1

Get out into the Beyond, 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.
Yeah, but... by Seriousity · 2009-11-26 08:14 · Score: 1

Can it run Linux?

--
This post was made in complete sincere seriousity; as such any attempts to derive humour are doomed to instant failure.
1. Re:Yeah, but... by md65536 · 2009-11-26 09:35 · Score: 1
  
  I think a machine like that is better suited for Windows, because it can offer an improvement. Users found that it would only crash reliably about 79% as often as expected.
2. Re:Yeah, but... by sxrysafis · 2009-11-26 11:57 · Score: 1
  
  This is the first computer that can and can't run Linux at the same time!
On the death of cats by jonaskoelker · 2009-11-26 08:58 · Score: 1

I knew this universe was violent!
Blame god. He goes and kills a kitten every night after he visits me to tuck me in.
Err... I mean... Forget I said anything. Yes, it's violent here. Ahem.
Anonymous Coward by Anonymous Coward · 2009-11-26 11:32 · Score: 0

79 per cent of the time it works every time
No pictures by chaynlynk · 2009-11-26 14:28 · Score: 1

makes this a worthless article. How do we even know it exists? There were no pictures!
Re:79% is the best you can expect in the Slow Zone by argent · 2009-11-26 16:10 · Score: 1

Hexapodia is the key insight.
Serious news for RSA? by Anonymous Coward · 2009-11-26 19:35 · Score: 0

I wonder if this will mean serious problems for RSA or is this far from beeing dangerous to break integer factorization?
The interesting problems work differently by billstewart · 2009-11-26 21:47 · Score: 1

For most of the problems that you'd want to solve with a quantum computer, the problem is in NP or maybe even P, so if the QC can guess the correct answer, you can verify that it's correct. For instance, for factoring large numbers that are a product of two primes, conventional computers can't guess the factors in usefully short times, but if somebody guesses or steals an answer, you can easily check whether it's correct or not. You don't need to do a best-of-N to figure out what's probably the answer.
On the other hand, your probability arguments assume that the probability of success is independent and identically distributed, randomly giving you either the correct answer or a bogus answer. There's no good reason to assume that, since quantum computers work by Magic - it may be that a given set of inputs will always produce the same output, so running it multiple times doesn't gain you anything.

--

Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Re:79% is the best you can expect in the Slow Zone by arethuza · 2009-11-27 00:57 · Score: 1

Somehow I don't think a digital signatures will work too well in the Beyond or the Transcend. And we think security is tricky here...