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Record-Low Error Rate For Qubit Processor
An anonymous reader writes "Thanks to advances in experimental design, physicists at the National Institute of Standards and Technology have achieved a record-low probability of error in quantum information processing with a single quantum bit (qubit) — the first published error rate small enough to meet theoretical requirements for building viable quantum computers. 'One error per 10,000 logic operations is a commonly agreed upon target for a low enough error rate to use error correction protocols in a quantum computer,' said Kenton Brown, who led the project as a NIST postdoctoral researcher. 'It is generally accepted that if error rates are above that, you will introduce more errors in your correction operations than you are able to correct. We've been able to show that we have good enough control over our single-qubit operations that our probability of error is 1 per 50,000 logic operations.'"
Another few orders of magnitude and they might approach vacuum tube-levels of reliability.
Don't blame me, I voted for Baltar.
The problem is that once you know what the error is, you don't know where the error is.
I mean, once you know where the error is, you don't know what the error is.
I mean, err... I'm not sure.
"They have some catching up to do"
Yea, that's the whole point of their efforts.
An important thing to recognize is that most of this experiment was done with a single qubit. Practical quantum computing will need to have this sort of error rate for thousands of qubits. The good news is that the methodology they used looks very promising. They used microwave beams rather than lasers to manipulate the ions. This has been I think suggested before but this may be the first successful use of that sort of thing. As TFA discusses, this drastically reduces the error rate as well as the rate of stray ions.
We are starting to move towards the point where quantum computers may be practical. But we're still a long way off. In the first few years of the last decade a few different groups successfully factored 15 as 3*5 using a quantum computer. (15 is the smallest number which is non-trivial to factor using a quantum computer since the fast factoring algorithm for quantum computers- Shore's algorithm- requires an odd composite number that is not a perfect power. It is easy to factor a perfect kth power a bit by looking instead at the kth root. And factoring an even number is easily reduced to factoring an odd number. So 15 is the smallest interesting case where the quantum aspects of the process matter.) Those systems used a classical NMR system http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance_(NMR)_quantum_computing which has since been seen as too limited. There are now a lot of different ideas of other approaches that will scale better but so far they haven't been that successful.
One important thing to realize is that quantum computers will not magically solve everything. They can do a few things quite quickly such as factor large numbers. But they can't for example solve NP complete problems to the best of our knowledge, and it is widely believed that NP complete problems cannot be solved in polynomial time with a quantum computer. That is, it is believed that BQP is a proper subset of NP. Unfortunately, right now we can't even show that that BQP is a subset of NP, let alone that it is a proper subset. Factoring big integers is useful mainly for a small number of number theorists and a large number of other people who want to break cryptography. There are a few other cryptographic systems that can also be broken more easily by a quantum computer but there's not that much else. However, that is changing and people getting a better and better understanding of what can be done with quantum computers. A lot of the work has involved clever stuff involving using quantum computers to quickly calculate stuff related to Fourier series. Moreover, once we get even the most marginally useful quantum computers there will be a lot more incentive to figure out what sorts of practical things can be done with them.
So the upshot is that these are still a long way off, but they are coming. The way it looked in the late 1990s or early 2000s it was reasonable to think that the technical difficulties would make them never practical. They still are a long way from being practical but right now it doesn't look like there are any fundamental physical barriers and it looks like in the long run the problems that do exist will be solved.
Am I the only one who has difficulty thinking of quantum computers as things that actually exist and do calculations? It's like my brain has placed "quantum computer" firmly into the category "things that are theoretically possible but unable to be built with current technology", and refuses to change it, even to "things that exist in the lab but won't be commercially viable for decades outside classified government work".
It isn't at all clear that D-Waves system is using any sort of quantum entanglement at all. D-Wave has had a long history of massive hype. See e.g. http://www.scottaaronson.com/blog/?p=431. It isn't at all clear that D-Waves commercial system can do any of the things that we expect a quantum computer to do like say factor integers using Shor's algorithm http://en.wikipedia.org/wiki/Shor's_algorithm. It seems that D-Wave has made a fast computer but there's very little evidence that it actually is using quantum processes any more than a normal computer. You could call your laptop a quantum computer because quantum mechanics is used in determining how the transistors function and you might be close to what D-Wave is claiming. The key is whether there are entangled qubits that we can get info from, and D-Wave has shown little indication of that. They have had a handful of research papers that sort of point in that direction but it is very hard to separate the hype from what they've actually done.
show that we have good enough control over our single-qubit operations that our probability of error is 1 per 50,000 logic operations.
They forgot to add: "we calculated this probability on our quantum computer"
Seven puppies were harmed during the making of this post.
You don't need such low error correction rates though. The key is that if the error rates are low enough you can then use clever error correcting mechanisms. But if the error rate from stray particles and other issues causing you to repeatedly lose quantum entanglement is too high then you can't use clever algorithms to deal with these problems. But if you have an error rate below about 1 in every 10,000 operations then you can use the good stuff. Note that by the entire nature of quantum computers even if we have practical ones it is unlikely that they will have an error rate in the ballpark of 1 in a billion. It would be nice if we could get that rate but it seems to be unlikely.
Only if you prove the errors are completely random you can put three chips next to each other and vote.
That's not how error detection and correction is performed.
12.00000000001
Sometimes the reason why no one laughs is not because they didn't get the joke.
What we really need is a "standardized" open-source quantum computing language so that we can develop and exchange quantum algorithms to prepare for the day when quantum computers are real.
Right now we have the QCL language, QCF for Matlab/Octave, and the Cove framework that could be used with any language, but it looks like there is really only a C# implementation right now.
None of these have really taken hold as a "standard" though, and probably elements of all of them could be brought together in something multi-platform and all-inclusive.
What do you get when you have THREE competing standards and you try to take elements of them to make something multi-platform and all inclusive?
FOUR competing standards
Yet another person who has no idea how standards actually work, but is apparently literate enough to read XKCD.
Yet another person who has no idea how standards actually work, but is apparently literate enough to read XKCD.
Do tell. How do you think they really work?
Clearly your sense of humor does not fully implement the standard.
Fascism should more properly be called corporatism because it is the merger of state and corporate power. -- Mussolini
You'll make fewer errors if you only jump on the disc when Coily is right behind you.
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They are just answers to questions you haven't asked yet.
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
Chances are pretty good that your Quantum Computer will be running at liquid helium temperatures, maybe 4 Kelvin or so. Your general purpose CPU won't. There have been projects to run CPUs at liquid-nitrogen temperatures, and that already tends to get into mechanical difficulties; you're probably not going to be running your overclocked Xeon down at 4K.
Also, the quantum computer isn't likely to be something you're pumping a lot of data through - you're more likely to set it up, have it magically give you a probably-correct answer, and feed that answer to another computer that figures out if it's actually correct and then does something with it. For instance, if you're using the QC as an oracle to factor large numbers, you'll have it give you the result, then let your general-purpose machine multiply the factors together to find out if they give the right result, and then you'll use a general-purpose machine to rip off the bank account whose private key you just cracked.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
I like standards. I believe everybody should have a set.
Do not mock my vision of impractical footwear
Now if someone could just implement Shors algorithm all 1-bit encryption algorithms will be rendered obsolete!
I thought it was funny... When I got the joke, that is.
weinersmith
...I'll wait.
Operation Guillotine is in effect.