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Interesting refutation by IBM here: In the preprint, it is argued that their device reached “quantum supremacy” and that “a state-of-the-art supercomputer woul
by oliveremberton 7y ago
Interesting refutation by IBM here:
In the preprint, it is argued that their device reached “quantum supremacy” and that “a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task.” We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity.
https://www.ibm.com/blogs/research/2019/10/on-quantum-supremacy/ https://www.ibm.com/blogs/research/2019/10/on-quantum-suprem...
- hamilyon2 7y agoThe margin between 200 seconds and 2.5 days still exists
- ewalk153 7y agoI think that’s where the > and with far greater fidelity comes into play.
- deleted 7y ago[deleted]
- reportgunner 7y agoI thought quantum supremacy was about having a quantum computer capable of doing more operations per second than any binary computer can do Do you think it wouldn't be possible to simply upgrade the supercomputer to shave some time off those 2.5 days ? To me it seems clear that everyone gullible already bought into the Cloud, ML/AI, CI/CD buzzwords and now they need a new buzzword to market.
- enkid 7y agoThat's not quantum supremacy. It's about doing something on a quantum computer that would be infeasible on a standard computer. This is because in some scenarios a single calculation by a quantum computer could be equivalent to a vast number (many trillions) of calculations made by a standard computer.
- reportgunner 7y ago> more operations per second than any binary computer can do > doing something on a quantum computer that would be infeasible on a standard computer Sorry, but I fail to see how these two are different.
- lippel82 7y agoThey use different "algorithms", so solving a problem can be done in very different ways for a quantum and a classical computer. Comparing the number of operations per second does not make sense because the advantage of quantum algorithms lies in the fact, that they can achieve the same results with (exponentially) fewer operations.
- reportgunner 7y agoWe can keep moving the goalposts and I can rephrase my claim to: > it's a state when a quantum computer can achieve results that would require more operations on a binary computer than a binary computer has proven to be able to do but the point will still stand. We can't say we achieved quantum supremacy for this one thing because binary computers still have supremacy over everyting else. I guess we can agree here that quantum supremacy was definitely not achieved since we are not clear on the definition of said quantum supremacy.
- enkid 7y agoNo, quantum supremacy is about quantum computers being better at one thing. Then there will be a reason to use them. It's like making a screwdriver when you already have a hammer. Sometime a hammer and nails is better and sometimes a screwdriver and screws is better. It's about picking the right tools for the job.
- hgoel 7y agoIt isn't about them being better in the sense of faster than a classical computer, but rather scaling. Quantum computing is attractive because we expect that some operations scale much better with size on one compared to classical computing. ie if for a task the quantum algorithm is O(n) while the classical version is O(n!)
- hoseja 7y agoI think it's about running algorithms with big-O complexities lower than can be ran on a classical computer, not actually more ops.
- comicjk 7y agoQuantum supremacy is about scaling (big-O notation) - taking a classically O(2^N) problem and making it polynomial. The empirical experiments are just to show that the scaling works, and the uncertainty comes from the fact that we still can't fit very large N problems into current quantum computers. Effectively, they don't have enough RAM to even load the problem (i.e. enough available quantum states).
- lallysingh 7y agoYes but nobody cares. The QC isn't cheap or available enough to be relevant is your can compute it reasonably well in a few days.
- photon-torpedo 7y agoAs far as I understand, the 2.5 days classical simulation gives you the total wavefunction, from which you can read the probability distribution. You only need to run it once. It's not clear to me whether the 200 seconds quantum computation is for getting (or rather sampling) the probability distribution, or for just one measurement. My point is, the classical simulation actually gives you much more data than the quantum computation -- you get the actual full probabilty distribution, not just an approximated sample of it (guess that's why IBM claims "higher fidelity").
- the8472 7y agoA physical system will always be the fastest implementation of a computer simulating its own physics. Some overhead is expected when using different hardware to simulate it. What matters is asymptotic computational and memory complexity.
- mellosouls 7y agoI haven't processed the blog, but considering IBMs resources wouldn't it be simpler to refute it by actually doing it in 2.5 days? Or is there some catch that undermines that headline claim?
- onion2k 7y agoI think the quote from IBM means it'd take 2.5 days to run. That doesn't include actually implementing it.
- forgot-my-pw 7y agoThat might be a pretty expensive run on a supercomputer
- svantana 7y agoThat's 2.5 days on the 13 MW Summit supercomputer, for a single run. Presumably you would need multiple runs to get good statistics.
- ehsankia 7y agoDoes it scale linearly? Is it 5 days on a half as good super computer? They just need to show that it can be done in any reasonable finite amount of time, not 2.5 days.
- earenndil 7y agoThe main bottleneck is memory/storage capacity, not speed. Beyond that (if you have the requisite storage capacity and bandwidth), yes: if you have half the FLOPS and double the time, you get the same result.
- sipjca 7y agoIs this the case? I thought that parallel speedup is not linear. so it might actually not be 2x slower but maybe 1.5x or something depending on IPC overhead and all that
- phh 7y agoIMO the whole IBM blog is interesting, your quote isn't just a summary. Basically what IBM is claiming is that Google's circuit doesn't do anything useful really, it is just meant to be very complicated to do in traditional computing systems. And even in this idealized position, Google's quantum computer doesn't transform an unsolvable problem into a solvable one. According to IBM, "Quantum Supremacy" means accomplishing something useful to the society, that simply wouldn't be possible to do otherwise. Google's article doesn't show any sign of that, IBM claim.
- mtgx 7y agoAll of that is true, but according to IBM's own definition of "quantum advantage" I think Google at least achieved that. All in all, it seems more of a battle of semantics, and the two companies talking past each other. It's kind of how everyone seems to interpret Moore's Law to mean "any progress in computational performance whatsoever" these days, as opposed to the original definition of "transistors doubling in the same space every 18-24 months," and then using that to "prove" that "Moore's Law is still alive." (it's not, and hasn't been for a long time). I think in the end what's important here is that it was proven that a quantum computer can do "something" (yes, even anything at all is a big milestone) significantly faster than a classical system. Because this is what matters in the end that quantum computers can do some tasks significantly faster than classical systems. They don't have to do only tasks that are "impossible" for classical systems to be useful. It's also why we use GPUs, FPGAs, and ASICs for some tasks, instead of just using CPUs for everything. I do agree that it was in Google's interest not to work so hard on optimizing the classical system for the simulation, to make its quantum computer look that much more impressive. But if the quantum computer is still faster, then it doesn't really matter.
- sanxiyn 7y agoNo, if your standard is "faster", even D-Wave achieved that. Quantum supremacy is about exponential speedup, and in light of IBM's claim, Google's claim of quantum supremacy is very much in doubt.
- IanCal 7y ago
- clSTophEjUdRanu 7y agoI think IBM is full of shit and badly needs this PR boost that is about to be snatched away by Google.
- dang 7y agoThere's also a separate thread discussing IBM's post: https://news.ycombinator.com/item?id=21333105 https://news.ycombinator.com/item?id=21333105.