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China Makes Quantum Leap In Developing Quantum Computer (scmp.com)
hackingbear writes: Researchers at the University of Science and Technology of China created a quantum device, called a boson sampling machine, that can now carry out calculations for five photons, but at a speed 24,000 times faster than previous experiments. Pan Jianwei, the lead scientist on the project, said that though their device was already (only) 10 to 11 times faster at carrying out the calculations than the first electronic digital computer, ENIAC, and the first transistor computer, TRADIC, in running the classical algorithm, their machine would eclipse all of the world's supercomputers in a few years. "Our architecture is feasible to be scaled up to a larger number of photons and with a higher rate to race against increasingly advanced classical computers," they said in the research paper published in Nature Photonics. This device is said to be the first quantum computer beating a real electronic classical computer in practice. Scientists estimate that the current faster supercomputers would struggle to estimate the behavior of 20 photons.
Just curious to read...
Paul B.
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I always struggle with understanding quantum computing concepts, but from the sound of things in the article, this is not some sort of general purpose quantum computer. Rather, it's a purpose-built computer dedicated to estimating the behavior of photons.
Why that specifically?
Based on what the article (and summary) said, modern computers struggle to estimate the behavior of 20 or more photons, but it's the sort of problem that quantum computers are theoretically capable of handling quite easily. Researchers are apparently suggesting that in order to disprove skeptics and bring in more support for quantum computing, we should build a quantum computer of this variety and then use it to estimate the behavior of 30 or more photons, because doing so would definitively prove to everyone that quantum computers can provide a massive advantage over traditional computing methods.
LOL, I see what you did there and it is kind of funny.... BUT, does it compute?
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It's irrelevant!
I love the term "classical computers"
Also makes me feel old!
Paper preprint...
Wikipage about boson sampling...
In principle, a large-scale boson-sampling machine would constitute an effective disproof against a foundational tenet in computer science: the Extended Church-Turing Thesis, which postulates that all realistic physical systems can be efficiently simulated with a (classical) probabilistic Turing machine.
The machine may not have any practical use, but it still is an interesting theoretical advance that might serve to challenge our understanding of computablity... Part of the theoretical importance of this area of research is the understanding of #P-complete problems.
The wikipedia articlenotes the theoretical significance of this...
A polynomial-time algorithm for solving a #P-complete problem, if it existed, would imply P = NP, and thus P = PH. No such algorithm is currently known.
now the US has something to steal from China
I doubt the headline writer saw what they did there though. A quantum leap is literally the smallest possible change to a system. So the headline suggests they have made the smallest possible improvement which is not very impressive at all.
The Chinese are expending significant resources building conventional supercomputers. Which suggests far more promise for quantum computers than current reality.
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And that is true for all the computing leaders at present. We know how to build very effective supercomputers. We think that quantum computers might be great, the promise is there in theory, but you'd be a fool to ditch your conventional HPC systems.
And even if quantum computing becomes "a thing", suspicions abound that they might only be good as a specialized co-processor. Need to factor a crazy large prime number? You send that to the quantum computing module. Need to run a web server, database, render some graphics, parse some text, meat & potatoes stuff? You still want a conventional processor.
Can anyone explain in simple language for stupid people (namely, me) how quantum computing could work? What little I know about particle physics suggest that they can't even detect particles directly (only in "probabilities"), so how can they use them to do computing? I suppose I could follow the links and read the scientific papers, but I struggle even with 'dummies' style books (e.g. Tao of Physics and Dancing Wu Li Masters), so I'm sure the papers would be over my head. (And if anyone has any *readable* books or links, feel free to pass them along.)
So, is it faster? As stated, NO. BUT it will be.... Another virtual creation brought to you by those who never can quite do it, but will be able to... in their own minds.
and their memory is swiss cheese. Got it.
is there a different kind of leap when developing a Quantum Computer? I mean, it's right there in the name and all...
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The first rule of quantum computing is that everyone talks about scaling their design up to more qubits, but no one actually does it.
See that "Preview" button?
This development is Very interesting, but it is not clear that it is immediately useful.
I have kept up the the latest in Quantum computing over the years. There is much controversy over exactly how powerful a quantum computer could be. We have all heard that a quantum computer could factor large integers thus breaking some tough cryptography, but this type of problem is far from the hardest "calculation" problem. Most Quantum computer scientists believe that NP hard problems are infeasible on quantum computers ( Scott Aaronson). In an attempt to answer the question "Are NP hard problems beyond quantum computer" Scott and others came up with The "Boson Sampling computer" This is just a large network of beam splitters, or fiber-optic couplers with N input and M outputs and X internal couplers. The idea is that when you put quantum correlated photons into the input ports, the question of where the photons are likely to show up at the output ports is very difficult to calculate. This calculation depends on something called the Matrix Permanent. As the number of ports grows, the size of the calculation grows exponentialy. So for the "boson sampling computer" , the Boson is just a photon. ( photons are even integer spin particles, thus Bosons, as opposed to half integer spin particles like electrons). The Boson sampling comuter is a kind of analog computer that "calculates" the probability distribution of photons traversing the system. So the experimenter runs the experiment many times sending many groups of correlated photons through the "hall or mirrors" mixer , seeing at what port they emerge from. in doing so they can reconstruct the Transfer Function of the combiner/splitter network. This effectively means that they have calculated a Matrix permanent for the system, which is NP hard to do.
So if you could do this, the Boson sampling computer would enable you to "measure" in a polynomialy growing time with increasing problem size, what would take exponential growing time with increasing problem size on any classical computer. If this can be realized ( and it looks like we currently have nearly all the technology to do so NOW), then this would be the first example of a quantum computer or quantum simulator that was exponential faster than a classical computer for an NP hard problem ( again this is harder than factoring).
Having this one concrete example of exponential quantum computer speedup would be a gigantic step in understanding the fundamentals of Computational complexity, and probably has profound implication in Math and Physics.
BUT there are still problems.... Like The Matrix Permanent is interesting, but it is not clear that useful problems can be mapped into a Matrix Permanent.....
AND.... Say you get a Boson Sampler that handles so many photons that no classical computer could reproduce the calculation in a lifetime of calculations... how do you know that the output is correct?
So the realization of a Boson Sampler is Very interesting, but I do not think we are in danger of Chinese Quantum Computers performing computational miracles just yet.
Wayne S
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- Herb Smathers
I suggest bigger cuts to the Office of Science budget. Why do we need to spend money developing better, faster supercomputers? We can let the Chinese do all the expensive R&D, then we can buy the finished product from them. No problem. It worked for drywall, why not quantum puters?
The Russians have won. They have made the world a cesspool of distrust, greed, fear and hate.
Smallest Possible Leap Forward!
So their breakthrough is a vanishingly small one?
in the TV show by the same name, all of the jumps were into the past. That would mean that they took steps backward...
The US had best be well in front in Quantum computing. The advantage gained by a foreign power may be too great to overcome if we allow them to get a bit ahead of us.