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Quantum Computer advantages

  1. Sep 18, 2017 #1

    ISamson

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    Hello,

    I have found out that in the future we might have quantum computers, which will be more powerful than today's computers. Instead of trying every option available to the computer, quantum computers will be able to try many different possible solutions at the same time. What would be some of the daily-life, scientific and social advantages of such technology?
    I was just wondering...
    Thanks.
     
  2. jcsd
  3. Sep 18, 2017 #2

    phinds

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    The people who have already developed quantum computers would be surprized to hear that it is still in the future.

    Have you done any research on this? What have you found ?
     
  4. Sep 19, 2017 #3

    f95toli

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    Have a look at the website for IBM's Quantum Experience, there you will find quite a lot of information about applications.
     
  5. Sep 19, 2017 #4

    russ_watters

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    Sorry, but such people do not exist; quantum computing is still in the theoretical/experimental stage of development, speculating on how they *might* work. There are no functional general purpose "quantum computers".
     
  6. Sep 19, 2017 #5

    phinds

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    Huh. I was sure that there had been a couple developed that we not yet in any way practical but were true quantum computers (very small number of qubits) and one that is bigger but arguably not necessarily a true quantum computer. I'm remembering that incorrectly?
     
  7. Sep 19, 2017 #6

    russ_watters

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    There is a company selling what they claim are quantum computers, but there are a great many academics who believe the product to be fraudulent or perhaps a "that isn't what that word means".
    https://en.m.wikipedia.org/wiki/D-Wave_Systems

    I haven't done much research on this, so I'm a bit unclear on why it would be so difficult to tell. Right now people are looking at its underwhelming performance, but I don't see why they can't just crack it open and look at the hardware. That might be a subject worthy of its own thread.

    Otherwise, that IBM project is a research project and they are not claiming it to be a general purpose quantum computer.
     
  8. Sep 19, 2017 #7

    phinds

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    Yes, that's the one that I was thinking of that there has been subject to considerable controversy.

    OK, I guess I read too much into it. Thanks.
     
  9. Sep 19, 2017 #8

    f95toli

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    No, there is disagreement about just how "quantum " the D-wave computer is; but I don't think anyone is claiming that it is fraudulent. The computers DO work (I know people who use them in their research) and there is certainly some quantum effects involved (entanglement of neighboring qubits). However, it is not clear whether the parameters they use (T1, T2 times for the qubits, strength of coupling, topology etc) are good enough to actually give you an exponential speedup compared to a "classical" annealer operating using only thermal effects.
    Note that the D-Wave computer is not a general purpose QC; but D-Wave has never claimed that it is. It is a quantum annealer which -if it works- would be be very good at solving a large class of important optimization problems; especially if they are able to scale if up a bit further.

    See above. Showing that something is actually a QC is a very hard problem; the only way that is known to work is to get it to do something exponentially faster than a classical computer but even that is problematic. D-Wave has already demonstrated speedup for a couple (perhaps more) optimization problems but in both cases someone was then able to come up with a new classical algorithm that could be run in polynomial time on an ordinary computer.
    Note that no one doubts that the basic building blocks of their circuit is "quantum" (they are just flux qubits).

    The IBM computer IS a general purpose QC (it supports all gate operations and can -at least in theory- be used for all known algorithms); it is just too small to do anything of practical importance.
     
  10. Sep 19, 2017 #9

    phinds

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    Yes, that's what I was referring to originally.
     
  11. Sep 22, 2017 #10

    f95toli

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  12. Sep 22, 2017 #11
    My understanding is these chips work as an ASIC attached to a classical computer system, which is used for solving NP-complete problems. The applications for QC in my field (cybersecurity) is breaking cryptography (something the NSA is said to have invested in), and machine learning, which has made huge improvements in user/system/process behavior analytics.
     
  13. Sep 22, 2017 #12
  14. Sep 22, 2017 #13

    FactChecker

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    There are two different quantum computer development directions that seem the most advanced. IBM is working on a processor that can do logic like Shor's algorithm to factor large integers. They have been able to put a couple of dozen qubits on the chip, so it is a long way from being a practical general purpose computer. D-wave has developed a quantum annealing computer that has a thousand qubits. The nature of quantum annealing makes it a poor choice for problems that require exact solutions based on logic like that required for Shor's algorithm. But it can still be very powerful for problems that fit it well. Google claims to show performance on a type of problem that is millions of times better than any traditional computer. Neither approach is ready for general purpose computing, but the potential is there.

    PS. Judging the capabilities of a quantum computer by its number of qubits can be tricky. Although two dozen qubits in an IBM chip may seem small, if it can find a 1-step solution of a problem with 224 ≈ 17 million possible combinations, that is nothing to sneeze at.
     
    Last edited: Sep 22, 2017
  15. Sep 22, 2017 #14

    StoneTemplePython

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    I'm not sure what you mean but this. The general view that I've read is for solving NP Complete or Hard-er problems, you get a quadratic speed-up in a quantum computer, not exponential. This neatly mirrors the shift from a 1 norm in classical probability to the 2 norm.

    If instead of solving, you just aim for "good", and you are using local search to drive down a cost function for an intractable problem (quite common, e.g. in deep learning), your search process may look like simulated annealing -- and it appears quantum annealing could have a big speedup over that.

    Here's a decent read on the matter:

    http://news.mit.edu/2015/3q-scott-aaronson-google-quantum-computing-paper-1211

    (I've also read Aaronson's book though it underperformed my expectations.)
     
  16. Sep 22, 2017 #15

    FactChecker

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    I agree. This is the type of problem for which quantum annealing could have a tremendous advantage. Also if there is some advantage to randomly selecting one of several near-optimal solutions (for instance, to keep an enemy guessing), then quantum annealing could do that.
     
  17. Nov 30, 2017 #16
    I came across this article while looking for AI advances. Quantum computer apparently are move formidable than just the speed of their processing. That being having the ability to breach security of all current computer systems. Can anybody elaborate on this capability.

    Edit: Is it the speed of the processing by which they can de-encrypt files?
     
    Last edited: Nov 30, 2017
  18. Nov 30, 2017 #17

    Mark44

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    Such a machine would be and not be a quantum computer, simultaneously. :oldbiggrin:
     
  19. Dec 1, 2017 #18
  20. Dec 1, 2017 #19
    There is the potential to break common encryption schemes in use today, but not all schemes are susceptible to this attack. See https://en.wikipedia.org/wiki/Quantum_computing#Potential
     
  21. Dec 4, 2017 #20
    Hi,...can someone explain to me how a quantum computer will work?it based on Copenhagen Interpretation and for the moment we don't know if the cat is dead or alive at the same time.We can live in a MWI Universe as far as we know...so the Super position maybe don't exist...
     
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