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Significant Advance in Quantum Computing

Posted by Zonk on from the they-put-the-q-in-quantum dept.

wcitech writes "Apparently scientists have been able to create circuitry that mimics the behavior of atom pairs by using superconductors." From the article: "The work, reported in the Feb. 25 issue of the journal Science, demonstrates that it is possible to measure the quantum properties of two interconnected artificial atoms at virtually the same time. Until now, superconducting qubits--quantum counterparts of the 1s and 0s used in today's computers--have been measured one at a time to avoid unwanted effects on neighboring qubits." The second Quantum computing revelation this month, in fact.

11 of 180 comments (clear)

  1. I'm not a quantum engineer by GreyWolf3000 · · Score: 4, Interesting

    This question may be stupid but...

    Would we need to read 32 quantum states at a time to get '32-bit' registers to build basic processors??

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    Slashdot: Where people pretend to be twice as smart as they really are by behaving like children.
    1. Re:I'm not a quantum engineer by MOBE2001 · · Score: 5, Interesting

      "Two entangled qubits, meanwhile, can simultaneously evaluate four inputs. Put another way, a traditional memory register with eight bits can store only one of a possible 28, or 256, digital "words," but a quantum register with eight qubits can represent and compute with all 256 words at once."

      So, If you get all possible answers simultaneously, how do you tell which one is the right answer to the problem you're working on?

    2. Re:I'm not a quantum engineer by Chmarr · · Score: 2, Interesting

      What you actually need is a function that flags 'this is the right answer', and then you just read off the inputs.

      For example, with a sufficiently large QC, you could find an input that matches a particular SHA-256 input INSTANTLY. Ie, "Give me the input where the output is equivalent to this hash".

  2. I'm guessing... by OneOver137 · · Score: 2, Interesting

    the whole paradigm of 'xx-bit processor' will go out the window once the technology matures and software makes full use of the capabilities.

  3. Booor-ing... by Goonie · · Score: 4, Interesting
    Why merely crack RSA and radically speed up quantum physics simulations? That's aiming far too low.

    Instead, Tien Kieu from my university wants to solve arbitrary Diophantine equations using quantum effects. If he's a) correct, and b) it becomes possible to create the required quantum behaviours for arbitrary equation, the following problems become solvable:

    • The halting problem for arbitrary Turing machines, with all that that would imply.
    • The Riemann hypothesis.
    • Goldbach's conjecture

      Needless to say, to say people are sceptical of Kieu's ideas is an understatement, but it's fun to speculate about the "what if"...

    --

    Any sufficiently advanced technology is indistinguishable from a rigged demo
    --Andy Finkel (J. Klass?)
    1. Re:Booor-ing... by IWannaBeAnAC · · Score: 2, Interesting
      Interesting. I am somewhat familiar with the 'Quantum Adiabatic Theorem', but you need to remember that it is a 'theorem' in the physics sense, not mathematical. ie, there isn't a proof, and moreover, a lot of people (including me) have doubts about it.

      Originally the theorem was proposed as a means of solving NP-complete problems on a quantum computer. ie. to show that for a quantum computer, P=NP. I don't think many people actually believe that, and there are no known algorithms for NP problems. That is wild enough, but it is *really* wild that Kieu is saying that it can solve the halting problem. If the adiabatic theorem really imples that the halting problem is solvable, then I think it is just a very big nail in the coffin of the 'theorem'.

      Aside: I thought the Reimann Hypothesis was formally undecidable? I also don't understand how the proof of Goldbach's conjecture would work. How can a finite computer test that the theorem is true for arbitarily large numbers? A symbolic proof is maybe possible, but then where does the computation come in? I guess I should read his paper....

  4. Re:What's the point? by Zeinfeld · · Score: 2, Interesting
    "This dramatic advantage of quantum computers is currently known to exist for only those three problems: factoring, discrete log, and quantum physics simulations."

    Actually it is slightly more general. Having spoken with some high powered cryptographers (i.e. the ones with the Turing awards) there is a strong suspiscion that any problem which allows a public key cryptosystem to be created will turn out to be efficient on a QC machine.

    There seems to be something pretty fundamental going on there. The really wierd part is that the speedup does not appear to apply to symmetric ciphers. So AES is secure even if RSA is bust.

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  5. More to it than that... by Goonie · · Score: 3, Interesting
    The halting problem cannot be solved for arbitrary Turing machines. Period. No algorithm, as we think of them, using quantum computers or not, will get around the fact that such a solution would create a logical inconsistency (a program could determine whether or not it itself would halt, and then do the opposite, but then it would have been wrong, which it can't be by assumption, and so reality bursts into flames). The only possible catch is that a technique that cannot be encoded in a Turing machine would not cause this particular logical inconsistency to arise.

    You've got it in one. According to Kieu, his system is a non-computable process; you can't simulate what it does on a Turing machine. Hence your objection doesn't apply to his claims.

    However, there are apparently lots of other objections.

    --

    Any sufficiently advanced technology is indistinguishable from a rigged demo
    --Andy Finkel (J. Klass?)
  6. Re:sounds like rainman autistic computer.... by ByteSlicer · · Score: 3, Interesting

    The similarity between brains and a quantum computer comes from the fact that the neurons in the brain also process the data in parallel. There is no quantum computing going on inside the brain. There recently was an article about an autistic savant explaining his calculation skills. Numbers are just shapes to him, and multiplying them means he just merges them in his head and reads back the emerged shape. Probably his visual cortex is doing the parallel operations on the shapes here (maybe similar to using the shader engines on your graphics card for doing calculations).

  7. Time issues in quantum theory by rjdegraaf · · Score: 2, Interesting
    From the article:
    ...demonstrates that it is possible to measure the quantum properties of two interconnected artificial atoms at virtually the same time.
    and the uncertainty in the energy of the quanta increases, due to the uncertainty relation!

    Also,

    ...virtually the same time.
    Time is relative to the observer, and quantum theory treats time linear but Einstein says otherwise. Take a look at an EPR situation in space-time (talk by Roger Penrose).
  8. Here's another question by Ryvar · · Score: 2, Interesting

    If we can read the state of two entangled atoms, is communication at greater-than-light speed now possible? Wouldn't this violate causality?

    Just curious.

    --Ryv