Forgot your password?
typodupeerror
Technology Hardware Science

New Quantum Record: 14 Entangled Bits 101

Posted by timothy
from the austrian-bits-are-more-highly-polished dept.
Tx-0 writes "Quantum physicists from the University of Innsbruck have set another world record: They have achieved controlled entanglement of 14 quantum bits (qubits) and, thus, realized the largest quantum register that has ever been produced. With this experiment the scientists have not only come closer to the realization of a quantum computer but they also show surprising results for the quantum mechanical phenomenon of entanglement. By now the Innsbruck experimental physicists have succeeded in confining up to 64 particles in an ion trap. 'We are not able to entangle this high number of ions yet,' says Thomas Monz. 'However, our current findings provide us with a better understanding about the behavior of many entangled particles.' And this knowledge may soon enable them to entangle even more atoms."
This discussion has been archived. No new comments can be posted.

New Quantum Record: 14 Entangled Bits

Comments Filter:
  • by Anonymous Coward

    Quantum first post!

  • "Superdecoherence" (Score:5, Interesting)

    by AdmiralXyz (1378985) on Sunday April 03, 2011 @11:54AM (#35700364)
    From TFA:

    In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly.

    This is somewhat troubling, isn't it? If the decay rate is quadratic in the number of qubits, and this turns out to be due to some fundamental physical law as opposed to limitations of the current technology, does that mean we can never have quantum computers with any significant amount of memory?

    • by DWMorse (1816016) on Sunday April 03, 2011 @11:59AM (#35700402) Homepage

      does that mean we can never have quantum computers with any significant amount of memory?

      16k ought to be enough for ANYbody.

      • does that mean we can never have quantum computers with any significant amount of memory?

        16k ought to be enough for ANYbody.

        Just how do you propose to know how much memory anyway?

      • by ZSpade (812879)
        That's what arrays are for, no?
    • by Anonymous Coward

      Since for some algorithms the computational power is exponential in the amount of quantum memory, you can do "significant" stuff without a lot of memory.

      • by Kjella (173770)

        Since for some algorithms the computational power is exponential in the amount of quantum memory, you can do "significant" stuff without a lot of memory.

        Compared to the gigabytes of memory on your average computer, sure. 1 kilobyte = 8192 bits would be huge. But 14 bits? At most 2^14 = 16384 "classic" operations at once. I've never heard how many IOPS you'll get from a quantum computer but my impression is that you need many more qubits to beat a supercomputer.

      • Since for some algorithms the computational power is exponential in the amount of quantum memory, you can do "significant" stuff without a lot of memory.

        That may be so, but I have a feeling that they'll still need to be able to implement at least three registers to accomplish anything, and they haven't quite made it up to being able to implement a single short int. The idea of quantum computing has a lot of potential, but so does holographic memory, and they've been promising results there since the 1960's. When you're fighting entropy on as many fronts as they are, there's good reason to be pessimistic.

    • by greeneggs2000 (739337) on Sunday April 03, 2011 @12:38PM (#35700648)

      From TFA:

      In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly.

      This is somewhat troubling, isn't it? If the decay rate is quadratic in the number of qubits, and this turns out to be due to some fundamental physical law as opposed to limitations of the current technology, does that mean we can never have quantum computers with any significant amount of memory?

      Not really. The researchers trapped and entangled 14 ions in a single ion trap. Quantum computers based on ion traps will have thousands of traps, with never more than one or two ions per trap. (Machines with hundreds of traps have been tested, ions moved between traps, etc.; see, e.g., [1]) It has been known since at least 1997 [2] that you can't have a scalable system with only a single ion trap (that would be true even were the decay rate quadratic in the number of ions per trap).

      [1] Home, J. P. et al. Complete methods set for scalable ion trap quantum information
      processing. Science 325, 1227–1230 (2009). arXiv:0907.1865 [quant-ph] [arxiv.org]
      [2] Wineland, D.J. et al. Experimental issues in coherent quantum state manipulation
      of trapped atomic ions. J. Res. Natl. Inst. Stand. Technol. 103, 259–328 (1998). arXiv:quant-ph/9710025 [arxiv.org]

      By the way, an arXiv link for this article is arXiv:1009.6126 [quant-ph] [arxiv.org].

      • by frnic (98517)

        "Quantum computers based on ion traps will have thousands of traps"

        Let me be the first to say, "Who could ever need more than thousands of ion traps..."

      • Someone please correct me if I'm wrong, but my understanding is that computing power depends on the number of entangled bits. The promise of quantum computers is that they can solve in O(N) time certain problems that a conventional computer would need O(exp(N)) time to solve - but only if all N bits are entangled. If you're limited to 16 entangled bits, you can't solve problems any larger than N=16 without losing the linear scaling.
    • by Anonymous Coward

      Well, doesn't reading the answer break the entanglement anyway? As far as I can tell, the full process of a quantum computation is to tangle up a fresh batch, do the computation (essentially trying every possible answer in the same instant), read it (collapses the state of the particles into the correct answer). So they only need to stay entangled for a very brief time. And the idea is to eventually get enough quantum bits together to do a Metric Crapload of computation all at once. In an analogy that is p

    • it depends if you can control the decay rater otherwise... physics is just a theory, until it's not then some apparent physical law doesn't mean much by the way of limitations.

  • Hell yeah! In a few years, I will be able to play Super Mario on a quantum computer!
    • by VortexCortex (1117377) <VortexCortex@Nos ... t-retrograde.com> on Sunday April 03, 2011 @12:35PM (#35700626)

      Hell yeah! In a few years, I will be able to play Super Mario on a quantum computer!

      Yes, but then you'll have to deal with Bowser's Peach Paradox -- The game will start with the Princess being both captured and not captured, and you'll only find out which if you complete the game and observe the ending.

      "I'm sorry Mario, but our Princess exists in a super position of both being in another castle, and awaiting your return safely at home."

      Only after you observe the game's ending will you discover the game's plot:
      You either attempted to save the Princess from the evil clutches of King Kupa,
      or it's another case of Mario going mad and destroying an innocent kingdom for no good reason.

      Of course the credits will either reveal that the game's events haven't taken place yet (it was all a dream (ala Mario 2), ), or that the story has all happened before, an infinite number of times, and the princes might have just been captured again!

      Talk about replayability...
      Insert Qubits to Contiue.

      • by infurnus (1897136)

        Only after you observe the game's ending will you discover the game's plot:
        You either attempted to save the Princess from the evil clutches of King Kupa,
        or it's another case of Mario going mad and destroying an innocent kingdom for no good reason.

        So basically, the plot to Braid?

        • by Dekker3D (989692)

          The plot to Braid, multiplied by Braid, with a little Braid thrown in.

          I
          CAN'T
          WAIT!

      • by grcumb (781340)

        Hell yeah! In a few years, I will be able to play Super Mario on a quantum computer!

        Yes, but then you'll have to deal with Bowser's Peach Paradox -- The game will start with the Princess being both captured and not captured, and you'll only find out which if you complete the game and observe the ending.

        Downside: Quantum superposition allows every event in the game to occur simultaneously and in parallel to the others, so the game is -quite literally- over before you know it.

    • by Plekto (1018050)

      It won't run any faster, though. The distances in a typical computer chip are so tiny and there are enough choke-points in a typical computer that it really won't run any faster. I think that's what people are forgetting - that this isn't about speed or faster computers but about long-distance communication.

      Now, being able to communicate with a person, say, on the moon, in real-time would be useful. Or a computer network between planets. Also, transmission from anyplace on the planet. Though that coul

      • Quantum entaglement can not be used for faster-than-light transmission of information.
        • by Plekto (1018050)

          If one pair or group was physically moved to the moon (in theory), it would effectively become FTL communication though no actual data is being transmitted anyplace. The potential advantage of quantum entanglement is that you do an end-run around the entire problem of distance. You could have a device in theory 20 LY away and get data from it instantly. Of course, there's the issue of bandwidth and all, as well as numerous technical issues concerning longevity and repeatability.

          My best guess for a poten

          • No.

            You can't use separated entangled qubits to send information faster than light. It doesn't work that way. There are a bunch of tricks and operations you can do, but none of them result in the other end being able to distinguish a change of state.

            • by Plekto (1018050)

              Well, we'll see. Some physicists think that we will be able to distinguish a change of state eventually (though this may be a LONG time in the future) and use it to do exactly this. Some do not. I think that we will overcome this "limitation" some day and be able to use it like this, since observing changes is really a technological problem on our end(kind of like how people said we couldn't ever fly to the moon. We can, but it takes amounts of energy and technology that 100 years ago, even, they would

              • by c0lo (1497653)

                Some physicists think that we will be able to distinguish a change of state eventually [...]. Some do not.

                Meanwhile, there is a group of physicist are in a superposition of the state thinking that FTL is and is not possible [newswise.com]... they pertain to the class of String Theorists.

                Paradoxically, the nature of their thinking state is totally opposite to quantum mechanics: any attempt to get an answer from their part will NOT result in a collapsing of their thinking state into one of the defined choices, but rather in setting the mind of the asking person into an indeterminate and fuzzy state (i.e. the "decoherence of the

                • by Plekto (1018050)

                  Heh. Then again, quantum physics may be a fancy kludge for something else. Similar to medieval astronomy and their horrendously complex calculations to make everything "fit". We just don't know yet. So far, attempts to unify all of the theories together have completely failed. Something is plainly wrong and needs to be thrown out or re-done (maybe all of it even).

                  I think that there is a way to "observe" such a change in state without actually observing it. We would need to be able to master gravity al

      • It won't run any faster, though. The distances in a typical computer chip are so tiny and there are enough choke-points in a typical computer that it really won't run any faster. I think that's what people are forgetting - that this isn't about speed or faster computers but about long-distance communication.

        Two words: Shor's algorithm [wikipedia.org]

        • by Plekto (1018050)

          Yes, I know about that. The issue is that while the processor might be faster, nothing attached to it is, so it effectively is spinning its wheels waiting for the rest of the system. You'd need a whole new motherboard design, new peripherals, new memory, and so on that could keep up. One weak link in the chain and the speed gains largely evaporate.

          • If you run Shor's algorithm on a quantum computer it will take polynomial time as opposed to exponential time on a classical computer for integer factorization. So yes, it is about speed and faster computers.
            • by Plekto (1018050)

              Technically, yes, but it's like having a 1000 hp car on L.A. freeways. In the end, nothing really goes a whole lot faster unless you were to redesign everything from the ground up to be able to operate at those speeds.

  • At the rate advances in quantum computing are coming, with more and more bits available to be used, I should be able to see quantum computers as powerful as ENIAC before I die! Alas, baring major medical advances, I'm unlikely to see anything as powerful as a quantum TI-99/4A...
  • big deal (Score:4, Funny)

    by Quiet_Desperation (858215) on Sunday April 03, 2011 @12:53PM (#35700760)

    I can get more things entangled by just leaving a couple extension cords unattended for a few days.

    • by jjohnson (62583)

      My wire-clothes-hanger closet computer is orders of magnitude more powerful than yours. I just need seed funding to commercialize it.

  • Unless they have some theoretical method of scaling up their design, this does not really bring us "closer" to useful quantum computing. In fact, TFA casts some doubt on scalability:

    In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits.

  • ...cut the chit-chat...does Linux run on it yet? scnr
  • by gweihir (88907) on Sunday April 03, 2011 @02:21PM (#35701502)

    Seriously, the speed the number of entangled quantums is rising with, clearly points to exponential increase in complexity. This means we will likely never see quantum computers that can be used for any real problem size. Not that this has been clear for about a decade or so.

    • The trouble is that no truly scalable proposal for QC has been developed yet. The hope would be that once a suitable system was found, it wouldn't be exponentially more difficult to add qbits. Photonic qbits have very different problems from trapped ions, for example. Not many research groups are attempting to build large systems because the potential for more extensive scaling isn't there, instead they're trying to develop systems that are scalable, then we'll see a push for large systems.

      It'll probably st

      • by gweihir (88907)

        I think what is difficult to ignore is the grant money you can still get for GC proposals. If the device gets exponentially more difficult to build when larger, exponentially more computing power does not mean anything. And there is rather strong indication that entangeling manipulating qbits at the same time gets exponentially harder with the number of qbits. I predict that Quantum Computers will not ever reach significant size, as conventional computers will not only simpler to build, but they do scale we

        • Yes, you're right. Let's give up on investigating compelling new directions in technology because there are hard problems associated with them. That's the way forward ;-)

          I'm quite certain that if the foundations for exploiting a larger computational basis are laid, the algorithms will follow.

  • I don't forsee anyone needing more than 14 bits.

  • Sigh...no hoverboards, flying cars, mr fusion or quantum computers :(

    It figures..that there would be no free lunch...all of the initial rants about instantly factoring huge numbers, solving impossibly complex problems have unsurprisingly turned out to be false.

    If you can't scale the number of qbits in a single coherent system QCs are doomed.. All of this talk of linking separatly entangled systems to produce more powerful QCs is crap. If you don't get anywhere near expontential scaling as a function of qbi

    • by Patch86 (1465427)

      All of this talk of linking separatly entangled systems to produce more powerful QCs is crap. If you don't get anywhere near expontential scaling as a function of qbits then game over.

      Why?

      Serious question. I honestly don't know much about q-computing, but batteries of small systems to make a single large system sounds pretty par for the course, technologically. Doesn't sound like there's any fundamental problem with that.

      • by Anonymous Coward

        Why?

        Serious question. I honestly don't know much about q-computing, but batteries of small systems to make a single large system sounds pretty par for the course, technologically. Doesn't sound like there's any fundamental problem with that.

        There is nothing wrong with QC.. I have no doubt it will be useful in the real world at some point in the future.

        The problem for me is that while yes you can always throw more CPUs at a problem there are whole classes of problems where this is infeasable. This was the whole point of QCs... To solve problems that were **impossible** to solve with "classic" computers.

        A massive supercomputer may be a several million times more powerful than my desktop and that makes it more capable and very useful...y

  • In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly.

    I've long said that I wouldn't take quantum computing seriously until I saw an equation depicting a scaling bound. That day finally dawns a decade into the hype cycle. Amazing. Seriously, following the field is

  • No fair! They changed the outcome by measuring it!

    -Stor

  • by haapi (16700)

    They couldn't have entangled a Z-80's worth of bits and called it good. Sigh.

    • by c0lo (1497653)

      They couldn't have entangled a Z-80's worth of bits and called it good. Sigh.

      Huh? Z80 [wikipedia.org] was an 8-bit processor. Granted, it had more registries than this one (if I remember well, it actually had a pair of registry sets).

  • You're saying it's 14 of these: http://www.guessmyimage.com/puzzle/silly-rabbit-trig-is-for-kids [guessmyimage.com]
  • Where every bit on one drive is entangled with the other.

    Move drive A any distance from drive B, data remains in sync. ....errr...or you buy one drive and the Gov has the other...hmmm....

<<<<< EVACUATION ROUTE <<<<<

Working...