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Quantum Entanglement of Macroscopic Diamonds 160

Posted by Soulskill
from the simultaneously-a-girl's-best-friend-and-not dept.
New submitter ananyo writes "A pair of diamond crystals has been linked by quantum entanglement — one of the first times that objects visible to the naked eye have been placed in a connected quantum state. 'This means that a vibration in the crystals could not be meaningfully assigned to one or other of them: both crystals were simultaneously vibrating and not vibrating (abstract). Quantum entanglement — interdependence of quantum states between particles not in physical contact — has been well established between quantum particles such as atoms at ultra-cold temperatures. But like most quantum effects, it doesn't tend to survive either at room temperature or in objects large enough to see with the naked eye.'"
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Quantum Entanglement of Macroscopic Diamonds

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  • weird. (Score:5, Funny)

    by notgm (1069012) on Friday December 02, 2011 @03:54PM (#38242976)

    this both gives me the chills, and doesn't.

    • Both are the same thing, which is infinite.

      Time and space are illusions*. Try to prove them and you will only produce paradoxes.

      * lunch time, doubly so.

      • by sehlat (180760)

        There is only Xul.

      • by wdef (1050680)
        That sounds all very nice but it also sounds like metaphysics. But do you want to unpack that for those of us who have some education in theoretical physics? I thought not.
      • by PJ6 (1151747)

        Both are the same thing, which is infinite.

        Time and space are illusions*. Try to prove them and you will only produce paradoxes.

        * lunch time, doubly so.

        If time didn't exist, everything would happen at once.

        Also, all observable dimensions (including timelike ones) are finite by definition.

    • by thomst (1640045)

      this both gives me the chills, and doesn't.

      Well, then, put on a sweater ...

      ... and don't.

    • by Darinbob (1142669)

      A great disturbance in the force, like a billion voices crying and not crying out.

  • by Slugster (635830) on Friday December 02, 2011 @03:58PM (#38243050)
    great..... we dump all this money in some eggheads' laps, and all they can think of is to make fancy adult toys
  • by Dutchmaan (442553) on Friday December 02, 2011 @03:58PM (#38243052) Homepage
    This is a first post, and yet it isn't!
  • so..... the two crystals each have atomic particles sharing the same nucleus or something?

    • by DogDude (805747)
      No, that's quantum physics. Seemingly unrelated particles can influence each other. It's been widely known and accepted as fact since Einstein's era. It's just unusual to see it happen with such particles.
      • by Yetihehe (971185)

        No, they can't really influence each others. If one of the entangled particles is under ANY influence, you have decoherence and they are not entangled anymore.

  • by niw3 (1029008) on Friday December 02, 2011 @04:00PM (#38243102)
    should be an experiment with a cat & some poison
    • by bhagwad (1426855)
      In this case, a woman can have an orgasm and not have it at the same time...since her state is intimately linked to the vibration of the device :D
  • 0.05 mm by .25 mm (Score:4, Informative)

    by Anonymous Coward on Friday December 02, 2011 @04:02PM (#38243126)

    They say that each phonon involves the coherent vibration of about 1016 atoms, corresponding to a region of the crystal about 0.05 millimetres wide and 0.25 millimetres long â" large enough to see with the naked eye.

    0.05 mm is roughly 1/4 the width of a human hair. Of course, I still can't see it, because it's just a patch of vibrations on a much larger diamond.

  • by RenHoek (101570) on Friday December 02, 2011 @04:04PM (#38243158) Homepage

    Neat... Now I can get a pair of diamond vibrators and please both my wife and mistress at the same time!

    • by roc97007 (608802) on Friday December 02, 2011 @04:07PM (#38243196) Journal

      Or not, at the same time.

    • Re:Harmony at last.. (Score:5, Informative)

      by Baloroth (2370816) on Friday December 02, 2011 @04:07PM (#38243200)
      Actually, no, because they are quantum entangled only one of them can vibrate at a time. So you can still only please one at at a time, you just don't know which one it will be until they tell you.
      • by blueg3 (192743)

        I was actually going to mention this, and was pleasantly surprised to discover someone else pointing out what the common superposed state of entangled objects is.

      • by Bucky24 (1943328)
        So (jokes aside) does that mean that if you vibrate one the other is forced to stop vibrating? (I don't understand quantum physics very well)
        • Re:Harmony at last.. (Score:5, Informative)

          by Baloroth (2370816) on Friday December 02, 2011 @04:40PM (#38243758)

          No. The experiment took one photon, and sent it along two possible paths without recording which path it took, which causes a vibration in one (and only one) diamond. Since the path of the photon was random, and not recorded, you cannot say which diamond is vibrating. The way the researchers put it (better than the summary IMO) is "Neither the statement 'this diamond is vibrating' nor 'this diamond is not vibrating' is true.” You cannot selectively vibrate one. In fact knowing which one vibrates destroys the entanglement. It does, however, tell you the state of the other diamond (the opposite) without observing it directly, which creates a few paradoxes and is the source of the whole 'spooky action thing.'

          Don't feel to bad if you don't understand it, even quantum physicists don't understand quantum physics very well. The mechanics behind what is really happening in entanglement is still unknown, there is only guesswork as to how it might happen.

          • by tom17 (659054)

            A great explanation, which made sense. But now I just have more questions. Like, "I will put a ball in one of these boxes, but I will not tell you which one I put it in. Now from your perspective, Neither the statement 'this box has the ball in it' nor 'this box does not have the ball in it' is true. You have no way of selecting which box I put the ball in." How is this any different?

            What I am saying is, I don't see how there is any 'entanglement' there. It's just either in one diamond or the other. It's on

            • by Baloroth (2370816)

              Well, as others point out I oversimplified things a bit. Quantum physics states that, in a sense, both and neither are vibrating so long as they are entangled, and only one actually vibrates once observed. However I believe that many view that as merely a mathematical system for approximating what is really going on (don't take my word for this, as I am by no means sure about this point), but that goes well past my knowledge. In your example, there is an objective reality about which box the ball is in. It

              • Re: (Score:2, Insightful)

                by Anonymous Coward

                Well, as others point out I oversimplified things a bit. Quantum physics states that, in a sense, both and neither are vibrating so long as they are entangled, and only one actually vibrates once observed. However I believe that many view that as merely a mathematical system for approximating what is really going on (don't take my word for this, as I am by no means sure about this point), but that goes well past my knowledge. In your example, there is an objective reality about which box the ball is in. It may or may not (and experiments indicate not) be true that there is an objective reality about which diamond is vibrating prior to the observation.

                But how can you prove that both diamonds were in a simultaneous state until observed? It seems just as likely that the photon went one way or the other and your just now finding out which way it went when you observed it.

                Just like the two boxes, one has a ball and one doesn't. Just cause you don't know which one has the ball, doesn't mean it simultaneously exists and doesn't exist.

                • by holmstar (1388267)
                  That's called a hidden variable theory, and experiments have been done that show that hidden variable theories are incorrect.
              • by mikael (484)

                Sounds like a programming concept called "lazy evaluation". A particular data field might be a combination of different input parameters. Sometimes it becomes more efficient not to update such values just when their inputs change, but only when they are read.

            • I had your problem for the longest of times too. No one seemed bothered that this given explanation was no different than a classical example. And it seems most people don't ever think about it to the level that you have. (So congratulations I guess).

              I think what you want to look at is Bell's Theorem. http://en.wikipedia.org/wiki/Bell's_theorem [wikipedia.org]
            • by doug141 (863552)

              I'd really love to get my head around this one day lol.

              then you should read http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/bell.html [ncsu.edu]

            • by narcc (412956)

              But now I just have more questions. Like, "I will put a ball in one of these boxes, but I will not tell you which one I put it in. Now from your perspective, Neither the statement 'this box has the ball in it' nor 'this box does not have the ball in it' is true. You have no way of selecting which box I put the ball in." How is this any different?

              It is very very different. In this case the "ball" is actually in both "boxes" at once. Upon observing one of the "boxes", the ball is in one or the other, but not before. (Reality has a lot to do with knowledge and knowability [what can, in principle, be known] -- in your case, the location of the ball is both known and knowable.)

              Freaky, isn't it? Relativity is just as wacky and unintuitive, but we managed to get used to that quickly enough.

            • by DrFalkyn (102068)

              A great explanation, which made sense. But now I just have more questions. Like, "I will put a ball in one of these boxes, but I will not tell you which one I put it in. Now from your perspective, Neither the statement 'this box has the ball in it' nor 'this box does not have the ball in it' is true. You have no way of selecting which box I put the ball in." How is this any different?

              What I am saying is, I don't see how there is any 'entanglement' there. It's just either in one diamond or the other. It's only our perception that doesn't know which one it is in.

              Understanding wave-particle duality and the nature of light is critical to understanding modern physics. The easiest way I know of explaining this is through double-slit experiment.

              With the double-slit experiment, you pass light between two slits that are space closely together (on the order of the wavelength of light). If you then place a screen some distance away from the slits, you will observe an interference pattern. Thomas Young used this experiment in the early 1800s and it appeared to settle

          • by bhagwad (1426855)
            Just to clarify - not being able to measure it doesn't mean there's an "underlying reality" which we haven't been able to observe. It's not that one of them really is vibrating and we just don't know which. They're both entagled meaning both of them are vibrating and not vibrating...or not.
          • by jpapon (1877296)
            What I really don't get is why observation would destroy the entanglement. That just doesn't seem possible. They either are entangled, or they aren't. Mere observation by a third unrelated party shouldn't matter. Someone needs to just kill that goddamn cat.
            • by holmstar (1388267)
              Observation requires interaction with the entangled object. Interacting with it causes the wave function to collapse and the object "chooses" a definite state. There is no way to passively observe the entangled object.
              • by jpapon (1877296)
                Yes the wave-particle duality is still an amazing thing to me, especially when applied to all matter rather than just high frequency EM radiation.
              • by narcc (412956)

                Interacting with it causes the wave function to collapse

                Well, that's actually a huge problem. See, if a particle interacts with the system, it too becomes entangled.

                The fact of the matter is that no one has a clue what causes the wave function to collapse (or if it even does at all).

          • by wdef (1050680)

            Don't feel to bad if you don't understand it, even quantum physicists don't understand quantum physics very well.

            Richard Feynman once said of quantum theory: "Don't ask how it can be like that. Nobody knows how it can be like that!"

            The mechanics behind what is really happening in entanglement is still unknown, there is only guesswork as to how it might happen.

            Not quite true at least for the other end of the process, the so-called collapse of the wave function, when one makes a measurement and entangled states decohere. As I've posted once before a while ago, what is going on there was worked out in detail by a gifted yet relatively unknown (outside of theoretical physics circles) Australian mathematical physicist, HS Green http://en.wikipedia.o [wikipedia.org]

          • by narcc (412956)

            The experiment took one photon, and sent it along two possible paths without recording which path it took, which causes a vibration in one (and only one) diamond.

            Not even close.

  • by Shadow of Eternity (795165) on Friday December 02, 2011 @04:05PM (#38243170)

    As near as I can understand this they're entangled so that vibrations in one are indistinguishable from vibrations in another, they both do the same thing at the same time (or near it at least)... doesn't this imply the ability to entangle two whatevers and transit information via entanglement induced vibrations?

    • by Baloroth (2370816) on Friday December 02, 2011 @04:18PM (#38243378)

      No, since when you establish the vibrations you don't know in which one it occurs. So while you could establish vibrations in a distant diamond (or particle), at least theoretically, you never know when you do so which one is actually vibrating. When they set it up, they used 1 photon that could travel and strike either diamond, creating the vibrations. Without measuring the photon's path, they didn't know which one it hit and therefore which on would be vibrating. This caused the entanglement.

      Two things: 1), the photon itself had to be able to strike both (so not FTL at all for this setup) and 2) no useful information was encoded in this experiment. One thing you could do, though, would be send one diamond one direction and the other another way. Either can know the other diamond's state by reading his own (the other is in the opposite), and no one else can, since anyone else reading it would collapse the state, and a second reading would have a different result (I believe this is more or less how quantum cryptography works). Quantum entanglement is useful for transferring information (in other cases), but the mechanics still don't allow FTL information transfer, they just allow you to encode more in less space by having two bits quantum entangled. I don't completely understand the physics of that.

      • by inviolet (797804)

        No, since when you establish the vibrations you don't know in which one it occurs. So while you could establish vibrations in a distant diamond (or particle), at least theoretically, you never know when you do so which one is actually vibrating. When they set it up, they used 1 photon that could travel and strike either diamond, creating the vibrations. Without measuring the photon's path, they didn't know which one it hit and therefore which on would be vibrating. This caused the entanglement.

        Close. The entanglement is created by the fact that the photon COULD HAVE chosen either one. Because the photon was not observed in such a way that it had to collapse into particle-ish behavior, the photon never had to choose which one to hit. Therefore, each crystal was AND was not hit by the photon. They only 'decide' who took the photon when the rest of reality (e.g. an observer, or an interaction with another incident particle) needs to know exactly who took it.

    • by blueg3 (192743)

      It doesn't. That would fall within "quantum teleportation". It turns out that you need to transmit information in order to perform meaningful quantum teleportation, so it can't be used to transmit information any faster than you already could. (Even though, without knowing the details of how quantum teleportation works, it certainly seems like one ought to be able to.)

    • by LateArthurDent (1403947) on Friday December 02, 2011 @04:23PM (#38243472)

      As near as I can understand this they're entangled so that vibrations in one are indistinguishable from vibrations in another, they both do the same thing at the same time (or near it at least)... doesn't this imply the ability to entangle two whatevers and transit information via entanglement induced vibrations?

      No, they are in opposite states. If you measure one of them, you'll determine that it is either vibrating or not. If it is vibrating, the other diamond is not, if it's not vibrating, the other diamond is vibrating. Before the measurement, they're entangled, so they are considered to be both vibrating and not vibrating simultaneously.

      That said, I don't know much about quantum effects, so I can't read the paper and understand it, but the description in the article made it seem like what's actually happening is just that the experiment is set up such that only one diamond can be vibrating, but you don't know which one it's going to be. So at all times, one of the diamonds is vibrating, the other is not, and you only know which is which when you measure one of them. Which doesn't sound like anything special. It's like me getting two playing cards, an Ace and a King, and putting them in a table face down. Then I ask you, "which one is the card in the left?" and you answer, "it's both a King and Ace. Until I flip it over, and then I can tell you what the other one is." Which is ridiculous, the card is one card specifically, you just don't know which one it is. So I suspect the media writeup screwed up, although it still seems way better than most, since they didn't mention stuff like ftl communications which pops up in almost every entanglement story even though we all know entanglement can't enable ftl communication.

      • by dreemernj (859414)
        I think it is a bit different then that since, as they mention, both diamonds are both vibrating and not vibrating simultaneously. It isn't the case that one is vibrating and the other is not vibrating and you just don't know yet because you haven't measured. They are both in both states until you measure. The entanglement means that when you measure one and collapse the superposition of simultaneously vibrating and not vibrating to determine which state it is in, the other diamond will be in the opposit
      • by narcc (412956)

        Quantum mechanics does sound ridiculous, but it's the best-tested theory we have. Again, it's not that you "don't know" or "can't know" which path, which crystal, which whatever -- it really is "both" (e.g. "both paths", "both crystals"). It's frighteningly unintuitive, but this has held up experimentally (see: Bell's Inequality).

        For some reason, slashdotters seem to desperately want to return to a nice, neat, deterministic, Newtonian billiard-ball universe where everything appeals to our intuition. Unfo

        • by wdef (1050680)
          Is this because computing science majors are lousy at physics or what? The reverse is usually not true - theoretical physicists can have trouble getting gigs in physics and, because of their powerful mathematical backgrounds and ability to deal with difficult levels of abstract thought, often end up working in computing areas. Google prefer to hire mathematics majors over CS majors.
        • by sFurbo (1361249)

          it's not that you "don't know" or "can't know" which path, which crystal, which whatever -- it really is "both" (e.g. "both paths", "both crystals").

          Doesn't that depend on the interpretation? In the Copenhagen intepretation, it is both. In the many-world interpretation, it does both, but in two different universes. In the de Broglie-Bohm interpretation, it follows one path, but the wave-function follows both.

      • by ThosLives (686517)

        This is also the part of quantum superposition that I don't understand. Given the text in the article and other things I've read, it does seem like it's the case you described with the cards. Yet the claim of quantum mechanics is is that, no, really, the diamonds (in the experiment) are indeed in both states simultaneously until they are measured. What I don't understand is how the measurement collapses the state, versus the collapse happening before the measurement (more like the cards).

        The conceptual p

        • by jfengel (409917)

          Nobody completely understands what "measurement" means, but in this case, what it means is that you have to interact the diamond with an even larger-scale system (i.e. your measurement apparatus, and then your eyeballs reading that measurement apparatus, and so on).

          The more mass you add to the experiment, the smaller the variation can be, until it is effectively nonexistent. It must be in one state or the other, and you know that the two states will necessarily be opposite.

          But as long as the objects are is

          • by ThosLives (686517)

            I did try to read and understand the article on Bell's theorem, but it didn't really elucidate anything to me. Perhaps I'll read it again...

            Ok, I've re-read it and I still don't understand it completely. The one interesting thing about Bell's inequality is that it (seems to?) only applies to correlations made on large numbers of trials rather than a specific trial itself. I'm not sure if I understood that correctly. I think I pretty clearly understood that the inequality only applies to entangled partic

        • by flosofl (626809)
          Not a PhD, but I think the point is they actually aren't in particular state before they are measured (observed). They're smeared across all possible states at the same time. So the coins are equally heads AND tails. It's not until observation happens that it collapses into a this coin is heads or this coin is tails. Look up the double slit photon experiment. I seem to remember reading it and ALMOST having an epiphany. You may fare better.

          And no, I cannot explain it or even understand WHY that is. All I
        • by bhagwad (1426855)
          No - the puzzling nature of entaglement lies in the fact that until you measure it, no result has actually occurred - even for a single quantum experiment. So in this case, it's not as if one of the diamonds is secretly vibrating and we just don't know which one. As Bell's experiments have proved multiple times, there's no "hidden reality." The two diamonds really are vibrating and not vibrating at the same time.

          Only when an observation is made, does the wave function "collapse" and only at that time d
        • by tom17 (659054)

          OK, I get what people are saying now. Not that 'it's in one state or the other, only measurement will show which one state' but that 'it is in BOTH states' and only measurement will make it become in one state.

          Fine, I would accept that, but I can't 'just accept' things. This will likely make life hard for me as I need to know why they think this. As without anything backing it up, it's just an 'idea'.

          So I imagine to understand the proof that something is in two states at once, I will need to learn quantum m

          • by bhagwad (1426855)
            It's been proved alright. But yes - to understand it completely you need some pretty heavy theoretical knowledge/math skills. As with most things in science these days, it's not "blindly accepting" if you choose whom to believe based on their authenticity. So "blindly accepting" something when the overwhelming majority of qualified scientists back it is a very smart move. Without doing that, I would have to doubt everything from relativity to the formation of starts. I've never actually tested whether or no
            • by tom17 (659054)

              Hmm. I can try I guess :)

              Don't forget that the overwhelming majority of qualified scientists have backed up lots of incorrect things over the eons of our scientific history. That said, I get that the scientific methods these days are far more strict and would not allow for such mistakes such as the word being flat and in he centre of the universe. But still, you have to wonder. It seems too odd to not have to wonder :)

      • by BitZtream (692029)

        I really wish people would stop using retarded statements like 'both are vibrating and not simultaneously since that is 100% wrong.

        Their states are undetermined, but they are in one specific state, not both. When you start making stupid states like 'its doing two opposite things at the same time' you start to make people realize that you don't actually understand what you're describing.

        Just like Schrodinger's cat. Its not that the cat is both alive and dead, its that you just cant' know, the explanation f

  • Next up, control a Mars rover in real-time.
  • When can we have a perfectly secure, instantaneous communicator that even works across universes and can be carried by tiny humanoids?

  • Entangled diamond jewelry -- how else can you demonstrate the superposition of your commitment to your one true love? (For 10 picoseconds.)
  • by Anonymous Coward

    Ansibles are mere steps away.

  • Does this mean my wife could have a diamond of twice the size, until she looks at it?
  • They say that each phonon involves the coherent vibration of about 1016 atoms, corresponding to a region of the crystal about 0.05 millimetres wide and 0.25 millimetres long — large enough to see with the naked eye.

    Problem is, if someone actually saw them the experiment wouldn't work.

  • Simultaneously are and are not a girl's best friend.
  • Detecting wavefunction collapse is trivial, just look for interference between the possible states, ala the two-slit experiment. HOWEVER, if the collapse of an entangled wavefunction can be detected, than FTL information transmission is possible, because collapsing one half of an entangled pair will instantly collapse the other half, causing the interference pattern (or whatever) to disappear. So what am I missing?
  • by dak664 (1992350) on Friday December 02, 2011 @06:29PM (#38245356) Journal

    Let us not lose sight of the fact that a photon is a statistical convenience, not a particle, and a phonon is even less a particle. You can't send "one photon" and detect "one phonon". These are statistical coincidence measurements that detect correlated behavior between the two diamonds after an electromagnetic interaction that can not transfer less than Planck's constant of action. Either diamond would show a 50% excitation in the absence of the signal from the other. Spooky action at a distance is inferred from correlation of the states over a large number of events. Which is why quantum computing is not going to be as fast as everyone thinks it will be.

  • Can you say: "Lodestone Resonator"?? :-O

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