Quantum Entanglement of Macroscopic Diamonds 160
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.'"
weird. (Score:5, Funny)
this both gives me the chills, and doesn't.
There is only "Here", There is only "Now" (Score:2)
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.
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There is only Xul.
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Call it what you like. I was using "Brahma" and "Reality". :-)
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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.
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Everything happens at once, all the time, forever.
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this both gives me the chills, and doesn't.
Well, then, put on a sweater ...
... and don't.
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A great disturbance in the force, like a billion voices crying and not crying out.
www.quantum-vibrator.xxx (Score:5, Funny)
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http://www.quora.com/Brian-Dodson-1/Electronics/answers [quora.com]
Quantum First Post! (Score:5, Funny)
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until we observe it, and cause your beloved post's wavefunction to collapse, and alas, you fail again.
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vibrating and not vibrating? (Score:2)
so..... the two crystals each have atomic particles sharing the same nucleus or something?
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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.
next step in this study (Score:4, Funny)
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0.05 mm by .25 mm (Score:4, Informative)
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.
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Harmony at last.. (Score:5, Funny)
Neat... Now I can get a pair of diamond vibrators and please both my wife and mistress at the same time!
Re:Harmony at last.. (Score:4, Funny)
Or not, at the same time.
Re:Harmony at last.. (Score:5, Informative)
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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.
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Re:Harmony at last.. (Score:5, Informative)
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.
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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
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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
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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.
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OK, _what's_ called a hidden state variable theory? Please? :)
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Yeah. and in layman terms please :)
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Hidden varriable theory is the idea that your model is incomplete - that there is some effect that is hidden to you that controls where the photon went,and which atom is actually vibrating. Those theories have been proven incorrect. See also http://en.wikipedia.org/wiki/Hidden_variable_theory [wikipedia.org]
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That's not entirely correct. Experiments show that either any hidden variable theory OR the principle of locality is incorrect. It could be that there is a non-local hidden variable theory that is correct.
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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.
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I think what you want to look at is Bell's Theorem. http://en.wikipedia.org/wiki/Bell's_theorem [wikipedia.org]
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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]
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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.
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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
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So it is all about perception then and not in reality. In my example, the perception is that it's entangled until observed, but in *reality* the ball is already in one of the boxes.
From what I read elsewhere in this thread, this is not how it actually works. In reality, something is in fact in both states and it is only the measurement that makes it settle into one state or the other. This just doesn't make sense so I would like to know why they are so sure about this :)
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There's lots of math behind the certainty, and a few experiments that confirm the math. :) And as someone else said - no one understands QM.
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>>In my example, the perception is that it's entangled until observed, but in *reality* the ball is already in one of the boxes.
Nope. (Well, in the non-quantum physical ball case, yeah, sure, one ball was in a box. But it's not a very good analogy.)
Your concept of 'realism' has to be thrown out the window. Or your belief in the speed of light as the great cosmic speed limit. Read more here: http://en.wikipedia.org/wiki/Principle_of_locality [wikipedia.org]
When you're not observing an electron, the electron ceases to
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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).
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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]
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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.
Someone correct me if I'm wrong but... (Score:5, Interesting)
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?
Re:Someone correct me if I'm wrong but... (Score:5, Informative)
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.
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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.
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QM predicts and experiments have verified that when pairs of entangled photons are passed through polarizing filters, they correlate at a rate that is a function of the difference in angle between the filters. If you do the same experiment with pairs of non-entangled photons, the results never correlate.
Go wrap your head around that. Seriously, think about it. In order for that kind of correlat
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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.)
Re:Someone correct me if I'm wrong but... (Score:4, Insightful)
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.
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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
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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.
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You're confusing a mathematical explanation for reality and reality itself.
Not at all. This isn't exactly the difficult bit of QM here! I'm astonished so many lay-persons still think so damn classically (It's like they're part of some Newtonian cult! Science moved on a long time ago.)
Go read up on the double-slit experiment (where the single photon takes both paths and interferes with itself) and, of course, Bells Inequality.
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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
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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
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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
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And no, I cannot explain it or even understand WHY that is. All I
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Only when an observation is made, does the wave function "collapse" and only at that time d
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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
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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 :)
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Ok, so I have tried to soak in Bells Theorem. http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/bell.html [ncsu.edu]
I made it up to the conclusion. I need to go through the probability math again slowly, but I trust they are right.
And my, that is odd. I guess I have to accept the results of those experiments and they don;t fit with locality. I am *starting* to get a grasp of this now, not that it makes (common) sense yet lol.
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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
FTL Communications (Score:1)
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Yeah, who needs the laws of physics anyways!?
You still need a, at most, speed of light communication channel to correlate the two.
Re:FTL Communications (Score:4, Informative)
Unfortunately, this is not the implementation of the universe.
Here are some answers to the question, Does quantum entanglement allow faster-than-light information transfer? [reddit.com], given by scientists.
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Except the vibrations are not controllable and only work once. All you can do is determine what state the current atom is in, you can't effect it, and as such, you can't affect change on the other end.
His Dark Materials (Score:2)
When can we have a perfectly secure, instantaneous communicator that even works across universes and can be carried by tiny humanoids?
Just in time for Christmas shopping (Score:2)
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Diamonds really are forever (Score:1)
Ansibles are mere steps away.
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I'd say ansibles are more of a quantum leap away.
Does this mean... (Score:2)
Large enough to see (Score:2)
Problem is, if someone actually saw them the experiment wouldn't work.
Diamonds: (Score:1)
Can we detect wavefunction collapse, or not? (Score:2)
Statistics not particles (Score:4, Interesting)
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.
Lodestone Resonator (Score:2)
Re:Is this again just a theory? (Score:5, Informative)
Did you actually read the article? "Cheap words" make up all science and literature. They explained everything they did in the article. Or do you expect them to post all their experimental data on this brief web article?
"When we detect the Stokes photon we know we have created a phonon, but we can't know even in principle in which diamond it now resides," says Walmsley. "This is the entangled state, for which neither the statement 'this diamond is vibrating' nor 'this diamond is not vibrating' is true."
To verify that the state has been made, the researchers fire a second laser pulse into the two crystals to 'read out' the phonon, from which the laser photon draws extra energy.
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A theory is the top of the food chain, otherwise known as a fact.
A theory is something never once proven wrong, and so far always shown to be correct.
Lies! How this particular bit of misinformation entered the mainstream I'll never know.
A theory is a predictive model. A hypothesis is a testable prediction. There are plenty of theories (that are still theories) which have been abandoned because the predictions they make are not supported by evidence and experiment. (You don't test a theory, you can't, you can only test the predictions that it makes!)
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when people talk about a superposition of two particles that are quantum entangled are they just saying "we know an event happened to one of these particles we just don't know which one until we look"
Not even close.