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Transportation Science

Scientists Teleport Information Between Ions a Meter Apart 220

Posted by Soulskill
from the perfecting-those-heisenberg-compensators dept.
erickhill writes with word that scientists from the University of Maryland have successfully transferred information from one charged atom to another without having it cross the intervening space of about one meter. The academic paper is available in the journal Science, though it requires a subscription to see more than the abstract. Scientists have previously teleported unmolested qubits between photons of light, and between photons and clouds of atoms. But researchers have long sought to teleport qubits between distant atoms. Light's high speed of travel makes photons good transporters of information, but for storing quantum information, atoms are a much better choice because they're easier to hold on to. 'This is a big deal,' comments Myungshik Kim, a quantum physicist at Queen's University Belfast in the United Kingdom. 'To store information as it is in quantum form, you have to have a teleportation scheme available between two stationary qubits. Then you can store them and manipulate them later on.'"
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Scientists Teleport Information Between Ions a Meter Apart

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  • by Anonymous Coward on Friday January 23, 2009 @09:07PM (#26584005)

    Are they positive?

  • Unmolested? (Score:5, Funny)

    by PhrostyMcByte (589271) <phrosty@gmail.com> on Friday January 23, 2009 @09:09PM (#26584031) Homepage

    Scientists have previously teleported unmolested qubits....

    Qubit molester insists entanglement was consensual, stay tuned for details at 11.

  • by Chris Burke (6130) on Friday January 23, 2009 @09:13PM (#26584059) Homepage

    All sources regarding quantum entanglement/teleportation are quite adamant that you can't use it to actually send information instantaneously. Despite there being "spooky action at a distance", any discernible information had to be transfered when you separated the photons themselves at sub-light speeds. In this case it would be atoms, but I assume it still applies? The article lists applications as super-fast quantum computers (I guess any functional quantum computer could be considered fast at what it does) and quantum encryption (a real application I've heard applied to quantum teleportation, though the encrypted data itself still has to travel at c or less).

    So, am I right, and this is basically the same ol' non-instant-communication but still quite cool kinda teleportation, only using atoms instead of photons? I'm just checking.

    • Re: (Score:2, Interesting)

      by Snowtred (1334453)
      Yeah, I know a little about Quantum, but this kind of teleportation stuff still confuses me. I know there is some kind of logic argument that shows that no actual information can be relayed by this means, but how exactly is the information being transfered? Is it at lightspeed, or something weirder?
      • Re: (Score:3, Funny)

        by flyingsquid (813711)
        Yeah, I know a little about Quantum, but this kind of teleportation stuff still confuses me. I know there is some kind of logic argument that shows that no actual information can be relayed by this means, but how exactly is the information being transfered? Is it at lightspeed, or something weirder?

        More importantly, does this kind of teleportation make the same cool sound as the teleportation the original "Star Trek"?

      • by grumbel (592662) <grumbel@gmx.de> on Saturday January 24, 2009 @05:02AM (#26586681) Homepage

        The way I understand it:

        * you generate two entangled quantum things
        * you move them apart
        * you look at one of them and figure out its state, by that you knock it out of the superposition
        * magic happens and the (inverse of that) state is transported to the other thing
        * you look at the other thing an confirm that the state is as expected

        Since the stuff is in superposition you shouldn't be able to tell its state beforehand, but due to looking at the other thing an teleportation you can. The other thing has the inverse state thing since they must obey conservation of angular momentum (i.e. one spins up, then the other spins down).

        Now what I don't get is why this involves any 'teleportation' or quantum weirdness at all. Analog experiment:

        * you have two boxes
        * you put into one of those boxes a ball at random
        * you move them apart
        * you look into your box and can now tell if a ball is in the other box or not
        * no magic necessary, no teleportation happens, since the state of both boxes is fixed from the start

        I don't get why this teleportation thing is anything special, since as far as I understand it, its completly normal and matches exactly what you would expect.

        • by Giant Electronic Bra (1229876) on Saturday January 24, 2009 @09:03AM (#26587835)

          Here's an illustration of the non-tranmission of information via entanglement.

          Suppose we have a pair of 'magic coins'. Either coin can be flipped and come up either heads or tails, and the other coin will always come up the opposite.

          Now, suppose 2 people meet in New York and agree that they will meet again in Oslo if Amy's coin comes up heads and Bill's coin comes up tails, or they will meet in Sidney if Bill's coin comes up heads and Amy's coin comes up tails. Then Amy goes to Peking and flips her coin. It comes up heads, so she meets Bill in Oslo.

          The information, which city they will meet in, was AGREED ON BEFORE HAND, it wasn't 'transmitted' by the flip of the coins. The information was in Amy's head when she went to Peking, it traveled by a classical channel governed by relativistic limitations.

          This can be seen explicitly if you assume that Amy and Bill DIDN'T agree on which face of the coins meant Oslo or Sidney. In that case when Bill and Amy flip their coins they DO know that their opposite number's coin came up the other way, but neither of them knows which city to go to! In other words, no information was conveyed between them BY the flip of the coins.

        • by sfazzio (1227616) on Saturday January 24, 2009 @10:16AM (#26588325)
          A completely valid arguement-- until 1964:
          http://en.wikipedia.org/wiki/Bell's_theorem [wikipedia.org]
          • by gr8_phk (621180) on Saturday January 24, 2009 @02:44PM (#26590673)
            Bell's theorem (which is a logical argument) and common sense (which we base logical arguments upon) are at odds. So the physicists side with "spooky action at a distance" because it's more phun. They've been taking the "magic" path ever since Einstein and relativity came along and said reality is unintuitive (which it is, but it follows from his assumptions which were based on observation). Witness "dark matter" and "dark energy" and "string theory".

            Back to the topic at hand, no one can explain what is different about a particle whose wave function has "collapsed" and one that hasn't. If you can tell the difference, then you can use entangled pairs to communicate instantly at a distance. One person makes a measurement or not, and the other guy checks for the collapsed-ness of his particle - instant transmission. But since no one knows what the collapse means we just chalk it all up as magic - or unknowable, or parallel universes, etc... By the way, the collapsedness of the particles wave function is therefore a hidden variable that we don't have access to. This proves the existence of hidden variables in contradiction to Bell's theorem, and offers the distinct possibility that the spin is also there all along as a "hidden variable".

            I thus predict that an overturn of at least one assumption in Bell's theorem will be one of the biggest headlines in physics some time this century.
    • Re: (Score:3, Interesting)

      As I understand, the essence of teleportation is that collapsing the wavefunction of the first particle (by measuring it) instantly collapses the wavefunction of the second particle. What I don't understand is why this does not represent transmission of the information that the first particle has been measured. Is it not possible to test whether the second particle's wavefunction has been collapsed by, say, sending it through slits?
      • by Anonymous Coward on Friday January 23, 2009 @09:49PM (#26584383)
        If you send a single particle through a slit, you'll get a single spot. If you send many particles through slits, you'll get many spots, just as if you hadn't used entanglement -- they'll be all over the place. Either way, you won't know whether the wavefunction was collapsed by your observation or prior to it by the collapse of an entangled particle's waveform.

        Say particles A and B are entangled, and you are in a position to observe B, but not A. You have no way to know whether A has already been observed, because B will look the same to you either way, unless you already know the state of A.

      • Mod patent up. (Score:3, Informative)

        by Hurricane78 (562437)

        Yeah. I will try to give a simplified explanation to non-experts (I'm just a curious guy myself):

        First you entangle two particles. Then you let one travel somewhere. (If at bumps into another particle on that way, the particle loses the entanglement.)
        Now if you "measure" the first particle, the "wavefunction" (the entanglement) of both particles collapses in a specific way.

        By measuring that traveled particle, you can get the information on how the other particle got manipulated when it lost the entanglement

        • Re:Mod patent up. (Score:5, Informative)

          by EdZ (755139) on Friday January 23, 2009 @10:36PM (#26584659)
          Oh, if it were that easy. When you collapse the wave function my measuring one 'end' of your hypothetical particle-block, you: have NO WAY of influencing HOW it collapses, and thus cannot send any information to the other 'end'. You cannot determine what spin you will observe, only that the opposite spin will be observed on the other particle.
        • Re:Mod patent up. (Score:4, Insightful)

          by tylerni7 (944579) on Friday January 23, 2009 @10:37PM (#26584661) Homepage
          I don't think that is how it works (although IANAP)

          If you check to see if a block you have is collapsed, then suddenly it becomes collapsed, even if it wasn't before. That means you can't tell what it was supposed to look like before.

          The other option is to only look at the entangled matter after you are sure it has collapsed, and see how the collapsing happened. However, this is also impossible. The way the qbits collapse is completely random, so you can't get any useful information out of reading them.

          The best way to think about it is you have two coins taped to each other head to tail or something.
          Then the coins are flipped, and separated without looking at them. Then take these coins to opposite ends of the universe.
          Now, as soon as one coin is observed, the value of the other coin is known as well. However, looking at either coin does not help to relay information. The only way to do that would be to know how the coin was going to land before looking at it. Or to be able to somehow observe the coin and know if the other has been observed.
          • If they can't tell that the other end has already collapsed when they check one end, then how do they know this whole entangling thing works and both ends collapse in tandem?

            • by shaitand (626655)

              Because the other end is at the opposite side of the lab. Light detect by their eyes tells them whether their assistant collapsed one end and the comparison of measurement tells them whether they read the same information their assistant did.

              But all of this verification requires information to be passed by ordinary non-quantum means and if you are going to do that you might as well just send a radio signal.

        • Because you would have to AGREE BEFOREHAND on what each collapse MEANT. Each series of measurements on each end is RANDOM. Thus all each end of the channel knows is a random number. They each know the SAME random number (or its inverse which is the same thing). It is just a random number, it contains no information.

          In order for information to be passed, the two sides would have to agree (by communicating using a classical channel) as to what they would interpret their random numbers to mean. The information

    • IANAPhysicist, but my understanding is that while light speed is still an issue in physical space, the information sharing is truly instantaneous in this sort of quantum entanglement. It's not a short delay as light travels that distance, but instantaneous.

      I think the way to think of it is this: there's another (or maybe many other) dimensions in the universe that our feeble minds can't perceive. They still exist, though, and things that may appear to be far apart in space (or even time-space) may be r
      • by Chris Burke (6130)

        IANAPhysicist, but my understanding is that while light speed is still an issue in physical space, the information sharing is truly instantaneous in this sort of quantum entanglement. It's not a short delay as light travels that distance, but instantaneous.

        Well the waveform collapse is instantaneous, yes, but as the WP [wikipedia.org] says, you can't actually use it to communicate information from one end to the other.

        I really don't understand the physics of why you're not really sharing information when the waveform coll

        • You would not violate causality. If you transmit the information about some bet from yesterday from A to B, and it reaches B yesterday, and B would instantly send it back, then it would reach A instantly after A transmitted the information.

          But I also wrote above [slashdot.org], how you could actually transmit information with it. I remember this from a "Spektrum der Wissenschaft" (German version of the "Scientific American") special issue.

          • Re: (Score:3, Informative)

            by Jamu (852752)

            Relativity implies that if information goes from A to B instantaneously for some observers, it also goes from A to B in finite time for some other observers. For all the other observers it goes from A to B in negative finite time, from B to A, in other words. For causality, for A to cause B, then information must always travel from A to B.

            Any instantaneous wavefunction collapse cannot transmit information from distant locations, it must create new information for those locations, i.e. a random value.

    • I just don't get it.

      You "entangle" two atoms creating the qubit. You separate the atoms, then read the qubit?

      Isn't the information already present in the entanglement, prior to the separation? Isn't it like spray-painting two objects red, sending them to opposite parts of the world and then proclaiming you've got a way to teleport information across the world, but can only send one message, "red" ?

      I'm sure with all the hype I must just misunderstand the whole thing.

      • Re: (Score:3, Insightful)

        by Chris Burke (6130)

        Well, I think that's roughly the essence of why you can't send information instantly. All information about the qubits is actually sent with the qubit itself as you separate them to whatever arbitrary distance you're going to do your 'teleportation' trick. It's a little less obvious to me exactly why that is... my understanding is that it's kinda like you have both a black and red marble and you send one around the world, well when one guy checks and sees that his marble is red, the other guy instantly k

        • by v1 (525388) on Friday January 23, 2009 @09:56PM (#26584431) Homepage Journal

          you have both a black and red marble and you send one around the world, well when one guy checks and sees that his marble is red, the other guy instantly knows that his marble is black.

          More to the point, the other guy can find out his marble is black, but only if you communicate to him that your marble was red. Thus information was transferred, but you have to communicate by other means to make it meaningful, which defeats the purpose. It's like sending someone an encrypted message over an insecure channel. Great until you realize you now have to send him the key over the same channel. Sure it's encrypted, but the means of making it useful renders it ineffective.

          • Re: (Score:3, Funny)

            by Chris Burke (6130)

            It's like sending someone an encrypted message over an insecure channel. Great until you realize you now have to send him the key over the same channel. Sure it's encrypted, but the means of making it useful renders it ineffective.

            Sure you can, you just need to use public key encryption. So I guess you're saying we need public key quantum entanglement?

            Just kidding, thanks for the clarification. :)

            • Re: (Score:3, Interesting)

              by drinkypoo (153816)

              So I guess you're saying we need public key quantum entanglement?

              Wouldn't it be hilarious if that turned out to be the case? If you just knew enough about the other member of your pair, that you could actually transmit information? It would make your comment one hell of a Doug Adams-type footnote.

        • Re: (Score:3, Funny)

          by jd (1658)

          Which goes to prove that teleporting physicists have lost their marbles.

    • Re: (Score:2, Informative)

      by plnix0 (807376)
      Right. The abstract:

      Quantum teleportation is the faithful transfer of quantum states between systems, relying on the prior establishment of entanglement and using only classical communication during the transmission. We report teleportation of quantum information between atomic quantum memories separated by about 1 meter. A quantum bit stored in a single trapped ytterbium ion (Yb+) is teleported to a second Yb+ atom with an average fidelity of 90% over a replete set of states. The teleportation protocol is based on the heralded entanglement of the atoms through interference and detection of photons emitted from each atom and guided through optical fibers. This scheme may be used for scalable quantum computation and quantum communication.

      So yes, this is not true "teleportation". It relies on light actually moving from one atom to another through optical fibers.

    • by sarkeizen (106737) on Friday January 23, 2009 @09:37PM (#26584273) Journal

      "teleportation" always seems to lead people to the wrong conclusions. This is about transferring the informational content of a qubit. Which you can't perfectly represent with a classical system. I can see how this as the one commenting physicist claims is a "big deal" when it comes to building quantum computers. But it's not about instantaneous matter transport or superluminal communication.

      I'm not sure what the article meant by ultra secure "quantum communication". Quantum teleportation *is* a quantum communication *channel* but it's unclear what kind of security they are talking about. Perhaps "Quantum Encryption" but that's another term that often sends people down the wrong track.

      • I'm not sure what the article meant by ultra secure "quantum communication". Quantum teleportation *is* a quantum communication *channel* but it's unclear what kind of security they are talking about.

        It's the same situation as in 'quantum cryptography'. That is, you can't eavesdrop on it, and while there is information being transferred 'classically' in the open, it gives no help in identifying what's being transferred. I agree it's a bit of a stretch though, because this is a fairly impractical scheme
    •   You could send something as simple as a yes/no - yes, I've read your message , or no, I haven't.

        Add a few more entanglements to it, and you could send more. One time pad X wrt x. If this particular part gets read, yes; if that other part doesn't get read, no.

        On/off? requiring a shared sequence.

        Someone who understands it better, correct me and be more clear, please.

      SB

      • by TapeCutter (624760) on Saturday January 24, 2009 @12:17AM (#26585307) Journal
        "You could send something as simple as a yes/no - yes, I've read your message , or no, I haven't. [snip] Someone who understands it better, correct me and be more clear, please."

        Analogy:
        I have two basket balls, one has a cat inside - I don't know which one.
        I send one basket ball to you.
        I open my basket ball (observation).
        I find it empty so I can deduce the cat is in yours (no information is transfered to you).
        I cannot tell if you have opened yours and observed the cat as dead or alive.
        You open yours and find a dead cat (observation).
        Information is transfered in the normal manner when you call me up and ask why I sent you a dead cat in a basketball.
        • Re: (Score:3, Informative)

          by sootman (158191)

          I have two basket balls, one has a cat inside - I don't know which one.

          The heavier one. Duh. :-)

    • AFAIK whether or not the information is somehow invisibly stored with the entangled entities and so travels with them as they are separated at V = C is an open question.
    • by myrdos2 (989497)
      "Now two American physicists have made an important breakthrough by proving that two quantum channels with zero capacity can carry information when used together. That's interesting because it indicates that physicists may have been barking up the wrong tree with this problem: it implies that the quantum capacity of a channel does not uniquely specify its ability for transmitting quantum information (abstract)."

      http://tech.slashdot.org/article.pl?sid=08/08/06 [slashdot.org]

      So does this mean it is possible to send inf
    • by symbolset (646467)

      Previously entangled qbits decay to the same state, even though their decay is separated by space and time.

      Therefore, it's not necessary for light in its travels to cover all the granular space bits between point A and point B. The line has gaps and lands, and touching the lands between A and B is optional.

      Did I miss something? You physicists and math weenies weigh in here.

    • by Khyber (864651)

      I thought it was as simple as just modifying the spin of one entangled particle half to make the other half change, and this could be used as a form of one-way data communication. I didn't think you'd have to store the information beforehand when splitting entangled particles.

      I've also heard that the 'spooky effect' may actually be faster than light. Not good for teleportation but great for data transmission. If we could just build a device, put it on the moon, and have it's entangled twin on earth, and we

    • 2 entangled quantum states are like 2 magic coins. When you flip one coin and it comes up heads, the other coin comes up tails.

      Now, suppose I flip my coin, and your 100 light years away. You don't know if I have flipped my coin or not, nor if it came up heads or tails. You flip yours, it comes up tails, you now know mine must have come up heads. What information has passed between us? ALL we each know is how the other's coin came up. There is no way to use that fact to communicate anything else.

      Now, you CAN

    • Here's yet another very simplified high-level explanation. Alice has a quantum state that is a superposition of 0 and 1, and she wants to teleport this state to Bob. With the help of an additional "entangled pair" that Alice and Bob share, Alice combines her state and her entangled pair half in a certain way, then makes a measurement that destroys her original quantum state. The measurement results in two classical bits. She transmits these two classical bits to Bob. Bob uses the classical bits to rec
  • TFA (The Science News article) states 'instantly' and I can't actually read the academic paper (bugmenot doesn't seem to have a working login) but does anyone who's more familiar with this area know whether or not it's actually limited to the speed of light, or if we're actually seeing something that's capable of moving faster.

    The article makes it sound as though it's instantaneous, but has this actually been measured to show that it's instantaneous or is the relatively short distance at which the "teleport

  • From the article they are saying that the entanglement has occurred, etc.... they also say that they know the entanglement occurs 1/100M times or so.

    My question... If observation destroys the situation they describe, how to they know the entanglement happened at all?

    Anyone know?

    • Re: (Score:2, Informative)

      They know it was entangled because they prepared the state way. For example, if you have a spin zero particle that splits up into two particles, and you measure one as spin up, the other must be necessarily spin down, no matter how far away it is, because of the conservation of angular momentum. Or you can think of a neutral particle splitting into positive and negative ones. So I guess it is ultimately the consequence of some conservation law.
  • Okay I am not a physicist, but am interested in understanding a bit more about what is going on here.

    Is the following description (model) a reaonably accurate portrayal of what is happening here?

    We have two atoms (A1 & A2) that are in two different (non-entangled) quantum states (Q1 & Q2), at two locations (L1 & L2) separated by 1 m, at which point we allow A1 to interact (quantum mechanically) with a photon which then is 'transmitted' along the vector (L2-L1) and is then 'received' at L2 and al

  • Bah! (Score:5, Funny)

    by GaryOlson (737642) <slashdot@NOSPaM.garyolson.org> on Friday January 23, 2009 @09:39PM (#26584295) Journal
    My mother always knew what I had done without anyone telling her. Or whatever I was going to do before I took action. I hear other mothers have the same ability. Therefore, all mothers must exist in some state of constant quantum communication with each other.
    • Mild correction: all mothers must exist in some state of constant quantum communication with their children.
  • by Nom du Keyboard (633989) on Friday January 23, 2009 @09:56PM (#26584433)
    Adds a whole new meaning to the term: wireless.
    • by markdavis (642305)

      Absolutely. Quantum computing aside, the idea of wireless communications via entanglement is absolutely fascinating. It could lead to instant communication with anyone, just about anywhere in the universe! No towers, no RFI, and absolutely secure from point to point. The major downside is that you probably have to have a centralized "entanglement switchboards" to actually relay the communications from one person to another, since you can't entangle every device to every other possible device. So that w

  • Just think, if they can figure out how this works or at least how to exploit it. You could use these for secure long distance communication. No more cell towers, just entangle some particles, put one in a rack and the other in the cell phone.

    I am curious to know if this "spooky action at a distance" as Einstein referred to it, is faster than light communication. We won't know this until we put one in a Mars rover and launch it. I would also be interested to know if these particles are entangled in anot

    • by blueg3 (192743)

      It is not faster-than-light communication. We will know immediately, and do. (You don't need large time scales to test "immediate" communications -- we can measure that to sufficient resolution on Earth.)

      I'm not sure your statement on "if [they] are entangled in another dimension" is really meaningful. Entanglement is a property of objects in quantum states.

      You can already exploit it, though -- it's fairly similar to the basis for quantum "encryption" (by one definition), which is not encryption at all, but

  • Damn... (Score:4, Funny)

    by fenix849 (1009013) on Friday January 23, 2009 @10:30PM (#26584625)

    Ok, who voted for the beammeupscotty tag?

    I can't think of a worse place to be beamed, than 'up scotty'.

  • You have two entangled particles A and B and send particle B somewhere else. Then you take a reading of A and call this reading X. You don't really know what is the meaning of X - did you observe it first or did someone else observed B first but you do know that if someone observed B next he will certainly get reading X back to him. Thus it's useless for communication.

    The only way this seems useful to me is if we need to keep something perfectly identical to something else, but it can't work that way either

  • Hey physics types: So I take it this can in no way lead to the future development of the transporter [wikipedia.org]?

  • Holy crap! The feminism thing is a tad too much to digest:

    Scientists have previously teleported unmolested qubits

    Unmolested?? Where they expecting that these female ions would be molested by male ions on their way to their homes???
    Why The Fuck they can't use normal words like "unchanged", "bit copy".
    This feminism thing has gone too far...
    I hope we go back to the pre-WW2 era when women were easier to control and men worked...

  • Assuming something like this works at much longer distances, this could be applied to interplanetary and interstellar communication.

    Imagine a martian colony being seamlessly connected to the internet on earth through circuits which utilize this kind of information.

    • Quantum entanglement cannot be used for classical information.
      • Quantum entanglement cannot be used for classical information.

        when last I heard of this on a documentary, it had to do with two particles mirroring each other's spin, and when that spin changed, it was mirrored.

        Sounds like binary to me.

        • No, it cannot be used for classical information due to the basic principles of quantum entanglement. You cannot send information over a channel when you don't know the spin of either entangled particle: this is equivalent to sending random binary data, because while you know the particle the other guy gets is going to be the opposite of yours, you don't know what particle you have.

          Think of it like this: you're a kid, you have a friend, Santa Claus has only two presents: a Game Boy and a rock. Christmas Day,

  • How much it faster then speed of light?

  • orson scott card's a visionary. See? [wikipedia.org]
  • to call quantum entanglement "teleportation".

  • The researchers then measured the first atom, thus destroying the delicate quantum information it contained, and also destroying the entanglement. That left the original qubit intact in only the second, recipient atom, completing the teleportation.

    If this works, then theoretically couldn't an attacker entangle a third qubit with the original two, measure that (and destroy the entanglement), and leave the two originals unchanged?

    (yes I know there's a prodigious amount of handwaving here, but it's *entangled*

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