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Transportation Science

Scientists Teleport Information Between Ions a Meter Apart 220

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 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.

  • by Snowtred ( 1334453 ) on Friday January 23, 2009 @09:17PM (#26584097)
    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?
  • by Normal_Deviate ( 807129 ) on Friday January 23, 2009 @09:21PM (#26584123)
    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 @09:41PM (#26584319)

    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.

    I am a physicist. This is absolutely correct. The whole language is convoluted and based on false premises... teleportation? Give me a break.

  • by mhall119 ( 1035984 ) on Friday January 23, 2009 @11:01PM (#26584817) Homepage Journal

    The 2-slit experiment observed quantum super-position, not entanglement. The quantum state was measured when the photons hit the opposite wall, and that measurement only measured the collapsed state, not the super-position. The super-position was only observed in the pattern of interference in the collapsed states.

    The super-position being measured was caused by the photon passing through the two-slits, so even if you took an entangled photon, collapsed it's partner, and sent it through the double-slit, it would still be in a super-position with regard to which slit it passed through, regardless of anything that happened to it's partner.

  • by Anonymous Coward on Saturday January 24, 2009 @12:07AM (#26585255)
    no you are wrong, the posts above you are closer.

    as you said in the post you linked, you are "just a curious guy". please don't deny most of the last century of physics just because something seems cool when you don't have any understanding of it.

  • by drinkypoo ( 153816 ) <> on Saturday January 24, 2009 @12:18AM (#26585321) Homepage Journal

    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.

  • by Phroggy ( 441 ) <slashdot3@phrog[ ]com ['gy.' in gap]> on Saturday January 24, 2009 @02:52AM (#26586045) Homepage


    Is there any way this could be used, not for sending FTL messages, but exchanging a cipher? You said you can't know which state you'll measure, but if you can measure some as-yet-unknown random state at one end and measure the corresponding state at the other end, then you should be able to use this random pattern of bits to encode a message, which would then be transferred through traditional (light speed or slower) means. The message could be intercepted in transmission, but the cipher couldn't be.

  • by Anonymous Coward on Saturday January 24, 2009 @10:05AM (#26588209)

    Are they positive?

    Actually, yes, necessarily: it is ytterbium.

  • 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.
  • by sfazzio ( 1227616 ) on Saturday January 24, 2009 @04:12PM (#26591611)
    What's with all of the physics time-travelers from the 1960s? Bell's theorem has repeatedly passed experimental muster, and has become a cornerstone of quantum information theory-- a field which has lead to any number of testable (and subsequently tested) predictions.

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