Teleportation

Discussion in 'Physics & Math' started by Rick, May 2, 2002.

  1. Rick Valued Senior Member

    Messages:
    3,336
    Quantum Teleportation

    Following are some of the interesting articles on teleportation:
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    Quantum Teleportation
    Teleportation is the name given by science fiction writers to the feat of making an object or person disintegrate in one place while a perfect replica appears somewhere else. How this is accomplished is usually not explained in detail, but the general idea seems to be that the original object is scanned in such a way as to extract all the information from it, then this information is transmitted to the receiving location and used to construct the replica, not necessarily from the actual material of the original, but perhaps from atoms of the same kinds, arranged in exactly the same pattern as the original. A teleportation machine would be like a fax machine, except that it would work on 3-dimensional objects as well as documents, it would produce an exact copy rather than an approximate facsimile, and it would destroy the original in the process of scanning it. A few science fiction writers consider teleporters that preserve the original, and the plot gets complicated when the original and teleported versions of the same person meet; but the more common kind of teleporter destroys the original, functioning as a super transportation device, not as a perfect replicator of souls and bodies.
    In 1993 an international group of six scientists, including IBM Fellow Charles H. Bennett, confirmed the intuitions of the majority of science fiction writers by showing that perfect teleportation is indeed possible in principle, but only if the original is destroyed. Meanwhile, other scientists are planning experiments to demonstrate teleportation in microscopic objects, such as single atoms or photons, in the next few years. But science fiction fans will be disappointed to learn that no one expects to be able to teleport people or other macroscopic objects in the foreseeable future, for a variety of engineering reasons, even though it would not violate any fundamental law to do so.

    Until recently, teleportation was not taken seriously by scientists, because it was thought to violate the uncertainty principle of quantum mechanics, which forbids any measuring or scanning process from extracting all the information in an atom or other object. According to the uncertainty principle, the more accurately an object is scanned, the more it is disturbed by the scanning process, until one reaches a point where the object's original state has been completely disrupted, still without having extracted enough information to make a perfect replica. This sounds like a solid argument against teleportation: if one cannot extract enough information from an object to make a perfect copy, it would seem that a perfect copy cannot be made. But the six scientists found a way to make an end-run around this logic, using a celebrated and paradoxical feature of quantum mechanics known as the Einstein-Podolsky-Rosen effect. In brief, they found a way to scan out part of the information from an object A, which one wishes to teleport, while causing the remaining, unscanned, part of the information to pass, via the Einstein-Podolsky-Rosen effect, into another object C which has never been in contact with A. Later, by applying to C a treatment depending on the scanned-out information, it is possible to maneuver C into exactly the same state as A was in before it was scanned. A itself is no longer in that state, having been thoroughly disrupted by the scanning, so what has been achieved is teleportation, not replication.

    As the figure to the left suggests, the unscanned part of the information is conveyed from A to C by an intermediary object B, which interacts first with C and then with A. What? Can it really be correct to say "first with C and then with A"? Surely, in order to convey something from A to C, the delivery vehicle must visit A before C, not the other way around. But there is a subtle, unscannable kind of information that, unlike any material cargo, and even unlike ordinary information, can indeed be delivered in such a backward fashion. This subtle kind of information, also called "Einstein-Podolsky-Rosen (EPR) correlation" or "entanglement", has been at least partly understood since the 1930s when it was discussed in a famous paper by Albert Einstein, Boris Podolsky, and Nathan Rosen. In the 1960s John Bell showed that a pair of entangled particles, which were once in contact but later move too far apart to interact directly, can exhibit individually random behavior that is too strongly correlated to be explained by classical statistics. Experiments on photons and other particles have repeatedly confirmed these correlations, thereby providing strong evidence for the validity of quantum mechanics, which neatly explains them. Another well-known fact about EPR correlations is that they cannot by themselves deliver a meaningful and controllable message. It was thought that their only usefulness was in proving the validity of quantum mechanics. But now it is known that, through the phenomenon of quantum teleportation, they can deliver exactly that part of the information in an object which is too delicate to be scanned out and delivered by conventional methods.

    This figure compares conventional facsimile transmission with quantum teleportation (see above). In conventional facsimile transmission the original is scanned, extracting partial information about it, but remains more or less intact after the scanning process. The scanned information is sent to the receiving station, where it is imprinted on some raw material (eg paper) to produce an approximate copy of the original. In quantum teleportation two objects B and C are first brought into contact and then separated. Object B is taken to the sending station, while object C is taken to the receiving station. At the sending station object B is scanned together with the original object A which one wishes to teleport, yielding some information and totally disrupting the state of A and B. The scanned information is sent to the receiving station, where it is used to select one of several treatments to be applied to object C, thereby putting C into an exact replica of the former state of A.


    interesting,isnt it?


    bye!
     
    Last edited: May 3, 2002
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  3. ChristCrusher Registered Senior Member

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    no, thats not really interesting, its commonplace knowledge and antequated discussion matter.





    INTERESTING would be some of the following:


    the time scale required to scan/model the human body

    the data space required to scan/model the individual/specific human body

    the cpu, ram, and bandwidth requirements to scan/model an human body

    the technological requirments needed to generate the ability to control the quantitative quantum engineering of an exact duplicate , in a dynamic, transient environment

    the energy needed to assemble a human body from (sub) molecular components

    the ethical and moral implications of an errored restructuring of data or data loss


    etc.....
     
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  5. Rick Valued Senior Member

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    Moral and ethical implications of Teleportation?

    gee...


    bye!
     
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  7. ChristCrusher Registered Senior Member

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    yes, such as:


    what level of error in 'reconstructing' a person is acceptable?
     
  8. (Q) Encephaloid Martini Valued Senior Member

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    zion

    If you're going to copy/paste an article, please supply the link. It is important to know the source of the article. It will also help to determine whether this thread belongs in pseudo-science.

    I suspect it does.
     
  9. Rick Valued Senior Member

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    3,336
    Q,

    you"d be the last person i expected not to have link about his article,i mean you know lot about these kind of stuff,isnt it?
    anyways when you google "teleportation"
    you"ll find tons of material about this confirmation experiment.

    this is the link(IBM research).
    ====================================================
    www.research.ibm.com/quantuminfo/teleportation/
    ====================================================

    what made you suspect that this is pseuso-science?
    i suppose you would say AI as pseudo-science?

    gee...


    bye!
     
  10. (Q) Encephaloid Martini Valued Senior Member

    Messages:
    20,855
    zion

    Thanks for the link.

    what made you suspect that this is pseuso-science?

    Because you conveniently left out the "Quantum" from your thread title. And this remark:

    But science fiction fans will be disappointed to learn that no one expects to be able to teleport people or other macroscopic objects in the foreseeable future, for a variety of engineering reasons, even though it would not violate any fundamental law to do so.

    i suppose you would say AI as pseudo-science?

    Much of it is pseudo-science. What specifically are you referring?
     
  11. Rick Valued Senior Member

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    3,336
    oops,sorry.
    i"ll edit it myself.






    bye!
     
  12. spookz Banned Banned

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    6,390
    The Innsbruck Experiment

    IMAGE DEPICTS the University of Innsbruck experimental setup for quantum teleportation. In the quantum teleportation process, physicists take a photon (or any other quantum-scale particle, such as an electron or an atom) and transfer its properties (such as its polarization, the direction in which its electric field vibrates) to another photon--even if the two photons are at remote locations. The scheme does not teleport the photon itself; only its properties are imparted to another, remote photon.

    Please Register or Log in to view the hidden image!


    Image: Malcolm Tarlton, American Institute of Physics

    Here is how it works: At the sending station of the quantum teleporter, Alice encodes a "messenger" photon (M) with a specific state: 45 degrees polarization. This travels towards a beamsplitter. Meanwhile, two additional "entangled" photons (A and B) are created. The polarization of each photon is in a fuzzy, undetermined state, yet the two photons have a precisely defined interrelationship. Specifically, they must have complementary polarizations. For example, if photon A is later measured to have horizontal (0 degrees) polarization, then the other photon must "collapse" into the complementary state of vertical (90 degrees) polarization.

    Entangled photon A arrives at the beamsplitter at the same time as the message photon M. The beamsplitter causes each photon to either continue toward detector 1 or change course and travel to detector 2. In 25% of all cases, in which the two photons go off into different detectors, Alice does not know which photon went to which detector. This inability for Alice to distinguish between the two photons causes quantum weirdness to kick in. Just by the very fact that the two photons are now indistinguishable, the M photon loses its original identity and becomes entangled with A. The polarization value for each photon is now indeterminate, but since they travel toward different detectors Alice knows that the two photons must have complementary polarizations.

    Since message photon M must have complementary polarization to photon A, then the other entangled photon (B) must now attain the same polarization value as M. Therefore, teleportation is successful. Indeed, Bob sees that the polarization value of photon B is 45 degrees: the initial value of the message photon.
     
  13. spookz Banned Banned

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    6,390
    University of Geneva in Switzerland

    Employing a facet of quantum mechanics that Albert Einstein called "spooky action at a distance," scientists have taken particles of light, destroyed them and then resurrected copies more than a mile away.

    Previous experiments in so-called quantum teleportation moved particles of light about a yard. The findings could aid the sending of unbreakable coded messages, which is limited to a few tens of miles.

    The new experiment used longer wavelengths of light than earlier ones, letting the scientists copy the light through standard glass fiber found in fiber optic cables.

    "The central issue is to move to telecom fibers and telecom wavelengths and telecom technology," said Dr. Nicolas Gisin, a physics professor at the University of Geneva and the senior author of an article today in the journal Nature. "This then allows us to go the long distance."

    The experiments are a primitive realization of the transporter in the "Star Trek" television series that beams people from starship to planet. In coming years, it may be possible to use teleportation to imprint the exact quantum configuration of one atom to another. But teleporting something from the everyday world like a person that contains more than a trillion trillion atoms is highly unlikely, if not impossible.

    Even with the light particles, photons, about one in a thousand were received at the other side.

    "You're not very sure to arrive," a researcher, Dr. Hugo Zbinden, said about human teleportation.

    Still, the experiments show that scientists can overcome a seemingly insurmountable conceptual barrier, the Heisenberg uncertainty principle. The principle states that the location and velocity of a particle cannot both be precisely measured at the same time. That would seem to make it impossible to teleport anything, even single particles, because without knowing their exact specifications they cannot be copied somewhere else.

    Devised in 1993 by scientists led by Dr. Charles H. Bennett of the I.B.M. Thomas J. Watson Research Center in Yorktown Heights, N.Y., quantum teleportation produces pairs of "entangled" light particles that can be thought of as a pair of encoding and decoding rings. A message is combined with the encoding light particle. That combination goes to the recipient, who uses the decoding photon to decipher the message. Because no one else has the decoding photon, no one else can decipher the message.

    Other encoding techniques using quantum cryptography are simpler, and a more immediate use for teleportation would be as a repeater. Photons almost all peter out after traveling about 50 miles through optical fiber. Teleportation would enable the creation of copies every 50 miles or so, letting the message be sent across an unlimited distance.


    nature pdf

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