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Quantum Teleportation across the Danube Demonstrated

  1. Aug 18, 2004 #1
    so this technology is going to one day be able to transport bigger stuff than a photon. or wtf :grumpy:
     
  2. jcsd
  3. Aug 19, 2004 #2

    ZapperZ

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    For those who also followed the string on "Neutrino telescope", this is EXACTLY an example of the kinds of problems I was trying to illustrate with the use of the word "teleportation".

    No where in this "Brief Communication" [1] did a photon got "teleported" as envisioned in an episode of Star Trek. I should also quote the first few sentences of Gisin's group paper[2] that has done similar stuff:

    "Matter and energy cannot be teleported (that is, transferred from one place to another without passing through intermediate locations). However, teleportation of quantum states (the ultimate structure of objects) is possible: only the structure is teleported - the matter stays at the source side and must be already present at the final location."

    Zz.

    [1] R. Ursin et al., Nature v.430, p.849 (2004).
    [2] I. Marcikiv et al., Nature v.421, p.509 (2003).
     
  4. Aug 20, 2004 #3
    Yes,unlike the situation in Star Trek,the original is destroyed,moreover In the light of current knowledge at least,it is impossible to teleport someone without sending information using also a conventional channel of communication.Remains however a big question,is indeed human consciousness only a function of (very complex) arrangements of matter?
     
  5. Aug 20, 2004 #4
    Well, I think that the title of the thread is misleading, the team of Zeilinger only demonstratrated long distance quantum entanglement in the Danube experiment,concretely an entanglement distance of 600 m, but there was not teleportation performed in the experiment
     
  6. Aug 20, 2004 #5

    ZapperZ

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    Well, to be able to demonstrate the entanglement, they have to make a measurement of the entangled properties at both locations. By simply making one measurement at one end, they automatically determined the property at the other end. This, by definition, is quantum teleportation. So I'm not sure why you think there was no "teleportation" in this experiment.

    Zz.
     
  7. Aug 20, 2004 #6
    It depends what one considers to be teleportation : we know how to transmit information "instantaneously". But relativity prevents it for energy.
    There is teleportation of information in labs like everyday or so :wink:
    There will never be energy teleportation :cry:
     
  8. Aug 20, 2004 #7

    ZapperZ

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    1. I didn't make up the definition of "quantum teleportation". So it is not up to me (nor you) to consider it anyway we like.

    2. I have already discussed my displeasure of the terminology.

    3. Transfer of ANY information (not just energy) faster than c is prohibited by Special Relativity. Quantum teleportation doesn't violate this.

    Zz.
     
  9. Aug 20, 2004 #8
    I am deeply confused. I totally agree with Zz's 1 & 2 points.
    But I don't understand 3. When did SR made statements about information ? Are you saying that energy is a form of information ? I thought those two things were different. I thought information is a well defined concept in QM only.
     
  10. Aug 20, 2004 #9
    Zz, I know I am not going to teach you physics. I would like to learn from you.

    You certainly already heard it : consider a huge scissors pair, at the scale of the solar system for instance. When the scissors are closing, the intersection of the two arms is travelling way faster than c. It is information travelling faster than c, but not associated with energy travelling faster than c. Where am I wrong ?
     
  11. Aug 20, 2004 #10

    ZapperZ

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    http://www.aip.org/pnu/1997/split/pnu350-1.htm
    http://www.physics.hku.hk/~phys1303/SolutionHW5.doc

    Zz.
     
  12. Aug 20, 2004 #11
    Thank you very much Zz !

    If you or anyone has a reference on what SR has to say about information by itself and how it is linked to energy, I would appreciate too. The two previous links are examples where information is not travelling faster the c. But as far as I understand classical texts on SR (and GR) they don't talk about information.
     
  13. Aug 20, 2004 #12

    ZapperZ

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    You need to understand the difference between "phase velocity" and such. Ultimately, the issue of SR depends on how we define light and light "wave".

    Refer to:

    http://www.mathpages.com/home/kmath210/kmath210.htm

    In particular, pay attention to the part where it says:

    Zz.
     
  14. Aug 21, 2004 #13
    You're right thanks. I wasn't aware of this experiment made in 2004. I thoght that he was talking about this other experiment of 2003 also accross the Danube, were only entanglement was performed, no teleportation
    http://physicsweb.org/article/news/7/6/20/1

    BTW (off-topic): Kisses to Mar, my girlfriend :smile:
     
    Last edited: Aug 21, 2004
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