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Quantum Teleportation Achieved Over 16 km In China 389

Posted by timothy
from the can-feel-it-from-here dept.
Laxori666 writes "Scientists in China have succeeded in teleporting information between photons farther than ever before. They transported quantum information over a free space distance of 16 km (10 miles), much farther than the few hundred meters previously achieved, which brings us closer to transmitting information over long distances without the need for a traditional signal."
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Quantum Teleportation Achieved Over 16 km In China

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  • ... I might stop having Cablemodem issues? Sexy!
  • Obligatory (Score:2, Funny)

    by Thoggins (1162149)
  • Yea but. (Score:5, Funny)

    by Pharmboy (216950) on Saturday May 22, 2010 @05:28PM (#32308766) Journal

    Unfortunately, what they transmitted was an email for Vi4gra, using an open wifi connection at a Starbucks 10 miles down the road.

  • by Anonymous Coward on Saturday May 22, 2010 @05:29PM (#32308770)

    Before you think this is awesome, this is not an ansible, information is transmitted at lightspeed only.

    • Re: (Score:2, Informative)

      ansible [wikipedia.org]

      Next time, define the terms yourself, you insensitive clod.

      • Re: (Score:2, Funny)

        by Anonymous Coward

        Asking people to look things up for you in an age where doing it yourself literally means putting your finger down, moving your hand one inch, and putting your finger down again, is pretty fucking contemptible.

    • Hey, lightspeed IS awesome.

      Note, however, that only information is sent, not the actual "item".

      The implication, of course is if you can "transmit" an arbitrary item, you can, by definition duplicate it. So, when we have this technology, you will be able to "have your cake and eat it too".

      Oddly it will also be the most altruistic, or selfish thing you can ever do. Consider; altruistic - you send a "copy" of yourself to do something cool. selfish, nasty task? send a "copy", not "you".

      This might be
  • by Anonymous Coward

    Not until they do it over the USA or even France, but not over China.

  • I don't get it (Score:5, Insightful)

    by Adrian Lopez (2615) on Saturday May 22, 2010 @05:37PM (#32308850) Homepage

    Isn't it impossible to transmit information via quantum entanglement? Since you cannot determine the state of an entangled particle, you cannot use it to "transmit" information until after you let the other end know, through conventional channels, what each possible state actually stands for. If that's the case, how exactly is this "quantum information transfer" supposed to work.

    • by pwilli (1102893)
      You are right. What TFA probably means is that Alice doesn't have to send Bob a traditional signal, because Charlie (the guy that creates the entanglement and distributes the 2 photons to Alice and Bob) does that classical comunication for them.
      • Re:I don't get it (Score:5, Informative)

        by pwilli (1102893) on Saturday May 22, 2010 @06:01PM (#32309092)
        To further clarify what I meant:

        - Charlie entangles Particles A+B
        - Charlie sends Alice Particle A over fiber
        - Charlie sends Bob Particle B over air
        - Alice measures A and sends Charlie information about measurement (classic part needed for actual information transfer)
        - Charlie sends classic information to Bob
        - Bob measures Particle B, combines result with classic information, and voila, Bob can reconstruct the information "sent" by Alice


        Clearly no way to transfer information securely or fast, but a proof that entanglement in Particle B for Bob can survive long transfer through air.
    • Sure you can determine the state of a particle. You can do something that will change its state in a predictable way. Then the other particle, which you haven't changed, changes at the same time.

      Which brings us to the question of Relativity: Since there is no such thing as simultaneous time in the universe, per Einstein - that is, what's simultaneous from one perspective is sequential from another - when does the untouched-but-entangled particle change state to match the one we've acted on in a determinativ

    • Re: (Score:3, Informative)

      by ianezz (31449)

      Since you cannot determine the state of an entangled particle, you cannot use it to "transmit" information until after you let the other end know, through conventional channels, what each possible state actually stands for

      As far as I know (very little, please correct me if I'm wrong), you can't neither predict nor influence the outcome of measurements, but you can be sure they will be the same at both ends, unless someone is eavesdropping in the middle. The flow of measures can then be used as a one time

  • Peer Reviewed (Score:5, Insightful)

    by areusche (1297613) on Saturday May 22, 2010 @05:39PM (#32308874)

    http://science.slashdot.org/story/10/04/19/0132246/Chinas-Research-Ambitions-Hurt-By-Faked-Results

    This story alone makes me skeptical about any major scientific breakthroughs until someone can peer review the results.

    Congrats to the hardworking people on the project, however I will be applauding their work with less skepticism when I hear that MIT, Cornell, CMU, etc confirm the results.

    • Re: (Score:3, Informative)

      My thoughts were exactly that when I read this. But this is published in Nature photonics, it cannot be all fake. There is a possibility of incorrect experiments/conclusion, but it cannot be complete BS.
    • Re:Peer Reviewed (Score:5, Informative)

      by Interoperable (1651953) on Saturday May 22, 2010 @08:32PM (#32310150)

      The work was done by Jian-Wei Pan, one of the leaders in the field and a very impressive researcher. You can bet that the result is accurate if his name is behind it. Furthermore, it's being published in Nature Photonics. Besides, the result is impressive, but not ground breaking. Extending the distance of the protocol requires some fancy techniques and a good deal of skill and expertise, but the results aren't surprising.

  • In what way are photons travelling down a fiber not a traditional signal? Sure, they are entangled, but you still have to ship photons around.

  • Contradictory (Score:3, Informative)

    by pwilli (1102893) on Saturday May 22, 2010 @05:46PM (#32308946)
    Why is TFA contradicting itself? A traditional signal is always needed, that's one fundamental principle of quantum comunication.
    • You still need a classical signal. Information still cannot be transmitted faster than light.

      It's possible there are esoteric uses for this if it could be scaled up dramatically in terms of the sophistication of the state transmitted, and this could matter for quantum computer communication some day, but I fail to see any real use for quantum teleportation today.

      I do have a BS in Physics, but that was 15 years ago and I have never done physics professionally - I got sucked up by the nice pay and abundant j

      • Re: (Score:3, Funny)

        by imamac (1083405)

        Information still cannot be transmitted faster than light.

        Sigh...subspace transmissions, hello???

    • by Sabalon (1684)

      Way I read it is that you need a traditional channel to get one of the photons to the other location. Once you've done that, change made at the first location are realized at the second station without the traditional channel.

      ie. You want to hear me a mile down the road, so you ride down the road with a walkie-talkie. Once you get there, we are able to communicate without a new radio being sent to you every time.

      • Re: (Score:2, Informative)

        by Athanasius (306480)

        Except each entangled pair is one-use only. You measure the state of one half of it, which instantly sets the same state in the other pair, and then they're no longer entangled (due to you having observed).

        Also you can't predict or set the state of half an entangled pair, only measure it, causing the waveform to randomly collapse. The only thing this gets you is secure transmission of a random sequence (many entangled pairs) of states, which you can then use as a one-time pad/key for conventional encry

  • Have they now... (Score:2, Informative)

    by QuasiRob (134012)

    "Scientists in China".

    Think I'll be waiting for independent verification of this one then...

    • This research group happens to be very well respected and is a leader in the field. They are, without question, some very good scientists.

  • QbitTorrent is going to give a few industries some serious headaches, good luck tracking and snooping on free space quantum teleportation.
  • by NicknamesAreStupid (1040118) on Sunday May 23, 2010 @01:31AM (#32311714)
    but no one was there to hear it. Would there still be information? Ah, the philosophy of quantum physics. I know nothing about physics, ever had a class. After reading 238 postings on this topic, I still know nothing but feel like I am in good company.

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