Sign in / up

back to article Quantum comms succeed over metro-scale fibre networks

Two groups both reported successfully teleporting state information across metro-scale fibre networks. A Chinese team is claiming a teleportation over a 30 km fibre in Haifei (the entanglement travelled nearly 16 km), while the University of Calgary used that city's fibre network to carry entanglement 6.2 km (preprint here). …

COMMENTS

Post your comment
House rules Send corrections
Add to 'My topics' unstar *
  1. frank ly

    I'm confused

    "Charlie measures A and B, in a way that prevents him knowing which photon he's measuring."

    Why is the state/content of Charlie's mind important?

    "During the BSM, Alice's particle A teleports its quantum state onto Bob's particle C."

    If B and C are the quantangled pair, how can it be A that has its state 'teleported' onto C?

    I've read this: https://en.wikipedia.org/wiki/Bell_state but I'm non the wiser.

    Also see: https://en.wikipedia.org/wiki/No-cloning_theorem which states that it is impossible to create an identical copy of an arbitrary unknown quantum state. Isn't that what was done when the state of A was teleported onto C?

    1 0 Reply
    1. TitterYeNot
      Reply Icon

      Re: I'm confused

      "If B and C are the quantangled pair, how can it be A that has its state 'teleported' onto C?"

      I think it works like this (though obviously as this is quantum mechanics I don't actually understand it, and my brain now hurts.)

      Photon A is not entangled. B and C are an entangled photon pair. A and C are sent down several kilometres of telecom grade fibre optic cable and interact (but are not observed prior to the interaction.) After the interaction, the state of C is shown to be teleported to its entangled photon B, which is still in its original location (i.e. it has has not been sent down the optic cable.)

      It sounds like what's different here compared to a classic Bell state teleportation experiment is that the two interacting photons A and C were sent over 6 km down an optic cable, rather than remaining local, and the teleported state 'recipient' B remained local rather than being sent a short distance away.

      So it looks like it's a demonstration of "spooky action at a distance" using commercial telecoms equipment. I think. Ow...

      1 0 Reply
    2. junglesnot
      Reply Icon

      Re: I'm confused

      I think it's because of the uncertainty principle. Now I'm going to lie down in a darkened Heisenberg box for a while ...

      0 0 Reply
  2. Doctor Syntax Silver badge

    "Bob creates an entangled pair, B and C;

    Bob sends B to Charlie and keeps C;"

    How does Charlie keep C? Photons tend not to hang about. They shove off at...well, quite fast, really.

    0 0 Reply
  3. Alister
    Joke

    successfully teleporting state information across metro-scale lines.

    Isn't this Wire Fraud?

    1 0 Reply
  4. PleebSmasher
    Paris Hilton

    Internet

    Does this mean we can say quantum teleportation has been achieved over the Internet?

    0 0 Reply
  5. A Nonny Moose

    Beam me up, Scotty

    Yes, well, this is all very nice, but let's get to the really important question:

    How much closer are we to getting Star Trek style Transporters?

    0 0 Reply
    1. Destroy All Monsters Silver badge
      Reply Icon

      Re: Beam me up, Scotty

      Not at all.

      The only way to transport something realistically in this uinverse seems to be to actually transport from point A to B. There is no use going through the hassle of beaming the whole E=mc² energy bunch...

      0 0 Reply

POST COMMENT House rules

Not a member of The Register? Create a new account here.

Forgotten password ?

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like