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Thread: Sending information via Quantum Entanglement

  1. #1 Sending information via Quantum Entanglement 
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    Hello,

    I recently read that faster than light communication was not possible with quantum entanglement because it required the use of a non-entangled particle and therefore was limited to light speed like everything else.

    In an entangled pair do they stop entanglement when the observation is made on end revealing the opposite state when viewed on the other end? What happens if one end were to be annihilated in a matter - antimatter
    reaction? Does the other side annihilate as well? If so, can scientists cause these types of state changes in real time and be able to time them precisely? If so, why couldn't information be gleaned using the passage of time
    being long for 0 and 1 for short? This falls apart unless there is a way for us to introduce a change on one side that is instantly seen on the other side without having having to influence it via measurement or observation...

    As always, I am just curious...

    Thanks!

    --RayTech


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  3. #2  
    KJW
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    Quote Originally Posted by raytech70 View Post
    In an entangled pair do they stop entanglement when the observation is made on end revealing the opposite state when viewed on the other end?
    A full measurement of one of the entangled pair of particles breaks the entanglement between them.


    Quote Originally Posted by raytech70 View Post
    What happens if one end were to be annihilated in a matter - antimatter
    reaction? Does the other side annihilate as well?

    That's not how entanglement works.


    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Brassica oleracea Strange's Avatar
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    The effects of entanglement are just a correlation of measurements made on the entangled pair (not a communication). So the only way to see that there is a correlation is to communicate the measurement information by some normal method (at the speed of light or slower).
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
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    So there is no known way to observe the state change without disrupting the entanglement? What about entangled photons... no way to change a state that would be observed without interfering?
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    Quote Originally Posted by raytech70 View Post
    So there is no known way to observe the state change without disrupting the entanglement? What about entangled photons... no way to change a state that would be observed without interfering?
    No. Entanglement isn't about the two particles (whatever they are) communicating with each other once they have been separated.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Okay, so when I introduce a state change by observing or measuring the particle, that state change can only be "detected" or "read" or "observed" if I go at it with the appropriate testing measure (which in turn detangles the pair?) And so that is why it requres a non-entangled particle to act as a controlling mechanism. So FTL or super-luminal transfer of information is impossible... darn.
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    At the time the two particles become entangled, each particle carries information about the other particle (not the state, but the relationship between them), so that when one particle is measured, the other particle is also measured. Note that for a measurement, the particle acts on the measuring device changing the state of the measuring device. But if one acts on one of the particles, changing the state of that particle, then it is only that particle that changes state. There is no communication of this change of state to the other particle.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    That makes sense to me now, but how then can any type of quantum communication occur-- I had read that quantum entanglement can only transfer information if it also uses a non-entangled particle to "x" and make that communication happen... do you know much about that?
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    Quote Originally Posted by raytech70 View Post
    That makes sense to me now, but how then can any type of quantum communication occur-- I had read that quantum entanglement can only transfer information if it also uses a non-entangled particle to "x" and make that communication happen... do you know much about that?
    I think (but am not sure) that in order for the experimental result from one particle to be correlated with the experimental result from the other particle, a classical communication channel is required, which will be limited by classical causality. This is because anything a remote experimenter does with his particles has no observable effect on my particles, and it is only by communicating our results to each other at the conclusion of the experiment that we can establish any correlation between our results.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by raytech70 View Post
    That makes sense to me now, but how then can any type of quantum communication occur-- I had read that quantum entanglement can only transfer information if it also uses a non-entangled particle to "x" and make that communication happen... do you know much about that?
    Or are you referring to such things as quantum teleportation? I'm not particularly familiar with the details of this.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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