Sunday, September 26, 2021

Quantum entanglement — information transfer?

we cannot transfer information faster than light yet by any means, including quantum entanglement.
however certain “type” of information can be transported.
see the thought experiment below —
Alice and Bob seperated by 1 light year and keeping a couple of entangled pairs of photons can communicate information about what was the spin of the first pair when one of them collapsed the wave function.
thus certain “type” of information can be transmitted. the information that can be transmitted is of the “chance” type.
you can transmit the outcome of a “roll of dice”
if Alice gets spin up….Bob will get spin down.
while alice/bob cannot control the outcome….they have the information regarding the outcome instanteously.
isn’t this some sort of instaneous “information transfer”?
halabund —
what if they have say 10 pairs of entangled particles…..both have 10 jars each. 1-1, 2-2 , 3-3…..10-10
now if alice collapses 2-2, 4-4 and 5-5…say….its means hello…..and if alice collapses 3-3 and 6-6…its means bye…….thus alice can transmit information…..what is the fallacy here?
1-1 = 1 jar with alice and the other jar having entangled particle of 1 in other jar with bob.
2-2 = same thing…..second pair of entangled particles.
what is ur email halabund? what is ur yahoo ID halabund?
if Alice collapses the wave function of one of her particles….would the entangled particle at Bob’s place also collapse simulatenously?


  1. theoretically, information CAN be transported faster than light by quantum entanglement.
    the only problem is that we haven’t figured out how to make this work, but I’m pretty sure it is possible.

  2. This is still considered one of the biggest problems of quantum mechanics. In my quantum mechanics class we discussed this a dillema that as of yet cannot be solved.

  3. You would first have to establish the entanglement and preserve it while moving the two photons a light year apart.
    IF you could do that, then in theory you could send a beam of entangled photons toward a receiver. By turning the receiver off and back on in a coded pattern, the transmitted photons would lose their entanglement in a pattern identical to the one in which the receiver was turned off– and this would not be dependent on the transit time of the photons– theoretically near-instantaneity.

  4. No, it would that would be Kinetic Energy Displacement. Think about it, if one has to move up the other has to move down they are directly connected to one another and they displace the other one because of displacement law. Information that we have now, with our technology limits us to the speed of light. However given that information if you could stretch space, and make it so that there is a wormhole connected to the other place they would still be a light year apart but technically next to eachother at the same time. If this is the case, and we are limited to speed of light, then we must find another way of sharing information other than by means of light speed. Is it possible for a person to be in two places at the same time. If multi-dimensional existance was proven, we could exist in layers of galaxies on top of eachother so I could be in multiple places at the same time, with one connected mind frame. Therefore I could be 1 million light years away from this dimensional position but would still be experience both. This would be the real definition of eternal existance.
    Say you have two identical earth’s, if one moves does the other move out of displacement cause and effect?

  5. This is the kind of question I like … 🙂
    No, this is not information transfer. I will try to enlighten the problem by formulating it more precisely.
    But first, I’d like to show that if you could tranfer information faster than light, you’d get a contradiction with special relativity.
    Suppose A can communicate some information faster than light to B. Let A sending the information be event 1, B receiving it event 2. If the message is travelling faster than light, it can be shown that in the reference frame of A, event 1 happens _before_ event 2, while in the reference frame of B event 1 happens _after_ event 2, which is a contradiction because Bob cannot receive the message before Alice sends it. If a light-signal cannot travel between events 1 and 2, we call them spacelike separated (at least in some other languages than English we do 🙂 ). Spacelike separated events don’t have a definite temporal order (the order depends on the reference frame).
    Of course, in your example there is a correlation between the outcome of Alice’s and Bob’s measurement, but it cannot be considered information transfer. They always knew that they would get opposite results, but they didn’t know who would get |up> and who would get |down>. Information transfer would mean that Alice already has a piece of data she knows, eg. a bit of 1, and she would like to transfer it to Bob. Bob’s gaining knowledge of this information is the result of Alice’s sending it. So there is a definite temporal order (and causal relationship) between these events. In the entagled particle-pair example she doesn’t have this piece of information before she does a measurement.
    However, you could say that A can transfer information like this: she does a measurement, and as the result of the measurement the wave function of both particles collapses, and B can measure to see if his particle is in a collapsed (|up> OR |down>) or superposed (|up> + phase_factor*|down>) state. So B will know if A has already measured or not! But B cannot decide which state the particle was in with only one measurement! And he can make only ONE measurement, because the measurement collapses the state. As a result he will always get either UP or DOWN, so he cannot tell if the original state was |up>+|down> or one of |up> or |down>.
    Of course if B could copy the state of his particle, he would be able to make multiple measurement on the same quantum-spin-state, but he cannot copy the state because of the no-cloning theorem (Zurek-Wootters, Nature, 1983 if I remember well, but anyway, see it on Wikipedia). Of course, if he would be able to copy the state, we would get a contradiction with special relativity.
    As satanorsanta pointed out there are still problems with the _interpretation_ of quantum mechanics (especially with the measurement postulate), but I wouldn’t consider this specific question unsolved.
    I know my English is not the best … I hope you will understand my reasoning. If you’s like to chat about these thing, send me a mail.

  6. How can Alice use this experiment to communicate any information to Bob?
    When Bob performs his measurement on the spin of his particle he’s either going to get up or down, there’s no way of knowing whether Alice has already collasped the wave function or whether the result of his measurement was a result of a 50/50 coin flip.


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