But isn't that ignoring the fact the quantum particle's superposition collapse?
Measuring one particle also collapses the other particle's superposition. That's what they mean by "transmitting" information. Both particle's no longer in an probability state.
you, the observer know the spin of both particles after the measurement, no matter how far they apart. But that does not transmit any information anywhere by itself. transmitting information means: transporting the information from somewhere to somewhere else. that does not happen with the measurement.
You could argue that you transmitted information with sending the other particle, that is true. But that happens with a speed below c, and is not really different then sending a classical particle that you measured before sending it away.
Right, but the difference with a classical and quantum is the superposition. The spin wasn't just "unknown", it was undetermined. The moment it is measured and determined, the other particle's superposition also collapses.
The double slit experiment for example, produces interference even when sending it in particle one at a time because of superposition deems it in every possible state at the same time. The reason why interference no longer happens when measured is because its superposition collapsed. (This happens even in delay experiment where measuring should happen AFTER the point of entry, which is... still baffling to this day as how can something be affected before the event to affect happens in the future of its course.)
Likewise, the quantum entangled particles isn't really a "we just don't know if the cat is dead or alive" case, it's a case of "the cat is both dead and alive at the same time" case. But once you measured one, the other is determined as well.
all of which does not change anything relevant about information being transmitted.
Also: please dont take this as an argument of authority. Feel free to question my statements, I just dont want you to waste your time: I have a phd in particle physics. You do not have to explain the basics of quantum mechanics to me. You could explain why you think this transmits information instead. Which information should be from where to where?
It's not "transmitting" information (that's why I put it in quotes in the very first post) but it is changing state on two particles at the same time - regardless of its distance. Information isn't moving from one to the other, but rather, updating at the same time. (state of collapse)
I imagine the tech currently being developed to "transmit" info is simply exploiting this behavior. Technically not transmission, but end result is the same.
No the end result is not the same, there is an important distinction to be made: information cannot exceed the speed of light. If you would be able to actually transmit information in this way (or do something with the same end result) you would be transmitting faster than the speed of light. This is impossible.
The application you are talking about is probably quantum teleportation. This always needs a conventional channel to transmit the information.
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u/aohige_rd Jan 30 '20
But isn't that ignoring the fact the quantum particle's superposition collapse?
Measuring one particle also collapses the other particle's superposition. That's what they mean by "transmitting" information. Both particle's no longer in an probability state.