Yeah I was glossing over a lot of the more hypothetical stuff and went off a tangent probably, but the two points I was making are
Data transfer in quantum communications does not require only setting a state and then they maintain that state and that’s it. Quantum teleportation allows for “modifying” the state later by entangling one side to another particle whose state you want to communicate.
The fact that the system of modern quantum communications relies on classical communication to know how to then measure the newly entangled state is not the only reason that quantum entanglement/teleportation doesn’t violate the speed of light. This side is still not as solid in understanding, but the information of the entanglement of the third particle is available seemingly instantaneously. It just requires 2 bits of information to know what measurement to take to get the new state. And you can’t measure all 4 possible ways because the first time you measure, the state is “modified” and you dont get a second chance since measurement on either side “modifies” the state seemingly randomly. But what you can do to prove that the state changed relatively instantaneously, is to set up a system where you entangle lots of particles. Then at exactly the same time entangle them to a third particle and randomly choose a method of measurement on the output side. Then throw out the results of output side that don’t match the 2 bits you send over classical means when they arrive. Those are the ones that should match. This doesn’t solve the issue of instantaneous communication, but does prove that if you had instant knowledge of which measurement to take, the information was available instantaneously. And this is glossing over some details in interpretation of the results, but the data itself is there if you knew how to interpret it.
Currently, it’s potentially useful in it’s current form because the quibit contains and “transmits” more information than the 2 bits sent over classical means if we can make the entanglement more reliable.
I was also out of date about the successful distance of quantum entanglement/teleportation. It has been done with satellites up to about 1,000km. Particles entangled, one half launched into orbit. Earthbound particle is entangled to a third particle which “changes/destroys” the previous state. 2 bits per particle are sent to the satellite via the internet or other classical means to know which of 4 measurement to take. The information from the third particle state is then read on the satellite. This has about a 90% accuracy rate currently, mostly due to the entanglement being broken or the state being changed by outside forces before the classical data are received.
Anyway, these are all glossing over some details and there is still a major piece we’re missing to make actual instantaneous communication, but it’s the best I can do in simple terms. And it’s definitely possible that there is no way for the output side to be read correctly without those 2 bits of classically transmitted information, at least for in our relative realm of existance. This is all also admittedly a decade or so out of date information since I haven’t kept up with it lately.
Yeah I was glossing over a lot of the more hypothetical stuff and went off a tangent probably, but the two points I was making are
Data transfer in quantum communications does not require only setting a state and then they maintain that state and that’s it. Quantum teleportation allows for “modifying” the state later by entangling one side to another particle whose state you want to communicate.
The fact that the system of modern quantum communications relies on classical communication to know how to then measure the newly entangled state is not the only reason that quantum entanglement/teleportation doesn’t violate the speed of light. This side is still not as solid in understanding, but the information of the entanglement of the third particle is available seemingly instantaneously. It just requires 2 bits of information to know what measurement to take to get the new state. And you can’t measure all 4 possible ways because the first time you measure, the state is “modified” and you dont get a second chance since measurement on either side “modifies” the state seemingly randomly. But what you can do to prove that the state changed relatively instantaneously, is to set up a system where you entangle lots of particles. Then at exactly the same time entangle them to a third particle and randomly choose a method of measurement on the output side. Then throw out the results of output side that don’t match the 2 bits you send over classical means when they arrive. Those are the ones that should match. This doesn’t solve the issue of instantaneous communication, but does prove that if you had instant knowledge of which measurement to take, the information was available instantaneously. And this is glossing over some details in interpretation of the results, but the data itself is there if you knew how to interpret it.
Currently, it’s potentially useful in it’s current form because the quibit contains and “transmits” more information than the 2 bits sent over classical means if we can make the entanglement more reliable.
I was also out of date about the successful distance of quantum entanglement/teleportation. It has been done with satellites up to about 1,000km. Particles entangled, one half launched into orbit. Earthbound particle is entangled to a third particle which “changes/destroys” the previous state. 2 bits per particle are sent to the satellite via the internet or other classical means to know which of 4 measurement to take. The information from the third particle state is then read on the satellite. This has about a 90% accuracy rate currently, mostly due to the entanglement being broken or the state being changed by outside forces before the classical data are received.
Anyway, these are all glossing over some details and there is still a major piece we’re missing to make actual instantaneous communication, but it’s the best I can do in simple terms. And it’s definitely possible that there is no way for the output side to be read correctly without those 2 bits of classically transmitted information, at least for in our relative realm of existance. This is all also admittedly a decade or so out of date information since I haven’t kept up with it lately.