11 ms·

No, it is not possible to communicate any information by measuring one side of the quantum state. This is the no communication theorem: https://en.m.wikipedia.o

by isaacg 4y ago

No, it is not possible to communicate any information by measuring one side of the quantum state. This is the no communication theorem: https://en.m.wikipedia.org/wiki/No-communication_theorem https://en.m.wikipedia.org/wiki/No-communication_theorem It's only possible to achieve correlations that are stronger than are classically possible without communication. Communication itself still cannot be achieved, by any sequence of measurements.

TrapLord_Rhodo 4y ago
Taken from your wiki link with a twist; "spooky correlation at a distance" does seem to be some amount of information. The paul revere joke was entirely out of scope, but the universe does seem to have some way to pull the strings behind the curtain here.
- kgwgk 4y ago
  > does seem to be some amount of information How so? How would you define information and its communication?
- zaphar 4y ago
  I don't have the background to really understand this but it sounds like: in order for information (we correlated our spins) to be passed you would first have to know what the other side is doing which requires side band communication which itself would be subject to the speed of light. But I might be missing something in my understanding.
- isaacg 4y ago
  There is something to that - there's a concept called "Quantum Nonlocality", which says that an accurate description of an entangled quantum system must be nonlocal - to predict what will happen, we need to look at the whole system at once. But nonlocality is different from the capacity for communication. To make accurate predictions about the measurements, one would need information from the earth and from mars. However, the results of the measurements cannot be used to transmit information. These two concepts - what is necessary for prediction and what the results can accomplish - often line up in the classical world, but in the quantum world they are quite distinct. So your intuition has merit, but it reveals quantum nonlocality, not quantum superluminal communication.

by isaacg 4y ago

TrapLord_Rhodo 4y ago

Taken from your wiki link with a twist; "spooky correlation at a distance" does seem to be some amount of information. The paul revere joke was entirely out of scope, but the universe does seem to have some way to pull the strings behind the curtain here.

kgwgk 4y ago
> does seem to be some amount of information How so? How would you define information and its communication?
zaphar 4y ago
I don't have the background to really understand this but it sounds like: in order for information (we correlated our spins) to be passed you would first have to know what the other side is doing which requires side band communication which itself would be subject to the speed of light. But I might be missing something in my understanding.
isaacg 4y ago
There is something to that - there's a concept called "Quantum Nonlocality", which says that an accurate description of an entangled quantum system must be nonlocal - to predict what will happen, we need to look at the whole system at once. But nonlocality is different from the capacity for communication. To make accurate predictions about the measurements, one would need information from the earth and from mars. However, the results of the measurements cannot be used to transmit information. These two concepts - what is necessary for prediction and what the results can accomplish - often line up in the classical world, but in the quantum world they are quite distinct. So your intuition has merit, but it reveals quantum nonlocality, not quantum superluminal communication.