3 ms·
It doesn't work like that: you can only measure the state, not set it. Measuring the state does change something (it collapses the wave function, in the Copenha
by roywiggins 5y ago
It doesn't work like that: you can only measure the state, not set it. Measuring the state does change something (it collapses the wave function, in the Copenhagen interpetation) but not in a way that's measurable by the person at the other end. You can't tell if the wave function collapsed just by measuring one of the entangled particles.
There's a theorem in QM the guarantees that you can't use measurements on entangled systems to communicate:
https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem
- ackbar03 5y agoSince you clearly know more than me what your talking about, is it correct to interpret the significance of china's quantum satellite communication as one of quantum cryptography (based on states changing post measurement) rather than potential high speed communication?
- roywiggins 5y agoThere's quantum superdense coding, which in theory could allow higher bandwidth (transmitting one qbit can be used to transmit two classical bits) but I believe the main point of quantum channels is for cryptography. If entanglement allowed FTL communication you'd see high-frequency traders already using it!