3 ms·

So if you have a pair of entangled particles A1 & A2, can the observer close to A2 quickly determine if A1 has been measured? I understand that you can't trans

So if you have a pair of entangled particles A1 & A2, can the observer close to A2 quickly determine if A1 has been measured? I understand that you can't transmit information using a single pair of particles, but what if you had a pair A1 & A2 and a second pair B1 & B2. If one side can immediately tell that A1 was measured before B1 or vice versa, it seems like that transmits a bit.

ars 18y ago
No you can't tell if it's been measured. Assume you are measuring angle on the photons: the angle of both sets always adds up to 0. So if you measure 10, he'll measure -10. So by measuring yours you know what he got, but that's it. You can't unmeasure it, and you can't tell what he did.