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So wait, if you can refresh the probabilities of a quantum property by making a second type of measurement (as described by the video in the article), why would

So wait, if you can refresh the probabilities of a quantum property by making a second type of measurement (as described by the video in the article), why wouldn't this work? Here's how you might send information between two entangled particles via some property: To send a 0 via property A: 1. Clear your measurement of property in A by measuring property B 2. Measure property A again 3. If A is not in state 0, goto 1 4. The other entangled particle should now read state 0 too To send a 1 via property A: 1. Clear your measurement of property in A by measuring property B 2. Measure property A again 3. If A is not in state 1, goto 1 4. The other entangled particle should now read state 1 too Maybe it would take a few more tries than expected occasionally, but if you give enough time to loop say, 10 times between measurements of the second particle, that's only a (1/1024)/2 = 1/2048 chance that the information is wrong! That's probably reliable enough for reasonably good error detection [1]. As long as the amount of time needed to get the first particle into a given state is less than the amount of time needed to send a photon to the second particle, it would seem that you could send information faster than c. 1. https://www.youtube.com/watch?v=-15nx57tbfc https://www.youtube.com/watch?v=-15nx57tbfc

db48x 11y ago
You've forgotten what a measurement is. A measurement is any interaction between particles. In the case of entangled photons, a measurement consists of allowing the photon to be absorbed by an atom. You only get one such measurement; any new photon emitted by that atom will have a spin which is no longer entangled with the spin of it's original twin. (Actually, they were more like anti-twins; one was up when the other was down, and visa-versa.) Even assuming you had two larger particles (let's say atoms) which were entangled, allowing you to make multiple measurements, nothing you change about one of them is communicated back to the other. If you measure a property of your atom you may also be able to determine the value of that property for the other, but in doing so you change the atom. You flip the spins of the electrons, or of the atom as a whole, etc. This is what "clearing your measurement" means; you no longer have any good information about that property. If you then remeasure that property, it's value is no longer correlated with the twin particle.

db48x 11y ago

You've forgotten what a measurement is. A measurement is any interaction between particles. In the case of entangled photons, a measurement consists of allowing the photon to be absorbed by an atom. You only get one such measurement; any new photon emitted by that atom will have a spin which is no longer entangled with the spin of it's original twin. (Actually, they were more like anti-twins; one was up when the other was down, and visa-versa.) Even assuming you had two larger particles (let's say atoms) which were entangled, allowing you to make multiple measurements, nothing you change about one of them is communicated back to the other. If you measure a property of your atom you may also be able to determine the value of that property for the other, but in doing so you change the atom. You flip the spins of the electrons, or of the atom as a whole, etc. This is what "clearing your measurement" means; you no longer have any good information about that property. If you then remeasure that property, it's value is no longer correlated with the twin particle.