4 ms·
One way would be to fire an entangled photon down both ends of fibre optic cable in the middle. On the sending end you could observe/ ignore it, and on reviving
by pippy 12y ago
One way would be to fire an entangled photon down both ends of fibre optic cable in the middle. On the sending end you could observe/ ignore it, and on reviving end you'd observe it.
We'd have to develop cables capable of preserving the entangled state of light particles, and a beam splitter that's more reliable. You could improve the bandwidth considerably by measuring the polarisation of the particle, even more if you could somehow encapsulate the entangled photon for a given period of time.
- tim333 12y agoStill wouldn't be much use for communicating. The observer would just see random photons.
- sgt101 12y agoPretty harsh to downvote this person for writing out an idea - ok, if you know the physics you might dismiss this, but dismiss with words not votes!
- Retra 12y agoThis is a very common idea. It is so common, in fact, that the only real way to not know why it is wrong is if you've never heard of entanglement or relativity before. I personally find it a bit insulting to propose something like this, as it assumes all those physicists working on quantum physics and relativity over the last hundred years were too dumb to think of this. Yet they all go around saying FTL communication is impossible? To suggest such a thing, you'd have to think they were all very stupid or you'd have to not be thinking at all.
- simias 12y agoTFA addresses this point directly so one can assume the parent didn't read the article before posting.
- gwern 12y ago> In 1935 Einstein, Podolsky, and Rosen published a thought experiment that seemed to produce a paradox in quantum mechanics, as well as demonstrating that it was incomplete. Their argument used the fact that there can be an apparent instantaneous interaction in the measurement of two separated particles that have been prepared in a certain "entangled" manner. Einstein called it "spooky action at a distance". It has been shown by Eberhard that no information can be passed using this effect; so there is no FTL communication, but the paradox is still very controversial. See the FAQ article The EPR Paradox and Bell's Inequality for more details.
- xg15 12y agoYou couldn't use this for communication as there is no way to "set" the spin of an entangled photon. You'd effectively have two receivers for the same random signal but no way to actually influence the signal. I think there was a HN link a while ago about ideas to use this as a perfectly secure key exchange mechanism for crypto. I don't know how serious this idea is, though.
- placeybordeaux 12y agoI believe OP was thinking that there was a way to tell if the photon had already collapsed it's state once before you collapse it by observing it. If that was the case you could convey information by collapsing the state or not. However as far as I know there is no information about if the photo is in a superposition just prior to observing or not.
- placeybordeaux 12y agoIf this worked you could cut down the travel time by doing this multiple times with the same distance between each node. However because when you observe the photon it collapses randomly and there is no way to tell if the photon has collapsed before you observed it or for the first time as you are observing it you don't actually have any information on if the other side observed it or not.
- placeybordeaux 12y agoIf this worked you could cut down the travel time by doing this multiple times with the same distance between each node. However because when you observe the photon it collapses randomly and there is no way to tell if the photon has collapsed before you observed it or for the first time as you are observing it you don't actually have any information on if the other side observed it or not.