5 ms·
Quantum entanglement means that pairs of particles can have correlated states regardless of the distance between them. It does not mean that if you push on one
by p-e-w 3y ago
Quantum entanglement means that pairs of particles can have correlated states regardless of the distance between them.
It does not mean that if you push on one particle, the other one lights up.
Imagine that two people are each given a coin with the property that whenever they flip those two coins simultaneously, they will either both come up heads, or both come up tails. How can you use that to communicate, that is, send information from one to the other? You can't. You can pre-arrange actions that you both will take when you see either heads or tails, but that's not communication.
- TechBro8615 3y agoBut if each side of the pair can only have a certain number of states, is it not possible to perturb one of them until it gets into a state such that you know based on entanglement that the other must be in its corollary state?
- johncolanduoni 3y agoGiven only an entangled qubit, the only thing you can do that will be “synchronized” with the other party is perform a measurement. Each measurement performed by either party will produce either a 0 or 1 without any “input” from the measurer or the other party. Any perturbation of the state that preserves the entanglement can only rotate it (which just alters what state your side considers 0 and 1).
- TechBro8615 3y agoThanks. While you were writing your comment I found this article [0] that does a decent job of explaining why my hypothetical system isn't possible. It first lays out the exact system I had in mind and then unfortunately debunks it :( I don't fully understand the subtleties, but the root problem seems to be that by measuring the state, you're perturbing the system and putting it into a new state, such that your measurement becomes irrelevant, as if you're always one step behind the message and can never catch up. > The only way that this problem could be circumvented is if there existed some way of making a quantum measurement that actually forced a particular outcome. (Note: this is not something permitted within the presently-known laws of physics.) [0] https://bigthink.com/starts-with-a-bang/quantum-entanglement-faster-than-light/ https://bigthink.com/starts-with-a-bang/quantum-entanglement...
- epicureanideal 3y agoYou could flip the coin at different time intervals like short and long dashes in Morse code.
- johncolanduoni 3y agoThe analogy is imperfect: with quantum states you cannot tell whether the other person performed a measurement or not.
- bombolo 3y agoYou're still flipping a coin… how is this communication?
- edf13 3y agoDon't you simply read the state of the other entangled coin? Heads = 1, Tails = 0?
- bradrn 3y agoYou have no control over the resulting state, though. In this analogy, if you have two entangled coins, all you know is that if you flip the coins at the same time you get the same result… you don’t have any control over what that result is, and unless you arranged it with them beforehand you don’t know when the other person flipped their coin.
- deleted 3y ago[deleted]