Quantum teleportation has begun to change the world - The Brighter Side of News

The article's title is misleading. It's really about quantum transmission of information, not teleportation. Regardless, this may further revolutionize everything since it means the instantaneous transmission of information.

What I don't understand and haven't seen discussed by the theoretical physicists is how this gets away with an apparent violation of Einstein's theory of special relativity. If the articles' description of quantum entanglement are correct, that would mean that information can be transmitted faster than the speed of light. I have been told that Special Relativity is not limited to objects with mass but should include information as well, but who knows? I certainly don't.

Here's my best crack at this one. Entanglement allows for information to pass between two entangled particles faster than light, but it doesn't allow that information to be useful. To my knowledge, two particles need to be very, very close together to be entangled. Once they are entangled, you then need to transport one of the particles away from the other one, and that happens much, much slower than the speed of light. Once the particles have been separated, then you can break their superposition and both will revert at the same time.

To use this for communication, you'd have to basically send a letter with the entangled, superimposed particle explaining the entire situation, and then you could monitor the particle to get information. It makes a great encryption tool, because you need one of the particles to get information to decode a message. However, it doesn't allow faster than light paradoxes due to the need to physically split up the entangled particles.

An epiphany moment for me regarding quantum entanglement, is that all particles are already entangled. Entangling particles is easy. Every particle you've ever met is entangled with countless other particles, and that entanglement gives rise to all the physical properties we see in different materials. Lack of entanglement is the reason that the quantum world is so weird. So the trick is not entangling 2 particles, but entangling only 2 particles and keeping them from entangling with everything lese

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To use this for communication, you'd have to basically send a letter with the entangled, superimposed particle explaining the entire situation, and then you could monitor the particle to get information. It makes a great encryption tool, because you need one of the particles to get information to decode a message. However, it doesn't allow faster than light paradoxes due to the need to physically split up the entangled particles.

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Understood. However, once they're physically split up, wouldn't you have instantaneous transmission of information?

I don't know, but this article says no

https://bigthink.com/starts-with-a-bang/quantum-entanglement-faster-than-light/

The big problem is trying to assign meaning to your entangled particle. Once you measure your own particle, then you instantly know the state of its entangled partner, but that's all. You can't influence the entangled particles to do anything. Your particle is going to show -1 or +1 when you measure it, and that means that you know the entangled particle is the same. Vice versa for the team with the other particle. But they can't write a coded binary message based on this, because they don't know what their particle is going to show. It's information, but it's not useful information.

The encryption side works, because you can have 100 different entangled particle pairs. You can measure your particles and use that to make a cipher. Then the other team could measure their entangled particles and use that to decode the cipher.

dreaded double post

dreaded triple post

ramblin_ag02 said:

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I don't know, but this article says no

https://bigthink.com/starts-with-a-bang/quantum-entanglement-faster-than-light/

The big problem is trying to assign meaning to your entangled particle. Once you measure your own particle, then you instantly know the state of its entangled partner, but that's all. You can't influence the entangled particles to do anything. Your particle is going to show -1 or +1 when you measure it, and that means that you know the entangled particle is the same. Vice versa for the team with the other particle. But they can't write a coded binary message based on this, because they don't know what their particle is going to show. It's information, but it's not useful information.

The encryption side works, because you can have 100 different entangled particle pairs. You can measure your particles and use that to make a cipher. Then the other team could measure their entangled particles and use that to decode the cipher.

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I've read a bunch of articles just like that one but none of them really explain. They just state conclusions without adequate explanations. My guess is that it's because the articles are written by journalists who don't really understand either but are just repeating what the physicists are telling them.

For example, from your quote above:

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But they can't write a coded binary message based on this, because they don't know what their particle is going to show.

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That statement has zero explanatory value and makes no sense. No one would seem to care "what their particle is going to show". If the particle flips from -1 to +1, doesn't that convey information?

Let me try to be more clear. You start with 2 particles in a superposition. That means their value is unknown (signified by the symbol ?). When they lose superposition, they will either be +1 or -1. There is no way to know which it will be and there is no way to "guide" that loss of superposition into the positive or negative.

Now take 2 of these particles and entangle them. Now when one loses superposition, the other will lose superposition simultaneously, and their next state will be linked. For example, both could be +1 or -1, but not mismatched.

You can separate the two particles and check their configuration, but you can't send information. One team checks their particle and it will either show +1 or -1, but they have no way to know which one. The entangled particle will match that. But you can't send a yes/no response because you have no control over whether your particle will be one or the other.

It's great for encryption though. Send 1000 pairs of entangled particles. Make a binary key out of the +1s and -1s, and then send the encrypted message. The receiver can make the key on their own using the entangled particles they have and decode the message. But you never have to send them the key