Entanglement setup that shouldn't allow for the transmission of info

In summary, the setup involves producing polarisation-entangled photon pairs and sending them to Alice and Bob. Alice measures the polarisations of her photons, while Bob may entangle them in a correlating or anti-correlating manner. However, due to the random nature of the entanglement swap, it is impossible to transmit information in this setup.
  • #1
entropy1
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Suppose we produce a polarisation-entangled photon pair ##A_1## and ##A_2##. Then we entangle another pair ##B_1## and ##B_2##.

Now suppose that these photons will not interact with anything, sending ##A_1## and ##B_1## to Alice and ##A_2## and ##B_2## to Bob.

Alice measures the polarisations of the pair of photons she received. Bob however doesn't measure them, but either entangles them correlative or anti-correlative.

I don't know a lot of aspects of this setup, but I ask: what makes transmission of information impossible?
 
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  • #2
Search for "entanglement swapping" in these forums. We had a huge thread about it, discussing all aspects about "transmission of information".
 
  • #3
entropy1 said:
Alice measures the polarisations of the pair of photons she received. Bob however doesn't measure them, but either entangles them correlative or anti-correlative.

I don't know a lot of aspects of this setup, but I ask: what makes transmission of information impossible?

The key word in your setup is the bolded "or". This is not something Bob can control when Bob performs an entanglement swap. A successful swap places the 2 photons in a random unknown state. (A random state obviously doesn't allow for much information to be present.)
 

FAQ: Entanglement setup that shouldn't allow for the transmission of info

What is entanglement setup?

Entanglement setup is a phenomenon in quantum mechanics where two or more particles become connected in such a way that the state of one particle is dependent on the state of the other, even when they are separated by large distances.

How does entanglement setup work?

Entanglement setup occurs when two particles are created or interact in such a way that their quantum states become correlated. This correlation means that the two particles are "entangled" and their states are connected, even when they are physically separated.

Can information be transmitted through entanglement setup?

No, information cannot be transmitted through entanglement setup. While the states of the entangled particles are connected, the actual information cannot be accessed or controlled. This is due to the no-communication theorem in quantum mechanics, which states that it is impossible to transmit information faster than the speed of light.

What are the potential applications of entanglement setup?

Entanglement setup has potential applications in quantum computing, quantum cryptography, and quantum teleportation. It could also be used to improve the accuracy of measurements and communications in various fields, such as astronomy and telecommunications.

Are there any limitations to entanglement setup?

Yes, there are limitations to entanglement setup. The entangled particles must be kept isolated from their surroundings in order to maintain their entangled state. Additionally, the entangled particles can only remain connected for a limited amount of time before they become disentangled due to external influences.

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