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In fiction, (notably Ernest Cline's novel Armada and Charles Stross's books Singularity Sky and Iron Sunrise) Quantum Entanglement is used for long distance communication.

In reality, given our current understanding, how feasible is this?

Is Quantum Entanglement potentially predictable enough and stable enough to act as a method of communication? I understand that our current level of technology might not be sofisticated enough to create such a device today (please correct me if I am wrong).

I am wondering if our current understanding of Quantum Entaglement today suggests that such a device may be possible in the future?

Or does our current understanding indicate that such a device would only be possible in the realms of fiction?

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    $\begingroup$ If simple communication is the aim, then since quantum entanglement cannot be used to send information faster than light, why not just use light? Light-speed communication is already widespread, and has been for many decades. $\endgroup$ – Allure Jan 8 '18 at 20:57
  • $\begingroup$ @Allure my bad then, I was under the impression that two entangled particles would both operate instantaneously to each other - does the information from one entangled particle propagate to the other at the speed of light? $\endgroup$ – Jimmery Jan 8 '18 at 21:01
  • $\begingroup$ Not exactly - the two entangled particles "communicate" instantaneously with one another, but this cannot be used to transmit information. It's not something that's easily understood without knowledge of QM unfortunately. Previous questions on this: physics.stackexchange.com/questions/9187/…, physics.stackexchange.com/questions/2206/… $\endgroup$ – Allure Jan 8 '18 at 21:08
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    $\begingroup$ The advantage of entanglement for communication is not the mythical FTL thing: it's tamper-proofness. Using entanglement makes interception very detectable. $\endgroup$ – tfb Jan 8 '18 at 21:12
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I just want to clarify the comments and say: Quantum entanglement is not a mean of communication, entangled particles do not send information to one an other. They're just set in a way (which we totally cannot comprehend), that knowing the state of one particle will always determine the state of the other. You cannot use such a system to send information.

For example, If you want to send information you would want to make a change in the state of one particle and then you would want the other one's state to change too. But changing a state of one particle means you will measure first, measurement breaks the entanglement.

However there are applications of this phenomenon, if you want to read further, most relevant is quantum teleportation.

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  • $\begingroup$ Phrases like "knowing the state of one particle will always determine the state of the other" are a) wrong and b) much more likely to completely confuse people than to give them some sort of half-understanding. Neither particle has a state (only the pair has a state), and if you tell people otherwise, you shouldn't be surprised if you find that they "totally cannot comprehend" the subject. $\endgroup$ – WillO Jan 8 '18 at 23:41

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