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Adeldor t1_j5oy5tv wrote

Reply to comment by DonaldFauntelroyDuck in Do you think we will ever be able to communicate faster than the speed of light using entangled particles? by DefenderOfTheButter

I had a look at your link, but didn't see anything indicating useful FTL communication.[*] Further, by all understanding, any such communication between points in our universe - even if attempting to bypass actual traversal through this space - results in time travel, raising the specter of causality violation. Regarding the paper's reference to "many worlds," that might be the only way around said violation. But again it would not be useful, as no information within the same timeline would be transferred.

[*]: If I missed it, could you highlight or quote the text?

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DonaldFauntelroyDuck t1_j5pcg2g wrote

My understanding of

In the second part of the paper, Schrödinger showed that an experimenter, by a suitable choice of operations carried out on one member of an entangled pair, possibly using additional ‘ancilla’ or helper particles, can ‘steer’ the second system into a chosen mixture of quantum states, with a probability distribution that depends on the entangled state.

Is that actually you can change one system by changing the other.

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Adeldor t1_j5pfez1 wrote

My understanding here is that the ancilla are themselves limited by the speed of light, thus limiting communication speed to the same, and this experiment's goal was to (dis)prove the apparent instant simultaneous collapse. But I'm very open to correction here.

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DonaldFauntelroyDuck t1_j5ph0zq wrote

I do understand this a bit different and would expect that this would be actually possible. According to the relativity theory the point is that the "spooky entaglement" happens at identical times everywhere.

Maybe this paper is better:

https://jqi.umd.edu/news/first-teleportation-between-distant-atoms

or this

https://www.engadget.com/fermilab-quantum-teleportation-report-221002594.html?guccounter=1&guce_referrer=aHR0cHM6Ly9kdWNrZHVja2dvLmNvbS8&guce_referrer_sig=AQAAAHDBA8t0ynTc7F_k2JnVOXRUIpUzqyyj6BpK9DaTzOdvmk8vuKSctX_ht_-IcN0TKwrrHOjDoS1-qEqAX-KVang2lQi9Sj0c0p3VyhlgiwMLK434JEf0guL7cBMpnQhja0vtR8N0LNGXNXnsvFjOJcNPnY2mAltkGs5yJGxlGIqn

"teleportation" is in my understanding "timeless" as it happens between entagled entities.

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Adeldor t1_j5pkthe wrote

While the teleportation is instantaneous, I don't think there's any way to bypass the need for ancilla to be transported "classically," which are required for the Bell measurements at the receiver.

And there's still the causality problem (manifest here as "information causality" - PDF). Of course, one should never say never, but it seems there's always a fundamental roadblock when it comes to FTL, regardless of the path taken.

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DonaldFauntelroyDuck t1_j5q1p39 wrote

I prefer hope and dreams that if you get a little foot in the door of physics you may bust it open some day. No argument from me that there is a long way to go and propably regulariy in the wrong direction. I am however also sure that we have enough glimpses seen that einstein is not the last of it.

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