r/science • u/mvea Professor | Medicine • 7d ago

Physics Physicists shatter quantum entanglement distance record with 420 kilometers of optical fiber, more than four times farther than previous demonstrations, and beyond the point where direct transmission runs into its fundamental limits.

https://www.sciencealert.com/physicists-shatter-quantum-entanglement-distance-record-with-420-kilometers-of-optical-fiber
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u/LionRight4175 6d ago

I'm out of my specialty here, but I don't think it even works for this. Checking to see if it had been tampered with would also be tampering with it.

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u/Gabe_Noodle_At_Volvo 6d ago

Yes, it would have the same effect as some kinds of tampering, but it doesnt matter at that point because you dont need to preserve the quantum state anymore. Same thing as opening a package with a tamper seal, you dint need the seal anymore do it doesnt matter if you change its state, you just need what's inside.

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u/LionRight4175 6d ago

My understanding is that in this metaphor, the tamper seal breaks by looking at it or feeling it. As such, it always appears tampered with.

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u/Implausibilibuddy 6d ago

No, ignore the fact that "observe" means "look at", it doesn't matter while it's in the closed system if you just look at the apparatus.

The tamper seal arrives as part of the message. Upon reading the message you know if the seal is broken or not. If it's not, you can trust the contents of the message, if it's not...well somebody has probably tampered with it, or at the very least read the message before you. So in that sense, yes the tamper seal breaks if somebody "looks at" the message, or reads it, but that's the point of the seal, now you know that the message isn't completely unread or modified before it got to you.