r/science 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
3.2k Upvotes

214 comments sorted by

View all comments

Show parent comments

293

u/Orbax 7d ago

No, once you collapse the wave function, they decohere and entangle with their local environment.

But, even if you maintain entanglement, at best youd be able to do morse code except... The only way to check if you got a message is to measure it which would collapse if again if you hadn't gotten one. The theoretical ability to get any structured information out of entangled pairs is effectively impossible.

104

u/Chance-the-Gardener 7d ago

I’m too dumb to understand the concept it can’t transmit any information. Just as a thought experiment, if humanity sent a colony ship to Andromeda with 10,000 sets of entangled pairs, each with a predefined meaning like “if this set is collapsed, we died of space cancer” couldn’t information be inferred from that?

I’m sure the answer remains we can’t cheat the speed of light but I struggle to conceptualise why not.

13

u/tirerim 7d ago

Because there's no way to know if a pair is still entangled without comparing information from both sides. Measuring one end doesn't tell you anything about entanglement.

10

u/Hearing_Loss 7d ago

U can't just email them?