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Researchers from Saarland University (UdS) have achieved an important breakthrough in Quantum Communication by demonstrating Quantum Entanglement and Teleportation over a 14 km long fiber link, the “Saarbrücken Quantum Communication Fiber Testbed”.

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[-] Deconceptualist@leminal.space 2 points 3 days ago* (last edited 3 days ago)

They observe/measure the local particle first (LA) which causes the entangled system to collapse into definite states. Then they measure the remote particle (RA) afterward to confirm that it matches the expectation.

They know the "when" that the wavefunction collapse occurs for RA -- it's the moment they chose to observe LA. The "magic" of entanglement is that it's not bound by the speed of light and effectively instantaneous.

[-] HubertManne@piefed.social 3 points 3 days ago

I think what he is trying to say is its not useful for communication if you need to know that the other placed tried to communicate before measuring. So the measurement could be one that sets the state or one just reading a state set afar.

[-] Deconceptualist@leminal.space 1 points 3 days ago

its not useful for communication if you need to know that the other placed tried to communicate before measuring.

But I don't think you do. The classic slower-than-light communication here is just to verify the results. Once this system is operational, then by measuring the remote particles, you know exactly what information was sent.

This of course assumes very good transmission fidelity (or error correction), and that the local sending side has some way to control the state their particle wavefunctions collapse into (otherwise they're just sending random noise).

[-] Ferk@lemmy.ml 1 points 3 days ago* (last edited 3 days ago)

the local sending side has some way to control the state their particle wavefunctions collapse into (otherwise they’re just sending random noise).

Do they? My impression is that, like the article says, "their states are random but always correlated". I think they are in fact measuring random values on each side, it's just that they correlate following Schroedinger's equation.

I believe the intention is not "sending" specific data faster than light.. but rather to "create Quantum Keys for secure information transmission". The information between the quantum particles is correlated in both sides, so they can try to use this random data to generate keys on each side in a way that they can be used to create a secure encryption for communication (a "Quantum Network that will be used for secure communication and data exchange between Quantum Computers"), but the encrypted data wouldn't travel faster than light.

[-] Deconceptualist@leminal.space 1 points 3 days ago

Ah yeah I bet you're right. I'm probably conflating the more serious articles I've read with aspirational (near-future sci-fi) material. Yes, quantum encryption should be much more practical and achievable.

this post was submitted on 30 Nov 2025
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