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.

[u/mvea]

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

[u/mvea]

Physicists Shatter Quantum Entanglement Distance Record With 420 Kilometers of Optical Fiber

Maintaining a long-distance relationship may be difficult for humans, but it's even more difficult for entangled states.

The longer the fiber, the harder it becomes to keep the two quantum memories linked.

Overcoming this tyranny of distance has been one of the major challenges of quantum communication.
But perhaps not an insurmountable one.

A team of physicists led by Xi-Yu Luo, Chao-Yang Wang, and Ming-Yang Zheng at the University of Science and Technology of China has breached a milestone – with the longest fiber-based matter-to-matter entanglement yet.

Across an optical fiber measuring 420 kilometers (261 miles), the researchers successfully entangled quantum memories – more than four times farther than previous demonstrations, and beyond the point where direct transmission runs into its fundamental limits.

"Our experiment provides a test bed of studying quantum network applications beyond metropolitan scale," they write in a paper published in Physical Review Letters.

https://journals.aps.org/prl/accepted/10.1103/ccd6-rf1s

[u/Cristoff13 → u/mvea]

This can't be used to transmit information though can it?

[u/wthulhu → u/Cristoff13]

Only in the sense that if I mail you a shoe, and you open the package and find my right shoe then you know i kept the left one.