The exchange of a secret key for encrypting and decrypting messages over a distance of 1,120 kilometers is reported in Nature this week. This achievement is made using entanglement-based quantum key distribution, a theoretically secure communication technique. Previous attempts to directly distribute quantum keys between two ground users under real-world conditions have reached distances of only around 100 kilometers.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/7-quantumcompu.jpg)
Source:
https://phys.org/news/2020-06-quantum-cryptography-keys-kilometers-previous.html