In an important step toward practical implementation of secure quantum-based communication, researchers have demonstrated secure measurement-device-independent quantum key distribution (MDI-QKD) transmission over a record-breaking 170 kilometers.
![](https://scx1.b-cdn.net/csz/news/tmb/2019/quantum.jpg)
Source:
https://phys.org/news/2020-08-approach-quantum-key.html