In theory, this means that the next generation of fiber networks -- assuming this femtosecond photodetector can be implemented commercially -- could be secured with quantum cryptography.

Update: On 18 April, Yilei Chen announced an issue with his algorithm which he does not know how to fix. This means the algorithm does not undermine the mathematics behind post-quantum cryptography.

Toshiba Research and Cambridge University in England are reporting that they have succeeded in building the first conventional fiber-optic network that's secured with quantum cryptography.