To add to that: a QKD with one-time pad[1] is proven secure. However, because many QKD implementations have low secret key rates (the highest in research is 10Mbps[2]; most commercial implementations do only a few Kbps) you won’t be doing high-bandwidth communication using that method.

[1] https://en.m.wikipedia.org/wiki/One-time_pad [2] https://www.toshiba.co.jp/about/press/2017_09/pr1501.htm