I'm not sure if GP is talking about this https://en.wikipedia.org/wiki/Quantum_key_distribution#Trojan-horse_attacks https://en.wikipedia.org/wiki/Quantum_key_d

I'm not sure if GP is talking about this https://en.wikipedia.org/wiki/Quantum_key_distribution#Trojan-horse_attacks https://en.wikipedia.org/wiki/Quantum_key_distribution#Troja... or not, but that's definitely an issue.