Quantum key distribution

Quantum key distribution (QKD) is a way of exchanging secret messages that are very secure. It works by using particles of light (called photons) to send messages between two people. The photons are sent in very special ways, so that if anyone else tries to read the message, they will know that it has been changed. This way, if someone tries to intercept the message, the people sending it will know, and they won't be able to read it.