Ekert protocol

In 1991 Artur Ekert proposed that quantum key distribution could be implemented using the quantum entangled states explored in the Einstein-Podolsky-Rosen (EPR) thought experiment. In his protocol, instead of Alice sending particles to Bob, there is a source that creates entangled particles and sends one to Alice and one to Bob.

The Ekert protocol reflects more accurately real-life scenarios as it considers distance limitations where quantum cryptography would involve a central source, like a satellite, sending the signals to multiple receivers.