There is herein provided a method of performing Quantum Key Distribution, the method including transmitting, in a first basis state, a first photon from a quantum transmitter to a quantum receiver; transmitting, in a second basis state, a second photon from the quantum transmitter to the quantum receiver, the second basis state being non-orthogonal to the first basis state and the transmitter and receiver being optically connected by both a first optical channel and a second optical channel, wherein transmitting the first photon from the quantum transmitter to the quantum receiver in the first basis state comprises: transmitting the first photon from the quantum transmitter to the quantum receiver along either the first optical channel or the second optical channel, wherein transmitting the second photon from the quantum transmitter to the quantum receiver in the second basis state comprises: transmitting a first portion of the probability distribution of the second photon from the transmitter to the receiver along the first optical channel; and transmitting a second portion of the probability distribution of the second photon from the transmitter to the receiver along the second optical channel.