Patent ID: 8054976

Claim:
A device for quantum key distribution, herein QKD, using a quantum signal of polarized photons, the device being intended for use with a complimentary apparatus, the device comprising: a QKD subsystem comprising a QKD transmitter for inter-working with a complimentary QKD receiver of said apparatus; and an alignment subsystem arranged to wirelessly interact with said apparatus to enable generation of adjustment signals for use in aligning the QKD transmitter and QKD receiver such that the QKD transmitter is pointing at the QKD receiver and the polarization axes of the QKD transmitter and QKD receiver are aligned, wherein the alignment subsystem comprises, an alignment beam transmitter for sending an alignment beam having an elongate cross-shape to said apparatus to enable the apparatus to generate first said adjustment signals for aligning the QKD transmitter and QKD receiver such that the QKD transmitter is pointing at the QKD receiver, wherein a section of the alignment beam is blocked out and wherein the QKD transmitter is to transmit the quantum signal in the blocked out section of the alignment beam.