Abstract: A method of aligning a quantum laser beam with a receiver, the method including: generating a quantum laser beam and a first classical, non-quantum, laser beam at a transmitter, the quantum laser beam and the first classical laser beam being substantially aligned in direction; transmitting the quantum laser beam and the first classical laser beam; and directing the quantum laser beam and first classical laser beam to a receiver; measuring the photon reception rate through the quantum laser beam at the receiver, and reporting the photon reception rate to the transmitter; at the transmitter, making a series of adjustments to the direction of the transmitted quantum laser beam and the first classical laser beam, and monitoring the reported photon reception rate; wherein, each of the series of adjustments is based, at least in part, on the effect of the preceding adjustment on the reported photon detection rate.

Abstract: A heading control system for an aircraft arranged to maintain a heading of an aircraft by controlling a nose wheel angle of the aircraft. The heading control system includes an interface arranged to receive a bias signal indicating a bias towards the port or the starboard of the aircraft and one or more processors. The one or more processors are arranged to determine, based on the bias signal, an offset angle defining an offset from a longitudinal axis of the aircraft and to perform a control process to control the nose wheel angle within an angular range based on the offset angle.