Hewlett-Packard Development Company, L.p.

Hewlett Packard Enterprise Development LP

Joanna Duligall

Radu Ionicioiu

David A Fattal

Raymond G Beausoleil

Timothy Paul Spiller

Michael R Tan

Keith Alexander Harrison

William John Munro

A direction sensor () includes sensor cells () that respectively correspond to different directions. Each of the sensor cells () includes a light sensor () and a grating () that couples incident light into the light sensor () when the incident light has a specific wavelength and is incident on the grating () along the direction corresponding to the sensor cell ().

Beam direction sensor

A handheld device includes: a transmitter or receiver of a signal beam for quantum key distribution; and a source of alignment beams that diverge from each other in a pattern that matches sensors on a station containing a receiver or transmitter for the quantum key distribution. The alignment beams from the handheld device are of sufficient intensity to produce on the station visible spots that facilitate manual alignment of the handheld device. The station can measure a position and a direction of respective alignment beams and dynamically steer the signal beam according to the measurements.

Photonic quantum system alignment using multiple beams

In order to facilitate alignment of a QKD transmitter and QKD receiver, the transmitter is provided with a retro-reflector for returning to the receiver a photon beam originating at the latter. The transmitter is arranged to polarization modulate the retro-reflected beam. The transmitter is provided both with an intensity detector for generating an indication of retro-reflected photon intensity, and an intensity-dependent controller for controlling the QKD transmitter in dependence on the detected photon intensity. In one embodiment, this control involves aborting operation of the QKD transmitter upon an unexpectedly high photon intensity being detected; in another embodiment, the intensity indication is used to control the attenuation of the retro-reflected beam so as stabilize the average retro-reflected photon count per unit time.

QKD transmitter and transmission method

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Gloucester, United Kingdom

Joanna Duligall