Abstract: A QKD terminal for entangled photon Quantum Key Distribution, including: a photon source configured to emit a pair of entangled photons on a QKD channel, a dynamic holographic device arranged downstream of the photon source on the QKD channel and configured to receive and redirect the pair of entangled photons; and a controller connected to the holographic device and configured to trigger the holographic device to redirect a first entangled photon of the pair of entangled photons to a first direction and a second entangled photon of the pair of entangled photons to a second direction different from the first direction. A QKD system and a method for quantum communication are also provided.

Abstract: A terminal for free-space optical communication, with a transmitting part generating first laser signals with a phase and/or amplitude encoded for forming a first laser beam, a beam combiner part forming the first laser beam by coherently combining, transmitting the first laser beam towards a target through an atmospheric channel, receiving a second laser beam having an altered second spatial beam pattern, and spatially dividing the second laser beam into a plurality of second laser signals, a receiving part configured to detect a phase and/or amplitude of second laser signals for determining a altered second spatial beam pattern, and a controller for determining the altered second spatial beam pattern by analyzing the second laser signals, estimate a first spatial beam pattern to be applied to the first laser beam as an estimated eigenmode of the atmospheric channel based on the second spatial beam pattern.

Abstract: A method for polarization compensation includes: (a) generating at least one beam of an electromagnetic wave; (b) sending the at least one beam through a physical medium; (c) receiving the at least one beam of an electromagnetic wave after it has traversed the physical medium; (d) measuring the intensity of the electromagnetic wave after it traverses a system of electromagnetic retarders; (e) determining the polarization of the electromagnetic wave after it traverses the system of electromagnetic retarders; (f) calculating the positions of the electromagnetic retarders to match the determined polarization of the electromagnetic wave with the polarization of the generated electromagnetic wave; and (g) compensating the effect of the physical medium on the polarization of the electromagnetic wave by setting the electromagnetic retarders according to the calculated positions.

Abstract: A photon source for quantum communication including a plurality of optical channels, each comprising: a light emitter configured to emit optical pulses, and a phase mask optically connected to the respective light emitter and configured to encode an orbital angular momentum into incident light, wherein each of the phase masks of each optical channel is configured to encode a mutually orthogonal orbital angular momentum to the optical pulses emitted by the light emitter of each optical channel to provide an encoded optical output; a controller electrically coupled to each light emitter in each optical channel and configured to control parameters of the optical pulses; and combining optics configured to combine the encoded optical output of each of the optical channels to form a single encoded optical signal.

Abstract: A method for Quantum Communication, including the steps: obtaining, by a detector, a base signal, wherein the base signal includes an indication of a background optical noise of a communication channel; determining, based on the obtained base signal, a width of a time gate value; applying to the detector the determined width of time gate; and obtaining a QKD signal including QKD signal pulses sent through the communication channel by applying the time gate having the determined width for filtering the background optical noise. A corresponding optical receiver, QKD pulse stream and QKD system for quantum communication are also provided.

Abstract: An optical detector for quantum communication, comprising an optical setup configured to separate a single-photon signal beam encoded by a plurality of photon states into a plurality of separated single-photon beams having mutually different photon states, and a camera comprising a plurality of detection elements arranged as a two-dimensional array forming a detection area. Each detection element is configured to resolve a single photon incident on the detection element and provide a corresponding electric signal. The camera is arranged such that the separated beams are incident on mutually different designated areas of the detection area. Each designated area comprises a plurality of detection elements. Also a method for quantum communication.

Abstract: An optical terminal for quantum communication, comprising a first terminal unit configured to receive and/or transmit a first signal beam from or to a first target terminal and having a first optical axis, a second terminal unit configured to receive and/or transmit a second signal beam from and/or to a second target terminal and having a second optical axis, and a connecting part to communicate with the terminal units, wherein each terminal units comprises: a telescope provided on an optical axis to collimate the respective signal beams, a beam corrector placed on the respective optical axis and configured to correct the respective optical signals beam over a predetermined field of view of the telescope, a steering system to adjust a propagation direction of the signal beams to the respective optical axis, and a coupling portion coupling the respective signal beams to the connecting part. Also a method for quantum communication.

Abstract: A method for assisting in designing a technical system by: receiving an input message; processing the input message using a neural network to identify a content of the input message and extract technical system requirements, wherein the technical system requirements include at least a component having at least one parameter and a constraint; generating a proposed system design by determining at least one parameter of the component based on the constraint using the neural network; generating a response message containing the proposed system design using the neural network; and providing the proposed system design, wherein the neural network is configured as a large language model, LLM, and trained with a plurality of template systems and template components in the related technical field.

Abstract: A method for assisting a worker in a production line by: receiving a vocal input message from the worker; converting the vocal input message into a text input message; processing the text input message using a neural network to identify the content of the text input message and extract a request about at least one item related to the production line, wherein the neural network is configured as a large language model, LLM, and trained with information about the items of the production line; generating a response message containing information about the item of the production line using the neural network; converting the response message into a vocal response message; and providing the vocal response message to the worker.

Abstract: A method for assisting a trainee during a pilot training on a pilot training simulator, comprising receiving a vocal input message from the trainee; converting the vocal input message into a text input message; processing the text input message by a neural network configured as a large language model, LLM, to identify the content of the text input message and extract at least a request related to the pilot training simulator; accessing and searching a database based on the request to determine an educational advice using the neural network, wherein the database includes data about an aircraft on which the pilot training is performed; generating a response message containing the educational advice using the neural network; converting the response message into a vocal response message; and providing the vocal response message to the trainee.

Abstract: An optical detector for quantum communication, comprising a photonic lantern comprising a multi-mode input port to receive a spatial multi-mode input signal, and a plurality of single-mode output ports connected to the multi-mode input port by respective light channels. The photonic lantern splits the input signal by guiding the input signal in the individual light channels into a plurality of mutually orthogonal spatial single-mode output signals and outputs the plurality of single-mode output signals through the single-mode output ports. A coherent beam combiner combines the single-mode output signals to form a single-mode combined output signal. A photodetector assembly comprising one or more single photon counters detects the combined output signal to provide a detection signal.

Abstract: Methods, systems, and devices for free-space optical communications. An aircraft includes a flat optical communication terminal on an external surface of the aircraft, the flat optical communication terminal being configured to communicate with a ground station via a free-space optical communication link.

Abstract: A method for Quantum Communication, including the steps: obtaining, by a detector, a base signal, wherein the base signal includes an indication of a background optical noise of a communication channel; determining, based on the obtained base signal, a width of a time gate value; applying to the detector the determined width of time gate; and obtaining a QKD signal including QKD signal pulses sent through the communication channel by applying the time gate having the determined width for filtering the background optical noise. A corresponding optical receiver, QKD pulse stream and QKD system for quantum communication are also provided.

Abstract: A QKD terminal for entangled photon Quantum Key Distribution, including: a photon source configured to emit a pair of entangled photons on a QKD channel, a dynamic holographic device arranged downstream of the photon source on the QKD channel and configured to receive and redirect the pair of entangled photons; and a controller connected to the holographic device and configured to trigger the holographic device to redirect a first entangled photon of the pair of entangled photons to a first direction and a second entangled photon of the pair of entangled photons to a second direction different from the first direction. A QKD system and a method for quantum communication are also provided.

Abstract: An optical transmitter for quantum communication, including a QKD channel comprising at least QKD light source and configured to emit a stream of QKD encoded pulses; a reference channel including a reference light source and configured to emit a stream of reference pulses; and a control circuit connected to the QKD channel and to the reference light channel. The control circuit is configured to control the QKD channel and the reference light channel to emit the reference pulses with a predetermined time delay to the QKD encoded pulses. A difference of a wavelength of the QKD encoded pulses and a wavelength of the reference pulses is 5 nm or less. A corresponding optical receiver, an optical system and a method for quantum communication are also provided.

Abstract: A photon source for quantum communication including a plurality of optical channels, each comprising: a light emitter configured to emit optical pulses, and a phase mask optically connected to the respective light emitter and configured to encode an orbital angular momentum into incident light, wherein each of the phase masks of each optical channel is configured to encode a mutually orthogonal orbital angular momentum to the optical pulses emitted by the light emitter of each optical channel to provide an encoded optical output; a controller electrically coupled to each light emitter in each optical channel and configured to control parameters of the optical pulses; and combining optics configured to combine the encoded optical output of each of the optical channels to form a single encoded optical signal.

Abstract: A method for polarization compensation includes: (a) generating at least one beam of an electromagnetic wave; (b) sending the at least one beam through a physical medium; (c) receiving the at least one beam of an electromagnetic wave after it has traversed the physical medium; (d) measuring the intensity of the electromagnetic wave after it traverses a system of electromagnetic retarders; (e) determining the polarization of the electromagnetic wave after it traverses the system of electromagnetic retarders; (f) calculating the positions of the electromagnetic retarders to match the determined polarization of the electromagnetic wave with the polarization of the generated electromagnetic wave; and (g) compensating the effect of the physical medium on the polarization of the electromagnetic wave by setting the electromagnetic retarders according to the calculated positions.

Abstract: A system for displaying an external environment of an aircraft inside the aircraft comprises optical couplers distributed across an outer surface of a fuselage and configured to capture light from the external environment of the aircraft; optical waveguides transmit the captured light from the optical couplers through the fuselage; at least one display arranged on the inside of the fuselage; and at least one of: a processing unit configured to receive the captured light, to reconstruct a digital live image by combining optical information contained in the captured light across the respective optical couplers, and to display the digital live image on the at least one display; and an optical beam expander configured to receive the captured light, to expand the captured light into a light beam carrying a visual live image of the external environment, and to project the visual live image on the at least one display.

Abstract: In order to improve free space optical communications, an optical communication terminal includes a laser source, a photo detecting apparatus and an optical input/output assembly. These components are controlled by a control logic. In order to have the optical communication terminal to be self-compatible, the optical input/output assembly selectively routes the outgoing beam and incoming beam depending on their respective beam polarization. To this end, the optical input/output assembly may include a polarizing beam splitter together with a quarter-wave plate.

Abstract: Methods, systems, and devices for free-space optical communications. An aircraft includes a flat optical communication terminal on an external surface of the aircraft, the flat optical communication terminal being configured to communicate with a ground station via a free-space optical communication link.