Abstract: The present invention relates to a quantum key distribution method 2000 for distributing a secret key over a quantum communication channel between a transmitter and a receiver, the method comprising the steps of: synchronizing S2100 a clock between the transmitter and the receiver, distributing S2200 the secret key from the transmitter to the receiver, wherein the synchronizing step S2100 comprises: a first transmitting step S2120 for transmitting a N-th bit of the clock from the transmitter to the receiver, a second transmitting step S2130 for transmitting acknowledgement of reception of the N-th bit from the receiver to the transmitter, a first checking step S2140 for checking if the N-th bit is a most significant bit of the clock, and an incrementing step S2150 for incrementing the value of N if the first checking step S2140 indicates that the N-th bit is not the most significant bit of the clock.

Abstract: A quantum key distribution (QKD) system comprising: an emitter (110) adapted to generate a QKD free-space signal, a transmitter station (220) adapted to receive the free-space signal from the emitter (110), and a remote QKD receiving station (250) supporting a QKD receiver (160) located at a different location than the transmitter station, wherein the transmitter station is adapted to receive said free space signal from the emitter and to forward said signal through a fiber link (400) to the QKD receiver (160) in said remote QKD receiving station (250).

Abstract: The invention relates to a IM bias voltage determining method adapted to determine an IM bias voltage corresponding to a desired Quantum Bit Error Rate based on the following formula Q ? ( V IM ) = Q 0 + R err R err + R cor where Q(VIM) is the QBER dependent of the IM bias voltage VIM, Q0 is the optimal minimal QBER, Rerr is the number of erroneous detections, Rcor is the number of correct detections and VIM is the IM bias voltage.

Abstract: The present invention relates to an Entropy measurement method comprising the steps of a start-up phase comprising powering on the entropy source unity, a signal emitting step comprising emitting a quantum signal characterized by an overall noise made of classical noise and quantum noise, a noise measurement step comprising measuring the statistics of overall noise through active pixels upon illumination and the statistics of classical noise through non-illuminated pixels, a quantum noise calculation step comprising calculating the quantum noise based on the difference between the overall noise and the classical noise, an health check step comprising comparing the resulting quantum noise to an expected quantum noise and/or a predetermined threshold and a health control step controlling the entropy source unit based on the result of the entropy estimation step.

Abstract: Some embodiments provide methods and apparatus for quantum random number generation based on a single bit or multi bit Quanta Image Sensor (QIS) providing single-photon counting over a time interval for each of an array of pixels of the QIS, wherein random number data is generated based on the number of photons counted over the time interval for each of the pixels.

Abstract: Some embodiments provide methods and apparatus for quantum random number generation based on a single bit or multi bit Quanta Image Sensor (QIS) providing single-photon counting over a time interval for each of an array of pixels of the QIS, wherein random number data is generated based on the number of photons counted over the time interval for each of the pixels.

Abstract: Free-Space key distribution method comprising exchanging information between an emitter (100) and a receiver (200) based on the physical layer wiretap channel model, comprising the steps of randomly preparing (710), at the emitter (100), one qubit encoded with one of two possible non-identical quantum states, sending (720) the encoded qubit to the receiver (200) through a physical layer quantum-enhanced wiretap channel (500), such that an eavesdropper (300) tapping said channel is provided with partial information about the said states only, detecting and measuring (730) the received quantum states, key sifting (740) between the emitter and the receiver through a classical channel, calculating (750, 760) an amount of information available to any eavesdropper (300) based on the detected and received quantum states.

Abstract: The present relates to a quantum communication system for free space quantum key distribution. An emitter and a receiver, the emitter and the receiver are two points distanced by a free space quantum communication channel, the emitter being designed for wirelessly transmitting data to the receiver via said free space optical communication channel. The receiver includes an optical device capable of receiving the data within a predetermined field of view extending from said optical device toward the receiver. The system is characterized in that the emitter further comprises a light protecting device attached on said emitter. The light protecting device is configured to prevent any light coming from the environment beyond the emitter to enter within the field of view of the receiver. The invention further relates to a method for optimizing free space quantum key distribution.

Abstract: Some embodiments provide methods and apparatus for quantum random number generation based on a single bit or multi bit Quanta Image Sensor (QIS) providing single-photon counting over a time interval for each of an array of pixels of the QIS, wherein random number data is generated based on the number of photons counted over the time interval for each of the pixels.

Abstract: A quantum key distribution (QKD) system comprising: an emitter (110) adapted to generate a QKD free-space signal, a transmitter station (220) adapted to receive the free-space signal from the emitter (110), and a remote QKD receiving station (250) supporting a QKD receiver (160) located at a different location than the transmitter station, wherein the transmitter station is adapted to receive said free space signal from the emitter and to forward said signal through a fiber link (400) to the QKD receiver (160) in said remote QKD receiving station (250).

Abstract: The present invention relates to a measuring device (3000) for measuring reflection in an optical fiber (1400), the device comprising: emitting means (3100) connected to the optical fiber (1400) and configured to emit light into the optical fiber (1400), measuring means (3300) connected to the optical fiber (1400) and configured to receive a reflected light from the optical fiber (1400), wherein the measuring means comprises a first photon detector (3310) and a second photon detector (3311), wherein the operation of the second photon detector (3311) and/or the reflected light reaching the second photon detector (3311) is controlled based on an output of the first photon detector (3310).

Abstract: The present disclosure in some embodiments provides a method and an apparatus for providing a quantum cryptographic key distribution stabilization, which can quickly and efficiently compensate for an error caused by a temperature change, a change in polarization of a transmission path of an optical system included in a quantum cryptographic key distribution system in a cost-effective manner working perfectly with the very conventional quantum cryptographic key distribution system.

Abstract: The present relates to a quantum communication system for free space quantum key distribution. An emitter and a receiver, the emitter and the receiver are two points distanced by a free space quantum communication channel, the emitter being designed for wirelessly transmitting data to the receiver via said free space optical communication channel. The receiver includes an optical device capable of receiving the data within a predetermined field of view extending from said optical device toward the receiver. The system is characterized in that the emitter further comprises a light protecting device attached on said emitter. The light protecting device is configured to prevent any light coming from the environment beyond the emitter to enter within the field of view of the receiver. The invention further relates to a method for optimizing free space quantum key distribution.

Abstract: The invention relates to a IM bias voltage determining method adapted to determine an IM bias voltage corresponding to a desired Quantum Bit Error Rate based on the following formula Q ? ( V IM ) = Q 0 + R err R err + R cor where Q(VIM) is the QBER dependent of the IM bias voltage VIM, Q0 is the optimal minimal QBER, Rerr is the number of erroneous detections, Rcor is the number of correct detections and VIM is the IM bias voltage.

Abstract: The invention relates to a QKD System Active combiner (200) adapted to be installed in a QKD apparatus, said QKD apparatus comprising an emitter (100), a receiver (110) and QKD systems (102/112), wherein the emitter (100) is adapted to send communication signals to the receiver (110) through the QKD System Active combiner (200), characterized in that the QKD System Active combiner (200) comprises an active attenuation system comprising a processing unit (230) adapted to automatically control at least one variable optical attenuator (150) through a control channel (290) in order to control an attenuation of a signal to be sent to the receiver, and a detector/monitor (240) adapted to monitor the intensity of the signal downstream the attenuation, and wherein the processing unit is adapted to control the variable optical attenuator (150) based on a QBER information or an intensity of a signal received by the receiver, sent by the QKD systems (112) through a classical channel (250).

Abstract: The present disclosure discloses a random number generating apparatus capable of equalizing the spatial intensity distribution of light signals that are radiated from a light resource and are input to individual pixels.

Abstract: Free-Space key distribution method comprising exchanging information between an emitter (100) and a receiver (200) based on the physical layer wiretap channel model, comprising the steps of randomly preparing (710), at the emitter (100), one qubit encoded with one of two possible non-identical quantum states, sending (720) the encoded qubit to the receiver (200) through a physical layer quantum-enhanced wiretap channel (500), such that an eavesdropper (300) tapping said channel is provided with partial information about the said states only, detecting and measuring (730) the received quantum states, key sifting (740) between the emitter and the receiver through a classical channel, calculating (750, 760) an amount of information available to any eavesdropper (300) based on the detected and received quantum states.

Abstract: The present invention relates to a measuring device (3000) for measuring reflection in an optical fiber (1400), the device comprising: emitting means (3100) connected to the optical fiber (1400) and configured to emit light into the optical fiber (1400), measuring means (3300) connected to the optical fiber (1400) and configured to receive a reflected light from the optical fiber (1400), wherein the measuring means comprises a first photon detector (3310) and a second photon detector (3311), wherein the operation of the second photon detector (3311) and/or the reflected light reaching the second photon detector (3311) is controlled based on an output of the first photon detector (3310).

Abstract: The present disclosure in some embodiments provides an apparatus and method for supplying quantum keys to multiple apparatuses in a quantum key distribution system. According to some embodiments of the present disclosure, an apparatus and method for supplying quantum keys enable Alice or Bob to deliver the quantum keys to the multiple transmitting apparatuses or receiving apparatuses, in real time without a delay.

Abstract: Some embodiments provide methods and apparatus for quantum random number generation based on a single bit or multi bit Quanta Image Sensor (QIS) providing single-photon counting over a time interval for each of an array of pixels of the QIS, wherein random number data is generated based on the number of photons counted over the time interval for each of the pixels.