Abstract: A system for random number generation includes a laser pulse driver; a laser diode emitting laser pulses; a fiber-optic unbalanced interferometer transforming laser radiation phase noise into amplitude modulation; an optical circulator/isolator that is used to prevent unwanted feedback into a laser cavity; a photodetector that detects the laser pulses from the interferometer; a digitizer that digitizes an output of the photodetector; a statistics control (SC) block that is used to calculate the probability density of the photodetector's output and to define a parameter ? that is related to a classical-to-quantum noise ratio and allows estimating random operation and providing attack resistance of the system; and a processor that receives the digitized output from the digitizer and outputs a true random bit sequence.

Abstract: A system for random number generation includes a laser pulse driver; a laser diode emitting laser pulses; a fiber-optic unbalanced interferometer transforming laser radiation phase noise into amplitude modulation; an optical circulator/isolator that is used to prevent unwanted feedback into a laser cavity; a photodetector that detects the laser pulses from the interferometer; a digitizer that digitizes an output of the photodetector; a statistics control (SC) block that is used to calculate the probability density of the photodetector's output and to define a parameter ? that is related to a classical-to-quantum noise ratio and allows estimating random operation and providing attack resistance of the system; and a processor that receives the digitized output from the digitizer and outputs a true random bit sequence.

Abstract: Quantum key distribution device includes a transmitter, including a light source, a first polarization controller, a phase modulator and an optical attenuator, all connected in series using a first optical fiber; a receiver, including a second polarization controller, a second phase modulator, a third polarization controller, a beamsplitter, and two single photon detectors, all connected in series using a second optical fiber; and a communication channel providing a light path from the transmitter to the receiver. The first and/or second optical fiber is a polarization maintaining fiber. The first and second phase modulators are actively controlled Pockels cell crystals, lithium niobate crystals or gallium arsenide crystals. The polarization controllers include a piezo-driven fiber compression device, a Pockels cell controller, a piezo-driven fiber twist device, or a non-linear optical crystal. The first and third polarization controllers use a ?/2 plate, or 45° fiber splice polarizer.

Abstract: The invention relates to quantum cryptography, and includes a communication system for transmitting a cryptographic key between the ends of a channel, including a transmitting node (Alice) comprising a beam splitter, an electro-optical attenuator, an amplitude modulator, a phase modulator, a storage line, a Faraday mirror, a synchronization detector; a receiving node (Bob) that includes avalanche photodiodes, a beam splitter, a circulator, a delay line, a phase modulator, a polarizing beam splitter, a Mach-Zehnder interferometer, and also a quantum channel for connecting these nodes. In this case, for the storage line is placed between the electro-optical phase modulator of the sender and the Faraday mirror. The limiting frequency of the laser pulse repetition at a fixed value of their width is increased, which makes it possible to use an autocompensation circuit at a frequency corresponding to the width of the laser pulse, which is the maximum possible result.

Abstract: The invention relates to quantum cryptography, and includes a communication system for transmitting a cryptographic key between the ends of a channel, including a transmitting node (Alice) comprising a beam splitter, an electro-optical attenuator, an amplitude modulator, a phase modulator, a storage line, a Faraday mirror, a synchronization detector; a receiving node (Bob) that includes avalanche photodiodes, a beam splitter, a circulator, a delay line, a phase modulator, a polarizing beam splitter, a Mach-Zehnder interferometer, and also a quantum channel for connecting these nodes. In this case, for the storage line is placed between the electro-optical phase modulator of the sender and the Faraday mirror. The limiting frequency of the laser pulse repetition at a fixed value of their width is increased, which makes it possible to use an autocompensation circuit at a frequency corresponding to the width of the laser pulse, which is the maximum possible result.