In order to achieve the dispersion of a processing load between communication devices that perform information transmission, an information communication system according to an exemplary aspect of the present invention includes a first transmission system configured to transmit information in a direction from a first communication device to a second communication device; and a second transmission system configured to transmit information in a direction opposite to the direction of the first transmission system, wherein part of transmission information is received as received information in each of the first transmission system and the second transmission system.

A transmitter for a continuous variable quantum communication system, the transmitter comprising: a coherent light source; a first controller, configured to apply a first signal to said coherent light source such that said coherent light source generates coherent light; a phase control element, configured to apply perturbations to said first signal, each perturbation producing a phase shift between parts of the generated coherent light; a first optical component, configured to produce optical intensity modulation, wherein said coherent light source is configured to supply said generated light to said optical component; a second controller, configured to apply a second signal to said optical component such that a light pulse is emitted during a period of time that a first part of the generated light is received, and a light pulse is emitted during a period of time that a second part of the generated light is received; an intensity control element, configured to modulate the amplitude of an emitted light pulse; wherein the phase control element and the intensity control element are configured to encode information in a continuum of values of the phase and amplitude of an emitted light pulse.

A quantum state measurement system includes a quantum state generator that generates an optical photon comprising a quantum state. A spectral converter modifies a spectrum of the optical photon and provides the optical photon comprising the quantum state with the modified spectrum. An optical switch switches the optical photon with the modified spectrum to one of a plurality of outputs. A measurement system determines a fidelity of the quantum state of the optical photon with the modified spectrum. A control system provides an electrical control signal to the quantum state generator in response to the determined fidelity of the quantum state that improves a fidelity of at least some subsequent generated optical photons comprising a quantum state that are generated by the quantum state generator after the optical photon.

One embodiment provides a system for facilitating distribution of quantum keys. During operation, the system receives, from a requester, a first request for a key, wherein the first request indicates a requested length for the key and identifying information of the requester. The system determines whether a subset pool of a general pool of keys is allocated to the requester based on the identifying information of the requester, wherein the keys in the general pool are generated by a quantum engine. In response to determining that a subset pool is not allocated to the requester, the system allocates a subset pool to the requester. The system obtains from the allocated subset pool a key with a length matching the requested length, and the system returns the obtained key to the requester.

A polarization controller comprising: (i) an optical fiber, and (ii) a carrier surrounding the optical fiber, the carrier comprising an off-center through hole with at least one collapsed region, such that the optical fiber is situated within the through hole and contacts the at least one collapsed region of the through hole, and the collapsed region exerts pressure on the optical fiber.

In an approach to improve the field of multi-cloud environments by detecting data corruption between storage systems. Embodiments perform information tunneling on data transferring between a source storage system and a target storage system. Further, embodiments determine a checksum data of a data payload does not match an Internet Protocol (IP) packet extracted checksum and a blockchain based checksum and compare the checksum data at the target storage system with the IP packet extracted checksum and the blockchain based checksum to identify one or more checksum mismatches. Additionally, embodiments identify a corruption in a data payload based on the comparison between the checksum data at the target storage system and the IP packet extracted checksum and the blockchain based checksum, validate the corruption in the data payload, and update respective entities of identified corruption in the data payload.

A method and apparatus for synchronizing a start-point of quantum data are disclosed. A method of determining a start-point of a quantum key distribution (QKD) protocol, at which a receiving apparatus of a QKD system starts the QKD protocol with a transmitting apparatus, includes receiving, by the receiving apparatus, an optical pulse sequence of a predetermined pattern from the transmitting apparatus, measuring, by the receiving apparatus, a predetermined quantum signal included in the optical pulse sequence, transmitting, by the receiving apparatus, a confirmation signal to the transmitting apparatus when the number of measurements of the predetermined quantum signal reaches a predetermined value, and determining, as the start-point, a point after one period of the optical pulse sequence from a point at which the number of measurements of the predetermined quantum signal has reached the predetermined value, or a point at which the confirmation signal has been transmitted.

A communication system comprising n transmitters and a receiver, where n is an integer of at least 2, each of said n transmitters comprising a light source and an encoder such that each transmitter is adapted to output an encoded pulse of light, said receiver comprising a first element, the system further comprising a timing circuit, the timing circuit being configured to synchronise the encoded pulses output by the transmitters such that interference between a light pulse sent from the first transmitter and a light pulse from the second transmitter, interfere at the first element, each transmitter further comprising a suppressing element adapted to stop light exiting one of the transmitters such that the system is switchable between a first operation mode where two transmitters output encoded pulses and where both pulses interfere at the interference element and a second mode of operation where just one transmitter transmits light pulses to said receiver, the suppressing element being controlled to stop light exiting the other transmitter.

The invention relates to a Quantum Key Distribution system comprising a transmitter 300 and a receiver 400 for exchanging a quantum key via a quantum channel 600 through a decoy-state three state protocol wherein the transmitter comprises a transmitter processing unit 340 adapted to use random numbers from a quantum random generator to select a quantum state to encode from different states of intensity and basis, a Pulsed light source 310 adapted to generate an optical pulse, a time-bin interferometer 320 through which the generated optical pulse passes and which transforms generated optical pulse into two coherent pulses separated by the time bin duration, a single intensity modulator 360 adapted to change the intensity of the two pulses individually according to the choice made by the transmitter processing unit 340, and a variable optical attenuator 370 adapted to reduce the overall signal intensity to the optimum photon number per pulse.

A system and method for quantum key distribution includes determining an intrinsic loss along a quantum channel; generating a pulse sequence; transmitting the pulse sequence via the quantum channel; receiving the pulse sequence; determining invalid signal positions and providing the invalid signal positions; determining a first reconciled signal from the first signal and the invalid signal positions, and determining a second reconciled signal from the second signal and the invalid signal positions; determining a total loss along the quantum channel from the at least one test pulse received, determining a signal loss from the total loss and the intrinsic loss, and providing the signal loss; determining a shared by error correcting the first reconciled signal and the second reconciled signal; and determining an amplified key from the shared key by shortening the shared key by a shortening amount that is determined from the signal loss.