WO2020020100A1 - 量子密钥传输装置及系统 - Google Patents

量子密钥传输装置及系统 Download PDF

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Publication number
WO2020020100A1
WO2020020100A1 PCT/CN2019/097103 CN2019097103W WO2020020100A1 WO 2020020100 A1 WO2020020100 A1 WO 2020020100A1 CN 2019097103 W CN2019097103 W CN 2019097103W WO 2020020100 A1 WO2020020100 A1 WO 2020020100A1
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Prior art keywords
signal
quantum
optical
polarization
local oscillator
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PCT/CN2019/097103
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English (en)
French (fr)
Inventor
李政宇
肖新华
吴裕平
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华为技术有限公司
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Priority to EP19841875.8A priority Critical patent/EP3820076B1/en
Publication of WO2020020100A1 publication Critical patent/WO2020020100A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography
    • H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
    • H04L2209/12—Details relating to cryptographic hardware or logic circuitry
    • H04L2209/122—Hardware reduction or efficient architectures

Definitions

  • the present application relates to the field of quantum communication technology, and in particular, to a quantum key transmission device and system.
  • Quantum secure communication is a new type of communication technology developed in the past thirty years.
  • Quantum confidential communication is the product of the combination of quantum characteristics and traditional cryptography. It mainly uses the basic principles and characteristics of quantum mechanics to ensure the security of communication.
  • quantum key transmission refers to carrying a random key in a quantum signal for transmission.
  • the transmitting end when performing quantum key transmission, can prepare a local oscillator signal and a quantum signal, and transmit the local oscillator signal and the quantum signal to the receiving end through the same channel. Since the light intensity of the local oscillator signal is much larger than that of the quantum signal, the local oscillator signal is likely to cause crosstalk to the quantum signal.
  • the transmitting end can usually use time division multiplexing and polarization multiplexing to isolate the local oscillator signal from the quantum signal.
  • time division multiplexing means that the sending times of the local oscillator signal and the quantum signal are different
  • polarization multiplexing means that the polarization directions of the local oscillator signal and the quantum signal when entering the optical fiber are orthogonal.
  • the receiving end When using time division multiplexing to transmit the local oscillator signal and the quantum signal, after receiving the local oscillator signal and the quantum signal, the receiving end needs to introduce an additional optical path difference to compensate for the delay between the quantum signal and the local oscillator signal. It will result in the inability to use integrated optical chips at the receiving end and miniaturization.
  • polarization multiplexing is used to transmit the local oscillator signal and quantum signal, the limited extinction ratio of the polarization multiplexing device will limit the strength of the local oscillator signal, resulting in a reduction in the signal-to-noise ratio at the receiving end.
  • This application provides a quantum key transmission device and system, which can be used to solve the problem that the receiving end cannot be miniaturized and the signal-to-noise ratio is reduced when time division multiplexing and polarization multiplexing are used to isolate the quantum signal and the local oscillator signal problem.
  • the technical solution is as follows:
  • a quantum key receiving device includes a laser, a beam splitter, a quantum signal preparation module, and a polarization control module.
  • the laser is used to output a first optical signal
  • the beam splitter is configured to receive the first optical signal, divide the first optical signal into a second optical signal and a third optical signal, send the second optical signal through a first optical fiber, and send the
  • the quantum signal preparation module sends the third optical signal
  • the quantum signal preparation module is configured to modulate the third optical signal to obtain a first modulation signal and a second modulation signal, and send the first modulation signal and the second modulation signal to the polarization control module.
  • the first modulation signal carries a random key to be transmitted
  • the second modulation signal carries reference data to be transmitted;
  • the polarization control module is configured to adjust the polarization directions of the first modulation signal and the second modulation signal, and attenuate the light intensities of the first modulation signal and the second modulation signal to obtain The quantum signal and the reference signal, wherein the quantum signal and the reference signal are sent out through a second optical fiber.
  • the quantum key sending device may adjust the polarization direction of the quantum signal and the reference signal through a polarization controller, and send the local oscillator signal and the adjusted quantum signal to different optical fibers for transmission.
  • a polarization controller may adjust the polarization direction of the quantum signal and the reference signal through a polarization controller, and send the local oscillator signal and the adjusted quantum signal to different optical fibers for transmission.
  • the quantum signal receiver at the receiving end does not need to introduce additional optical path differences for delay compensation. So that the receiving end can be integrated and miniaturized.
  • the optical fiber used to transmit quantum signals no longer needs to allocate resources for the transmission of local oscillator signals, that is, all resources in the optical fiber can be used for quantum signals. Transmission, increasing the transmission ratio of quantum signals per unit time.
  • the light of the second optical signal is stronger than the light of the third optical signal.
  • the apparatus further includes a receiver and a processor
  • the receiver is configured to receive polarization direction control information and send the polarization direction control information to the processor;
  • the processor is configured to process the polarization direction control information to obtain a first control signal, and send the first control signal to the polarization controller;
  • the polarization control module is specifically configured to adjust the polarization directions of the first modulation signal and the second modulation signal based on the first control signal.
  • the polarization direction control information may be angle information indicating a polarization angle to be adjusted, which is fed back by a receiving end according to a detection result generated by detecting a reference signal and a local oscillator signal.
  • the quantum signal preparation module includes a quantum random number generator, a processor, and a modulator;
  • the quantum random number generator is configured to generate a random number and send the random number to the processor.
  • the processor is configured to generate a random key according to the random number, and generate a quantum control signal according to the random key; and is further configured to generate a reference control signal according to the stored reference data, and combine the quantum control signal and the Sending the reference control signal to the modulator;
  • the modulator is configured to modulate the third optical signal according to the quantum control signal to obtain a first modulation signal;
  • the optical signal is modulated to obtain a second modulation signal; and the first modulation signal and the second modulation signal are sent to the polarization control module.
  • the polarization control module includes a polarization controller and an attenuator; the polarization controller is configured to adjust the polarization directions of the first modulation signal and the second modulation signal, and adjust The first modulated signal and the second modulated signal are sent to the attenuator; the attenuator is used to attenuate the adjusted first modulated signal to obtain the quantum signal; The second modulated signal is attenuated to obtain the reference signal.
  • the polarization control module includes a polarization controller and an attenuator; the attenuator is configured to attenuate the first modulation signal and the second modulation signal to obtain an attenuated first Sending the modulated signal and the attenuated second modulated signal to the polarization controller; the attenuated first modulated signal and the attenuated second modulated signal; The polarization direction of the attenuated first modulation signal is adjusted to obtain the quantum signal; the polarization direction of the attenuated second modulation signal is adjusted to obtain the reference signal.
  • the wavelength of the second optical signal is different from that of other optical signals transmitted in the first optical fiber
  • the wavelength of the third optical signal is different from that of other optical signals transmitted in the second optical fiber.
  • the wavelengths are different.
  • the second optical fiber is further configured to transmit a coherent optical signal, and a transmission direction of the coherent optical signal transmitted in the second optical fiber and a quantum signal transmitted in the second optical fiber are transmitted. In the opposite direction.
  • the polarization controller is set on the quantum signal path of the quantum key receiving device, and the polarization direction of the quantum signal is adjusted according to the polarization direction control information fed back by the quantum key receiving device according to the detection result, so that the quantum density is
  • the polarization direction of the quantum signal received by the key receiving device can be consistent with the polarization direction of the received local oscillator signal or the difference between the two can be fixed, or the polarization direction of the received quantum signal can be kept stable at all times. In one polarization direction, the interference effect between the quantum signal and the local oscillator signal is improved, thereby ensuring the accuracy of the detection result.
  • the prepared quantum signal can be sent to the second fiber for transmission after passing through the polarization controller, and the polarization controller itself has a certain attenuation effect on the signal, the third optical signal after modulation When attenuating to obtain a quantum signal, the attenuator can reduce the attenuation of the signal accordingly, reduce the workload of the attenuator, and will not affect the strength of the local oscillator signal.
  • a quantum key sending device in a second aspect, includes a laser, a beam splitter, a quantum signal preparation module, and a polarization controller.
  • the laser is used to output a first optical signal
  • the beam splitter is configured to receive the first optical signal, divide the first optical signal into a second optical signal and a third optical signal, send a second optical signal to the polarization controller, and send the second optical signal to the quantum
  • the signal preparation module sends the third optical signal
  • the quantum signal preparation module is configured to modulate the third optical signal to obtain a quantum signal and a reference signal, and send the quantum signal and the reference signal through a second optical fiber, and the quantum signal carries to be transmitted Random key
  • the polarization controller is configured to adjust a polarization direction of the second optical signal, and send the adjusted second optical signal as a local oscillator signal through a first optical fiber.
  • the quantum key sending device can adjust the polarization direction of the local oscillator signal through a polarization controller, and send the quantum signal and the adjusted local oscillator signal to different optical fibers for transmission. It is necessary to isolate the local oscillator signal and the quantum signal by time division multiplexing and polarization multiplexing. On this basis, the quantum key receiving device does not need to introduce additional optical path difference for delay compensation, so that The receiving end can be integrated and miniaturized. In addition, since the polarization multiplexing device is no longer needed, the limitation on the strength of the local oscillator signal caused by the limited extinction ratio of the polarization multiplexing device is solved, and the received signal-to-noise ratio is improved.
  • the optical fiber used to transmit quantum signals no longer needs to allocate resources for the transmission of local oscillator signals, that is, all resources in the optical fiber can be used for quantum signals. Transmission, increasing the transmission ratio of quantum signals per unit time.
  • the light of the second optical signal is stronger than the light of the third optical signal.
  • the apparatus further includes a receiver and a processor
  • the receiver is configured to receive polarization direction control information and send the polarization direction control information to the processor;
  • the processor is configured to process the polarization direction control information to obtain a first control signal, and send the first control signal to the polarization controller;
  • the polarization controller is specifically configured to adjust a polarization direction of the second optical signal based on the first control signal to obtain a local oscillator signal.
  • the polarization direction control information may be angle information indicating a polarization angle to be adjusted, which is fed back by a receiving end according to a detection result generated by detecting a reference signal and a local oscillator signal.
  • the wavelength of the second optical signal is different from that of other optical signals transmitted in the first optical fiber
  • the wavelength of the third optical signal is different from that of other optical signals transmitted in the second optical fiber.
  • the wavelengths are different.
  • the second optical fiber is further configured to transmit a coherent optical signal, and a transmission direction of the coherent optical signal transmitted in the second optical fiber and a quantum signal transmitted in the second optical fiber are transmitted. In the opposite direction.
  • the polarization rotation of the local oscillator signal and the quantum signal is different during the transmission process.
  • a polarization controller can be provided in the quantum key sending device, and the polarization controller can adjust the current based on the polarization direction control information fed back by the quantum key receiving device according to the detection result.
  • the polarization direction of the vibration signal so that the polarization direction of the local oscillator signal received by the quantum key receiving device and the polarization direction of the received quantum signal can be kept consistent or the difference between the two is fixed, or the received
  • the polarization direction of the local oscillator signal can always be stabilized in one polarization direction, so as to improve the interference effect between the quantum signal and the local oscillator signal, thereby ensuring the accuracy of the detection result.
  • a quantum key receiving device includes a quantum detection module and a polarization control module.
  • the polarization control module is configured to receive a local oscillator signal from a first optical fiber, adjust a polarization direction of the local oscillator signal, and send the adjusted local oscillator signal to the quantum detection module;
  • the quantum detection module is configured to receive a quantum signal and a reference signal from a second optical fiber, and detect the adjusted local oscillator signal, the quantum signal, and the reference signal to obtain a detection result, wherein the quantum signal Carrying a random key, and the detection result includes key information of the random key;
  • the polarization control module is configured to receive a quantum signal and a reference signal from the second optical fiber, adjust a polarization direction of the quantum signal and the reference signal, and send the adjusted quantum signal and reference signal to the quantum detection module. ;
  • the quantum detection module is configured to receive a local oscillator signal from the first optical fiber, detect the local oscillator signal, the adjusted quantum signal, and the adjusted reference signal to obtain the detection result.
  • the quantum key receiving device may receive a local oscillator signal and a quantum signal transmitted through two different optical fibers, and control the local oscillator signal through a polarization control module provided in the local oscillator signal path or the quantum signal path. Or the direction of polarization of a quantum signal. Since the quantum signal and the local oscillator signal are not separated by time division multiplexing and polarization multiplexing during transmission, the quantum key receiving device does not need to introduce additional optical path difference for delay compensation, so that the quantum The key receiving device can be integrated and miniaturized.
  • the polarization direction of the local oscillator signal or the quantum signal can be kept consistent or the difference between the two is fixed, or the local The polarization direction of the vibration signal can always be stabilized in one polarization direction, so as to improve the interference effect between the quantum signal and the local oscillator signal, thereby ensuring the accuracy of the detection result.
  • a polarization direction of the reference signal is consistent with a polarization direction of the quantum signal, and the reference signal carries reference data, and the polarization control module includes a polarization controller;
  • the polarization controller is configured to receive the local oscillator signal from the first optical fiber, adjust a polarization direction of the local oscillator signal to a first polarization direction, and send the adjusted local oscillator to the quantum detection module. signal;
  • the quantum detection module is specifically configured to receive the adjusted local oscillator signal, receive the quantum signal and the reference signal from the second optical fiber, and perform an adjustment on the adjusted local oscillator signal and the reference signal.
  • the interference signal is detected to obtain the reference data measurement value; if the deviation between the reference data measurement value and the stored reference data is not greater than the allowable deviation, the interference signal of the quantum signal and the adjusted local oscillator signal Performing detection to obtain the detection result; if the deviation between the reference data measurement value and the stored reference data is greater than the allowable deviation, generating a second control signal based on the reference data measurement value, and
  • the polarization controller sends the second control signal;
  • the polarization controller is further configured to receive the second control signal, update the polarization direction of the local oscillator signal based on the second control signal, and resend the adjusted local oscillator signal to the quantum detection module. .
  • the reference signal carries reference data
  • the polarization control module includes a polarization controller
  • the polarization controller is configured to receive the quantum signal and the reference signal from the second optical fiber, adjust a polarization direction of the quantum signal and the reference signal to a first polarization direction, and provide the quantum signal to the quantum detection module. Send the adjusted quantum signal and reference signal;
  • the quantum detection module is specifically configured to receive the adjusted quantum signal and reference signal, receive the local oscillator signal from the first optical fiber, and interfere with the adjusted reference signal and the local oscillator signal. Perform detection to obtain the reference data measurement value; if the deviation between the reference data measurement value and the stored reference data is not greater than the allowable deviation, detect the interference signal of the adjusted quantum signal and the local oscillator signal To obtain the detection result; if a deviation between the reference data measurement value and the stored reference data is greater than the allowable deviation, a fourth control signal is generated based on the reference data measurement value, and is directed toward the polarization The controller sends the fourth control signal;
  • the polarization controller is further configured to receive the fourth control signal, update the polarization directions of the quantum signal and the reference signal based on the fourth control signal, and resend the adjusted quantum to the quantum detection module. Signal and adjusted reference signal.
  • the polarization control module includes a beam splitter, a polarization analyzer, and a polarization controller;
  • the beam splitter is configured to receive the local oscillator signal from the first optical fiber, divide the local oscillator signal into a fourth optical signal and a fifth optical signal, and send the fourth optical signal to the polarization analyzer.
  • the polarization analyzer is configured to analyze a polarization direction of the fourth optical signal, generate a third control signal based on the polarization direction of the fourth optical signal and a target polarization direction, and send the third control to the polarization controller.
  • Signal, the direction deviation between the target polarization direction and the polarization direction of the quantum signal is not greater than a preset value;
  • the polarization controller is configured to adjust the polarization direction of the fifth optical signal to the target polarization direction according to the third control signal, and send the adjusted fifth optical signal to the quantum detection module;
  • the quantum detection module is specifically configured to receive an adjusted fifth optical signal, receive the quantum signal and the reference signal from the second optical fiber, and perform an adjustment on the adjusted fifth optical signal, the quantum signal, and The reference signal is detected to obtain the detection result.
  • a light intensity of the fourth optical signal is smaller than a light intensity of the fifth optical signal.
  • a quantum key receiving device includes a first polarization beam splitter, a second polarization beam splitter, a first quantum heterodyne detector, a second quantum heterodyne detector, and a processor. ;
  • the first polarization beam splitter is configured to receive a local oscillator signal from a first optical fiber, divide the local oscillator signal into a sixth optical signal and a seventh optical signal, and send the local oscillator signal to the first quantum heterodyne detector.
  • a sixth optical signal sending the seventh optical signal to the second quantum heterodyne detector;
  • the second polarization beam splitter is configured to receive the quantum signal and the reference signal from a second optical fiber, divide the reference signal into an eighth optical signal and a ninth optical signal, and divide the quantum signal into a tenth An optical signal and an eleventh optical signal, sending the eighth optical signal and the tenth optical signal to the first quantum heterodyne detector, and sending the ninth light to the second quantum heterodyne detector A signal and an eleventh optical signal, the quantum signal carrying a random key;
  • the first quantum heterodyne detector is configured to detect interference signals of the sixth optical signal and the eighth optical signal, obtain a regular component of the eighth optical signal, and detect the sixth optical signal and the first optical signal.
  • An interference signal of the ten optical signals to obtain a regular component of the tenth optical signal, and sending the regular component of the eighth optical signal and the regular component of the tenth optical signal to the processor;
  • the second quantum heterodyne detector is configured to detect interference signals of the seventh optical signal and the ninth optical signal, obtain a regular component of the ninth optical signal, and detect the seventh optical signal and the first optical signal.
  • An interference signal of the eleventh optical signal to obtain a regular component of the eleventh optical signal, and sending the regular component of the ninth optical signal and the regular component of the eleventh optical signal to the processor;
  • the processor is configured to process the regular component of the eighth optical signal and the regular component of the ninth optical signal to obtain a signal parameter; and based on the signal parameter, the regular component and the regular component of the tenth optical signal The regular component of the eleventh optical signal is processed to obtain an initial key, where the initial key includes key information of the random key.
  • the polarization control module may not be provided in the quantum key receiving device, and the local oscillation signal, the quantum signal, and the reference signal are split by the first polarization beam splitter and the second polarization beam splitter, respectively.
  • the regular component of the reference signal and the regular component of the quantum signal are measured by the first quantum heterodyne detector and the second quantum heterodyne detector, respectively, and then the signal parameters are calculated based on the regular components of the reference signal.
  • the regular component of the quantum signal is processed to obtain the initial key, so as to eliminate the influence of polarization rotation and ensure the accuracy of the obtained key information.
  • a quantum key transmission system in a fifth aspect, includes a quantum key sending device and a quantum key receiving device.
  • the quantum key sending device is a device according to any one of the foregoing first aspect or the second possible implementation manner;
  • the quantum key receiving device is configured to receive a local oscillator signal from the first optical fiber, and receive the adjusted quantum signal and the adjusted reference signal from the second optical fiber. Detecting the adjusted quantum signal and the adjusted reference signal to obtain a detection result, wherein the detection result includes key information of the random key;
  • the quantum key sending device includes a laser, a beam splitter, and a quantum signal preparation module; the laser is configured to output a first optical signal; the beam splitter is configured to receive the first optical signal, and convert the first optical signal The signal is divided into a second optical signal and a third optical signal, and the second optical signal is sent out through the first optical fiber, and the third optical signal is sent to the quantum signal preparation module; Therefore, the third optical signal is modulated to obtain a quantum signal and a reference signal, and the quantum signal and the reference signal are sent out through a second optical fiber, where the quantum signal carries a random key to be transmitted;
  • the quantum key receiving device is the device according to the foregoing third aspect or any possible implementation manner of the fourth aspect.
  • An embodiment of the present application provides a quantum key sending device.
  • the polarization direction of a quantum signal and a reference signal can be adjusted by a polarization controller, and the local oscillator signal and the adjusted quantum signal are sent to different optical fibers for transmission.
  • no additional optical path difference needs to be introduced into the quantum signal receiver at the receiving end for delay. Time compensation, so that the receiving end can be integrated and miniaturized.
  • the optical fiber used to transmit quantum signals no longer needs to allocate resources for the transmission of local oscillator signals, that is, all resources in the optical fiber can be used for quantum The transmission of signals increases the transmission ratio of quantum signals per unit time.
  • FIG. 1 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application.
  • FIG. 9 is a schematic structural diagram of a quantum key receiving device according to an embodiment of the present application.
  • FIG. 10 is a schematic structural diagram of a quantum key receiving device according to an embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a quantum key receiving device according to an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a quantum key receiving device according to an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a quantum key receiving device according to an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a quantum key transmission system according to an embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of a quantum key transmission system according to an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a quantum key sending device according to an embodiment of the present application. As shown in FIG. 1, the device includes a laser 101, a beam splitter 102, a quantum signal preparation module 103, and a polarization controller 104.
  • the laser 101 is configured to output a first optical signal.
  • the beam splitter 102 is configured to receive a first optical signal, divide the first optical signal into a second optical signal and a third optical signal, send the second optical signal through a first optical fiber, and send the signal to the quantum signal preparation module 103 Sending a third optical signal;
  • the quantum signal preparation module 103 is configured to modulate the third optical signal to obtain a quantum signal and a reference signal, and send the quantum signal and the reference signal to the polarization controller 104, and the quantum signal carries a random key to be transmitted
  • the polarization controller 104 is configured to adjust the polarization direction of the quantum signal and the reference signal, and send the adjusted quantum signal and the adjusted reference signal through the second optical fiber.
  • the light of the second optical signal is stronger than the light of the third optical signal
  • the laser 101 may be a laser capable of generating a light signal with a narrow line width and linear polarization, a laser that emits a pulsed laser signal with a stable phase relationship, or a laser that emits a continuous laser signal.
  • the laser 101 includes an output port, and the laser 101 can output a first optical signal through the output port.
  • other optical signals may be transmitted in the first optical fiber and the second optical fiber.
  • the first optical fiber and the second optical fiber may also transmit signals. There are classical coherent optical signals. Based on this, in the embodiment of the present application, the laser 101 may output a first optical signal having a different wavelength from other optical signals transmitted in the first optical fiber and the second optical fiber.
  • the beam splitter 102 may include one input port and two output ports.
  • the input port of the beam splitter 102 is connected to the output port of the laser 101.
  • the beam splitter 102 can receive the first optical signal sent by the laser 101 through the included input port, and convert the first optical signal according to the beam splitting ratio of the beam splitter 102.
  • An optical signal is divided into a second optical signal and a third optical signal. Among them, since the light intensity of the local oscillator signal is generally stronger, the better, so the light signal with the larger light intensity after the beam splitting can be used as the second light signal, and the light signal with the lower light intensity can be used as the third light signal.
  • the beam splitting ratio of the beam splitter 102 may be 10:90 or 1:99.
  • the beam splitter 102 may output the second optical signal through the included first output port and output the third optical signal through the included second output port.
  • the first output port of the beam splitter 102 may be directly connected to the first optical fiber, or the first output port of the beam splitter 102 may be connected to the first optical fiber through a coupler, so that from the first output port The output second optical signal will be sent as a local oscillator signal through the first optical fiber.
  • the second output port of the beam splitter 102 may be connected to the quantum signal preparation module 103. In this way, the beam splitter 102 can send the third optical signal to the quantum signal preparation module 103 through the second output port.
  • the quantum signal preparation module 103 can receive the third optical signal sent by the beam splitter 102, and modulate the third optical signal based on the random key and reference data, so as to obtain the quantum signal carrying the random key and the reference data. Reference signal.
  • the quantum signal preparation module 103 may include a quantum random number generator 1031, a processing module 1032, a modulator 1033, and an attenuator 1034.
  • the quantum random number generator 1031 is configured to generate a random number and send the random number to the processing module 1032.
  • the processing module 1032 can process the random number according to the protocol standard to generate a random key, and generate a random key for controlling the modulator 1033 to modulate the quantum based on the random key.
  • the processing module 1032 may also generate a control signal for controlling the modulator 1033 to modulate the reference signal according to the stored reference data.
  • the processing module 1032 can send the above two control signals to the modulator 1033.
  • the modulator 1033 can modulate the third optical signal based on the above two control signals to obtain a quantum signal and a reference signal, and cause the quantum signal and the reference signal to be located in different frequency bands respectively; the modulator 1033 sends the modulated signal to attenuation
  • the attenuator 1034 and the attenuator 1034 attenuate the strength of the modulated signal, thereby obtaining a quantum signal carrying a random key and a reference signal carrying reference data.
  • the quantum signal preparation module 103 may send the quantum signal and the reference signal in a time division manner, that is, the processing module 1032 in the quantum signal preparation module 103 may be within a certain period of time. , Generating a quantum control signal for controlling the modulator 1033 according to the random key, and further controlling the modulator 1033 for modulation by the quantum control signal to obtain a quantum signal. In another period different from this period, a reference control signal for controlling the modulator 1033 may be generated based on the reference data, and the modulator 1033 may be modulated according to the reference control signal to obtain a reference signal.
  • the quantum signal preparation module 103 may also send the quantum signal and the reference signal in a polarization multiplexing manner, that is, When the quantum signal preparation module 103 inputs the quantum signal and the reference signal to the channel, the polarization directions of the quantum signal and the reference signal may be orthogonal.
  • the modulator may be a dual polarization modulator, for example, a dual polarization orthogonality. Phase shift keying (Dual Polarization-Quadrature Phase Shift Keying, DP-QPSK) modulator.
  • DP-QPSK Phase shift keying
  • the polarization controller 104 may include a first input port, a second input port, and an output port.
  • the polarization controller 104 may receive the quantum signal and the reference signal sent by the quantum signal preparation module 103 through the first input port included, and receive the first control signal through the second input port. After that, the polarization controller 104 may receive the first control signal according to the first control signal.
  • the polarization direction of the quantum signal and the reference signal is adjusted, and the adjusted quantum signal and the adjusted reference signal are output through an included output port.
  • the output port of the polarization controller 104 may be directly connected to the second optical fiber, or may be connected to the second optical fiber through a coupler. In this way, the adjusted quantum signal and the adjusted reference output from the output port of the polarization controller 104 The signal can be sent through the second fiber.
  • the first control signal may be a control signal generated and fed back by the quantum key receiving device based on a detection result obtained by detecting the reference signal and the local oscillator signal.
  • the quantum key receiving device may generate and feed back the polarization direction control information only based on the detection result obtained by detecting the reference signal and the local oscillator signal, and the quantum key sending device may The polarization direction control information is processed to obtain a first control signal.
  • the quantum key transmitting apparatus may further include a receiver 105 and a processor 106.
  • the receiver 105 is configured to receive the polarization direction control information and send the polarization direction control information to the processor 106; the processor 106 is configured to receive the polarization direction control information, process the polarization direction control information, and obtain a first control signal, and Sending a first control signal to the polarization controller 104; the polarization controller 104 is specifically configured to adjust the polarization directions of the quantum signal and the reference signal based on the first control signal.
  • the receiver 105 may include an input port and an output port. Through this input port, the receiver 105 can receive the polarization direction control information fed back by the quantum key receiving device.
  • the polarization direction control information may be angle information indicating a polarization angle to be adjusted. After receiving the polarization direction control information, the receiver 105 may output the polarization direction control information to the processor 106 through an output port.
  • the processor 106 may include an input port and an output port.
  • the input port included in the processor 106 is connected to the output port of the receiver 105. In this way, the processor 106 may receive the polarization direction control information sent by the receiver 105 through the included input port. .
  • the output port included in the processor 106 may be connected to the second input port of the polarization controller 104. In this way, after the processor 106 processes the polarization direction control information to obtain the first control signal, the output port may be included through the included output port. A first control signal is sent to the polarization controller 104.
  • the quantum key receiving device since the quantum key receiving device usually encodes the angle to be adjusted and sends it, after the receiver 105 sends the received polarization direction control information to the processor 106, the processor 106 can receive the received information according to the quantum key.
  • the protocol standard negotiated in advance by the device decodes the polarization direction control information to obtain the polarization angle to be adjusted. After that, the processor 106 can generate an analog signal according to the polarization angle, and the analog signal is used to control the polarization controller.
  • the polarization controller 104 can adjust the polarization direction of the quantum signal and the reference signal sent by the quantum signal preparation module 103 based on the first control signal, and then obtain the adjusted quantum signal. And reference signals.
  • the quantum key receiving device may further include a beam splitter 107 and a reference signal preparation module 108.
  • the input port of the beam splitter 107 is connected to the second output port of the beam splitter 102, the first output port of the beam splitter 107 is connected to the modulator 1033 included in the quantum signal preparation module 103, and the second The output port is connected to the reference signal preparation module 108.
  • the beam splitter 107 can receive the third optical signal sent by the beam splitter 102 through the second output port through the included input port.
  • the beam splitter 107 may divide the third optical signal into two optical signals, wherein the beam splitter 107 may pass one of the two optical signals through the included first output
  • the port is sent to the modulator 1033, and another optical signal is sent to the reference signal preparation module through the second output port.
  • the modulator 1033 in the quantum signal preparation module 103 can receive the optical signal sent by the beam splitter 107 and modulate the received optical signal with reference to the method described above, so that the first reference signal and the quantum signal are located in different frequency bands, respectively. .
  • the reference signal preparation module 108 may receive another optical signal sent by the beam splitter 107 and modulate the received optical signal to obtain a second reference signal, where the second reference signal, the first reference signal, and the quantum signal They are in different frequency bands.
  • the reference signal preparation module 108 may include a frequency shifter 1081, a processing module 1082, a modulator 1083, and an attenuator 1084.
  • the second output port of the beam splitter 107 is connected to the input port of the frequency shifter 1081.
  • the frequency shifter 1081 can receive another optical signal sent by the beam splitter 107 through the included input port.
  • the frequency shifter 1081 may perform a small frequency offset on the received optical signal. After that, the frequency shifter 1081 can send the frequency-shifted optical signal to the modulator 1083.
  • the processing module 1082 may generate a control signal for controlling the modulator 1084 to modulate the reference signal according to the stored reference data. After that, the processing module 1082 may send the control signal to the modulator 1083 through the output port.
  • the modulator 1083 includes two input ports and one output port.
  • the first input port of the modulator 1083 can be connected to the output port of the frequency shifter 1081. In this way, the modulator 1083 can receive the frequency-shifted optical signal sent by the frequency shifter 1081 through the included first input port.
  • the second input port of the modulator 1083 is connected to the output port of the processing module 1082. In this way, through the included second input port, the modulator 1083 can receive the control signal sent by the processing module 1082 for modulating the second reference signal. After receiving the control signal sent by the processing module 1082, the modulator 1083 can modulate the frequency-shifted optical signal sent by the received frequency shifter 1081 based on the control signal, and send the modulated signal to the output port through Attenuator 1084.
  • the modulated signal carries the same reference data as the first reference signal.
  • the attenuator 1084 can attenuate the modulated signal to obtain a second reference signal, and send the second reference signal to the polarization controller 104.
  • the polarization controller 104 can receive the first reference signal, the quantum signal, and the second reference signal. At the same time, the polarization controller 104 can also receive the first control signal, and the first reference signal, the quantum signal, and the second reference signal are received according to the first control signal. The polarization direction of the reference signal is adjusted. After that, the polarization controller can send the first reference signal, the quantum signal, and the second reference signal after adjusting the polarization direction through the included output port through the second optical fiber.
  • the A reference signal preparation module is set in the key sending device, and the second reference signal can be generated by a separate reference signal preparation module.
  • the light intensity of the second reference signal can be controlled separately, thereby making the light of the second reference signal strong.
  • the first reference signal and the second reference signal are sent to the receiving end at the same time.
  • the receiving end receives two reference signals, that is, the light intensity of the reference signal will be greatly increased.
  • the key information carried in the quantum signal can be recovered more accurately.
  • the quantum signal preparation module 103 may include a quantum random number generator 1031, a processing module 1032, and a modulator 1033; the reference signal preparation module 108 may include a frequency shifter 1081, a processing module 1082, and a modulator 1083.
  • the above device functions are consistent with the description of the embodiment in FIG. 5, and details are not described herein again.
  • the output of the modulator 1033 and the output of the modulator 1083 are connected to the polarization controller 104. After the polarization adjustment, the adjusted signal is sent to the attenuator 109 to obtain the adjusted first reference signal and the second reference signal. And quantum signals, and sent out through the second fiber.
  • the light intensity of the signal assigned to the reference signal preparation module 108 by the beam splitter 107 is higher than the light intensity assigned to the quantum signal preparation module 103.
  • the quantum key sending device may send a local oscillator signal through a first optical fiber, and send an adjusted quantum signal and a reference signal through a second optical fiber.
  • the first optical fiber and the second optical fiber may be optical fibers specially provided between the quantum key transmitting device and the quantum key receiving device for quantum communication.
  • a quantum communication system including a quantum key transmitting device and a quantum key receiving device can share two optical fibers with a classical coherent communication system for signal transmission.
  • the first optical fiber and the second optical fiber in the embodiments of the present application can be used not only for quantum communication, but also for transmitting coherent optical signals in a classic coherent communication system.
  • the wavelength of the second optical signal may be different from that of other coherent optical signals in the first optical fiber.
  • the wavelength of the third optical signal used to generate the quantum signal and the reference signal can also be The wavelengths of other coherent optical signals transmitted in the second fiber are different.
  • the transmission direction of the coherent optical signal transmitted in the second optical fiber is opposite to the transmission direction of the quantum signal transmitted in the second optical fiber.
  • the quantum key sending device may adjust the polarization direction of the quantum signal and the reference signal through a polarization controller, and send the local oscillator signal and the adjusted quantum signal to different optical fibers for transmission.
  • the quantum key receiving device as the receiving end does not need to introduce additional optical path differences for delay. Time compensation, so that the receiving end can be integrated and miniaturized.
  • the limitation on the strength of the local oscillator signal caused by the limited extinction ratio of the polarization multiplexing device is solved, and the received signal-to-noise ratio is improved.
  • the optical fiber used to transmit quantum signals no longer needs to allocate resources for the transmission of local oscillator signals, that is, all resources in the optical fiber can be used for quantum signals. Transmission, increasing the transmission ratio of quantum signals per unit time.
  • a polarization controller 104 can be provided in the quantum key transmitting device, and the polarization controller 104 can control the polarization direction according to the detection result of the quantum key receiving device according to the detection result.
  • the polarization controller is set in a quantum signal path, because the prepared quantum signal can be sent to the second optical fiber for transmission after passing through the polarization controller, and the polarization controller
  • the signal itself has a certain attenuation effect. Therefore, when the modulated third optical signal is attenuated to obtain a quantum signal, the attenuator can reduce the attenuation of the signal accordingly and reduce the workload of the attenuator.
  • the polarization controller is disposed after the quantum signal preparation module.
  • the polarization controller may be disposed inside the quantum signal preparation module.
  • the device includes a laser 201, a beam splitter 202, a quantum signal preparation module 203, and a polarization control module 204.
  • the quantum signal preparation module 203 includes a quantum random number generator 2031, a processing module 2032, and a modulator 2033.
  • the polarization control module 204 includes a polarization controller 2041 and an attenuator 2042.
  • the function of the laser 201 reference may be made to the explanation of the laser 101 in the foregoing embodiment, and the function of the beam splitter 202 may refer to the description of the beam splitter 102 in the foregoing embodiment, which is not repeatedly described in this embodiment of the present application.
  • the quantum random number generator 2031 included in the quantum signal preparation module 203 is used to generate a random number, and sends the random number to the processing module 2032.
  • the processing module 2032 can process the random number according to the protocol standard to generate a random key, and generate a random key for controlling the modulator 2033 to modulate the quantum based on the random key. In addition to the control signal of the signal, the processing module 2032 may also generate a control signal for controlling the modulator 2033 to modulate the reference signal according to the stored reference data. After that, the processing module 2032 can send the above two control signals to the modulator 2033.
  • the modulator 2033 can receive the control signal sent by the processing module 2032 and the third optical signal sent by the beam splitter 202, and modulate the third optical signal based on the control signal to obtain a quantum signal and a reference signal, and make the quantum signal and the reference
  • the signals are respectively located in different frequency bands, and the modulator 2033 sends the modulated signal to the polarization controller 2041.
  • the polarization controller 2041 may be configured to receive the first control signal and the modulated signal sent by the modulator 2033, and adjust the polarization direction of the modulated signal based on the first control signal, and send the adjusted polarization direction to the attenuator 2042.
  • the first control signal may be a control signal generated and fed back by a quantum key receiving device based on a detection result obtained by detecting a reference signal and a local oscillator signal.
  • the attenuator 2042 is used to attenuate the strength of the signal after adjusting the polarization direction, thereby obtaining a quantum signal carrying a random key and a reference signal carrying reference data, and sending the quantum signal and the reference signal through a second optical fiber.
  • the quantum key sending apparatus may further include a receiver 205 and a processor 206.
  • a receiver 205 and the processor 206 For the functions of the receiver 205 and the processor 206, reference may be made to the functions of the receiver 105 and the processor 106 in the foregoing embodiments, and details are not described herein again in this embodiment of the present application.
  • the polarization controller is between the modulator and the attenuator, that is, the polarization controller can be set in a quantum signal path. Because the polarization controller itself has a certain attenuation effect on the signal, the polarization controller is The controller is set before the attenuator, and the intensity of the signal after the polarization direction is adjusted by the polarization controller will be reduced. In this way, when the attenuator attenuates the signal after the polarization direction is adjusted, the attenuation strength can be appropriately reduced, which reduces the Attenuator workload.
  • the polarization controller is disposed on the quantum signal path for adjusting the polarization directions of the quantum signal and the reference signal.
  • the polarization controller may also be disposed on the local oscillator signal path, that is, used to adjust the polarization direction of the local oscillator signal.
  • the device includes a laser 301, a beam splitter 302, a polarization controller 303, and a quantum signal preparation module 304.
  • the laser 301 is configured to output a first optical signal.
  • the beam splitter 302 is configured to receive a first optical signal, divide the first optical signal into a second optical signal and a third optical signal, send a second optical signal to the polarization controller 303, and send the second optical signal to the quantum signal preparation module 103.
  • the third optical signal wherein the light of the second optical signal is stronger than the light intensity of the third optical signal; the polarization controller 303 is configured to adjust the polarization direction of the second optical signal and pass the adjusted second optical signal through the first A fiber is sent out.
  • the quantum signal preparation module 304 is configured to modulate the third optical signal to obtain a quantum signal and a reference signal, and send the quantum signal and the reference signal through a second optical fiber.
  • the beam splitter 302 may include one input port and two output ports.
  • the input port of the beam splitter 302 is connected to the output port of the laser 101.
  • the beam splitter 302 can receive the first optical signal sent by the laser 301 through the included input port, and the first optical signal sent by the beam splitter 302
  • An optical signal is divided into a second optical signal and a third optical signal.
  • the beam splitting ratio of the beam splitter 302 may be 10:90 or 1:99.
  • the beam splitter 302 may output the second optical signal through the included first output port, and output the third optical signal through the included second output port.
  • the first output port of the beam splitter 102 is connected to the first input port of the polarization controller 303.
  • the second optical signal can be sent to the polarization controller 303 through the first output port of the beam splitter.
  • the second output port of the beam splitter 302 may be connected to the quantum signal preparation module 304. In this way, the beam splitter 302 can send the third optical signal to the quantum signal preparation module 304 through the second output port.
  • the polarization controller 303 may include a first input port, a second input port, and an output port.
  • the polarization controller 303 may receive the second optical signal sent by the beam splitter 302 through the included first input port, and receive the first control signal through the second input port. After that, the polarization controller 303 may receive the second control signal according to the first control signal. The polarization direction of the second optical signal is adjusted, and the adjusted second optical signal is output through an included output port.
  • the output port of the polarization controller 303 may be directly connected to the first optical fiber, or may be connected to the first optical fiber through a coupler or a circulator. In this way, the polarization controller 303 may use the adjusted second optical signal as a local oscillator signal. Send it out through the first fiber.
  • the first control signal may be a control signal generated and fed back by the quantum key receiving device based on a detection result obtained by detecting the reference signal and the local oscillator signal.
  • the quantum key sending apparatus may further include a receiver 305 and a processor 306.
  • the quantum key receiving device can generate and feedback the polarization direction control information according to the detection result obtained by detecting the reference signal and the local oscillator signal, and the quantum key transmitting device can receive the polarization direction through the receiver 305
  • the control information is processed by the processor 306 to obtain the first control signal.
  • the implementation of the quantum signal preparation module 304 can also refer to the related implementation of the quantum signal preparation module 103 shown in FIG. 4 in the foregoing embodiment, and can also refer to the implementation of the quantum signal preparation module 203 shown in FIG. 6 in the foregoing embodiment. Related implementation manners are not repeated in the embodiments of the present application.
  • the output port of the quantum signal preparation module 304 may be directly connected to the second optical fiber, or may be connected to the second optical fiber through a coupler or a circulator. In this way, after preparing the quantum signal and the reference signal, the quantum signal preparation module 304 can send the quantum signal and the reference signal through the second optical fiber.
  • the quantum key sending device further includes a beam splitter 307 and a reference signal preparation module 308.
  • the beam splitter 307 is configured to split the third optical signal into two beams, one A beam is sent to the quantum signal preparation module 304, and another beam is sent to the reference signal preparation module 308;
  • the reference device preparation module may refer to a related implementation manner of the reference signal preparation module 108 shown in FIG. 5 in the foregoing embodiment, This application does not limit this.
  • the quantum key sending device can adjust the polarization direction of the local oscillator signal through a polarization controller, and send the quantum signal and the adjusted local oscillator signal to different optical fibers for transmission. It is necessary to isolate the local oscillator signal and the quantum signal by time division multiplexing and polarization multiplexing. On this basis, the quantum key receiving device does not need to introduce additional optical path difference for delay compensation, so that The receiving end can be integrated and miniaturized. Moreover, since it is no longer necessary to isolate by time division multiplexing, the limitation on the strength of the local oscillator signal due to the limited extinction ratio of the polarization multiplexing device is solved, and the received signal-to-noise ratio is improved.
  • the optical fiber used to transmit quantum signals no longer needs to allocate resources for the transmission of local oscillator signals, that is, all resources in the optical fiber can be used for quantum signal transmission. Transmission increases the transmission ratio of quantum signals per unit time.
  • the polarization rotation of the local oscillator signal and the quantum signal is different during the transmission process.
  • a polarization controller can be provided in the quantum key sending device, and the polarization controller can use the polarization controller to control the polarization direction control information fed back by the quantum key receiving device according to the detection result.
  • Adjust the polarization direction of the local oscillator signal so that the polarization direction of the local oscillator signal received by the quantum key receiving device and the polarization direction of the received quantum signal can be kept consistent or the difference between the two is fixed, or The polarization direction of the received local oscillator signal can always be stabilized in one polarization direction, so as to improve the interference effect between the quantum signal and the local oscillator signal, thereby ensuring the accuracy of the detection result.
  • the foregoing embodiment mainly introduces a quantum key sending device provided by an embodiment of the present application.
  • the quantum key transmitting device can not only send the local oscillator signal and the quantum signal to different optical fibers for transmission, but also can adjust the polarization direction of the quantum signal or the local oscillator signal to make the quantum key receiving device as the receiving end.
  • the received local oscillator signal and quantum signal can maintain the same polarization direction or fixed direction difference after different polarization rotations, or the local oscillator signal or quantum signal received by the quantum key receiving device can always be stabilized at one polarization. Direction to ensure the accuracy of the detection results.
  • the quantum key sending device may not include a polarization controller, that is, the quantum key sending device may only be responsible for sending the local oscillator signal and the quantum signal to different optical fibers, respectively. Transmission, and the polarization direction of the received local oscillator signal or quantum signal is adjusted by the quantum key receiving device, so that the local oscillator signal and the quantum signal can maintain the same polarization direction or direction after different polarization rotations occur The difference is fixed.
  • an embodiment of the present application provides a quantum key receiving apparatus.
  • the device includes a quantum detection module 401 and a polarization control module 402.
  • the polarization control module 402 is configured to receive the local oscillator signal from the first optical fiber and adjust the polarization direction of the local oscillator signal.
  • the vector detection module 401 sends the adjusted local oscillator signal;
  • the quantum detection module 401 is configured to receive the local oscillator signal from the second optical fiber.
  • the quantum signal and the reference signal detect the adjusted local oscillator signal, the quantum signal, and the reference signal to obtain a detection result.
  • the quantum signal carries a random key, and the detection result includes key information of the random key.
  • the polarization control module 402 may include a polarization controller 4021.
  • the polarization controller 4021 may include a first input port, a second input port, and an output port.
  • the first input port of the polarization controller 4021 may be directly connected to the first optical fiber, or the first input port of the polarization controller 4021 may be connected to the first optical fiber through a coupler or a circulator.
  • the polarization controller 4021 can receive the local oscillator signal sent by the quantum key transmitting device through the first optical fiber.
  • the polarization controller 4021 can receive the second control signal generated by the quantum detection module 401 based on the detection result of the local oscillator signal and the reference signal before the current time. After that, the polarization controller may adjust the polarization direction of the local oscillator signal to the first polarization direction based on the second control signal, and send the adjusted local oscillator signal to the vector detection module.
  • the first polarization direction may be related to the quantum signal.
  • the polarization direction of is the same, or it can be a fixed direction difference from the polarization direction of the quantum signal.
  • the reference signal carries reference data, which is negotiated in advance between the quantum key sending device and the quantum key receiving device.
  • the polarization direction of the reference signal is consistent with the polarization direction of the quantum signal.
  • the polarization controller 4021 receives the local oscillator signal for the first time, the local oscillator signal is adjusted to a preset polarization direction, and the vector sub-signal detection module 401 sends the adjusted local oscillator signal.
  • the vibration signal that is, if the local oscillation signal is received for the first time, the polarization of the local oscillation signal is adjusted to the first polarization direction during the first adjustment, which means that the local oscillation signal is adjusted to a preset polarization direction .
  • the quantum detection module 401 may include a first input port, a second input port, and an output port.
  • the first input port includes a quantum signal and a reference signal sent by the quantum key sending device through the second optical fiber. Through the included second input port, the quantum detection module 401 can receive the adjusted local oscillator signal.
  • the quantum detection module 401 may, when receiving the quantum signal and the reference signal, extract a reference signal from a frequency band where the reference signal is located, and The reference signal and the interference signal of the adjusted local oscillator signal are detected to obtain the reference data measurement value.
  • the interference effect between the reference signal and the adjusted local oscillator signal is better, that is, the polarization direction of the adjusted local oscillator signal is appropriate Because the polarization direction of the reference signal and the quantum signal are the same, the interference effect of the adjusted local oscillator signal when it interferes with the quantum signal will also be better.
  • the quantum detection module 401 can The interference signal of the adjusted local oscillator signal is measured to obtain a detection result, and then the key information of the random key is obtained according to the detection result.
  • the quantum detection module 401 may generate a second control signal according to a difference between the reference data measurement value and the reference data, and output the second control signal to the polarization controller 4021 through an output port.
  • the quantum detection module 401 may determine the relationship between the reference signal and the local oscillator signal by continuously adjusting the direction of the local oscillator signal when receiving the reference signal.
  • the quantum detection module 401 may be a quantum detector that detects a signal with a single polarization direction, or a quantum detector that detects a signal with an orthogonal polarization direction, which is not limited in this application.
  • the polarization controller 4021 may further include a second input port, which is connected to the output port of the quantum detection module 401, and is configured to receive a second control signal sent by the quantum detection module 401, and to receive a current received signal based on the second control signal.
  • the polarization direction of the local oscillator signal is adjusted, and the adjusted local oscillator signal is re-transmitted by the vector detection module until the difference between the reference data measurement value detected by the quantum detection module 401 and the reference data is not greater than the allowable deviation, Then, according to the polarization direction of the local oscillator signal adjusted last time, the polarization direction of the subsequent received local oscillator signals is adjusted.
  • the polarization control mode 402 may include a polarization controller 4021, a beam splitter 4022, and a polarization analyzer 4023.
  • the beam splitter 4022 is configured to receive the local oscillator signal from the first optical fiber, divide the local oscillator signal into a fourth optical signal and a fifth optical signal, and send the fourth optical signal to the polarization analyzer 4023, and to the polarization controller 4021.
  • the fifth optical signal is sent, and the light intensity of the fourth optical signal is less than that of the fifth optical signal; the polarization analyzer 4023 is configured to receive the fourth optical signal, analyze the polarization direction of the fourth optical signal, and based on the fourth optical signal's A third control signal is generated by the polarization direction and the target polarization direction, and the third control signal is sent to the polarization controller 4021; the polarization controller 4021 is configured to receive the fifth optical signal and the third control signal, and convert the fifth optical signal based on the third control signal
  • the polarization direction is adjusted to the target polarization direction, and the vector sub-detection module 401 sends the adjusted fifth optical signal; the quantum detection module 401 is specifically configured to receive the adjusted fifth optical signal, and receive the quantum signal and the reference signal from the second optical fiber , Detecting the adjusted fifth optical signal, the quantum signal, and the reference signal to obtain a detection result.
  • the beam splitter 4022 includes an input port, a first output port, and a second output port.
  • the input port of the beam splitter 4022 may be directly connected to the first optical fiber, or may be connected to the first optical fiber through a coupler or a circulator. In this way, through the included input port, the beam splitter 4022 can receive a quantum key transmitting device.
  • a local oscillator signal sent through the first optical fiber. After that, the beam splitter 4022 can divide the received local oscillator signal into a fourth optical signal and a fifth optical signal according to a certain beam splitting ratio. The fourth optical signal will be used to analyze the polarization direction.
  • the light intensity can be small, and the fifth optical signal will interfere with the quantum signal and the reference signal as the local oscillator signal. Therefore, it is necessary to ensure that the light intensity of the fifth optical signal reaches a certain intensity. Based on this, when splitting by the beam splitter 4022, the light intensity of the fourth optical signal can be relatively small.
  • the beam splitting ratio may be 1:99, and beam splitting is performed according to the beam splitting ratio to obtain a fourth optical signal that accounts for 1% of the local oscillator signal and a fifth optical signal that accounts for 99% of the local oscillator signal.
  • the beam splitter 4022 may send the fourth optical signal to the polarization analyzer 4023 through the first output port, and send the fifth optical signal to the polarization controller 4021 through the second output port. .
  • the polarization analyzer 4023 may include an input port and an output port.
  • the input port is connected to the first output port of the beam splitter 4022.
  • the polarization analyzer 4023 can receive the fourth optical signal through the input port.
  • the polarization analyzer can analyze the polarization direction of the fourth optical signal, and compare the polarization direction of the fourth optical signal obtained with the analysis with the target polarization direction, so that The difference between the polarization direction and the target polarization direction generates a third control signal.
  • the third control signal is output through a included output port.
  • the polarization controller 4021 includes a first input port, a second input port, and an output port.
  • the first input port is connected to the second output port of the beam splitter 4022. In this way, the polarization controller 4021 can receive the fifth optical signal output by the beam splitter 4022.
  • the second input port is connected to the output port of the polarization analyzer 4023. In this way, the polarization controller 4021 can receive the third control signal output by the polarization analyzer 4023.
  • the polarization controller 4021 may adjust the polarization direction of the fifth optical signal to the target polarization direction based on the received third control signal, and send the adjusted fifth optical signal through the output port vector sub-detection module 401.
  • the direction deviation between the target polarization direction and the polarization direction of the quantum signal is not greater than a preset value.
  • the direction deviation is 0, it indicates that the polarization directions of the quantum signal and the local oscillator signal are consistent. At this time, The interference effect of the quantum signal and the local oscillator signal is the best.
  • the preset value may be as small as possible.
  • the preset value may be 5 °, 8 °, 10 °, or the like.
  • the quantum detection module 401 can receive the adjusted fifth optical signal sent by the polarization controller 4021, and detect the interference signal between the adjusted fifth optical signal and the quantum signal, thereby obtaining key information including a random key. Detection results.
  • An optical amplifier may also be provided.
  • the optical amplifier may be disposed before the polarization control module, or may be disposed between the polarization control module and the quantum detection module. That is, the quantum key receiving device can receive the local oscillator signal transmitted in the first optical fiber through the optical amplifier, amplify the local oscillator signal, and then output the amplified local oscillator signal to the polarization control module for polarization direction. Adjustment.
  • the quantum key receiving device may perform the polarization direction of the local oscillator signal through the polarization control module, and then input the adjusted local oscillator signal to the optical amplifier module for power amplification, and then output the amplified local oscillator signal to quantum detection. Module.
  • the quantum key receiving device may receive a local oscillator signal and a quantum signal transmitted through two different optical fibers, and obtain a detection result based on the received local oscillator signal and the quantum signal.
  • the quantum signal and the local oscillator signal do not need to be separated by time division multiplexing and polarization multiplexing. Therefore, the quantum key receiving device does not need to introduce an additional optical path difference for delay compensation, thereby making the quantum key receiving device Can be integrated and miniaturized.
  • the quantum key receiving device can adjust the polarization direction of the local signal by setting a polarization control module in the local signal path. So that the polarization direction of the adjusted local oscillator signal and the polarization direction of the quantum signal can be kept consistent or the difference between the two is fixed, or the polarization direction of the adjusted local oscillator signal can always be stabilized in one polarization direction In this way, the interference effect of the quantum signal and the local oscillator signal is improved, thereby ensuring the accuracy of the detection result.
  • the polarization direction of the local oscillator signal is adjusted by setting a polarization control module in the local oscillator signal path.
  • the polarization control module may also be set in a quantum signal path of the quantum key receiving device, and the polarization direction of the quantum signal is adjusted to make the polarization direction of the quantum signal and the local signal polarize by adjusting the polarization direction of the quantum signal.
  • the direction deviation between directions is not greater than a preset value.
  • a quantum key receiving device includes a quantum detection module 501 and a polarization control module 502.
  • the polarization control module 502 is configured to receive the quantum signal and the reference signal from the second optical fiber, and adjust the polarization direction of the quantum signal and the reference signal.
  • the vector detection module 501 sends the adjusted quantum signal and the reference signal; After receiving the local oscillator signal from the first optical fiber, the local oscillator signal, the adjusted quantum signal, and the adjusted reference signal are detected to obtain a detection result.
  • the polarization control module 502 may be a polarization controller.
  • the polarization control module 502 may include a first input port, a second input port, and an output port.
  • the first input port of the polarization control module 502 may be directly connected to the second optical fiber, or the first input port of the polarization control module 502 may be connected to the second optical fiber through a coupler or a circulator.
  • the polarization control module 502 can receive the quantum signal and the reference signal sent by the quantum key transmitting device through the second optical fiber.
  • the polarization control module 502 can receive a fourth control signal generated by the quantum detection module 501 based on the detection results of the local oscillator signal and the reference signal before the current time. Thereafter, the polarization control module 502 may adjust the polarization direction of the quantum signal and the reference signal to the first polarization direction based on the fourth control signal, and the vector detection module 501 sends the adjusted quantum signal and the reference signal.
  • the reference signal carries reference data, which is negotiated in advance between the quantum key sending device and the quantum key receiving device.
  • the polarization direction of the reference signal is consistent with the polarization direction of the quantum signal.
  • the vector sub-signal detection module 501 sends the The adjusted quantum signal and reference signal, that is, if the quantum signal and reference signal are received for the first time, adjusting the polarization of the quantum signal and the reference signal to the first polarization direction during the first adjustment refers to the quantum signal And the reference signal is adjusted to a preset polarization direction.
  • the quantum detection module 501 may include a first input port, a second input port, and an output port.
  • the first input port included can receive the local oscillator signal sent by the quantum key sending device through the first optical fiber.
  • the quantum detection module 501 can receive the adjusted quantum signal and the reference signal sent by the polarization control module 502.
  • the quantum detection module 501 can extract the adjusted quantum signal and the reference signal from the frequency band where the reference signal is located when receiving the adjusted quantum signal and reference signal.
  • the reference signal, and the interference signal of the adjusted reference signal and the local oscillator signal are detected to obtain a reference data measurement value.
  • the quantum The detection module 501 may measure interference signals of the adjusted quantum signal and the local oscillator signal to obtain a detection result, and then obtain key information of a random key according to the detection result.
  • the quantum detection module 501 may generate a fourth control signal according to a difference between the reference data measurement value and the reference data, and output the fourth control signal to the polarization control module 502 through an output port.
  • the polarization control module 502 can receive the fourth control signal sent by the quantum detection module 501 through the included second input port, adjust the polarization direction of the currently received quantum signal and reference signal based on the fourth control signal, and re-vector detection Module 501 sends the adjusted quantum signal and reference signal until the difference between the reference data measurement value and the reference data detected by the quantum detection module 501 is not greater than the allowable deviation, according to the last adjusted quantum signal and reference signal.
  • the polarization direction is used to adjust the polarization direction of the subsequent received quantum signals and reference signals.
  • the polarization control module 502 may determine the interference between the reference signal and the local oscillator signal by continuously adjusting the direction of the reference signal when receiving the reference signal The polarization direction of the reference signal when the effect is the best, and when the quantum signal is received, the quantum signal is adjusted according to the polarization direction of the final reference signal to improve the interference effect between the adjusted local oscillator signal and the quantum signal, thereby ensuring Accuracy of detection results.
  • the quantum key receiving device may receive a local oscillator signal and a quantum signal transmitted through two different optical fibers, and obtain a detection result based on the received local oscillator signal and the quantum signal.
  • the quantum signal and the local oscillator signal do not need to be separated by time division multiplexing and polarization multiplexing. Therefore, the quantum key receiving device does not need to introduce an additional optical path difference for delay compensation, thereby making the quantum key receiving device Can be integrated and miniaturized.
  • the quantum key receiving device does not need to perform polarization compensation, which reduces additional components and line losses.
  • the quantum key receiving device can set the polarization direction of the quantum signal and the reference signal by setting a polarization control module in the quantum signal path. Adjust so that the polarization direction of the adjusted quantum signal is consistent with the polarization direction of the local oscillator signal or the difference between the two is fixed, or the polarization direction of the adjusted quantum signal is always stable at one In the direction of polarization, the interference effect between the quantum signal and the local oscillator signal is improved, thereby ensuring the accuracy of the detection result.
  • the quantum key receiving device described in the above embodiment mainly uses a polarization control module to eliminate the problem of inconsistent polarization rotation caused by using different optical fibers to transmit quantum signals and local oscillator signals.
  • the quantum key receiving apparatus may also eliminate the problem of inconsistent polarization rotation through other implementation manners.
  • a quantum key receiving device includes a first polarization beam splitter 601, a second polarization beam splitter 602, a first quantum heterodyne detector 603, and a second quantum external Difference detector 604 and processor 605.
  • the first polarization beam splitter 601 is configured to receive a local oscillator signal from a first optical fiber, divide the local oscillator signal into a sixth optical signal and a seventh optical signal, and send the sixth optical signal to the first quantum heterodyne detector. , Sending a seventh optical signal to the second quantum heterodyne detector.
  • the first polarization beam splitter 601 may include an input port, a first output port, and a second output port.
  • the input port of the first polarization beam splitter 601 may be directly connected to the first optical fiber, or the input port of the first polarization beam splitter 601 may be connected to the first optical fiber through a coupler or a circulator.
  • the first polarization beam splitter 601 can receive the local oscillator signal sent by the quantum key transmitting device through the first optical fiber.
  • the first polarization beam splitter 601 may divide the local oscillator signal into a sixth optical signal and a seventh optical signal, and output the sixth optical signal through the first output port, and output the seventh optical signal through the second output port.
  • the second polarization beam splitter 602 is configured to receive a quantum signal and a reference signal from a second optical fiber, divide the reference signal into an eighth optical signal and a ninth optical signal, and divide the quantum signal into a tenth optical signal and an eleventh optical signal. Sending an eighth optical signal and a tenth optical signal to the first quantum heterodyne detector, and sending a ninth optical signal and an eleventh optical signal to the second quantum heterodyne detector, and the quantum signal carries a random key.
  • the second polarization beam splitter 602 may include an input port, a first output port, and a second output port.
  • the input port of the second polarization beam splitter 602 may be directly connected to the second optical fiber, or the input port of the second polarization beam splitter 602 may be connected to the second optical fiber through a coupler or a circulator. Through this input port, the second polarization beam splitter 602 can receive the quantum signal and the reference signal sent by the quantum key transmitting device through the second optical fiber.
  • the quantum signal and the reference signal may be sent by time division multiplexing. Therefore, when the second polarization beam splitter 602 receives the reference signal, the reference signal is divided into an eighth optical signal and a ninth optical signal. The eighth optical signal is output through the first output port, and the ninth optical signal is output through the second output port. When receiving a quantum signal, the second polarization beam splitter 602 divides the quantum signal into a tenth optical signal and an eleventh optical signal, and outputs the tenth optical signal through the first output port, and outputs the first through the second output port. Eleven light signals.
  • the first quantum heterodyne detector 603 is configured to receive a sixth optical signal, an eighth optical signal, and a tenth optical signal, and detect interference signals of the sixth optical signal and the eighth optical signal to obtain a regular component of the eighth optical signal.
  • An interference signal between the sixth optical signal and the tenth optical signal is detected to obtain a regular component of the tenth optical signal, and the regular component of the eighth optical signal and the regular component of the tenth optical signal are sent to the processor 605.
  • the first quantum heterodyne detector 603 when the first quantum heterodyne detector 603 receives the sixth optical signal and the eighth optical signal, it can detect interference signals of the sixth optical signal and the eighth optical signal, thereby obtaining a regular component of the eighth optical signal. And sends a regular component of the eighth optical signal to the processor 605.
  • the regular components of the tenth optical signal and the sixth optical signal can be detected to obtain the regular component of the tenth optical signal, and the regular component of the tenth optical signal is sent to the processor 605.
  • the second quantum heterodyne detector 604 is configured to receive the seventh optical signal, the ninth optical signal, and the eleventh optical signal, and detect interference signals of the seventh optical signal and the ninth optical signal to obtain a regular component of the ninth optical signal. , Detecting an interference signal between the seventh optical signal and the eleventh optical signal to obtain a regular component of the eleventh optical signal, and sending the regular component of the ninth optical signal and the regular component of the eleventh optical signal to the processor 605.
  • the second quantum heterodyne detector 604 When the first quantum heterodyne detector 603 receives the eighth optical signal, the second quantum heterodyne detector 604 will receive the ninth optical signal. At this time, the second quantum heterodyne detector 604 may The interference signals of the nine optical signals and the seventh optical signals are detected to obtain a regular component of the ninth optical signal, and the regular component of the ninth optical signal is sent to the processor 605.
  • the first quantum heterodyne detector 603 receives the tenth optical signal
  • the second quantum heterodyne detector 604 will receive the eleventh optical signal. At this time, the second quantum heterodyne detector 604 may detect the tenth optical signal. An interference signal of one optical signal and the seventh optical signal is detected to obtain a regular component of the eleventh optical signal, and the regular component of the eleventh optical signal is sent to the processor 605.
  • the processor 605 receives the regular component of the eighth optical signal, the regular component of the tenth optical signal, the regular component of the ninth optical signal, and the regular component of the eleventh optical signal, and the regular component of the eighth optical signal and the ninth optical signal Processing the regular components of the to obtain the signal parameters, and processing the regular components of the tenth optical signal and the regular components of the eleventh optical signal based on the signal parameters to obtain the initial key, which includes the key of the random key information.
  • the processor 605 may The regular component of the signal and the regular component of the ninth optical signal are processed to obtain a signal parameter, where the signal parameter may include a first intensity transmittance, a second intensity transmittance, a first phase, and a second phase.
  • the first intensity transmittance refers to the intensity transmittance of the signal output from the first output port of the second polarization beam splitter 602 after the reference signal enters the second polarization beam splitter 602.
  • the second intensity transmittance refers to the intensity transmittance of the signal output from the first output port of the first polarization beam splitter 601 after the local oscillator signal enters the first polarization beam splitter 601.
  • the first phase refers to the ninth optical signal determined when the second quantum heterodyne detector 604 receives the ninth optical signal and determines the phase of the eighth optical signal when the first quantum heterodyne detector 603 receives the eighth optical signal.
  • the second phase refers to the sixth optical signal when the first quantum heterodyne detector 603 receives the sixth optical signal and determines the phase of the eighth optical signal when the first quantum heterodyne detector 603 receives the eighth optical signal. The phase.
  • the processor 605 When the processor 605 receives the regular component of the tenth optical signal sent by the first quantum heterodyne detector 603 and the regular component of the eleventh optical signal sent by the second quantum heterodyne detector, it may be based on the determined signal parameters
  • the regular component of the tenth optical signal and the regular component of the eleventh optical signal are processed to obtain an initial key, and the initial key includes key information including a random key.
  • the quantum key sending device may send the quantum signal and the reference signal in a frequency division multiplexing manner.
  • the second polarization beam splitter 602 will receive the quantum at the same time.
  • Signal and reference signal and divide the quantum signal and reference signal into a twelfth light signal and a thirteenth light signal, and output a twelfth light signal through a first output port, and a thirteenth light through a second output port signal.
  • the first quantum heterodyne detector 603 When the first quantum heterodyne detector 603 receives the twelfth optical signal, it can detect the interference signal of the twelfth optical signal and the sixth optical signal, thereby obtaining a regular component of the twelfth optical signal, and processing it
  • the router 605 sends regular components of the twelve optical signals.
  • the second quantum heterodyne detector 604 receives the thirteenth optical signal, it can detect the interference signal between the thirteenth optical signal and the seventh optical signal, thereby obtaining a regular component of the thirteenth optical signal, and sending it to the processor. 605 sends regular components of the thirteen optical signals.
  • the processor 605 may extract the first regular component of the reference signal from the regular components of the twelfth optical signal, and from the regularity of the thirteenth optical signal.
  • the second regular component of the reference signal is extracted from the components, the signal parameter is determined based on the first regular component and the second regular component of the reference signal, and the regular component of the quantum signal in the twelfth optical signal and the thirteenth are based on the signal parameter.
  • the regular component of the quantum signal in the optical signal is processed to obtain the initial key.
  • the processor 605 may change the twelfth optical signal according to the frequency band where the reference signal is located.
  • a regular component of the reference signal and a regular component of the thirteenth optical signal are respectively extracted in a frequency band where the reference signal is located, so as to obtain a first regular component and a second regular component of the reference signal.
  • the quantum key receiving device may separately split the local oscillator signal, the quantum signal, and the reference signal through the first polarization beam splitter and the second polarization beam splitter, and then pass the first quantum heterodyne.
  • the detector and the second quantum heterodyne detector measure the regular component of the reference signal and the regular component of the quantum signal, and then calculate the signal parameters based on the regular component of the reference signal.
  • the regular component of the quantum signal is processed according to the signal parameter. Get the initial key. It can be seen that, in the embodiment of the present application, it is not necessary to set a polarization control module in the quantum key receiving device. The method described above can eliminate the influence of polarization rotation and ensure the accuracy of the obtained key information.
  • the foregoing embodiments mainly introduce the quantum key transmitting device and the quantum key receiving device for quantum key transmission.
  • the embodiment of the present application will provide a quantum key transmission system.
  • the system may include a quantum key transmitting device 701, a quantum key receiving device 702, a first optical fiber 703, and a second optical fiber 704, where the quantum key transmitting device 701 and the quantum key receiving device 702 pass through the first optical fiber 703 and The second optical fiber 704 is used for communication, and the first optical fiber 703 is used for transmitting a local oscillator signal, and the second optical fiber 704 is used for transmitting a quantum signal and a reference signal.
  • the quantum key sending device 701 in the quantum key transmission system may be any kind of quantum key sending device shown in FIG. 1-8.
  • the quantum key receiving device 702 The quantum key receiving device may not include a device for controlling the polarization direction.
  • the quantum key receiving device 702 may include a quantum detection module instead of a polarization control module.
  • the quantum key receiving device 702 in the quantum key transmission system may be any quantum key receiving device shown in FIG. 9-13.
  • the quantum key transmitting device 701 may Does not include polarization controller.
  • the quantum key sending device 701 may include a laser, a beam splitter, and a quantum signal preparation module, but does not include a polarization controller.
  • the quantum key sending device 701 may further include a laser, a beam splitter, and a quantum signal preparation module. Reference signal preparation module without polarization controller.
  • the quantum key sending device 701 in the quantum key transmission system may be any quantum key sending device shown in FIG. 1-8, and the quantum key The quantum key receiving device 702 in the transmission system may be any quantum key receiving device shown in FIGS. 9-13.
  • two optical fibers are used to transmit coherent optical signals to implement bidirectional communication.
  • a quantum key sending device and a quantum key receiving device Communication is also performed through two optical fibers. Based on this, in the embodiment of the present application, the quantum key sending device and the quantum key receiving device can share the two optical fibers with a classic coherent communication system for signal transmission.
  • an embodiment of the present application provides a quantum key transmission system for mixing transmission of quantum signals and coherent optical signals.
  • the system includes a first communication base station 80 and a second communication base station 90.
  • the first communication base station 80 and the second communication base station 20 implement bidirectional communication through the first optical fiber and the second optical fiber.
  • the first communication base station 80 includes a quantum key transmitting device 801, a first coherent optical transmitting device 802, a first coherent optical receiving device 803, a first coupler 804, and a second coupler 805.
  • the second communication base station 90 includes a quantum key receiving device 901, a second coherent optical receiving device 902, a second coherent optical transmitting device 903, a third coupler 904, and a fourth coupler 905.
  • the first coherent optical transmitting device 802 is connected to the first optical fiber through a first coupler, and is configured to send a coherent optical signal to the second coherent optical receiving device 902 through the first optical fiber.
  • the second coherent optical transmitting device 903 is connected to the first coherent optical transmitting device 903 through a fourth coupler.
  • the second optical fiber connection is configured to send a coherent optical signal to the first coherent optical receiving device 803 through the second optical fiber. That is, coherent signal transmission from the first communication base station 80 to the second communication base station 90 can be achieved by the first coherent optical transmitting device 802 and the second coherent optical receiving device 902.
  • the second coherent optical transmitting device 903 and the first coherent optical receiving device 803 can implement coherent signal transmission from the second communication base station 90 to the first communication base station 80.
  • the quantum key transmitting device 801 and the coherent optical signal transmitted by the first coherent optical transmitting device 802 are transmitted on the first optical fiber at the same time, the quantum key transmitting device 801 and the first coherent light are transmitted.
  • the transmitting device 802 can be connected to the first optical fiber through the first coupler 804. In this way, when receiving the local oscillator signal sent by the quantum key transmitting device 801 and the coherent optical signal sent by the first coherent optical transmitting device 802, the first coupler 804 can couple the local oscillator signal and the coherent optical signal, and Send it through the first connected fiber.
  • the wavelength of the local oscillator signal is different from the wavelength of the coherent optical signal.
  • the third coupler 904 is connected to the first optical fiber.
  • the third coupler 904 can receive the signal transmitted by the first optical fiber that is coupled by the coherent optical signal and the local oscillator signal, and decode the received signal. Coupled to obtain the local oscillator signal and the coherent optical signal sent by the first coherent optical transmitting device 802. After that, the third coupler 904 may send the coherent optical signal sent by the first coherent optical transmitting device 802 to the second coherent optical receiving device 902, and send the local oscillator signal to the quantum key receiving device 901.
  • the quantum key sending device 801 is connected to the second optical fiber through the second coupler 805, so that the quantum key sending device 801 can send the quantum signal and the reference signal to the second coupler 805, and the second coupling The coupler 805 sends the quantum signal and the reference signal to the fourth coupler 905 through the second optical fiber.
  • the second coupler 805 may also be configured to receive a coherent optical signal sent by the fourth coupler 905 through the second optical fiber, and send the coherent optical signal to the first coherent optical receiving device 803.
  • the fourth coupler 905 is configured to receive the quantum signal and the reference signal from the second optical fiber, and send the quantum signal and the reference signal to the quantum key receiving device 901. At the same time, the fourth coupler 905 is further configured to receive a coherent optical signal sent by the second coherent optical transmitting device 903 and send the coherent optical signal to the first coherent optical receiving module 803 through the second optical fiber and the second coupler. .
  • the first coupler 804, the second coupler 805, the third coupler 904, and the fourth coupler 905 can all be wavelength-selectable couplers.
  • they can be Wavelength Division Multiplexing (WDM). Coupler.
  • WDM Wavelength Division Multiplexing
  • the first communication base station may include multiple quantum key sending devices, and accordingly, the second communication base station may include a quantum secret The same number of quantum key receiving devices as the key transmitting devices are provided, and the multiple quantum key transmitting devices of the first communication base station and the quantum key receiving devices in the second communication base station correspond one-to-one.
  • the first communication base station may further include a plurality of quantum key receiving devices, and accordingly, the second communication base station may include a quantum corresponding to each of the plurality of quantum key receiving devices. Key transmission device to realize two-way transmission of quantum signals.
  • the quantum key sending device and the quantum key receiving device can share two optical fibers with a classic coherent communication system for signal transmission. In this way, not only the receiving end is integrated, miniaturized, and additional components are reduced. And line loss, and realize the mixing of classical coherent optical signals and quantum signals.
  • the program may be stored in a computer-readable storage medium.
  • the storage medium mentioned may be a read-only memory, a magnetic disk or an optical disk.

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Abstract

本申请公开了一种量子密钥传输装置及系统，属于量子通信技术领域。在本申请中，量子密钥传输装置可以通过偏振控制器调整量子信号和参考信号的偏振方向，并将本振信号和调整后的量子信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，接收端的量子信号接收机中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。

Description

量子密钥传输装置及系统
本申请要求于2018年07月23日提交的申请号为201810813907.8、申请名称为“量子密钥传输装置及系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及量子通信技术领域，特别涉及一种量子密钥传输装置及系统。
背景技术
量子保密通信是近三十年来发展起来的一种新型的通信技术。量子保密通信是量子特性与传统密码结合的产物，主要利用量子力学的基本原理和特性来确保通信的安全性。当前，量子保密通信中最接近实用的技术是量子密钥传输。其中，量子密钥传输是指将随机密钥携带在量子信号中进行传输。
在现有技术中，当进行量子密钥传输时，发送端可以制备本振信号和量子信号，并将本振信号和量子信号通过同一信道向接收端传输。由于本振信号的光强要远远大于量子信号的光强，因此，本振信号很容易对量子信号产生串扰。为了减小本振信号对量子信号的串扰，发送端通常可以采用时分复用和偏振复用对本振信号和量子信号进行隔离。其中，时分复用是指本振信号和量子信号的发送时刻有所差别，偏振复用是指本振信号和量子信号在进入光纤时的偏振方向是正交的。
当采用时分复用来传输本振信号和量子信号时，接收端在接收到本振信号和量子信号之后，需要引入额外的光程差来补偿量子信号和本振信号之间的延时，这将导致接收端无法使用集成光学芯片，无法小型化。而采用偏振复用来传输本振信号和量子信号时，偏振复用器件的有限消光比将会限制本振信号的强度，导致接收端的信噪比下降。
发明内容
本申请提供了一种量子密钥传输装置及系统，可以用于解决采用时分复用和偏振复用来隔离量子信号和本振信号时，所导致的接收端无法小型化且信噪比下降的问题。所述技术方案如下：
第一方面，提供了一种量子密钥接收装置，所述装置包括激光器、分束器、量子信号制备模块和偏振控制模块；
所述激光器用于输出第一光信号；
所述分束器用于接收所述第一光信号，将所述第一光信号分为第二光信号和第三光信号，将所述第二光信号通过第一光纤发送出去，并向所述量子信号制备模块发送所述第三光信号；
所述量子信号制备模块用于，对所述第三光信号进行调制，得到第一调制信号和第二调制信号，向所述偏振控制模块发送所述第一调制信号和所述第二调制信号，其中，所述第一调制信号携带待传输的随机密钥，所述第二调制信号携带待传输的参考数据；
所述偏振控制模块用于，对所述第一调制信号和所述第二调制信号的偏振方向进行调整， 以及对所述第一调制信号和所述第二调制信号的光强进行衰减，得到量子信号和参考信号，其中，所述量子信号和所述参考信号通过第二光纤发送出去。
在本申请实施例中，量子密钥发送装置可以通过偏振控制器调整量子信号和参考信号的偏振方向，并将本振信号和调整后的量子信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，接收端的量子信号接收机中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。并且，由于不再需要偏振复用来传输本振信号和量子信号，因此，解决了由于偏振复用器件的有限消光比所导致的对本振信号的强度的限制，提高了接收到的信噪比。另外，由于不再需要通过时分复用进行隔离，因此，用于传输量子信号的光纤不再需要分配资源用于本振信号的传输，也即，该光纤中的全部资源均可以用于量子信号的传输，提高了单位时间内量子信号的传输比例。
在一种可能的实现方式中，所述第二光信号的光强大于所述第三光信号的光强。
在一种可能的实现方式中，所述装置还包括接收器和处理器，
所述接收器用于接收偏振方向控制信息，并向所述处理器发送所述偏振方向控制信息；
所述处理器用于对所述偏振方向控制信息进行处理，得到第一控制信号，并向所述偏振控制器发送所述第一控制信号；
所述偏振控制模块具体用于，基于所述第一控制信号对所述第一调制信号和所述第二调制信号的偏振方向进行调整。
其中，偏振方向控制信息可以是接收端根据对参考信号和本振信号进行探测生成的探测结果反馈的用于指示要调整的偏振角度的角度信息。
在一种可能的实现方式中，所述量子信号制备模块包括量子随机数发生器、处理器和调制器；所述量子随机数发生器用于产生随机数，并向所述处理器发送所述随机数；所述处理器用于根据所述随机数，生成随机密钥，并根据所述随机密钥生成量子控制信号；还用于根据存储的参考数据生成参考控制信号，将所述量子控制信号和所述参考控制信号发送给所述调制器；所述调制器用于根据所述量子控制信号对所述第三光信号进行调制，得到第一调制信号；根据所述参考控制信号对所述第三光信号进行调制，得到第二调制信号；将所述第一调制信号和所述第二调制信号发送给所述偏振控制模块。
在一种可能的实现方式中，所述偏振控制模块包括偏振控制器和衰减器；所述偏振控制器用于对所述第一调制信号和所述第二调制信号的偏振方向进行调整，将调整后的第一调制信号和调整后的第二调制信号发送给所述衰减器；所述衰减器用于对所述调整后的第一调制信号进行衰减，得到所述量子信号；对所述调整后的第二调制信号进行衰减，得到所述参考信号。
在一种可能的实现方式中，所述偏振控制模块包括偏振控制器和衰减器；所述衰减器用于对所述第一调制信号和所述第二调制信号进行衰减，得到衰减后的第一调制信号和衰减后的第二调制信号，将所述衰减后的第一调制信号和所述衰减后的第二调制信号发给所述偏振控制器；所述偏振控制器，用于对所述衰减后的第一调制信号的偏振方向进行调整，得到所述量子信号；对所述衰减后的第二调制信号的偏振方向进行调整，得到所述参考信号。
在一种可能的实现方式中，所述第二光信号与所述第一光纤中传输的其他光信号的波长不同，所述第三光信号与所述第二光纤中传输的其他光信号的波长不同。
在一种可能的实现方式中，所述第二光纤还用于传输相干光信号，且所述第二光纤中传输的相干光信号的传输方向和所述第二光纤中传输的量子信号的传输方向相反。
在本申请实施例中，将偏振控制器设置在量子密钥接收装置的量子信号路，根据量子密钥接收装置根据探测结果反馈的偏振方向控制信息来调整量子信号的偏振方向，以使得量子密钥接收装置接收到的量子信号的偏振方向与接收到的本振信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者保持接收到的量子信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。另外，由于制备好的量子信号要经过偏振控制器之后才能被送入第二光纤中进行传输，而偏振控制器本身对信号就具有一定的衰减作用，因此，在将调制后的第三光信号进行衰减以得到量子信号时，衰减器可以相应地减小对信号的衰减力度，降低了衰减器的工作负荷，且不会对本振信号的强度造成任何影响。
第二方面，提供了一种量子密钥发送装置，所述装置包括激光器、分束器、量子信号制备模块和偏振控制器；
所述激光器用于输出第一光信号；
所述分束器用于接收所述第一光信号，将所述第一光信号分为第二光信号和第三光信号，向所述偏振控制器发送第二光信号，并向所述量子信号制备模块发送所述第三光信号；
所述量子信号制备模块用于，对所述第三光信号进行调制，得到量子信号和参考信号，将所述量子信号和所述参考信号通过第二光纤发送出去，所述量子信号携带待传输的随机密钥；
所述偏振控制器用于，对所述第二光信号的偏振方向进行调整，通过第一光纤将调整后的第二光信号作为本振信号发送出去。
在本申请实施例中，量子密钥发送装置可以通过偏振控制器调整本振信号的偏振方向，并将量子信号和调整后的本振信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，量子密钥接收装置中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。并且，由于不再需要偏振复用器件，因此，解决了由于偏振复用器件的有限消光比所导致的对本振信号的强度的限制，提高了接收到的信噪比。另外，由于不再需要通过时分复用进行隔离，因此，用于传输量子信号的光纤不再需要分配资源用于本振信号的传输，也即，该光纤中的全部资源均可以用于量子信号的传输，提高了单位时间内量子信号的传输比例。
在一种可能的实现方式中，所述第二光信号的光强大于所述第三光信号的光强。
在一种可能的实现方式中，所述装置还包括接收器和处理器，
所述接收器用于接收偏振方向控制信息，并向所述处理器发送所述偏振方向控制信息；
所述处理器用于对所述偏振方向控制信息进行处理，得到第一控制信号，并向所述偏振控制器发送所述第一控制信号；
所述偏振控制器具体用于，基于所述第一控制信号对所述第二光信号的偏振方向进行调整，得到本振信号。
其中，偏振方向控制信息可以是接收端根据对参考信号和本振信号进行探测生成的探测结果反馈的用于指示要调整的偏振角度的角度信息。
在一种可能的实现方式中，所述第二光信号与所述第一光纤中传输的其他光信号的波长不同，所述第三光信号与所述第二光纤中传输的其他光信号的波长不同。
在一种可能的实现方式中，所述第二光纤还用于传输相干光信号，且所述第二光纤中传输的相干光信号的传输方向和所述第二光纤中传输的量子信号的传输方向相反。
在通过两根光纤分别来传输本振信号和量子信号时，在传输过程中，本振信号和量子信号发生的偏振旋转是不同的，这样，为了保证量子密钥接收装置在接收到本振信号和量子信号之后，可以得到更加准确的探测结果，量子密钥发送装置中可以设置有偏振控制器，通过该偏振控制器，根据量子密钥接收装置根据探测结果反馈的偏振方向控制信息来调整本振信号的偏振方向，以使得量子密钥接收装置接收到的本振信号的偏振方向与接收到的量子信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者保持接收到的本振信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。
第三方面，提供了一种量子密钥接收装置，所述装置包括量子探测模块和偏振控制模块；
所述偏振控制模块用于从第一光纤接收本振信号，并调整所述本振信号的偏振方向，向所述量子探测模块发送调整后的本振信号；
所述量子探测模块用于从第二光纤接收量子信号和参考信号，对所述调整后的本振信号、所述量子信号和所述参考信号进行探测，得到探测结果，其中，所述量子信号携带有随机密钥，所述探测结果包括所述随机密钥的密钥信息；
或
所述偏振控制模块用于从所述第二光纤接收量子信号和参考信号，并调整所述量子信号和所述参考信号的偏振方向，向所述量子探测模块发送调整后的量子信号和参考信号；
所述量子探测模块用于从所述第一光纤接收本振信号，对所述本振信号、所述调整后的量子信号和所述调整后的参考信号进行探测，得到所述探测结果。
在本申请实施例中，量子密钥接收装置可以接收通过两根不同的光纤传输的本振信号和量子信号，并通过设置在本振信号路或量子信号路的偏振控制模块来控制本振信号或量子信号的偏振方向。由于在传输过程中量子信号和本振信号没有采用时分复用和偏振复用的方式进行隔离，因此，量子密钥接收装置中就不需要引入额外的光程差进行延时补偿，从而使得量子密钥接收装置可以集成化、小型化。因此也避免了由于偏振复用器件的有限消光比所导致的本振信号的强度受限的问题，提高了接收端的信噪比。另外，通过偏振控制模块对本振信号或量子信号的偏振方向进行调整，可以使得本振信号的偏振方向与量子信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者使得本振信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。
在一种可能的实现方式中，所述参考信号的偏振方向与所述量子信号的偏振方向一致，且所述参考信号携带参考数据，所述偏振控制模块包括偏振控制器；
所述偏振控制器用于从所述第一光纤接收所述本振信号，将所述本振信号的偏振方向调整为第一偏振方向，并向所述量子探测模块发送所述调整后的本振信号；
所述量子探测模块具体用于接收所述调整后的本振信号，从所述第二光纤接收所述量子 信号和所述参考信号，对所述调整后的本振信号和所述参考信号的干涉信号进行探测，得到参考数据测量值；若所述参考数据测量值与存储的所述参考数据之间的偏差不大于允许偏差，则对所述量子信号和调整后的本振信号的干涉信号进行探测，得到所述探测结果；若所述参考数据测量值与存储的所述参考数据之间的偏差大于所述允许偏差，则基于所述参考数据测量值生成第二控制信号，并向所述偏振控制器发送所述第二控制信号；
所述偏振控制器还用于接收所述第二控制信号，基于所述第二控制信号更新所述本振信号的偏振方向，并重新向所述量子探测模块发送所述调整后的本振信号。
在一种可能的实现方式中，所述参考信号携带参考数据，所述偏振控制模块包括偏振控制器；
所述偏振控制器用于从所述第二光纤接收所述量子信号和所述参考信号，将所述量子信号和所述参考信号的偏振方向调整为第一偏振方向，并向所述量子探测模块发送调整后的量子信号和参考信号；
所述量子探测模块具体用于接收所述调整后的量子信号和参考信号，从所述第一光纤接收所述本振信号，对所述调整后的参考信号和所述本振信号的干涉信号进行探测，得到参考数据测量值；若所述参考数据测量值与存储的所述参考数据之间的偏差不大于允许偏差，则对调整后的量子信号和所述本振信号的干涉信号进行探测，得到所述探测结果；若所述参考数据测量值与存储的所述参考数据之间的偏差大于所述允许偏差，则基于所述参考数据测量值生成第四控制信号，并向所述偏振控制器发送所述第四控制信号；
所述偏振控制器还用于接收所述第四控制信号，基于所述第四控制信号更新所述量子信号和所述参考信号的偏振方向，并重新向所述量子探测模块发送调整后的量子信号和调整后的参考信号。
在一种可能的实现方式中，所述偏振控制模块包括分束器、偏振分析仪和偏振控制器；
所述分束器用于从所述第一光纤接收所述本振信号，将所述本振信号分为第四光信号和第五光信号，并向所述偏振分析仪发送所述第四光信号，向所述偏振控制器发送所述第五光信号；
所述偏振分析仪用于分析所述第四光信号的偏振方向，基于所述第四光信号的偏振方向与目标偏振方向生成第三控制信号，向所述偏振控制器发送所述第三控制信号，所述目标偏振方向与所述量子信号的偏振方向之间的方向偏差不大于预设数值；
所述偏振控制器用于，根据所述第三控制信号将所述第五光信号的偏振方向调整为所述目标偏振方向，并向所述量子探测模块发送调整后的第五光信号；
所述量子探测模块具体用于接收调整后的第五光信号，从所述第二光纤接收所述量子信号和所述参考信号，对所述调整后的第五光信号、所述量子信号和所述参考信号进行探测，得到所述探测结果。
在一种可能的实现方式中，所述第四光信号的光强小于所述第五光信号的光强。
第四方面，提供了一种量子密钥接收装置，所述装置包括第一偏振分束器、第二偏振分束器、第一量子外差探测器、第二量子外差探测器和处理器；
所述第一偏振分束器用于从第一光纤接收本振信号，将所述本振信号分为第六光信号和第七光信号，并向所述第一量子外差探测器发送所述第六光信号，向所述第二量子外差探测 器发送所述第七光信号；
所述第二偏振分束器用于从第二光纤接收所述量子信号和所述参考信号，将所述参考信号分为第八光信号和第九光信号，将所述量子信号分为第十光信号和第十一光信号，向所述第一量子外差探测器发送所述第八光信号和所述第十光信号，向所述第二量子外差探测器发送所述第九光信号和第十一光信号，所述量子信号携带有随机密钥；
所述第一量子外差探测器用于探测所述第六光信号和所述第八光信号的干涉信号，得到所述第八光信号的正则分量，探测所述第六光信号与所述第十光信号的干涉信号，得到所述第十光信号的正则分量，向所述处理器发送所述第八光信号的正则分量和所述第十光信号的正则分量；
所述第二量子外差探测器用于探测所述第七光信号和所述第九光信号的干涉信号，得到所述第九光信号的正则分量，探测所述第七光信号与所述第十一光信号的干涉信号，得到所述第十一光信号的正则分量，向所述处理器发送所述第九光信号的正则分量和所述第十一光信号的正则分量；
所述处理器用于，对所述第八光信号的正则分量和所述第九光信号的正则分量进行处理，得到信号参数；基于所述信号参数对所述第十光信号的正则分量和所述第十一光信号的正则分量进行处理，得到初始密钥，所述初始密钥包括所述随机密钥的密钥信息。
在本申请实施例中，量子密钥接收装置中可以不必设置偏振控制模块，而是通过第一偏振分束器和第二偏振分束器分别对本振信号、量子信号和参考信号进行分束，之后，再通过第一量子外差探测器和第二量子外差探测器分别测量参考信号的正则分量和量子信号的正则分量，进而根据参考信号的正则分量计算信号参数，最终根据该信号参数对量子信号的正则分量进行处理，以得到初始密钥，以此来消除偏振旋转带来的影响，保证得到的密钥信息的准确性。
第五方面，提供了一种量子密钥传输系统，所述量子密钥传输系统包括量子密钥发送装置和量子密钥接收装置；
所述量子密钥发送装置为前述第一方面或第二方面中任一种可能的实现方式所述的装置；
所述量子密钥接收装置用于从所述第一光纤接收本振信号，从所述第二光纤接收所述调整后的量子信号和所述调整后的参考信号，对所述本振信号、所述调整后的量子信号和所述调整后的参考信号进行探测，得到探测结果，其中，所述探测结果包括所述随机密钥的密钥信息；
或者，
所述量子密钥发送装置包括激光器、分束器和量子信号制备模块；所述激光器用于输出第一光信号；所述分束器用于接收所述第一光信号，将所述第一光信号分为第二光信号和第三光信号，将所述第二光信号通过第一光纤发送出去，并向所述量子信号制备模块发送所述第三光信号；所述量子信号制备模块用于，对所述第三光信号进行调制，得到量子信号和参考信号，将所述量子信号和所述参考信号通过第二光纤发送出去，其中，所述量子信号携带待传输的随机密钥；
所述量子密钥接收装置为前述第三方面或第四方面中任一种可能的实现方式所述的装置。
上述第二方面、第三方面、第四方面和第五方面所获得的技术效果与第一方面中对应的 技术手段获得的技术效果近似，在这里不再赘述。
本申请提供的技术方案带来的有益效果至少包括：
本申请实施例提供了一种量子密钥发送装置，可以通过偏振控制器调整量子信号和参考信号的偏振方向，并将本振信号和调整后的量子信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，接收端的量子信号接收机中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。并且，由于不再需要通过偏振复用来隔离本振信号和量子信号，因此，解决了由于偏振复用器件的有限消光比所导致的对本振信号的强度的限制，提高了接收端的信噪比。另外，由于也不再需要通过时分复用进行隔离，因此，用于传输量子信号的光纤不再需要分配资源用于本振信号的传输，也即，该光纤中的全部资源均可以用于量子信号的传输，提高了单位时间内量子信号的传输比例。
附图说明
图1是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图2是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图3是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图4是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图5是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图6是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图7是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图8是本申请实施例提供的一种量子密钥发送装置的结构示意图；
图9是本申请实施例提供的一种量子密钥接收装置的结构示意图；
图10是本申请实施例提供的一种量子密钥接收装置的结构示意图；
图11是本申请实施例提供的一种量子密钥接收装置的结构示意图；
图12是本申请实施例提供的一种量子密钥接收装置的结构示意图；
图13是本申请实施例提供的一种量子密钥接收装置的结构示意图；
图14是本申请实施例提供的一种量子密钥传输系统的结构示意图；
图15是本申请实施例提供的一种量子密钥传输系统的结构示意图。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请实施方式作进一步地详细描述。
图1是本申请实施例提供的一种量子密钥发送装置的结构示意图。如图1所示，该装置包括激光器101、分束器102、量子信号制备模块103和偏振控制器104。
其中，激光器101用于输出第一光信号。分束器102用于接收第一光信号，将第一光信号分为第二光信号和第三光信号，将第二光信号通过第一光纤发送出去，并向所述量子信号制备模块103发送第三光信号；量子信号制备模块103用于，对第三光信号进行调制，得到量子信号和参考信号，向偏振控制器104发送量子信号和参考信号，量子信号携带待传输的随机密钥；偏振控制器104用于，对量子信号和参考信号的偏振方向进行调整，通过第二光 纤将调整后的量子信号和调整后的参考信号发送出去。可选地，第二光信号的光强大于第三光信号的光强
示例性的，该激光器101可以为能够产生窄线宽、线偏振的光信号的激光器，可以为发射具有稳定相位关系的脉冲激光信号的激光器，也可以为发射连续激光信号的激光器。其中，激光器101包括一个输出端口，激光器101可以通过该输出端口输出第一光信号。可选地，由于后续通过第一光纤和第二光纤传输信号时，该第一光纤和第二光纤中可能还会传输有其他光信号，例如，该第一光纤和第二光纤中还可能传输有经典相干光信号，基于此，在本申请实施例中，激光器101可以输出与该第一光纤和第二光纤中传输的其他光信号的波长不同的第一光信号。
分束器102可以包括一个输入端口和两个输出端口。其中，分束器102的输入端口与激光器101的输出端口连接，分束器102可以通过包括的输入端口接收激光器101发送的第一光信号，并按照该分束器102的分束比例将第一光信号分为第二光信号和第三光信号。其中，由于本振信号的光强通常越强越好，因此，可以将分束后光强较大的光信号作为第二光信号，而将光强较小的光信号作为第三光信号，其中，该分束器102的分束比例可以为10:90或者是1:99等。
在将第一光信号分为第二光信号和第三光信号之后，分束器102可以通过包括的第一输出端口输出第二光信号，并通过包括的第二输出端口输出第三光信号。需要说明的是，分束器102的第一输出端口可以直接与第一光纤连接，或者，分束器102的第一输出端口可以通过耦合器与第一光纤连接，这样，从第一输出端口输出的第二光信号将作为本振信号通过第一光纤发送出去。而分束器102的第二输出端口可以与量子信号制备模块103连接。这样，通过该第二输出端口，分束器102可以将第三光信号发送至量子信号制备模块103。
量子信号制备模块103可以接收分束器102发送的第三光信号，并基于随机密钥和参考数据对该第三光信号进行调制，从而得到携带有随机密钥的量子信号和携带有参考数据的参考信号。
示例性的，参见图2，量子信号制备模块103可以包括量子随机数发生器1031、处理模块1032、调制器1033和衰减器1034。其中，量子随机数发生器1031用于产生随机数，并向处理模块1032发送该随机数。处理模块1032在接收到量子随机数发生器1031发送的随机数之后，可以按照协议标准对该随机数进行处理，从而生成随机密钥，并根据该随机密钥生成用于控制调制器1033调制量子信号的控制信号，除此之外，处理模块1032还可以根据存储的参考数据生成用于控制调制器1033调制参考信号的控制信号。之后，处理模块1032可以向调制器1033发送上述两种控制信号。调制器1033可以基于上述两种控制信号对第三光信号进行调制，得到量子信号和参考信号，并使量子信号和参考信号分别位于不同的频段上；调制器1033将调制后的信号发送给衰减器1034，衰减器1034对调制后的信号的强度进行衰减，从而得到携带有随机密钥的量子信号和携带有参考数据的参考信号。
可选地，在一种可能的实现方式中，量子信号制备模块103可以采用时分的方式来发送量子信号和参考信号，也即，量子信号制备模块103中的处理模块1032可以在某个时段内，根据随机密钥生成用于控制调制器1033的量子控制信号，进而通过该量子控制信号控制调制器1033进行调制，得到量子信号。而在与该时段不同的的另一个时段内，则可以根据参考数据生成用于控制调制器1033的参考控制信号，进而根据该参考控制信号控制调制器1033进 行调制，得到参考信号。
可选地，除了可以通过时分复用或者频分复用的方式来发送量子信号和参考信号之外，量子信号制备模块103还可以通过偏振复用的方式来发送量子信号和参考信号，也即，量子信号制备模块103在将量子信号和参考信号输入到信道时，量子信号与参考信号的偏振方向可以是正交的，此时，调制器可以为双偏振调制器，例如，双偏振正交相移键控(Dual Polarization-Quadrature Phase Shift Keying，DP-QPSK)调制器。
偏振控制器104可以包括第一输入端口、第二输入端口和输出端口。偏振控制器104可以通过包括的第一输入端口接收量子信号制备模块103发送的量子信号和参考信号，并通过第二输入端口接收第一控制信号，之后，偏振控制器104可以根据第一控制信号对量子信号和参考信号的偏振方向进行调整，并通过包括的输出端口输出调整后的量子信号和调整后的参考信号。其中，偏振控制器104的输出端口可以直接与第二光纤连接，也可以通过耦合器与第二光纤连接，这样，从偏振控制器104的输出端口输出的调整后的量子信号和调整后的参考信号可以通过第二光纤发送出去。
需要说明的是，第一控制信号可以是量子密钥接收装置基于对参考信号和本振信号进行探测得到的探测结果生成并反馈的控制信号。
可选地，在一种可能的实现方式中，量子密钥接收装置可以只根据对参考信号和本振信号进行探测得到的探测结果，生成并反馈偏振方向控制信息，由量子密钥发送装置来对该偏振方向控制信息进行处理，进而得到第一控制信号。在这种情况下，参见图3，该量子密钥发送装置中还可以包括接收器105和处理器106。其中，接收器105用于接收偏振方向控制信息，并向处理器106发送偏振方向控制信息；处理器106用于接收偏振方向控制信息，对偏振方向控制信息进行处理，得到第一控制信号，并向偏振控制器104发送第一控制信号；偏振控制器104具体用于，基于第一控制信号对量子信号和参考信号的偏振方向进行调整。
需要说明的是，接收器105可以包括输入端口和输出端口。通过该输入端口，接收器105可以接收量子密钥接收装置反馈的偏振方向控制信息。其中，该偏振方向控制信息可以是用于指示要调整的偏振角度的角度信息。接收器105接收到该偏振方向控制信息之后，可以通过输出端口将该偏振方向控制信息输出至处理器106。
处理器106可以包括输入端口和输出端口，其中，处理器106包括的输入端口与接收器105的输出端口连接，这样，处理器106可以通过包括的输入端口接收接收器105发送的偏振方向控制信息。而处理器106包括的输出端口则可以与偏振控制器104的第二输入端口进行连接，这样，在处理器106对该偏振方向控制信息进行处理得到第一控制信号之后，可以通过包括的输出端口向偏振控制器104发送第一控制信号。
其中，由于量子密钥接收装置通常会将要调整的角度进行编码之后发送，因此，接收器105在将接收到的偏振方向控制信息发送至处理器106之后，处理器106可以根据与量子密钥接收装置事先协商好的协议标准，对该偏振方向控制信息进行解码，从而得到要调整的偏振角度，之后，处理器106可以根据该偏振角度生成模拟信号，该模拟信号即为用于控制偏振控制器104进行偏振方向调整的第一控制信号。
偏振控制器104在通过第二输入端口接收到第一控制信号之后，可以基于第一控制信号对量子信号制备模块103发送的量子信号和参考信号的偏振方向进行调整，进而得到调整后的量子信号和参考信号。
可选地，在一种可能的实现方式中，为了提高参考信号的光强，以便在两条光纤的相位和偏振变化比较快的情况下，接收端能够根据该参考信号更准确的恢复量子信号携带的密钥信息，参见图4，该量子密钥接收装置还可以包括有分束器107和参考信号制备模块108。
其中，分束器107的输入端口与分束器102的第二输出端口连接，分束器107的第一输出端口与量子信号制备模块103包括的调制器1033连接，分束器107的第二输出端口则与参考信号制备模块108连接。这样，分束器107可以通过包括的输入端口接收分束器102通过第二输出端口发送的第三光信号。分束器107在接收到第三光信号之后，可以将第三光信号分为两束光信号，其中，分束器107可以将两束光信号中的一束光信号通过包括的第一输出端口发送至调制器1033，而将另一束光信号用过第二输出端口发送至参考信号制备模块。
量子信号制备模块103中的调制器1033可以接收分束器107发送的光信号，并参考前述介绍的方法对接收到的光信号进行调制，使得第一参考信号和量子信号分别位于不同的频段上。
参考信号制备模块108可以接收分束器107发送的另一束光信号，并对接收到的光信号进行调制，从而得到第二参考信号，其中，第二参考信号和第一参考信号、量子信号所处的频段不同。
示例性的，参考信号制备模块108可以包括移频器1081、处理模块1082、调制器1083和衰减器1084。其中，分束器107的第二输出端口与移频器1081的输入端口连接，这样，移频器1081可以通过包括的输入端口接收分束器107发送的另一束光信号。在接收到分束器107发送的光信号之后，移频器1081可以将接收到的光信号进行少量的频率偏移。之后，移频器1081可以将频率偏移后的光信号发送至调制器1083。
处理模块1082可以根据存储的参考数据生成用于控制调制器1084调制参考信号的控制信号，之后，处理模块1082可以通过输出端口将该控制信号发送至调制器1083。
调制器1083包括两个输入端口和一个输出端口。其中，调制器1083的第一输入端口可以与移频器1081的输出端口连接，这样，调制器1083可以通过包括的第一输入端口接收移频器1081发送的频率偏移后的光信号。调制器1083的第二输入端口与处理模块1082的输出端口连接，这样，通过包括的第二输入端口，调制器1083可以接收处理模块1082发送的用于调制第二参考信号的控制信号。调制器1083在接收到处理模块1082发送的控制信号之后，可以基于该控制信号对接收到的移频器1081发送的频率偏移的光信号进行调制，并将调制后的信号通过输出端口发送至衰减器1084。其中，调制后的信号与第一参考信号携带有相同的参考数据。
衰减器1084在接收到调制后的信号之后，可以对该调制后的信号进行衰减，从而得到第二参考信号，并将第二参考信号发送至偏振控制器104。
偏振控制器104可以接收第一参考信号、量子信号和第二参考信号，同时，偏振控制器104还可以接收第一控制信号，并根据第一控制信号对第一参考信号、量子信号和第二参考信号的偏振方向进行调整，之后，偏振控制器可以通过包括的输出端口将调整偏振方向后的第一参考信号、量子信号和第二参考信号通过第二光纤发送出去。
在本申请实施例中，由于量子信号的光强非常小，因此，与量子信号一起生成的第一参考信号也很难达到很高的光强，而在该种实现方式中，通过在量子密钥发送装置中设置参考信号制备模块，第二参考信号可以通过单独的参考信号制备模块来生成，这样，第二参考信 号的光强则可以进行单独的控制，从而使得第二参考信号的光强大于第一参考信号的光强，这样，将第一参考信号和第二参考信号同时向接收端发送，接收端接收到两份参考信号，也即参考信号的光强将大大提高，在此基础上，根据该参考信号可以更为准确的恢复量子信号中携带的密钥信息。
可选地，量子信号制备模块103可以包括量子随机数发生器1031，处理模块1032和调制器1033；参考信号制备模块108可以包括移频器1081，处理模块1082和调制器1083。上述器件功能与图5实施例描述一致，在此不再赘述。调制器1033的输出端和调制器1083的输出端均与偏振控制器104相连，经过偏振调整后，将调整后的信号发送给衰减器109，得到调整后的第一参考信号，第二参考信号和量子信号，并通过第二光纤发送出去。可选地，分束器107的分给参考信号制备模块108的信号的光强高于分给所述量子信号制备模块103的光强。
在本申请实施例中，量子密钥发送装置可以通过第一光纤发送本振信号，通过第二光纤发送调整后的量子信号和参考信号。其中，第一光纤和第二光纤可以是专门设置于量子密钥发送装置和量子密钥接收装置之间用于量子通信的光纤。可选地，在一种可能的实现方式中，考虑到经典相干通信系统中，存在通过两根光纤来传输相干光信号，以此来实现双向通信的场景；因此，在本申请实施例中，包括有量子密钥发送装置和量子密钥接收装置的量子通信系统可以与经典相干通信系统共用两根光纤进行信号的传输。也即，本申请实施例中的第一光纤和第二光纤不仅可以用于量子通信，还可以用于在经典相干通信系统中传输相干光信号。在此基础上，为了将在第一光纤中传输的第二光信号和其他相干光信号区分隔离开来，第二光信号的波长可以与第一光纤中的其他相干光信号的波长不同。同时，为了将在第二光纤中传输的量子信号和参考信号与第二光纤中传输的其他相干光信号区分隔离开来，用于生成量子信号和参考信号的第三光信号的波长也可以与第二光纤中传输的其他相干光信号的波长不同。可选地，所述第二光纤中传输的相干光信号的传输方向和所述第二光纤中传输的量子信号的传输方向相反。
在本申请实施例中，量子密钥发送装置可以通过偏振控制器调整量子信号和参考信号的偏振方向，并将本振信号和调整后的量子信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，作为接收端的量子密钥接收装置中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。并且，解决了由于偏振复用器件的有限消光比所导致的对本振信号的强度的限制，提高了接收到的信噪比。另外，由于不再需要通过时分复用进行隔离，因此，用于传输量子信号的光纤不再需要分配资源用于本振信号的传输，也即，该光纤中的全部资源均可以用于量子信号的传输，提高了单位时间内量子信号的传输比例。
另外，在通过两根光纤分别来传输本振信号和量子信号时，在传输过程中，本振信号和量子信号发生的偏振旋转是不同的，这样，为了保证量子密钥接收装置在接收到本振信号和量子信号之后，可以得到更加准确的探测结果，量子密钥发送装置中可以设置有偏振控制器104，通过该偏振控制器104，根据量子密钥接收装置根据探测结果反馈的偏振方向控制信息来调整量子信号的偏振方向，以使得量子密钥接收装置接收到的量子信号的偏振方向与接收到的本振信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者保持接收到的量子信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干 涉效果，进而保证探测结果的准确性。
还需要说明的是，在本申请实施例中，将偏振控制器设置在量子信号路，由于制备好的量子信号要经过偏振控制器之后才能被送入第二光纤中进行传输，而偏振控制器本身对信号就具有一定的衰减作用，因此，在将调制后的第三光信号进行衰减以得到量子信号时，衰减器可以相应地减小对信号的衰减力度，降低了衰减器的工作负荷。
在上述实施例中，偏振控制器设置在量子信号制备模块之后，可选地，偏振控制器还可以设置在量子信号制备模块内部。
参见图6，提供了另一种量子密钥发送装置。如图6所示，该装置中包括激光器201、分束器202，量子信号制备模块203和偏振控制模块204。其中，量子信号制备模块203包括量子随机数发生器2031、处理模块2032、调制器2033；偏振控制模块204包括偏振控制器2041、衰减器2042。
其中，激光器201的功能可以参考前述实施例中激光器101的解释说明，分束器202的功能可以参考前述实施例中分束器102的解释说明，本申请实施例在此不再赘述。
需要说明的是，量子信号制备模块203包括的量子随机数发生器2031用于产生随机数，并向处理模块2032发送该随机数。
处理模块2032在接收到量子随机数发生器2031发送的随机数之后，可以按照协议标准对该随机数进行处理，从而生成随机密钥，并根据该随机密钥生成用于控制调制器2033调制量子信号的控制信号，除此之外，处理模块2032还可以根据存储的参考数据生成用于控制调制器2033调制参考信号的控制信号。之后，处理模块2032可以向调制器2033发送上述两种控制信号。
调制器2033可以接收处理模2032发送的控制信号，并接收分束器202发送的第三光信号，基于控制信号对第三光信号进行调制，得到量子信号和参考信号，并使量子信号和参考信号分别位于不同的频段上，调制器2033将调制后的信号发送给偏振控制器2041。
偏振控制器2041可以用于接收第一控制信号以及调制器2033发送的调制后的信号，并基于第一控制信号对调制后的信号的偏振方向进行调整，向衰减器2042发送调整偏振方向后的信号。其中，该第一控制信号可以是量子密钥接收装置基于对参考信号和本振信号进行探测得到的探测结果生成并反馈的控制信号。
衰减器2042用于对调整偏振方向后的信号的强度进行衰减，从而得到携带有随机密钥的量子信号和携带有参考数据的参考信号，并通过第二光纤发送该量子信号和参考信号。
可选地，该量子密钥发送装置还可以包括接收器205和处理器206。其中，该接收器205和处理器206的功能可以参考前述实施例中接收器105和处理器106的功能，本申请实施例在此不再赘述。
在本申请实施例中，偏振控制器在调制器与衰减器之间，也即，可以将偏振控制器设置在量子信号路，由于偏振控制器本身对信号存在一定的衰减作用，因此，将偏振控制器设置在衰减器之前，经过偏振控制器调整偏振方向后的信号的强度将会减小，这样，衰减器对该调整偏振方向后的信号进行衰减时可以适当的减小衰减力度，降低了衰减器的工作负荷。
在上述实施例中，偏振控制器被设置在量子信号路，用于对量子信号和参考信号的偏振 方向进行调整。可选地，在一种可能的实现方式中，偏振控制器也可以被设置在本振信号路，也即，用于对本振信号的偏振方向进行调整。接下来将对偏振控制器设置在本振信号路的实现方式进行详细的解释说明。
参见图7，提供了一种量子密钥发送装置，该装置包括激光器301、分束器302、偏振控制器303和量子信号制备模块304。
其中，激光器301用于输出第一光信号。分束器302用于接收第一光信号，将第一光信号分为第二光信号和第三光信号，向偏振控制器303发送第二光信号，并向所述量子信号制备模块103发送第三光信号，其中，第二光信号的光强大于第三光信号的光强；偏振控制器303用于对第二光信号的偏振方向进行调整，将调整后的第二光信号通过第一光纤发送出去。量子信号制备模块304用于对第三光信号进行调制，得到量子信号和参考信号，并将量子信号和参考信号通过第二光纤发送出去。
其中，激光器301的功能可以参考前述实施例中激光器101的解释说明，本申请实施例在此不再赘述。
分束器302可以包括一个输入端口和两个输出端口。其中，分束器302的输入端口与激光器101的输出端口连接，分束器302可以通过包括的输入端口接收激光器301发送的第一光信号，并按照该分束器302的分束比例将第一光信号分为第二光信号和第三光信号。其中，由于本振信号的光强通常越强越好，因此，可以将分束后光强较大的光信号作为第二光信号，而将光强较小的光信号作为第三光信号，其中，该分束器302的分束比例可以为10:90或者是1:99。
在将第一光信号分为第二光信号和第三光信号之后，分束器302可以通过包括的第一输出端口输出第二光信号，并通过包括的第二输出端口输出第三光信号。需要说明的是，分束器102的第一输出端口与偏振控制器303的第一输入端口连接，这样，通过该分束器的第一输出端口可以将第二光信号发送至偏振控制器303。而分束器302的第二输出端口可以与量子信号制备模块304连接。这样，通过该第二输出端口，分束器302可以将第三光信号发送至量子信号制备模块304。
偏振控制器303可以包括第一输入端口、第二输入端口和输出端口。其中，偏振控制器303可以通过包括的第一输入端口接收分束器302发送的第二光信号，并通过第二输入端口接收第一控制信号，之后，偏振控制器303可以根据第一控制信号对第二光信号的偏振方向进行调整，并通过包括的输出端口输出调整后的第二光信号。其中，偏振控制器303的输出端口可以直接与第一光纤连接，也可以通过耦合器或环形器与第一光纤连接，这样，偏振控制器303可以将调整后的第二光信号作为本振信号通过第一光纤发送出去。
需要说明的是，第一控制信号可以是量子密钥接收装置基于对参考信号和本振信号进行探测得到的探测结果生成并反馈的控制信号。
可选地，在一种可能的实现方式中，该量子密钥发送装置中还可以包括接收器305和处理器306。在这种情况下，量子密钥接收装置可以根据对参考信号和本振信号进行探测得到的探测结果生成并反馈偏振方向控制信息，而该量子密钥发送装置可以通过接收器305接收该偏振方向控制信息，并由处理器306对该偏振方向控制信息进行处理，以得到第一控制信号。
需要说明的是，接收器305和处理器306的功能可以参考前述实施例中接收器105处理 器106的解释说明，本申请实施例在此不再赘述。
量子信号制备模块304的实现方式同样可以参考前述实施例中如图4所示的量子信号制备模块103的相关实现方式，也可以参考前述实施例中如图6所示的量子信号制备模块203的相关实现方式，本申请实施例在此不再赘述。
需要说明的是，量子信号制备模块304的输出端口可以直接与第二光纤连接，也可以通过耦合器或环形器与第二光纤进行连接。这样，量子信号制备模块304在制备得到量子信号和参考信号之后，可以将该量子信号和参考信号通过该第二光纤发送出去。
可选地，如图8所示，所述量子密钥发送装置还包括分束器307和参考信号制备模块308，所述分束器307用于将所述第三光信号分成两束，一束发送给所述量子信号制备模块304，另一束发送给参考信号制备模块308；所述参考设备制备模块可以参考前述实施例中如图5所示的参考信号制备模块108的相关实现方式，本申请对此不做限定。
在本申请实施例中，量子密钥发送装置可以通过偏振控制器调整本振信号的偏振方向，并将量子信号和调整后的本振信号分别送入不同的光纤中进行传输，这样，就不需要再通过时分复用和偏振复用的方式来对本振信号和量子信号进行隔离，在此基础上，量子密钥接收装置中就不需要再引入额外的光程差进行延时补偿，从而使得接收端可以集成化、小型化。并且，由于不再需要通过时分复用进行隔离，因此，解决了由于偏振复用器件的有限消光比所导致的对本振信号的强度的限制，提高了接收到的信噪比。另外，不再需要通过时分复用进行隔离，因此，用于传输量子信号的光纤不再需要分配资源用于本振信号的传输，也即，该光纤中的全部资源均可以用于量子信号的传输，提高了单位时间内量子信号的传输比例。
另外，在通过两根光纤分别来传输本振信号和量子信号时，在传输过程中，本振信号和量子信号发生的偏振旋转是不同的，这样，为了保证量子密钥接收装置在接收到本振信号和量子信号之后，可以得到更加准确的探测结果，量子密钥发送装置中可以设置有偏振控制器，通过该偏振控制器，根据量子密钥接收装置根据探测结果反馈的偏振方向控制信息来调整本振信号的偏振方向，以使得量子密钥接收装置接收到的本振信号的偏振方向与接收到的量子信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者保持接收到的本振信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。
前述实施例中主要介绍了本申请实施例提供的一种量子密钥发送装置。该量子密钥发送装置不仅可以将本振信号和量子信号分别送入不同的光纤进行传输，而且，可以对量子信号或本振信号的偏振方向进行调整，以使得作为接收端的量子密钥接收装置接收到的本振信号和量子信号在发生的不同的偏振旋转后能够保持偏振方向一致或者方向差固定，或者是使得量子密钥接收装置接收到的本振信号或量子信号能够始终稳定在一个偏振方向上，从而保证探测结果的准确性。可选地，在一种可能的实现方式中，量子密钥发送装置可以不包括偏振控制器，也即，量子密钥发送装置可以仅负责将本振信号和量子信号分别送入不同的光纤进行传输，而由量子密钥接收装置对接收到的本振信号或量子信号的偏振方向进行调整，以此来使得本振信号和量子信号在发生的不同的偏振旋转后能够保持偏振方向一致或者方向差固定。
基于上述描述，参见图9，本申请实施例提供了一种量子密钥接收装置。该装置包括量 子探测模块401和偏振控制模块402。
其中，偏振控制模块402用于从第一光纤接收本振信号，并调整本振信号的偏振方向，向量子探测模块401发送调整后的本振信号；量子探测模块401用于从第二光纤接收量子信号和参考信号，对调整后的本振信号、量子信号和参考信号进行探测，以得到探测结果，量子信号携带有随机密钥，探测结果包括随机密钥的密钥信息。
示例性的，在一种可能的实现方式中，参见图10，偏振控制模块402可以包括偏振控制器4021。在这种情况下，该偏振控制器4021可以包括有第一输入端口、第二输入端口和输出端口。其中，该偏振控制器4021的第一输入端口可以直接与第一光纤连接，或者，该偏振控制器4021的第一输入端口可以通过耦合器或环形器与第一光纤连接。通过该第一输入端口，偏振控制器4021可以接收量子密钥发送装置通过第一光纤发送的本振信号。通过第二输入端口，偏振控制器4021可以接收量子探测模块401在当前时刻之前基于本振信号和参考信号的探测结果生成的第二控制信号。之后，偏振控制器可以基于该第二控制信号将该本振信号的偏振方向调整为第一偏振方向，并向量子探测模块发送调整后的本振信号，其中，第一偏振方向可以与量子信号的偏振方向一致，也可以与量子信号的偏振方向成一个固定方向差。
其中，参考信号携带有参考数据，该参考数据是量子密钥发送装置和量子密钥接收装置事先协商好的。并且，参考信号的偏振方向和量子信号的偏振方向一致。另外，需要说明的是，若该偏振控制器4021为首次接收到本振信号，则将该本振信号调整到一个预设的偏振方向上，并向量子信号探测模块401发送该调整后的本振信号，也即，若为首次接收到本振信号，则在第一次调整时，将本振信号的偏振调整为第一偏振方向是指将本振信号调整到一个预设的偏振方向上。
量子探测模块401可以包括第一输入端口、第二输入端口和输出端口。其中，通过包括的第一输入端口，可以接收量子密钥发送装置通过第二光纤发送的量子信号和参考信号。通过包括的第二输入端口，量子探测模块401可以接收调整后的本振信号。其中，若该量子信号和参考信号是通过频分复用的方式发送的，则量子探测模块401在接收到量子信号和参考信号时，可以从参考信号所在的频段上提取参考信号，并对该参考信号和调整后的本振信号的干涉信号进行探测，以得到参考数据测量值。若参考数据测量值与存储的参考数据之间的偏差不大于允许偏差，则说明参考信号和调整后的本振信号的干涉效果较好，也即，调整后的本振信号的偏振方向是合适的，由于参考信号与量子信号的偏振方向是一致的，因此，调整后的本振信号在与量子信号发生干涉时的干涉效果也将较好，基于此，量子探测模块401可以对量子信号与调整后的本振信号的干涉信号进行测量，以得到探测结果，进而根据该探测结果获取随机密钥的密钥信息。
当然，若参考数据测量值与存储的参考数据之间的偏差大于允许偏差，则说明参考信号和调整后的本振信号的干涉效果较差，此时，需要继续调整本振信号的偏振方向，因此，量子探测模块401可以根据该参考数据测量值和参考数据之间的差值生成第二控制信号，并通过输出端口输出该第二控制信号给偏振控制器4021。
可选地，若参考信号和量子信号是通过时分复用的方式发送的，则量子探测模块401在接收到参考信号时，可以通过不断调整本振信号的方向来确定参考信号与本振信号的干涉效果最好时的本振信号的偏振方向，并在接收到量子信号时，按照最终确定的本振信号的偏振方向来调整本振信号，以提升调整后的本振信号与量子信号的干涉效果，进而保证探测结果 的准确性。
其中，量子探测模块401可以为探测单一偏振方向信号的量子探测器，也可以为探测正交偏振方向信号的量子探测器，本申请不做限定。
偏振控制器4021还可以包括第二输入端口，该第二输入端口与量子探测模块401的输出端口连接，用于接收量子探测模块401发送的第二控制信号，基于第二控制信号对当前接收到的本振信号的偏振方向进行调整，并重新向量子探测模块发送调整后的本振信号，直到量子探测模块401检测到的参考数据测量值与参考数据之间的差值不大于允许偏差时，则按照最后一次调整的本振信号的偏振方向来调整后续接收到的本振信号的偏振方向。
可选地，在另一种可能的实现方式中，参见图11，偏振控制模402可以包括偏振控制器4021、分束器4022和偏振分析仪4023。
其中，分束器4022用于从第一光纤接收本振信号，将本振信号分为第四光信号和第五光信号，并向偏振分析仪4023发送第四光信号，向偏振控制器4021发送第五光信号，第四光信号的光强小于第五光信号的光强；偏振分析仪4023用于接收第四光信号，分析第四光信号的偏振方向，并基于第四光信号的偏振方向与目标偏振方向生成第三控制信号，向偏振控制器4021发送第三控制信号；偏振控制器4021用于接收第五光信号和第三控制信号，基于第三控制信号将第五光信号的偏振方向调整为目标偏振方向，并向量子探测模块401发送调整后的第五光信号；量子探测模块401具体用于接收调整后的第五光信号，从第二光纤接收量子信号和参考信号，对调整后的第五光信号、量子信号和参考信号进行探测，以得到探测结果。
需要说明的是，在该种实现方式中，分束器4022包括输入端口、第一输出端口和第二输出端口。其中，分束器4022的输入端口可以直接与第一光纤连接，也可以通过耦合器或环形器与第一光纤连接，这样，通过包括的输入端口，分束器4022可以接收量子密钥发送装置通过第一光纤发送的本振信号。之后，分束器4022可以将接收到的本振信号按照一定的分束比例分为第四光信号和第五光信号，其中，第四光信号将被用于进行偏振方向的分析，因此，光强可以较小，而第五光信号将作为本振信号与量子信号和参考信号进行干涉，因此需要保证第五光信号的光强达到一定的强度。基于此，在通过分束器4022分束时，第四光信号的光强可以相对较小。示例性的，分束比例可以为1:99，按照该分束比例进行分束，得到占本振信号1％的第四光信号和占本振信号99％的第五光信号。
在得到第四光信号和第五光信号之后，分束器4022可以通过第一输出端口向偏振分析仪4023发送第四光信号，并通过第二输出端口向偏振控制器4021发送第五光信号。
偏振分析仪4023可以包括输入端口和输出端口。其中，输入端口与分束器4022的第一输出端口连接，这样，通过该输入端口，偏振分析仪4023可以接收第四光信号。在接收到第四光信号之后，偏振分析仪可以对第四光信号的偏振方向进行分析，并将分析得到的第四光信号的偏振方向与目标偏振方向进行比较，从而根据第四光信号的偏振方向与目标偏振方向之间的差值生成第三控制信号。通过包括的输出端口输出该第三控制信号。
偏振控制器4021包括第一输入端口、第二输入端口和输出端口。其中，第一输入端口与分束器4022的第二输出端口连接，这样，偏振控制器4021可以接收分束器4022输出的第五光信号。第二输入端口与偏振分析仪4023的输出端口连接，这样，偏振控制器4021可以接收偏振分析仪4023输出的第三控制信号。偏振控制器4021可以基于接收到的第三控制信号 对第五光信号的偏振方向调整为目标偏振方向，并通过输出端口向量子探测模块401发送调整后的第五光信号。
需要说明的是，目标偏振方向与量子信号的偏振方向之间的方向偏差不大于预设数值，当该方向偏差为0时，表明量子信号与本振信号的偏振方向是一致的，此时，量子信号和本振信号的干涉效果是最好的。当然，若该方向偏差大于0，则随着方向偏差的增大，本振信号与量子信号的干涉效果将逐渐变差。因此，在本申请实施例中，该预设数值可以尽可能取较小的值，例如，该预设数值可以为5°、8°或10°等等。
量子探测模块401可以接收偏振控制器4021发送的调整后的第五光信号，并对调整后的第五光信号与量子信号的干涉信号进行探测，从而得到包含有随机密钥的密钥信息的探测结果。
可选地，由于本振信号在传输过程中存在功率衰减，而为了保证本振信号和量子信号的干涉效果，本振信号的功率需要达到一定的强度，基于此，在该量子密钥接收装置中还可以设置有光放大器。其中，该光放大器可以设置在偏振控制模块之前，也可以设置在偏振控制模块与量子探测模块之间。也即，量子密钥接收装置可以通过该光放大器接收第一光纤中传输的本振信号，并对该本振信号进行放大，之后，将放大后的本振信号输出至偏振控制模块进行偏振方向的调整。或者，量子密钥接收装置可以通过偏振控制模块对本振信号的偏振方向进行之后，将调整后的本振信号输入该光放大模块进行功率放大，之后，将放大后的本振信号输出至量子探测模块。
在本申请实施例中，量子密钥接收装置可以接收通过两根不同的光纤传输的本振信号和量子信号，并基于接收到的本振信号和量子信号来获取探测结果，由于在传输过程中量子信号和本振信号不需要采用时分复用和偏振复用的方式进行隔离，因此，量子密钥接收装置中就不需要引入额外的光程差进行延时补偿，从而使得量子密钥接收装置可以集成化、小型化。并且，由于不再需要偏振复用来隔离本振信号和量子信号，因此也避免了由于偏振复用器件的有限消光比所导致的本振信号的强度受限的问题，提高了接收端的信噪比。
另外，由于本振信号和量子信号在两根光纤传输时发生的偏振旋转不同，因此，量子密钥接收装置中可以通过在本振信号路设置偏振控制模块来对本振信号的偏振方向进行调整，以使得调整后的本振信号的偏振方向与量子信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者使得调整后的本振信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。
在图9-图11所提供的量子密钥接收装置中，通过在本振信号路设置偏振控制模块来对本振信号的偏振方向进行调整。可选地，在一种可能的实现方式中，也可以将偏振控制模块设置在量子密钥接收装置的量子信号路，通过调整量子信号的偏振方向来使得量子信号的偏振方向与本振信号偏振方向之间的方向偏差不大于预设数值。
示例性的，参见图12，提供了一种量子密钥接收装置，该装置包括量子探测模块501和偏振控制模块502。
其中，偏振控制模块502用于从第二光纤接收量子信号和参考信号，并调整量子信号和参考信号的偏振方向，向量子探测模块501发送调整后的量子信号和参考信号；量子探测模块501用于从第一光纤接收本振信号，对本振信号、调整后的量子信号和调整后的参考信号 进行探测，以得到探测结果。
需要说明的是，偏振控制模块502可以为偏振控制器。该偏振控制模块502可以包括第一输入端口、第二输入端口和输出端口。其中，该偏振控制模块502的第一输入端口可以直接与第二光纤连接，或者，该偏振控制模块502的第一输入端口可以通过耦合器或环形器与第二光纤连接。通过该第一输入端口，偏振控制模块502可以接收量子密钥发送装置通过第二光纤发送的量子信号和参考信号。通过第二输入端口，偏振控制模块502可以接收量子探测模块501在当前时刻之前基于本振信号和参考信号的探测结果生成的第四控制信号。之后，偏振控制模块502可以基于该第四控制信号将该量子信号和参考信号的偏振方向调整为第一偏振方向，并向量子探测模块501发送调整后的量子信号和参考信号。
其中，参考信号携带有参考数据，该参考数据是量子密钥发送装置和量子密钥接收装置事先协商好的。并且，参考信号的偏振方向和量子信号的偏振方向一致。另外，需要说明的是，若该偏振控制模块502为首次接收到量子信号和参考信号，则将该量子信号和参考信号调整到一个预设的偏振方向上，并向量子信号探测模块501发送该调整后的量子信号和参考信号，也即，若为首次接收到量子信号和参考信号，则在第一次调整时，将量子信号和参考信号的偏振调整为第一偏振方向是指将量子信号和参考信号调整到一个预设的偏振方向上。
量子探测模块501可以包括第一输入端口、第二输入端口和输出端口。其中，通过包括的第一输入端口，可以接收量子密钥发送装置通过第一光纤发送的本振信号。通过包括的第二输入端口，量子探测模块501可以接收偏振控制模块502发送的调整后的量子信号和参考信号。其中，若该量子信号和参考信号是通过频分复用的方式发送的，则量子探测模块501在接收到调整后的量子信号和参考信号时，可以从参考信号所在的频段上提取调整后的参考信号，并对该调整后的参考信号和本振信号的干涉信号进行探测，以得到参考数据测量值。若参考数据测量值与存储的参考数据之间的偏差不大于允许偏差，则说明调整后的参考信号和调整后的本振信号的干涉效果较好，也即，调整后的参考信号的偏振方向是合适的，由于调整后的参考信号与调整后的量子信号的偏振方向是一致的，因此，本振信号在与调整后的量子信号发生干涉时的干涉效果也将较好，基于此，量子探测模块501可以对调整后的量子信号与本振信号的干涉信号进行测量，以得到探测结果，进而根据该探测结果获取随机密钥的密钥信息。
当然，若参考数据测量值与存储的参考数据之间的偏差大于允许偏差，则说明调整后的参考信号和本振信号的干涉效果较差，此时，需要继续调整参考信号量子信号的偏振方向，因此，量子探测模块501可以根据该参考数据测量值和参考数据之间的差值生成第四控制信号，并通过输出端口输出该第四控制信号至偏振控制模块502。
偏振控制模块502可以通过包括的第二输入端口接收量子探测模块501发送的第四控制信号，基于第四控制信号对当前接收到的量子信号和参考信号的偏振方向进行调整，并重新向量子探测模块501发送调整后的量子信号和参考信号，直到量子探测模块501检测到的参考数据测量值与参考数据之间的差值不大于允许偏差时，则按照最后一次调整的量子信号和参考信号的偏振方向来调整后续接收到的量子信号和参考信号的偏振方向。
可选地，若参考信号和量子信号是通过时分复用的方式发送的，则偏振控制模块502在接收到参考信号时，可以通过不断调整参考信号的方向来确定参考信号与本振信号的干涉效果最好时的参考信号的偏振方向，并在接收到量子信号时，按照最终确定的参考信号的偏振 方向来调整量子信号，以提升调整后的本振信号与量子信号的干涉效果，进而保证探测结果的准确性。
在本申请实施例中，量子密钥接收装置可以接收通过两根不同的光纤传输的本振信号和量子信号，并基于接收到的本振信号和量子信号来获取探测结果，由于在传输过程中量子信号和本振信号不需要采用时分复用和偏振复用的方式进行隔离，因此，量子密钥接收装置中就不需要引入额外的光程差进行延时补偿，从而使得量子密钥接收装置可以集成化、小型化。并且，量子密钥接收装置也不需要再进行偏振补偿，减少了额外的器件和线路损耗。
另外，由于本振信号和量子信号在两根光纤传输时发生的偏振旋转不同，因此，量子密钥接收装置中可以通过在量子信号路设置偏振控制模块来对量子信号和参考信号的偏振方向进行调整，以使得调整后的量子信号的偏振方向与本振信号的偏振方向能够保持一致或者是保持二者之间的差值固定，或者是使得调整后的量子信号的偏振方向能够始终稳定在一个偏振方向上，以此来提升量子信号和本振信号的干涉效果，进而保证探测结果的准确性。
上述实施例介绍的量子密钥接收装置主要是通过偏振控制模块来消除采用不同光纤传输量子信号和本振信号时所造成的偏振旋转不一致的问题。可选地，在一种可能的实现方式中，量子密钥接收装置也可以通过其他实现方式来消除偏振旋转不一致的问题。
示例性的，参见图13，提供了一种量子密钥接收装置，该装置包括第一偏振分束器601、第二偏振分束器602、第一量子外差探测器603、第二量子外差探测器604和处理器605。
其中，第一偏振分束器601用于从第一光纤接收本振信号，将本振信号分为第六光信号和第七光信号，并向第一量子外差探测器发送第六光信号，向第二量子外差探测器发送第七光信号。
需要说明的是，该第一偏振分束器601可以包括有输入端口、第一输出端口和第二输出端口。其中，该第一偏振分束器601的输入端口可以直接与第一光纤连接，或者，该第一偏振分束器601的输入端口可以通过耦合器或环形器与第一光纤连接。通过该输入端口，第一偏振分束器601可以接收量子密钥发送装置通过第一光纤发送的本振信号。之后，第一偏振分束器601可以将该本振信号分为第六光信号和第七光信号，并通过第一输出端口输出第六光信号，通过第二输出端口输出第七光信号。
第二偏振分束器602用于从第二光纤接收量子信号和参考信号，将参考信号分为第八光信号和第九光信号，将量子信号分为第十光信号和第十一光信号，向第一量子外差探测器发送第八光信号和第十光信号，向第二量子外差探测器发送第九光信号和第十一光信号，量子信号携带有随机密钥。
需要说明的是，第二偏振分束器602可以包括有输入端口、第一输出端口和第二输出端口。其中，该第二偏振分束器602的输入端口可以直接与第二光纤连接，或者，该第二偏振分束器602的输入端口可以通过耦合器或环形器与第二光纤连接。通过该输入端口，第二偏振分束器602可以接收量子密钥发送装置通过第二光纤发送的量子信号和参考信号。
其中，量子信号和参考信号可以是通过时分复用的方式发送的，因此，第二偏振分束器602在接收到参考信号时，将该参考信号分为第八光信号和第九光信号，并通过第一输出端口输出第八光信号，通过第二输出端口输出第九光信号。在接收到量子信号时，第二偏振分束器602将该量子信号分为第十光信号和第十一光信号，并通过第一输出端口输出第十光信 号，通过第二输出端口输出第十一光信号。
第一量子外差探测器603用于接收第六光信号、第八光信号和第十光信号，探测第六光信号和第八光信号的干涉信号，以得到第八光信号的正则分量，探测第六光信号与第十光信号的干涉信号，以得到第十光信号的正则分量，向处理器605发送第八光信号的正则分量和第十光信号的正则分量。
其中，第一量子外差探测器603在接收到第六光信号和第八光信号时，可以对第六光信号和第八光信号的干涉信号进行探测，从而得到第八光信号的正则分量，并将第八光信号的正则分量发送至处理器605。在接收到第十光信号时，则可以对第十光信号和第六光信号的正则分量进行探测，得到第十光信号的正则分量，并向处理器605发送第十光信号的正则分量。
第二量子外差探测器604用于接收第七光信号、第九光信号和第十一光信号，探测第七光信号和第九光信号的干涉信号，以得到第九光信号的正则分量，探测第七光信号与第十一光信号的干涉信号，以得到第十一光信号的正则分量，向处理器605发送第九光信号的正则分量和第十一光信号的正则分量。
其中，当第一量子外差探测器603接收到第八光信号时，第二量子外差探测器604将可以接收到第九光信号，此时，第二量子外差探测器604可以对第九光信号和第七光信号的干涉信号进行探测，以得到第九光信号的正则分量，并向处理器605发送第九光信号的正则分量。当第一量子外差探测器603接收到第十光信号时，第二量子外差探测器604将可以接收到第十一光信号，此时，第二量子外差探测器604可以对第十一光信号和第七光信号的干涉信号进行探测，以得到第十一光信号的正则分量，并向处理器605发送第十一光信号的正则分量。
处理器605接收第八光信号的正则分量、第十光信号的正则分量、第九光信号的正则分量和第十一光信号的正则分量，对第八光信号的正则分量和第九光信号的正则分量进行处理，以得到信号参数，基于信号参数对第十光信号的正则分量和第十一光信号的正则分量进行处理，以得到初始密钥，初始密钥包括随机密钥的密钥信息。
当处理器605接收到第一量子外差探测器603发送的第八光信号的正则分量和第二量子外差探测器发送的第九光信号的正则分量时，处理器605可以对第八光信号的正则分量和第九光信号的正则分量进行处理，从而得到信号参数，其中，该信号参数可以包括第一强度透过率、第二强度透过率、第一相位和第二相位。其中，第一强度透过率是指参考信号进入第二偏振分束器602之后，从第二偏振分束器602的第一输出端口输出的信号的强度透过率。第二强度透过率是指本振信号进入第一偏振分束器601之后，从第一偏振分束器601的第一输出端口输出的信号的强度透过率。第一相位是指以第一量子外差探测器603接收到第八光信号时第八光信号的相位为参考确定的第二量子外差探测器604接收到第九光信号时第九光信号的相位。第二相位是指以第一量子外差探测器603接收到第八光信号时第八光信号的相位为参考确定的第一量子外差探测器603接收到第六光信号时第六光信号的相位。
当处理器605接收到第一量子外差探测器603发送的第十光信号的正则分量和第二量子外差探测器发送的第十一光信号的正则分量时，可以基于已确定的信号参数对第十光信号的正则分量和第十一光信号的正则分量进行处理，从而得到初始密钥，该初始密钥包括有随机密钥的密钥信息。
可选地，在一种可能的实现方式中，量子密钥发送装置可能是通过频分复用的方式来发送量子信号和参考信号的，这样，第二偏振分束器602将同时接收到量子信号和参考信号，并将该量子信号和参考信号分为第十二光信号和第十三光信号，并通过第一输出端口输出第十二光信号，通过第二输出端口输出第十三光信号。
第一量子外差探测器603在接收到第十二光信号时，可以对第十二光信号和第六光信号的干涉信号进行探测，从而得到第十二光信号的正则分量，并向处理器605发送十二光信号的正则分量。第二量子外差探测器604在接收到第十三光信号时，可以对十三光信号和第七光信号的干涉信号进行探测，从而得到第十三光信号的正则分量，并向处理器605发送十三光信号的正则分量。
处理器605在接收到第十二光信号和第十三光信号的正则分量之后，可以从第十二光信号的正则分量中提取参考信号的第一正则分量，从第十三光信号的正则分量中提取参考信号的第二正则分量，基于参考信号的第一正则分量和第二正则分量确定信号参数，并基于该信号参数对第十二光信号中的量子信号的正则分量以及第十三光信号中的量子信号的正则分量进行处理，从而得到初始密钥。
其中，由于参考信号和量子信号是通过频分复用的方式进行发送的，参考信号和量子信号分别占用不同的频段，因此，处理器605可以根据参考信号所在的频段，从第十二光信号的正则分量和第十三光信号的正则分量中分别提取位于参考信号所在的频段内的正则分量，从而得到参考信号的第一正则分量和第二正则分量。
在本申请实施例中，量子密钥接收装置可以通过第一偏振分束器和第二偏振分束器分别对本振信号、量子信号和参考信号进行分束，之后，再通过第一量子外差探测器和第二量子外差探测器分别测量参考信号的正则分量和量子信号的正则分量，进而根据参考信号的正则分量计算信号参数，最终根据该信号参数对量子信号的正则分量进行处理，以得到初始密钥。由此可见，在本申请实施例中，量子密钥接收装置中可以不必设置偏振控制模块，通过上述介绍的方法即可以消除偏振旋转带来的影响，保证得到的密钥信息的准确性。
前述实施例中主要介绍了用于量子密钥传输的量子密钥发送装置和量子密钥接收装置，接下来，本申请实施例将提供一种量子密钥传输系统。
参见图14，提供了一种量子密钥传输系统。该系统中可以包括量子密钥发送装置701、量子密钥接收装置702、第一光纤703和第二光纤704，其中，量子密钥发送装置701和量子密钥接收装置702通过第一光纤703和第二光纤704进行通信，并且，第一光纤703用于传输本振信号，第二光纤704用于传输量子信号和参考信号。
需要说明的是，该量子密钥传输系统中的量子密钥发送装置701可以为图1-8所示的任一种量子密钥发送装置，在这种情况下，该量子密钥接收装置702也可以不包括用于控制偏振方向的器件的量子密钥接收装置。例如，该量子密钥接收装置702中可以包括量子探测模块而不包括偏振控制模块。
可选地，该量子密钥传输系统中的量子密钥接收装置702可以为图9-13所示的任一种量子密钥接收装置，在这种情况下，量子密钥发送装置701中可以不包括偏振控制器。例如，量子密钥发送装置701中可以包括激光器、分束器、量子信号制备模块，而不包括偏振控制器；量子密钥发送装置701中还可以包括激光器、分束器、量子信号制备模块，参考信号制 备模块，而不包括偏振控制器。
可选地，在一种可能的实现方式中，该量子密钥传输系统中的量子密钥发送装置701可以为图1-8所示的任一种量子密钥发送装置，且该量子密钥传输系统中的量子密钥接收装置702可以为图9-13所示的任一种量子密钥接收装置。
可选地，考虑到经典相干通信系统中是通过两根光纤来传输相干光信号，以此来实现双向通信的，而在本申请实施例中，量子密钥发送装置和量子密钥接收装置之间也是通过两根光纤进行通信，基于此，在本申请实施例中，量子密钥发送装置和量子密钥接收装置可以与经典相干通信系统共用两根光纤进行信号的传输。
基于此，参见图15，本申请实施例提供了一种量子信号和相干光信号进行混传的量子密钥传输系统。该系统包括第一通信基站80和第二通信基站90。并且，第一通信基站80和第二通信基站20通过第一光纤和第二光纤来实现双向通信。
其中，第一通信基站80包括量子密钥发送装置801、第一相干光发送装置802、第一相干光接收装置803、第一耦合器804和第二耦合器805。
第二通信基站90包括量子密钥接收装置901、第二相干光接收装置902、第二相干光发送装置903、第三耦合器904和第四耦合器905。
需要说明的是，量子密钥发送装置801和量子密钥接收装置812的实现方式可以参考图14中所示的量子密钥发送装置701和量子密钥接收装置702的实现方式。
第一相干光发送装置802通过第一耦合器与第一光纤连接，用于通过第一光纤向第二相干光接收装置902发送相干光信号，第二相干光发送装置903通过第四耦合器与第二光纤连接，用于通过第二光纤向第一相干光接收装置803发送相干光信号。也即，通过第一相干光发送装置802与第二相干光接收装置902可以实现从第一通信基站80向第二通信基站90的相干信号传输。而通过第二相干光发送装置903和第一相干光接收装置803可以实现从第二通信基站90向第一通信基站80的相干信号传输。
另外，由于量子密钥发送装置801发送的本振信号与第一相干光发送装置802发送的相干光信号同时在第一光纤上进行传输，因此，在量子密钥发送装置801和第一相干光发送装置802均可以通过第一耦合器804与第一光纤连接。这样，第一耦合器804在接收到量子密钥发送装置801发送的本振信号和第一相干光发送装置802发送的相干光信号时，可以将该本振信号和相干光信号进行耦合，并通过连接的第一光纤发送出去。其中，本振信号的波长与相干光信号的波长不同。
相应地，第三耦合器904与第一光纤连接，这样，第三耦合器904可以接收第一光纤中传输的由相干光信号和本振信号耦合后的信号，并对接收到的信号进行解耦，得到本振信号和第一相干光发送装置802发送的相干光信号。之后，第三耦合器904可以将第一相干光发送装置802发送的相干光信号发送给第二相干光接收装置902，将本振信号发送给量子密钥接收装置901。
还需要说明的是，量子密钥发送装置801通过第二耦合器805与第二光纤连接，这样，量子密钥发送装置801可以将量子信号和参考信号发送至第二耦合器805，第二耦合器805再通过第二光纤将该量子信号和参考信号发送至第四耦合器905。除此之外，第二耦合器805还可以用于接收第四耦合器905通过第二光纤发送的相干光信号，并将该相干光信号发送至 第一相干光接收装置803。
第四耦合器905用于从第二光纤接收量子信号和参考信号，并将该量子信号和参考信号发送至量子密钥接收装置901。与此同时，第四耦合器905还用于接收第二相干光发送装置903发送的相干光信号，并将该相干光信号通过第二光纤和第二耦合器发送至第一相干光接收模块803。
其中，第一耦合器804、第二耦合器805、第三耦合器904和第四耦合器905均可以为波长可选择的耦合器，例如，可以为波分复用(Wavelength Division Multiplexing，WDM)耦合器。
可选地，在一种可能的实现方式中，在上述量子密钥传输系统中，第一通信基站可以包括多个量子密钥发送装置，相应地，在第二通信基站中可以包括与量子密钥发送装置的数量相等的量子密钥接收装置，且第一通信基站多个量子密钥发送装置和第二通信基站中的量子密钥接收装置一一对应。
进一步地，第一通信基站中还可以包括多个量子密钥接收装置，相应地，第二通信基站中可以包括对多个量子密钥接收装置中的每个量子密钥接收装置相对应的量子密钥发送装置，以此来实现量子信号的双向传输。
在本申请实施例中，量子密钥发送装置和量子密钥接收装置可以与经典相干通信系统共用两根光纤进行信号的传输，这样，不仅使得接收端集成化、小型化，减少了额外的器件和线路损耗，而且，实现了经典相干光信号与量子信号的混传。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。
以上所述为本申请提供的实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (15)

  1. 一种量子密钥发送装置，其特征在于，所述装置包括激光器、分束器、量子信号制备模块和偏振控制模块；
    所述激光器用于输出第一光信号；
    所述分束器用于接收所述第一光信号，将所述第一光信号分为第二光信号和第三光信号，将所述第二光信号通过第一光纤发送出去，并向所述量子信号制备模块发送所述第三光信号；
    所述量子信号制备模块用于，对所述第三光信号进行调制，得到第一调制信号和第二调制信号，向所述偏振控制模块发送所述第一调制信号和所述第二调制信号，其中，所述第一调制信号携带待传输的随机密钥，所述第二调制信号携带待传输的参考数据；
    所述偏振控制模块用于，对所述第一调制信号和所述第二调制信号的偏振方向进行调整，以及对所述第一调制信号和所述第二调制信号的光强进行衰减，得到量子信号和参考信号，其中，所述量子信号和所述参考信号通过第二光纤发送出去。
  2. 如权利要求1所述的装置，其特征在于，所述第二光信号的光强大于所述第三光信号的光强。
  3. 如权利要求1或2所述的装置，其特征在于，所述装置还包括接收器和处理器，
    所述接收器用于接收偏振方向控制信息，并向所述处理器发送所述偏振方向控制信息；
    所述处理器用于对所述偏振方向控制信息进行处理，得到第一控制信号，并向所述偏振控制器发送所述第一控制信号；
    所述偏振控制模块具体用于，基于所述第一控制信号对所述第一调制信号和所述第二调制信号的偏振方向进行调整。
  4. 如权利要求1或2所述的装置，其特征在于，所述量子信号制备模块包括量子随机数发生器、处理器和调制器；
    所述量子随机数发生器用于产生随机数，并向所述处理器发送所述随机数；
    所述处理器用于根据所述随机数，生成随机密钥，并根据所述随机密钥生成量子控制信号；还用于根据存储的参考数据生成参考控制信号，将所述量子控制信号和所述参考控制信号发送给所述调制器；
    所述调制器用于根据所述量子控制信号对所述第三光信号进行调制，得到第一调制信号；根据所述参考控制信号对所述第三光信号进行调制，得到第二调制信号；将所述第一调制信号和所述第二调制信号发送给所述偏振控制模块。
  5. 如权利要求4所述的装置，其特征在于，所述偏振控制模块包括偏振控制器和衰减器；
    所述偏振控制器用于对所述第一调制信号和所述第二调制信号的偏振方向进行调整，将调整后的第一调制信号和调整后的第二调制信号发送给所述衰减器；
    所述衰减器用于对所述调整后的第一调制信号进行衰减，得到所述量子信号；对所述调整后的第二调制信号进行衰减，得到所述参考信号。
  6. 如权利要求4所述的装置，其特征在于，所述偏振控制模块包括偏振控制器和衰减器；
    所述衰减器用于对所述第一调制信号和所述第二调制信号进行衰减，得到衰减后的第一调制信号和衰减后的第二调制信号，将所述衰减后的第一调制信号和所述衰减后的第二调制 信号发给所述偏振控制器；
    所述偏振控制器，用于对所述衰减后的第一调制信号的偏振方向进行调整，得到所述量子信号；对所述衰减后的第二调制信号的偏振方向进行调整，得到所述参考信号。
  7. 如权利要求1或2所述的装置，其特征在于，所述第二光信号与所述第一光纤中传输的其他光信号的波长不同，所述第三光信号与所述第二光纤中传输的其他光信号的波长不同。
  8. 如权利要求1或2所述的装置，其特征在于，所述第二光纤还用于传输相干光信号，且所述第二光纤中传输的相干光信号的传输方向和所述第二光纤中传输的量子信号的传输方向相反。
  9. 一种量子密钥接收装置，其特征在于，所述装置包括量子探测模块和偏振控制模块；
    所述偏振控制模块用于从第一光纤接收本振信号，并调整所述本振信号的偏振方向，向所述量子探测模块发送调整后的本振信号；
    所述量子探测模块用于从第二光纤接收量子信号和参考信号，对所述调整后的本振信号、所述量子信号和所述参考信号进行探测，得到探测结果，其中，所述量子信号携带有随机密钥，所述探测结果包括所述随机密钥的密钥信息；
    或
    所述偏振控制模块用于从所述第二光纤接收量子信号和参考信号，并调整所述量子信号和所述参考信号的偏振方向，向所述量子探测模块发送调整后的量子信号和参考信号；
    所述量子探测模块用于从所述第一光纤接收本振信号，对所述本振信号、所述调整后的量子信号和所述调整后的参考信号进行探测，得到所述探测结果。
  10. 如权利要求9所述的装置，其特征在于，所述参考信号的偏振方向与所述量子信号的偏振方向一致，且所述参考信号携带参考数据，所述偏振控制模块包括偏振控制器；
    所述偏振控制器用于从所述第一光纤接收所述本振信号，将所述本振信号的偏振方向调整为第一偏振方向，并向所述量子探测模块发送所述调整后的本振信号；
    所述量子探测模块具体用于接收所述调整后的本振信号，从所述第二光纤接收所述量子信号和所述参考信号，对所述调整后的本振信号和所述参考信号的干涉信号进行探测，得到参考数据测量值；若所述参考数据测量值与存储的所述参考数据之间的偏差不大于允许偏差，则对所述量子信号和调整后的本振信号的干涉信号进行探测，得到所述探测结果；若所述参考数据测量值与存储的所述参考数据之间的偏差大于所述允许偏差，则基于所述参考数据测量值生成第二控制信号，并向所述偏振控制器发送所述第二控制信号；
    所述偏振控制器还用于接收所述第二控制信号，基于所述第二控制信号更新所述本振信号的偏振方向，并重新向所述量子探测模块发送所述调整后的本振信号。
  11. 如权利要求9所述的装置，其特征在于，所述参考信号携带参考数据，所述偏振控制模块包括偏振控制器；
    所述偏振控制器用于从所述第二光纤接收所述量子信号和所述参考信号，将所述量子信号和所述参考信号的偏振方向调整为第一偏振方向，并向所述量子探测模块发送调整后的量子信号和参考信号；
    所述量子探测模块具体用于接收所述调整后的量子信号和参考信号，从所述第一光纤接收所述本振信号，对所述调整后的参考信号和所述本振信号的干涉信号进行探测，得到参考 数据测量值；若所述参考数据测量值与存储的所述参考数据之间的偏差不大于允许偏差，则对调整后的量子信号和所述本振信号的干涉信号进行探测，得到所述探测结果；若所述参考数据测量值与存储的所述参考数据之间的偏差大于所述允许偏差，则基于所述参考数据测量值生成第四控制信号，并向所述偏振控制器发送所述第四控制信号；
    所述偏振控制器还用于接收所述第四控制信号，基于所述第四控制信号更新所述量子信号和所述参考信号的偏振方向，并重新向所述量子探测模块发送调整后的量子信号和调整后的参考信号。
  12. 如权利要求9所述的装置，其特征在于，所述偏振控制模块包括分束器、偏振分析仪和偏振控制器；
    所述分束器用于从所述第一光纤接收所述本振信号，将所述本振信号分为第四光信号和第五光信号，并向所述偏振分析仪发送所述第四光信号，向所述偏振控制器发送所述第五光信号；
    所述偏振分析仪用于分析所述第四光信号的偏振方向，基于所述第四光信号的偏振方向与目标偏振方向生成第三控制信号，向所述偏振控制器发送所述第三控制信号，所述目标偏振方向与所述量子信号的偏振方向之间的方向偏差不大于预设数值；
    所述偏振控制器用于，根据所述第三控制信号将所述第五光信号的偏振方向调整为所述目标偏振方向，并向所述量子探测模块发送调整后的第五光信号；
    所述量子探测模块具体用于接收调整后的第五光信号，从所述第二光纤接收所述量子信号和所述参考信号，对所述调整后的第五光信号、所述量子信号和所述参考信号进行探测，得到所述探测结果。
  13. 如权利要求12所述的装置，其特征在于，所述第四光信号的光强小于所述第五光信号的光强。
  14. 一种量子密钥接收装置，其特征在于，所述装置包括第一偏振分束器、第二偏振分束器、第一量子外差探测器、第二量子外差探测器和处理器；
    所述第一偏振分束器用于从第一光纤接收本振信号，将所述本振信号分为第六光信号和第七光信号，并向所述第一量子外差探测器发送所述第六光信号，向所述第二量子外差探测器发送所述第七光信号；
    所述第二偏振分束器用于从第二光纤接收所述量子信号和所述参考信号，将所述参考信号分为第八光信号和第九光信号，将所述量子信号分为第十光信号和第十一光信号，向所述第一量子外差探测器发送所述第八光信号和所述第十光信号，向所述第二量子外差探测器发送所述第九光信号和第十一光信号，所述量子信号携带有随机密钥；
    所述第一量子外差探测器用于探测所述第六光信号和所述第八光信号的干涉信号，得到所述第八光信号的正则分量，探测所述第六光信号与所述第十光信号的干涉信号，得到所述第十光信号的正则分量，向所述处理器发送所述第八光信号的正则分量和所述第十光信号的正则分量；
    所述第二量子外差探测器用于探测所述第七光信号和所述第九光信号的干涉信号，得到所述第九光信号的正则分量，探测所述第七光信号与所述第十一光信号的干涉信号，得到所述第十一光信号的正则分量，向所述处理器发送所述第九光信号的正则分量和所述第十一光 信号的正则分量；
    所述处理器用于，对所述第八光信号的正则分量和所述第九光信号的正则分量进行处理，得到信号参数；基于所述信号参数对所述第十光信号的正则分量和所述第十一光信号的正则分量进行处理，得到初始密钥，所述初始密钥包括所述随机密钥的密钥信息。
  15. 一种量子密钥传输系统，其特征在于，所述量子密钥传输系统包括量子密钥发送装置和量子密钥接收装置；
    所述量子密钥发送装置为权利要求1-8中任一项所述的装置；
    所述量子密钥接收装置用于从所述第一光纤接收本振信号，从所述第二光纤接收所述调整后的量子信号和所述调整后的参考信号，对所述本振信号、所述调整后的量子信号和所述调整后的参考信号进行探测，得到探测结果，其中，所述探测结果包括所述随机密钥的密钥信息；
    或者，
    所述量子密钥发送装置包括激光器、分束器和量子信号制备模块；所述激光器用于输出第一光信号；所述分束器用于接收所述第一光信号，将所述第一光信号分为第二光信号和第三光信号，将所述第二光信号通过第一光纤发送出去，并向所述量子信号制备模块发送所述第三光信号；所述量子信号制备模块用于，对所述第三光信号进行调制，得到量子信号和参考信号，将所述量子信号和所述参考信号通过第二光纤发送出去，其中，所述量子信号携带待传输的随机密钥；
    所述量子密钥接收装置为权利要求9-13中任一项所述的装置。
PCT/CN2019/097103 2018-07-23 2019-07-22 量子密钥传输装置及系统 WO2020020100A1 (zh)

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