Quantum key distribution method and device based on quantum light and synchronous light

Abstract

The invention discloses a quantum key distribution method and device based on quantum light and synchronous light, and belongs to the technical field of quantum key distribution, and the method comprises the steps: generating first quantum light and first synchronous light through a laser of a transmitting end according to a wavelength difference value at an interval of 4-6 DWDM channels; coupling the first quantum light and the first synchronous light into a first optical signal, transmitting the first optical signal to a receiving end through a same fiber, so that the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain second quantum light and second synchronous light, and extracting a clock signal from the second synchronous light to obtain a synchronous clock, and performing basis vector comparison and bit error rate calculation in combination with the second quantum light and a synchronous clock, generating a key, and completing key distribution. Therefore, the problems of pulse broadening and bit error rate increase caused by dispersion when the synchronous light and the quantum light are transmitted in the same fiber in the long-distance quantum key distribution system in the prior art can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum key distribution, and relates to a quantum key distribution method and device based on quantum light and synchronous light. Background Art

[0002] In the power system, high-precision time synchronization technology is required to ensure the safe and stable operation of the power grid. With the application of quantum key distribution (QKD) technology in power communications, high-precision time synchronization between the transmitter and the receiver has become a key requirement. The efficient and stable transmission of quantum light and synchronization light is an important basis for achieving this requirement.

[0003] In traditional quantum key distribution systems, there are two main schemes for the transmission of synchronization light and quantum light: one is to transmit the synchronization light through independent optical fibers. Although this avoids interference, it requires additional optical fiber resources and is costly. The other is the same-fiber wavelength division multiplexing (WDM) scheme. Although the optical fiber is shared, the spontaneous radiation noise and crosstalk of the synchronization light will increase the quantum light bit error rate. Moreover, when transmitted over long distances (such as around 200 km), the dispersion effect will further broaden the pulse, reduce the time resolution, and affect the clock recovery accuracy and system stability. Summary of the Invention

[0004] The present application provides a quantum key distribution method and device based on quantum light and synchronous light, which can solve the problems of pulse broadening and increased bit error rate caused by dispersion when synchronous light and quantum light are transmitted on the same fiber in long-distance quantum key distribution systems in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a quantum key distribution method based on quantum light and synchronous light, which is applicable to the transmitting end of a quantum key distribution device, and the quantum key distribution method includes:

[0006] Generate a first quantum light and a first synchronization light by using a laser at the transmitting end at a wavelength difference of a preset number of DWDM channels; wherein the preset number is 4, 5, or 6;

[0007] The first quantum light and the first synchronization light are coupled into a first optical signal, which is transmitted to a receiving end via the same fiber, so that the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light. A clock signal is extracted from the second synchronization light to obtain a synchronization clock. The second quantum light and the synchronization clock are combined to perform basis vector comparison and bit error rate calculation to generate a key and complete key distribution.

[0008] Compared with the existing technology, the embodiments of the present application have the following beneficial effects: quantum light and synchronization light are generated by the transmitting end laser with a wavelength difference of 4-6 DWDM channels, which increases the wavelength spacing between the two and effectively reduces the crosstalk and noise interference between synchronization light and quantum light; quantum light and synchronization light are coupled into a first optical signal and transmitted through the same fiber, avoiding the additional laying of independent optical fibers and reducing the system deployment cost; dispersion compensation processing is performed on the optical signal at the receiving end, which can reduce the pulse broadening caused by fiber dispersion and improve the time resolution; the signal separation operation ensures that the quantum light and synchronization light are correctly detected respectively; the clock signal is extracted from the synchronization light to achieve high-precision time synchronization between the transmitting end and the receiving end; the basis vector comparison and bit error rate calculation are combined with quantum light and the synchronization clock to ensure the accuracy and stability of key generation. The overall solution effectively solves the problem of pulse broadening caused by crosstalk and dispersion between synchronization light and quantum light in long-distance transmission through the synergistic effect of wavelength design of spaced DWDM channels, same-fiber transmission and dispersion compensation, and ultimately achieves stable operation of quantum key distribution.

[0009] In some embodiments of the first aspect of the present application, the transmitting end includes an EDFA amplifier and a narrow bandwidth filter; and generating the first quantum light and the first synchronization light by using wavelength differences of a preset number of DWDM channels at intervals includes:

[0010] Generate the first quantum light and the original synchronization light with a wavelength difference of a preset number of DWDM channels;

[0011] The original synchronization light is subjected to signal amplification and filtering processing respectively through an EDFA amplifier and a narrow bandwidth filter to obtain a first synchronization light.

[0012] Compared with the existing technology, the above embodiment has the following beneficial effects: the EDFA amplifier set at the transmitting end can amplify the original synchronous light signal, increase its power to compensate for transmission loss, and ensure that the receiving end has sufficient power for clock recovery; the narrow bandwidth filter filters the amplified synchronous light, which can narrow its spectral width, reduce crosstalk and noise caused by an excessively wide spectrum, and avoid adverse effects on wavelength division multiplexing.

[0013] In some embodiments of the first aspect of the present application, the amplifying and filtering the original synchronization light to obtain the first synchronization light includes:

[0014] Amplifying the power of the original synchronization light by a gain of 20-40 dB through an EDFA amplifier to obtain an original first synchronization light;

[0015] The spectrum width of the original first synchronization light is narrowed to 0.15-0.2 nm by a narrow bandwidth filter to obtain the first synchronization light.

[0016] Compared with the existing technology, the above embodiment has the following beneficial effects: the EDFA amplifier performs a gain amplification of 20-40dB on the original synchronization light, which can increase the synchronization light power to meet transmission requirements. At the same time, this gain range can effectively compensate for the loss of long-distance transmission and avoid signal distortion caused by excessive amplification; the narrow bandwidth filter narrows the synchronization light spectrum width to 0.15-0.2nm. While suppressing spontaneous emission noise, this spectrum width range maintains the intensity of the synchronization light signal, enhances the wavelength isolation from quantum light, and reduces the risk of interference.

[0017] In some embodiments of the first aspect of the present application, the transmitting end further includes a wavelength division multiplexer; and coupling the first quantum light and the first synchronization light into a first optical signal includes:

[0018] The first quantum light and the first synchronization light are combined into the same optical fiber through the wavelength division multiplexer to obtain the first optical signal.

[0019] Compared with the existing technology, the above embodiment has the following beneficial effects: quantum light and synchronous light are combined into the same optical fiber through a wavelength division multiplexer, thereby achieving efficient combined transmission of the two, ensuring the stability and reliability of the same-fiber transmission, and improving the utilization rate of optical fiber resources.

[0020] In some embodiments of the first aspect of the present application, the receiving end includes a dispersion compensation module; the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light, including:

[0021] According to the dispersion compensation module, dispersion compensation is performed on the first optical signal to obtain a second optical signal; wherein the dispersion compensation module is a dispersion compensating optical fiber or a chirped fiber grating;

[0022] The second optical signal is subjected to signal separation to obtain a second quantum light and a second synchronization light.

[0023] Compared to existing technologies, the above-described embodiments offer the following advantages: Dispersion-compensating fiber, with its high negative dispersion coefficient, can compensate for the positive dispersion of transmission fiber through length matching, making it suitable for overall dispersion compensation in long-distance transmission. Chirped fiber Bragg gratings achieve dispersion compensation by introducing varying delays to optical signals of different wavelengths through a periodically varying grating structure. Their low insertion loss makes them suitable for high-precision compensation of dispersion at localized or specific wavelengths, avoiding the effects of additional losses on weak quantum optical signals. The optional nature of these two modules provides the system with a flexible dispersion compensation solution, effectively reducing or eliminating pulse broadening caused by fiber dispersion, ensuring both the temporal resolution and clock recovery accuracy of the optical signal at the receiving end, and ultimately guaranteeing the stability of quantum key distribution.

[0024] In some embodiments of the first aspect of the present application, the receiving end further includes: a wavelength division multiplexer; and the signal separation of the second optical signal to obtain the second quantum light and the second synchronization light includes:

[0025] According to the wavelength division multiplexer, the second optical signal is wavelength demultiplexed to separate the second quantum light and the second synchronization light; wherein the non-adjacent channel isolation of the wavelength division multiplexer is greater than 90dB, and the adjacent channel isolation is greater than 60dB.

[0026] Compared with the existing technology, the above embodiment has the following beneficial effects: the receiving end demultiplexes the optical signal through a wavelength division multiplexer (non-adjacent channel isolation >90dB, adjacent channel isolation >60dB). This high isolation parameter design can effectively separate quantum light and synchronous light, reduce crosstalk between signals, ensure that the quantum light detector and synchronous light detector respectively receive pure signals, and reduce the bit error rate.

[0027] In some embodiments of the first aspect of the present application, the receiving end further includes: a synchronous light detector and a clock recovery module; and extracting the clock signal from the second synchronous light to obtain the synchronous clock includes:

[0028] According to the synchronous light detector, converting the second synchronous light into a corresponding electrical signal;

[0029] The clock recovery module is used to extract the clock signal from the electrical signal to obtain a synchronous clock; wherein the clock recovery module is a clock extraction circuit based on a phase-locked loop or a delay-locked loop.

[0030] Compared to existing technologies, the above embodiments offer the following advantages: a synchronous optical detector converts the second synchronous light into an electrical signal, facilitating subsequent electronic processing. A phase-locked loop (PLL) uses phase comparison and feedback control mechanisms to accurately track phase changes in the synchronous optical signal, suppress noise interference, and output a low-jitter clock that is phase-aligned with the input signal. A delay-locked loop (DLL) compensates for signal transmission delays by adjusting the delay line, achieving high-resolution time alignment for narrow-pulse synchronous optical signals and further reducing clock jitter. A clock recovery module based on a PLL or DLL can extract the clock signal with high precision, achieving time synchronization between the transmitter and receiver.

[0031] In some embodiments of the first aspect of the present application, the receiving end further includes a quantum light detector; and combining the second quantum light with a synchronous clock to perform basis vector comparison and bit error rate calculation to generate a key includes:

[0032] detecting the polarization state of the second quantum light according to the quantum light detector and extracting quantum state information therein;

[0033] Based on the quantum state information and the synchronous clock, basis vector comparison and bit error rate calculation are performed to generate a key.

[0034] Compared with the existing technology, the above embodiment has the following beneficial effects: the quantum light detector detects the polarization state of the second quantum light and extracts the quantum state information, and combines the synchronous clock to perform basis vector comparison and bit error rate calculation, thereby ensuring the accuracy and security of key generation.

[0035] In a second aspect, the present invention further provides a quantum key distribution device based on quantum light and synchronous light, comprising: a transmitting end, an optical fiber, and a receiving end;

[0036] Wherein, the transmitting end and the receiving end are connected via the optical fiber;

[0037] The transmitting end includes a laser, an EDFA amplifier, a narrow bandwidth filter and a wavelength division multiplexer;

[0038] The receiving end includes a dispersion compensation module, a wavelength division multiplexer, a synchronous optical detector, a clock recovery module and a quantum optical detector;

[0039] The transmitting end is used to execute a quantum key distribution method based on quantum light and synchronous light as described in any one of the above embodiments.

[0040] Compared with the prior art, the above embodiments of the present application have the following beneficial effects: quantum light and synchronization light are generated by the transmitting end laser with a wavelength difference of 4-6 DWDM channels, which increases the wavelength spacing between the two and effectively reduces the crosstalk and noise interference between synchronization light and quantum light; quantum light and synchronization light are coupled into a first optical signal and transmitted through the same fiber, avoiding the additional laying of independent optical fibers and reducing system deployment costs; dispersion compensation processing is performed on the optical signal at the receiving end, which can reduce pulse broadening caused by fiber dispersion and improve time resolution; signal separation operation ensures that quantum light and synchronization light are correctly detected respectively; clock signal is extracted from synchronization light to achieve high-precision time synchronization between the transmitting end and the receiving end; basis vector comparison and bit error rate calculation are performed by combining quantum light and synchronization clock to ensure the accuracy and stability of key generation. The overall solution effectively solves the problem of pulse broadening caused by crosstalk and dispersion between synchronization light and quantum light in long-distance transmission through the synergistic effect of wavelength design of spaced DWDM channels, same-fiber transmission and dispersion compensation, and ultimately achieves stable operation of quantum key distribution.

[0041] In some embodiments of the second aspect of the present application, the wavelength range of the first quantum light covers an idle channel of a C-band DWDM system.

[0042] Compared with the existing technology, the above embodiment has the following beneficial effects: the wavelength range of the first quantum light covers the idle channels of the C-band DWDM system, avoiding wavelength conflicts with existing communication services, improving the compatibility of the system with existing optical communication networks, and facilitating actual deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 : A schematic flow chart of a quantum key distribution method based on quantum light and synchronous light provided in some embodiments of the present invention.

[0044] Figure 2 : A schematic structural diagram of a quantum key distribution device based on quantum light and synchronous light provided in some embodiments of the present invention. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] Example 1:

[0047] Please refer to Figure 1 To address the problems of pulse broadening and increased bit error rate caused by dispersion when synchronous light and quantum light are transmitted on the same fiber in conventional long-distance quantum key distribution systems, an embodiment of the present invention provides a quantum key distribution method based on quantum light and synchronous light, which is applicable to the transmitting end of a quantum key distribution device. The quantum key distribution method includes steps S1 to S2:

[0048] Step S1: Generate a first quantum light and a first synchronization light by using a laser at the transmitting end with a wavelength difference of a preset number of DWDM channels; wherein the preset number is 4, 5 or 6.

[0049] Furthermore, the transmitting end includes an EDFA amplifier and a narrow bandwidth filter; the generation of the first quantum light and the first synchronization light by using the wavelength difference of a preset number of DWDM channels can be achieved by the following preferred implementation, including steps S11-S12, as follows:

[0050] S11: Generate a first quantum light and an original synchronization light with a wavelength difference of a preset number of DWDM channels;

[0051] S12: performing signal amplification and filtering processing on the original synchronization light through an EDFA amplifier and a narrow bandwidth filter, respectively, to obtain a first synchronization light.

[0052] In this preferred embodiment, the EDFA amplifier set at the transmitting end can amplify the original synchronous light signal, increase its power to compensate for transmission losses, and ensure that the receiving end has sufficient power for clock recovery; the narrow bandwidth filter filters the amplified synchronous light, which can narrow its spectral width, reduce crosstalk and noise caused by the excessively wide spectrum, and avoid adverse effects on wavelength division multiplexing.

[0053] Furthermore, the step S12 can be implemented by the following preferred implementation, including steps S121-S122, as follows:

[0054] S121: Amplify the power of the original synchronization light by a gain of 20-40 dB through an EDFA amplifier to obtain an original first synchronization light;

[0055] S122: Using a narrow bandwidth filter, narrow the spectral width of the original first synchronization light to 0.15-0.2 nm to obtain the first synchronization light.

[0056] In this preferred embodiment, the EDFA amplifier performs a gain amplification of 20-40dB on the original synchronization light, which can increase the synchronization light power to meet transmission requirements. At the same time, this gain range can effectively compensate for the loss of long-distance transmission and avoid signal distortion caused by excessive amplification; the narrow bandwidth filter narrows the synchronization light spectrum width to 0.15-0.2nm. This spectrum width range suppresses spontaneous radiation noise while maintaining the intensity of the synchronization light signal, enhancing the wavelength isolation from the quantum light and reducing the risk of interference.

[0057] In specific implementations, separate lasers are used to generate synchronization light and quantum light, respectively. The quantum light source has a central wavelength of 1550±0.1nm (e.g., 1549.32nm), a pulse width of less than 100ps, and a repetition rate of 1GHz, covering the idle channels of the C-band DWDM system. The synchronization light source has a clock frequency of 250kHz, a pulse width of less than 50ps, and is separated from the quantum light by 4-6 DWDM channels (i.e., 3.2-4.8nm). For example, if the central wavelength of the quantum light source is 1549.32nm, the synchronization light source has a central wavelength of 1552.52nm, separated by 4 DWDM channels.

[0058] After generating the synchronization light, it needs to be power amplified and filtered. This embodiment utilizes an EDFA amplifier and a narrow-bandwidth filter to achieve this. The EDFA amplifier provides gain amplification (20-40dB) on the synchronization light signal. The amplified synchronization light signal then passes through a narrow-bandwidth filter, leveraging the interference effect of multilayer dielectric films to selectively filter specific wavelengths, thereby narrowing the spectral width to 0.15-0.2nm. These processes effectively prevent crosstalk and noise interference caused by excessively broad spectrum after amplification, preventing the negative impact on wavelength division multiplexing (WDM) and compensating for long-distance transmission losses. Field verification has shown that when equipped with these two modules, the receiving end power remains stable within the range of -10 to -60dBm over a 200km transmission distance. The effective range of traditional QKD is typically 100-120km. By combining the EDFA amplifier and narrow-bandwidth filter, the effective transmission distance can be extended to nearly 200km.

[0059] Step S2: The first quantum light and the first synchronization light are coupled into a first optical signal, which is transmitted to a receiving end through the same fiber, so that the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light, and extracts a clock signal from the second synchronization light to obtain a synchronization clock. The second quantum light and the synchronization clock are combined to perform basis vector comparison and bit error rate calculation to generate a key, thereby completing key distribution.

[0060] Furthermore, the transmitting end further includes a wavelength division multiplexer, and the step S2 of coupling the first quantum light and the first synchronization light into a first optical signal can be specifically implemented by the following preferred implementation, including step S21, which is specifically as follows:

[0061] S21: Combine the first quantum light and the first synchronization light into the same optical fiber through the wavelength division multiplexer to obtain the first optical signal.

[0062] In practice, a wavelength division multiplexer (WDM) can be used to combine quantum light and processed synchronization light (i.e., the first quantum light and the first synchronization light) onto a single optical fiber for transmission. Furthermore, 1550nm single-mode fiber (SMF) can be used, with a link length ≥ 200km, a link loss ≤ 0.2dB / km, and a dispersion coefficient of 17ps / nm / km. Quantum optical channels can share fibers with classical communication systems (such as 1550nm band data channels), but the two must be separated by ≥ 10nm to avoid interference.

[0063] In this preferred embodiment, quantum light and synchronous light are combined into the same optical fiber through a wavelength division multiplexer, achieving efficient combined transmission of the two, ensuring the stability and reliability of the same-fiber transmission, and improving the utilization rate of optical fiber resources.

[0064] Furthermore, the receiving end includes a dispersion compensation module; the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light, which can be specifically implemented by the following preferred embodiment, including steps S22-S23, as follows:

[0065] S22: Perform dispersion compensation on the first optical signal according to the dispersion compensation module to obtain a second optical signal; wherein the dispersion compensation module is a dispersion compensating fiber or a chirped fiber grating;

[0066] S23: Perform signal separation on the second optical signal to obtain a second quantum light and a second synchronization light.

[0067] In specific implementation, before separating the synchronization light and quantum light, the optical signal transmitted over a long distance can first be dispersion compensated by the dispersion compensation module to reduce or eliminate the pulse broadening caused by fiber dispersion by 90%-110%.

[0068] In this preferred embodiment, the dispersion-compensating fiber has a high negative dispersion coefficient, which can compensate for the positive dispersion of the transmission fiber through length matching, making it suitable for overall dispersion compensation in long-distance transmission. The chirped fiber grating achieves dispersion compensation by introducing different delays to optical signals of different wavelengths through a periodically varying grating structure. Its low insertion loss makes it suitable for high-precision compensation of dispersion at localized or specific wavelengths, avoiding the impact of additional losses on weak quantum optical signals. The optional nature of these two modules provides the system with a flexible dispersion compensation solution, effectively reducing or eliminating pulse broadening caused by fiber dispersion, jointly ensuring the time resolution and clock recovery accuracy of the optical signal at the receiving end, and ultimately guaranteeing the stability of quantum key distribution.

[0069] After dispersion compensation, the synchronization light and quantum light can be separated by a wavelength division multiplexer. The separated quantum light is detected by a quantum light detector (e.g., a single photon detector (SPD) with a detection efficiency ≥15%, a dark count rate ≤10-6 / gate, and operating in the wavelength band of the quantum light). The separated synchronization light is input into a clock recovery module for clock extraction, achieving high-precision time synchronization between the transmitter and receiver. The specific method is as follows:

[0070] Furthermore, the receiving end further includes a wavelength division multiplexer; and step S23 can be implemented by the following preferred implementations, specifically as follows:

[0071] According to the wavelength division multiplexer, the second optical signal is wavelength demultiplexed to separate the second quantum light and the second synchronization light; wherein the non-adjacent channel isolation of the wavelength division multiplexer is greater than 90dB, and the adjacent channel isolation is greater than 60dB.

[0072] In this preferred embodiment, the receiving end demultiplexes the optical signal through a wavelength division multiplexer (non-adjacent channel isolation >90dB, adjacent channel isolation >60dB). This high isolation parameter design can effectively separate quantum light and synchronous light, reduce crosstalk between signals, ensure that the quantum light detector and synchronous light detector respectively receive pure signals, and reduce the bit error rate.

[0073] Furthermore, the receiving end further includes: a synchronous light detector and a clock recovery module; the extraction of the clock signal from the second synchronous light to obtain the synchronous clock can be achieved by the following preferred implementation, including steps S24-S25, as follows:

[0074] S24: converting the second synchronization light into a corresponding electrical signal according to the synchronization light detector;

[0075] S25: Utilize the clock recovery module to extract the clock signal from the electrical signal to obtain a synchronous clock; wherein the clock recovery module is a clock extraction circuit based on a phase-locked loop or a delay-locked loop.

[0076] In a specific implementation, the synchronous optical detector may be an avalanche photodiode (APD); the clock recovery module uses a clock extraction circuit based on a phase-locked loop (PLL) or a delay-locked loop (DLL), and the input optical power sensitivity is -10 to -60 dBm.

[0077] In this preferred embodiment, a synchronous light detector converts the second synchronization light into an electrical signal for subsequent electronic processing. A phase-locked loop (PLL) uses phase comparison and feedback control mechanisms to accurately track phase changes in the synchronization light signal, suppress noise interference, and output a low-jitter clock that is phase-aligned with the input signal. A delay-locked loop (DLL) compensates for signal transmission delays by adjusting the delay line, achieving high-resolution time alignment for narrow-pulse synchronization light signals and further reducing clock jitter. A clock recovery module based on the PLL or DLL can extract the clock signal with high precision, achieving time synchronization between the transmitter and receiver.

[0078] Furthermore, the receiving end further includes a quantum light detector; the combining of the second quantum light and the synchronous clock to perform basis vector comparison and bit error rate calculation to generate a key can be achieved by the following preferred implementation, including steps S26-S27, as follows:

[0079] S26: Detecting the polarization state of the second quantum light according to the quantum light detector, and extracting quantum state information therein;

[0080] S27: Perform basis vector comparison and bit error rate calculation based on the quantum state information and the synchronous clock to generate a key.

[0081] In this preferred embodiment, the quantum light detector detects the polarization state of the second quantum light and extracts the quantum state information, and combines the synchronous clock to perform basis vector comparison and bit error rate calculation, thereby ensuring the accuracy and security of key generation.

[0082] In summary, compared with the prior art, the above embodiments of the present application have the following beneficial effects: quantum light and synchronization light are generated by the transmitting end laser with a wavelength difference of 4-6 DWDM channels, which increases the wavelength spacing between the two and can effectively reduce the crosstalk and noise interference between synchronization light and quantum light; quantum light and synchronization light are coupled into a first optical signal and transmitted through the same fiber, avoiding the additional laying of independent optical fibers and reducing the system deployment cost; the receiving end performs dispersion compensation processing on the optical signal, which can reduce the pulse broadening caused by fiber dispersion and improve the time resolution; the signal separation operation ensures that the quantum light and synchronization light are correctly detected respectively; the clock signal is extracted from the synchronization light to achieve high-precision time synchronization between the transmitting end and the receiving end; the basis vector comparison and bit error rate calculation are combined with quantum light and the synchronization clock to ensure the accuracy and stability of key generation. The overall solution effectively solves the pulse broadening problem caused by crosstalk and dispersion between synchronization light and quantum light in long-distance transmission through the synergistic effect of wavelength design of interval DWDM channels, same-fiber transmission and dispersion compensation, and ultimately achieves stable operation of quantum key distribution.

[0083] Example 2:

[0084] Please refer to Figure 2 Based on the same inventive concept, an embodiment of the present invention discloses a quantum key distribution device based on quantum light and synchronous light, comprising: a transmitting end, an optical fiber, and a receiving end;

[0085] Wherein, the transmitting end and the receiving end are connected via the optical fiber;

[0086] The transmitting end includes a laser (including a quantum optical laser and a synchronous optical laser), an EDFA amplifier (i.e. Figure 2 erbium-doped fiber amplifiers in ), narrow bandwidth filters, and wavelength division multiplexers;

[0087] The receiving end includes a dispersion compensation module, a wavelength division multiplexer, a synchronous optical detector, a clock recovery module and a quantum optical detector (i.e. Figure 2 single photon detectors in );

[0088] The transmitting end is used to execute a quantum key distribution method based on quantum light and synchronous light as described in any one of the above-mentioned embodiments.

[0089] exist Figure 2In the system, the synchronous light detector uses an avalanche photodiode (APD), which can be integrated with the clock recovery module. After the synchronous light detector is used to convert the synchronous light into the corresponding electrical signal, the clock recovery module can be used to extract the clock signal from the electrical signal to obtain the synchronous clock.

[0090] Preferably, the wavelength range of the first quantum light covers an idle channel of a C-band DWDM system.

[0091] In this preferred embodiment, the wavelength range of the first quantum light covers the idle channels of the C-band DWDM system, avoiding wavelength conflicts with existing communication services, improving the compatibility of the system with existing optical communication networks, and facilitating actual deployment.

[0092] In summary, compared with the existing technology, the embodiments of the present application have the following beneficial effects: quantum light and synchronous light are generated by the transmitting end laser with a wavelength difference of 4-6 DWDM channels, which increases the wavelength spacing between the two and can effectively reduce the crosstalk and noise interference between the synchronous light and the quantum light; the quantum light and the synchronous light are coupled into the first optical signal and transmitted through the same fiber, avoiding the additional laying of independent optical fibers and reducing the system deployment cost; the receiving end performs dispersion compensation processing on the optical signal, which can reduce the pulse broadening caused by optical fiber dispersion and improve the time resolution; the signal separation operation ensures that the quantum light and the synchronous light are correctly detected respectively; the clock signal is extracted from the synchronous light to achieve high-precision time synchronization between the transmitting end and the receiving end; the basis vector comparison and bit error rate calculation are combined with the quantum light and the synchronous clock to ensure the accuracy and stability of the key generation. The overall solution effectively solves the pulse broadening problem caused by crosstalk and dispersion between the synchronous light and the quantum light in long-distance transmission through the synergistic effect of the wavelength design of the spaced DWDM channels, the same fiber transmission and dispersion compensation, and ultimately achieves the stable operation of quantum key distribution.

[0093] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. Similarly, in order to streamline the application and help understand one or more of the various inventive aspects, in the above description of the exemplary embodiments of the application, the various features of the embodiments of the application are sometimes grouped together into a single embodiment, figure, or description thereof. Wherein, the claims that follow the specific embodiment are hereby clearly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the application.

[0094] Those skilled in the art will appreciate that the modules in the devices of the embodiments can be adaptively changed and installed in one or more devices different from the embodiments. The modules, units, or components in the embodiments can be combined into one module, unit, or component, and furthermore, they can be divided into multiple submodules, subunits, or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive.

Claims

1. A quantum key distribution method based on quantum light and synchronous light, characterized in that: Applicable to a transmitting end of a quantum key distribution device, the quantum key distribution method includes: Generate a first quantum light and a first synchronization light by using a laser at the transmitting end at a wavelength difference of a preset number of DWDM channels; wherein the preset number is 4, 5, or 6; The first quantum light and the first synchronization light are coupled into a first optical signal, which is transmitted to a receiving end via the same fiber, so that the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light. A clock signal is extracted from the second synchronization light to obtain a synchronization clock. The second quantum light and the synchronization clock are combined to perform basis vector comparison and bit error rate calculation to generate a key and complete key distribution.

2. A quantum key distribution method based on quantum light and synchronous light according to claim 1, characterized in that: The transmitting end includes an EDFA amplifier and a narrow bandwidth filter; the wavelength difference of the DWDM channels with a preset number of intervals is used to generate the first quantum light and the first synchronization light, including: Generate the first quantum light and the original synchronization light with a wavelength difference of a preset number of DWDM channels; The original synchronization light is subjected to signal amplification and filtering processing respectively through an EDFA amplifier and a narrow bandwidth filter to obtain a first synchronization light.

3. A quantum key distribution method based on quantum light and synchronous light according to claim 2, characterized in that: The performing signal amplification and filtering processing on the original synchronization light to obtain the first synchronization light includes: Amplifying the power of the original synchronization light by a gain of 20-40 dB through an EDFA amplifier to obtain an original first synchronization light; The spectrum width of the original first synchronization light is narrowed to 0.15-0.2 nm by a narrow bandwidth filter to obtain the first synchronization light.

4. The quantum key distribution method based on quantum light and synchronous light according to claim 1, characterized in that: The transmitting end further includes a wavelength division multiplexer; and coupling the first quantum light and the first synchronization light into a first optical signal includes: The first quantum light and the first synchronization light are combined into the same optical fiber through the wavelength division multiplexer to obtain the first optical signal.

5. The quantum key distribution method based on quantum light and synchronous light according to claim 1, characterized in that: The receiving end includes a dispersion compensation module; the receiving end performs dispersion compensation processing and signal separation on the first optical signal to obtain a second quantum light and a second synchronization light, including: According to the dispersion compensation module, dispersion compensation is performed on the first optical signal to obtain a second optical signal; wherein the dispersion compensation module is a dispersion compensating optical fiber or a chirped fiber grating; The second optical signal is subjected to signal separation to obtain a second quantum light and a second synchronization light.

6. A quantum key distribution method based on quantum light and synchronous light according to claim 5, characterized in that: The receiving end further includes: a wavelength division multiplexer; the signal separation of the second optical signal to obtain the second quantum light and the second synchronization light includes: According to the wavelength division multiplexer, the second optical signal is wavelength demultiplexed to separate the second quantum light and the second synchronization light; wherein the non-adjacent channel isolation of the wavelength division multiplexer is greater than 90dB, and the adjacent channel isolation is greater than 60dB.

7. The quantum key distribution method based on quantum light and synchronous light according to claim 1, characterized in that: The receiving end further includes: a synchronous light detector and a clock recovery module; extracting the clock signal from the second synchronous light to obtain a synchronous clock includes: According to the synchronous light detector, converting the second synchronous light into a corresponding electrical signal; The clock recovery module is used to extract the clock signal from the electrical signal to obtain a synchronous clock; wherein the clock recovery module is a clock extraction circuit based on a phase-locked loop or a delay-locked loop.

8. The quantum key distribution method based on quantum light and synchronous light according to claim 7, characterized in that: The receiving end further includes a quantum light detector; and the step of combining the second quantum light with a synchronous clock to perform basis vector comparison and bit error rate calculation to generate a key includes: detecting the polarization state of the second quantum light according to the quantum light detector and extracting quantum state information therein; Based on the quantum state information and the synchronous clock, basis vector comparison and bit error rate calculation are performed to generate a key.

9. A quantum key distribution device based on quantum light and synchronous light, characterized in that: include: Transmitter, optical fiber and receiver; Wherein, the transmitting end and the receiving end are connected via the optical fiber; The transmitting end includes a laser, an EDFA amplifier, a narrow bandwidth filter and a wavelength division multiplexer; The receiving end includes a dispersion compensation module, a wavelength division multiplexer, a synchronous optical detector, a clock recovery module and a quantum optical detector; The transmitting end is used to execute a quantum key distribution method based on quantum light and synchronous light according to any one of claims 1 to 8.

10. A quantum key distribution device based on quantum light and synchronous light according to claim 9, characterized in that: The wavelength range of the first quantum light covers the idle channels of the C-band DWDM system.

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