A multi-path multi-protocol parallel continuous variable quantum key distribution system and method

Abstract

The present application relates to the field of quantum key distribution, and provides a kind of multi-channel multi-protocol parallel continuous variable quantum key distribution system and method, the system includes Alice end's emission light source, double polarization IQ modulator, double polarization multicarrier quantum key generation module, optical attenuator, wavelength division multiplexer, quantum random number generator 1, Alice post-processing module 1 and Alice post-processing module 2;Bob end's wavelength division demultiplexer, polarization beam splitter 1, local oscillator light source, polarization beam splitter 2, frequency shifter, optical coupler 1, balanced detection module 1, analog-digital conversion module 1, optical coupler 2, balanced detection module 2, analog-digital conversion module 2, MIMO quantum key digital processing module, quantum random number generator 2, Bob post-processing module 1 and Bob post-processing module 2.The present application can multiply promote the security code rate of traditional CV-QKD system, and can flexibly, efficiently meet the encryption application needs of different users.

Description

Technical Field

[0001] This invention relates to the field of quantum key distribution, and more specifically, to a multi-path, multi-protocol parallel continuous variable quantum key distribution system and method. Background Technology

[0002] Quantum Key Distribution (QKD), as the most mature and widely used quantum communication technology, leverages its information-theoretical security based on fundamental principles of quantum physics, combined with one-time pad technology, to become one of the core means of ensuring information security in the "post-quantum" era. After more than 40 years of development, QKD technology has gradually moved from basic research to practical applications, forming two major technical systems: Discrete Variable (DV) and Continuous Variable (CV). CV-QKD, by encoding quantum key information onto the canonical components of an optical field and decoding the information using zero / heterodyne coherent detection technology, possesses significant advantages such as compatibility with classical coherent optical communication systems, high key rates over short to medium distances, mature devices, and ease of integration. These characteristics make it a promising candidate for high-speed applications in quantum metropolitan area networks / access networks, becoming an important direction for promoting the practical application of quantum communication technology.

[0003] After nearly 30 years of development, CV-QKD systems have achieved significant research results in basic theoretical research, key technology breakthroughs, and engineering prototype development. However, their practical applications are still constrained by the following two factors. Firstly, the current CV-QKD system's security bit rate at typical transmission distances is still insufficient to meet the high-speed encryption requirements of "one-time pad" encryption. For example, recent reports indicate that the security bit rate of CV-QKD systems over a 100km transmission distance is in the sub-Mbps range, only sufficient for "one-time pad" encryption applications in standard definition video. Currently, the two mainstream solutions for improving the security bit rate and transmission distance of CV-QKD systems (system repetition frequency enhancement and system noise optimization) are gradually facing technical bottlenecks due to limitations in device bandwidth and non-ideal characteristics. Secondly, with the surge in the number of encrypted users and the demand for encryption applications within quantum metropolitan / access networks, existing single-path, single-protocol QKD systems are gradually demonstrating insufficient application performance in high-speed quantum communication networks. To address the aforementioned issues, researchers have largely adopted a multi-system QKD approach to achieve multi-path, multi-protocol quantum key distribution. This not only significantly improves the overall secure transmission performance of the QKD system but also flexibly meets the encryption application needs of different users and scenarios. However, in practical applications, multi-system QKD deployment is not only complex but also expensive, making large-scale application difficult. Summary of the Invention

[0004] This invention aims to provide a multi-path, multi-protocol parallel continuous-variable quantum key distribution system and method. It achieves multi-path, multi-protocol parallel quantum key distribution in both the polarization and frequency domains, significantly improving the security code rate of traditional CV-QKD systems and flexibly and efficiently meeting the diverse encryption application needs of multiple users. Furthermore, this invention combines inter-frequency transmission technology and MIMO (Multiple-Input, Multiple-Output) demodulation technology to address the insufficient performance improvement of multi-path, multi-protocol parallel quantum key distribution. It also employs local oscillator frequency shifting and frequency configuration schemes to solve the problems of high bandwidth requirements and low efficiency in coherent detection of dual-polarization quantum signals, ultimately realizing a high-performance multi-path, multi-protocol CV-QKD system.

[0005] In a first aspect, the present invention provides a multi-path, multi-protocol parallel continuous variable quantum key distribution system, including an Alice end and a Bob end; The Alice terminal includes a light source, a dual-polarization IQ modulator, a dual-polarization multi-carrier quantum key generation module, an optical attenuator, a wavelength division multiplexer, a quantum random number generator 1, an Alice post-processing module 1, and an Alice post-processing module 2. The Bob terminal includes a wave demultiplexer, a polarization beam splitter 1, a local oscillator light source, a polarization beam splitter 2, a frequency shifter, an optical coupler 1, a balanced detection module 1, an analog-to-digital converter 1, an optical coupler 2, a balanced detection module 2, an analog-to-digital converter 2, a MIMO quantum key digital processing module, a quantum random number generator 2, a Bob post-processing module 1, and a Bob post-processing module 2. At the Alice end, the transmitting light source, dual-polarization IQ modulator, optical attenuator, and wavelength division multiplexer are cascaded with optical fibers. Alice post-processing module 1 and Alice post-processing module 2 are optically connected to the wavelength division multiplexer, respectively. The dual-polarization multi-carrier quantum key generation module is electrically connected to the dual-polarization IQ modulator, and data-connected to quantum random number generator 1, Alice post-processing module 1, and Alice post-processing module 2, respectively. At the Bob end, one optical fiber of the wavelength demultiplexer is connected to polarization beamsplitter 1, and the other two optical fibers are connected to Bob post-processing module 1 and Bob post-processing module 2, respectively. One optical fiber of polarization beamsplitter 1 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with optical coupler 2 and balanced detection module 1. 2; The local oscillator light source and polarization beam splitter 2 are connected by optical fiber. One optical fiber of polarization beam splitter 2 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with frequency shifter, optical coupler 2 and balanced detection module 2. Balanced detection module 1 is electrically connected to analog-to-digital converter 1, and balanced detection module 2 is electrically connected to analog-to-digital converter 2. MIMO quantum key digital signal processing module is connected to analog-to-digital converter 1, analog-to-digital converter 2, Bob post-processing module 1, and Bob post-processing module 2 for data transmission. Quantum random number generator 2 is connected to Bob post-processing module 1 and Bob post-processing module 2 for data transmission. The wavelength division multiplexer at Alice end and the wavelength demultiplexer at Bob end are connected by optical fiber through an optical fiber channel.

[0006] Secondly, the present invention provides a multi-path, multi-protocol parallel continuous variable quantum key distribution method, comprising: The optical carrier signal output from the transmitting light source is directly modulated into a dual-polarization IQ modulator into a dual-polarization multi-carrier modulated optical signal. The upper and lower branches of the dual-polarization IQ modulator are respectively loaded with quantum key electrical signals generated by the dual-polarization multi-carrier quantum key generation module. I x , Q x and I y , Q y The dual-polarization multi-carrier modulated optical signal is attenuated to 2 by an optical attenuator. N Multiple protocol parallel QKD signal optical path; Alice post-processing module 1 and Alice post-processing module 2 respectively output classic data negotiation optical path 1 and classic data negotiation optical path 2, and are combined with 2 N The multi-protocol parallel QKD signal light reaches Bob's end via a fiber optic channel through wavelength division multiplexing; Classical data negotiation light 1, Classical data negotiation light 2 and 2 N The multi-protocol parallel QKD signal light is separated by a beam demultiplexer and then sent to Bob post-processing module 1, Bob post-processing module 2, and polarization beam splitter 1; 2 NThe multi-protocol parallel QKD signal light is split into two by a polarization beam splitter. x and y Two polarization directions N The multi-protocol parallel QKD signal light is transmitted to optical coupler 1 and optical coupler 2 respectively; the local oscillator light output from the local oscillator source is split by polarization beam splitter 2. x and y Two paths, one directly to optical coupler 1 and the other to optical coupler 2 after frequency shifting via a frequency shifter; the local oscillator light with the same polarization direction and... N Balanced coherent detection is performed on multi-path parallel QKD signal light, and the detection results are converted from analog to digital. x and y Two polarization directions N The multi-path parallel quantum signal is then demodulated by the MIMO quantum key distribution module to obtain the digital signal. x and y polarization direction N Initial quantum key; x and y polarization direction N The initial quantum key is input into Bob post-processing module 1 and Bob post-processing module 2 for parameter estimation, and then processed in conjunction with Alice post-processing module 1 and Alice post-processing module 2 to finally achieve... x polarization direction N Road quantum key distribution y polarization direction N Output of the quantum key.

[0007] In some embodiments, the dual-polarization multi-carrier quantum key generation module generates a quantum key electrical signal. I x , Q x and I y , Q y ,include: High-speed quantum random binary data streams are converted into 1×2 serial-to-parallel data streams. x and y A high-speed quantum random binary data stream with two branches, the two branches are then converted into 1× N Serial-to-parallel conversion N A path-independent, low-speed quantum random binary data stream, then formed into two branches with arbitrary modulation through independent arbitrary distribution mapping. N The quantum key, and respectively as x and y polarization direction N Original road data; Two branchesN After inserting a predetermined proportion of the quantum key into the training sequence, multi-carrier modulation processing is performed, and a multi-carrier quantum key is formed through parallel-to-serial conversion. The multi-carrier quantum keys formed from the two branches are then processed separately. x and y The sampling rate formed on the branch is f n and effective bandwidth Δf q Multicarrier quantum key serial digital signal; x The insertion frequency of the multi-carrier quantum key serial digital signal in the branch is f p After obtaining the pilot signal, extract its real and imaginary parts and convert them to digital-to-analog conversion. I x and Q x ; y The branched multi-carrier quantum key serial digital signal has an insertion frequency of 1000 MHz. f p The pilot signal, then at a frequency of f s The frequency shifting process is then performed, and finally, the real and imaginary parts are extracted and converted to digital-to-analog conversion. I y and Q y .

[0008] In some embodiments, by configuring pilot frequencies f p Frequency shift f s and effective bandwidth Δf This ensures inter-frequency transmission between classical pilot light and quantum signal light, as well as between multi-path, multi-protocol parallel QKD.

[0009] In some embodiments, the multicarrier modulation processing employs inverse Fourier transform or filter banks.

[0010] In some embodiments, the multi-carrier quantum key formed by the two branches is subjected to upsampling and matched filtering processes, respectively.

[0011] In some embodiments, the MIMO quantum key digital signal processing module performs digital signal demodulation, including: The two digital signals output by analog-to-digital converter 1 and analog-to-digital converter 2 respectively i x and i y Process and obtain x Quantum signal with polarization direction E x and pilot signalP x ,as well as y Quantum signal with polarization direction E y and pilot signal P y ; A pilot-based MIMO polarization and phase estimation algorithm is used to track polarization and phase information and complete the process. x and y Rapid polarization correction and phase compensation of the quantum signal in the polarization direction, followed by serial-to-parallel conversion and multi-carrier demodulation processing. x and y Polarization directions are formed respectively N The initial compensation quantum signal of the path; Will x and y obtained by polarization direction N The initial compensation quantum signal is then subjected to residual noise equalization compensation based on the training sequence to eliminate residual multi-effect noise, ultimately achieving... x and y The polarization directions were obtained respectively N Initial quantum key of the path.

[0012] In some embodiments, the two digital signals output by analog-to-digital converter 1 and analog-to-digital converter 2 are respectively... i x and i y The processing includes frequency offset estimation, bandpass filtering, quadrature downconversion, and matched filtering.

[0013] In some embodiments, the multicarrier demodulation process includes Fourier transform or inverse filter bank.

[0014] In some embodiments, the processing performed by Alice post-processing module 1 and Alice post-processing module 2 includes data negotiation, key error correction, and private key amplification.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention employs dual polarization and multi-carrier transmission technology, enabling parallel multi-path and multi-protocol quantum key distribution in both the polarization and frequency domains. This not only significantly improves the security code rate of traditional CV-QKD systems but also flexibly and efficiently meets the diverse encryption application needs of multiple users.

[0016] 2. This invention combines heterogeneous frequency transmission technology and MIMO digital processing technology, which not only avoids crosstalk between classical pilot light and quantum light as well as between multi-path multi-protocol parallel QKD signal light, but also achieves precise demodulation of multi-path multi-protocol parallel quantum keys in the data domain, ensuring high-performance multi-path multi-protocol quantum key distribution.

[0017] 3. This invention achieves low-frequency and same-frequency detection of dual-polarized quantum signal light by frequency shifting the local oscillator light and rationally configuring the frequency relationship of the optical signal. This not only facilitates accurate digital correction of dual-polarized quantum signals, but also effectively reduces the detection bandwidth requirements of the entire CV-QKD system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a multi-path, multi-protocol parallel continuous variable quantum key distribution system provided in an embodiment of the present invention.

[0019] Figure 2 This is a flowchart illustrating the generation of dual-polarization multi-carrier quantum keys in a multi-path, multi-protocol parallel continuous variable quantum key distribution method provided in an embodiment of the present invention.

[0020] Figure 3 This is a flowchart of MIMO quantum key digital signal processing in a multi-path, multi-protocol parallel continuous variable quantum key distribution method provided in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] Example like Figure 1 As shown, this embodiment of the invention provides a multi-path, multi-protocol parallel continuous variable quantum key distribution system, including an Alice end and a Bob end; The Alice terminal includes a light source, a dual-polarization IQ modulator, a dual-polarization multi-carrier quantum key generation module, an optical attenuator, a wavelength division multiplexer, a quantum random number generator 1, an Alice post-processing module 1, and an Alice post-processing module 2. The Bob terminal includes a wave demultiplexer, a polarization beam splitter 1, a local oscillator light source, a polarization beam splitter 2, a frequency shifter, an optical coupler 1, a balanced detection module 1, an analog-to-digital converter 1, an optical coupler 2, a balanced detection module 2, an analog-to-digital converter 2, a MIMO quantum key digital processing module, a quantum random number generator 2, a Bob post-processing module 1, and a Bob post-processing module 2. In the Alice-end, the transmitting light source, dual-polarization IQ modulator, optical attenuator, and wavelength division multiplexer are cascaded with optical fibers. Alice post-processing module 1 and Alice post-processing module 2 are optically connected to the wavelength division multiplexer, respectively. The dual-polarization multi-carrier quantum key generation module is electrically connected to the dual-polarization IQ modulator and data-connected to quantum random number generator 1, Alice post-processing module 1, and Alice post-processing module 2, respectively. In the Bob-end, one optical fiber of the wavelength division multiplexer is connected to polarization beamsplitter 1, and the other two optical fibers are connected to Bob post-processing module 1 and Bob post-processing module 2, respectively. One optical fiber of polarization beamsplitter 1 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with optical coupler 2 and balanced detection module 1. Module 2; The local oscillator light source and polarization beam splitter 2 are connected by optical fiber. One optical fiber of polarization beam splitter 2 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with frequency shifter, optical coupler 2 and balanced detection module 2. Balanced detection module 1 is electrically connected to analog-to-digital converter 1, and balanced detection module 2 is electrically connected to analog-to-digital converter 2. MIMO quantum key digital signal processing module is connected to analog-to-digital converter 1, analog-to-digital converter 2, Bob post-processing module 1, and Bob post-processing module 2 for data transmission. Quantum random number generator 2 is connected to Bob post-processing module 1 and Bob post-processing module 2 for data transmission. The wavelength division multiplexer at Alice end and the wavelength demultiplexer at Bob end are connected by optical fiber through an optical fiber channel.

[0024] Based on the above-described multi-path, multi-protocol parallel continuous variable quantum key distribution system, this invention also provides a multi-path, multi-protocol parallel continuous variable quantum key distribution method, comprising the following steps: Step 1: The output wavelength of the emitting light source is λ q The 1550nm optical carrier signal is directly fed into a dual-polarization IQ modulator and modulated into a dual-polarization multi-carrier modulated optical signal. This dual-polarization multi-carrier modulated optical signal is then attenuated to 2nm by an optical attenuator. N =10-channel multi-protocol parallel QKD signal optical, wherein the upper and lower branches of the dual-polarization IQ modulator are respectively loaded with quantum key electrical signals generated by the dual-polarization multi-carrier quantum key generation module.I x , Q x and I y , Q y ,like Figure 2 As shown, the specific generation process is as follows: (1) The 160Gbps quantum random binary data stream is converted from a 1×2 serial-to-parallel transmission. x and y The two branches are 80Gbps quantum random binary data streams, which are then converted from 1×5 serial-parallel to parallel streams. N =5 independent 16Gbps quantum random binary data streams; then... x The five quantum random binary data streams in the branch are mapped using QPSK, 16QAM, 64QAM, 256QAM, and Gaussian modulation distributions, respectively. N =5-way multi-protocol quantum key distribution y The five quantum random binary data streams in the branch are mapped using 8PSK, 32QAM, 512QAM, 1024QAM, and Gaussian modulation distributions, respectively. N =5-way multi-protocol quantum key distribution, and respectively used as x and y polarization direction N =5 channels of raw data; (2) Two branches N Five multi-protocol quantum keys are each inserted into a 1 / 5 ratio of the training sequence, then an inverse Fourier transform is performed, followed by a parallel-to-serial conversion. x and y Repetition frequency formed on the two branches f rep =5GHz multi-carrier quantum key; the multi-carrier quantum key formed by the two branches is upsampled and root-raised cosine filtered (roll-off factor of 0.3) respectively. x and y The sampling rate formed on the branch is f n =40GSa / s, effective bandwidth is Δf =6.5GHz multi-carrier quantum key serial digital signal; (3) x The multi-carrier quantum key serial digital signal insertion pilot frequency of the branch is f p After obtaining a 5GHz sine wave signal, its real and imaginary parts are extracted and converted from digital to analog. I x and Q xThe first insertion frequency of the multi-carrier quantum key serial digital signal in the y-branch is... f p =5GHz pilot signal, then at a frequency of f s The frequency shifting process is 10GHz, and finally the real and imaginary parts are converted to analog-to-digital conversion. I y and Q y .

[0025] Step 2: Alice post-processing module 1 and Alice post-processing module 2 output wavelengths respectively. λ Classical data negotiation for light 1 and wavelength (1=1310nm) λ The classic data negotiation light 2 with a wavelength of 1460nm is used, and together with 10 multi-protocol parallel QKD signal lights, it reaches Bob's end through the fiber optic channel via wavelength division multiplexing. Step 3: Classical data negotiation beam 1, classical data negotiation beam 2, and the 10-channel multi-protocol parallel QKD signal beam are separated by a wave demultiplexer and sent to Bob post-processing module 1, Bob post-processing module 2, and polarization beam splitter 1, respectively; the 10-channel multi-protocol parallel QKD signal beam is split by polarization beam splitter 1. x and y Two polarization directions N =5-channel multi-protocol parallel QKD signal light, which arrive at optical coupler 1 and optical coupler 2 respectively; the local oscillator output wavelength is λ q =1550nm local oscillator light (i.e., the frequency difference between the local oscillator light and the transmitting optical carrier) Δf AB =0) is divided by polarization beam splitter 2 into x and y Two paths in the polarization direction: one goes directly to optical coupler 1, and the other is frequency-shifted via a frequency shifter. f s =10GHz reaches optical coupler 2.

[0026] Step 4: Local oscillator light with the same polarization direction and N =5-channel multi-protocol parallel QKD signal light is used for balanced coherent detection, and the detection results are converted from analog to digital. x and y Two polarization directions N Five parallel quantum signals are generated, and then the MIMO quantum key distribution module demodulates the digital signals to obtain the desired results. x and y polarization direction N =5-way initial quantum key; such as Figure 3 As shown, the specific processing flow of the MIMO quantum key digital signal processing module is as follows: (1) The two digital signals output by analog-to-digital converter 1 and analog-to-digital converter 2 i x and i y The results were obtained through frequency offset estimation, bandpass filtering, quadrature downconversion, and root-raised cosine matched filtering. x Quantum signal with polarization direction E x and pilot signal P x ,as well as y Quantum signal with polarization direction E y and pilot signal P y ; (2) The polarization and phase estimation algorithm based on pilot signals is used to track polarization and phase information and complete the process. x and y Rapid polarization correction and phase compensation of quantum signals in polarization direction, followed by serial-to-parallel conversion and Fourier transform. x and y The polarization directions were obtained respectively N =5-channel initial compensation quantum signal; (3) x and y obtained by polarization direction N =5-channel initial compensation quantum signals are used for residual noise equalization compensation based on the training sequence to eliminate residual multi-effect noise, and finally in x and y The polarization directions were obtained respectively N =5 initial quantum keys.

[0027] Step 5: x and y polarization direction N Five initial quantum keys are input into Bob post-processing module 1 and Bob post-processing module 2 for parameter estimation, and then combined with Alice post-processing module 1 and Alice post-processing module 2 for data negotiation, key error correction, and private key amplification, ultimately achieving... x polarization direction N =5-way quantum key distribution y polarization direction N =5-channel quantum key output.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-path, multi-protocol parallel continuous variable quantum key distribution method, characterized in that, include: The optical carrier signal output from the transmitting light source is directly modulated into a dual-polarization IQ modulator into a dual-polarization multi-carrier modulated optical signal. The upper and lower branches of the dual-polarization IQ modulator are respectively loaded with quantum key electrical signals generated by the dual-polarization multi-carrier quantum key generation module. I x , Q x and I y , Q y The dual-polarization multi-carrier modulated optical signal is attenuated to 2 by an optical attenuator. N Multiple protocol parallel QKD signal optical path; Alice post-processing module 1 and Alice post-processing module 2 respectively output classic data negotiation optical path 1 and classic data negotiation optical path 2, and are combined with 2 N The multi-protocol parallel QKD signal light reaches Bob's end via a fiber optic channel through wavelength division multiplexing; Classical data negotiation light 1, Classical data negotiation light 2 and 2 N The multi-protocol parallel QKD signal light is separated by a beam demultiplexer and then sent to Bob post-processing module 1, Bob post-processing module 2, and polarization beam splitter 1; 2 N The multi-protocol parallel QKD signal light is split into two by a polarization beam splitter. x and y Two polarization directions N The multi-protocol parallel QKD signal light is transmitted to optical coupler 1 and optical coupler 2 respectively; the local oscillator light output from the local oscillator source is split by polarization beam splitter 2. x and y Two paths, one directly to optical coupler 1 and the other to optical coupler 2 after frequency shifting via a frequency shifter; the local oscillator light with the same polarization direction and... N Balanced coherent detection is performed on multi-path parallel QKD signal light, and the detection results are converted from analog to digital. x and y Two polarization directions N The multi-path parallel quantum signal is then demodulated by the MIMO quantum key distribution module to obtain the digital signal. x and y polarization direction N Initial quantum key; x and y polarization direction N The initial quantum key is input into Bob post-processing module 1 and Bob post-processing module 2 for parameter estimation, and then processed in conjunction with Alice post-processing module 1 and Alice post-processing module 2 to finally achieve... x polarization direction N Road quantum key distribution y polarization direction N Output of the quantum key; The dual-polarization multi-carrier quantum key generation module generates quantum key electrical signals. I x , Q x and I y , Q y ,include: High-speed quantum random binary data streams are converted into 1×2 serial-to-parallel data streams. x and y A two-branch high-speed quantum random binary data stream, the two branches are then converted into 1× N Serial-to-parallel conversion N A path-independent, low-speed quantum random binary data stream, then formed into two branches with arbitrary modulation through independent arbitrary distribution mapping. N The quantum key, and respectively as x and y polarization direction N Original road data; Two branches N After inserting a predetermined proportion of the quantum key into the training sequence, multi-carrier modulation processing is performed, and a multi-carrier quantum key is formed through parallel-to-serial conversion. The multi-carrier quantum keys formed from the two branches are then processed separately. x and y The sampling rate formed on the branch is f n and effective bandwidth Δf q Multicarrier quantum key serial digital signal; x The insertion frequency of the multi-carrier quantum key serial digital signal in the branch is f p After obtaining the pilot signal, extract its real and imaginary parts and convert them to digital-to-analog conversion. I x and Q x ; y The branched multi-carrier quantum key serial digital signal has an insertion frequency of 1000 MHz. f p The pilot signal, then at a frequency of f s The frequency shifting process is then performed, and finally, the real and imaginary parts are extracted and converted to digital-to-analog conversion. I y and Q y .

2. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 1, characterized in that, By configuring pilot frequencies f p Frequency shift f s and effective bandwidth Δf This ensures inter-frequency transmission between classical pilot light and quantum signal light, as well as between multi-path, multi-protocol parallel QKD.

3. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 1, characterized in that, The multi-carrier modulation processing employs inverse Fourier transform or filter banks.

4. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 1, characterized in that, The multi-carrier quantum key formed by the two branches is then upsampled and matched filtered.

5. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 1, characterized in that, The MIMO quantum key distribution digital signal processing module performs digital signal demodulation, including: The two digital signals output by analog-to-digital converter 1 and analog-to-digital converter 2 respectively i x and i y Process and obtain x Quantum signals in polarization direction E x and pilot signal P x ,as well as y Quantum signals in polarization direction E y and pilot signal P y ; A pilot-based MIMO polarization and phase estimation algorithm is used to track polarization and phase information and complete the process. x and y Rapid polarization correction and phase compensation of the quantum signal in the polarization direction, followed by serial-to-parallel conversion and multi-carrier demodulation processing. x and y Polarization directions are formed respectively N The initial compensation quantum signal of the path; Will x and y obtained by polarization direction N The initial compensation quantum signal is then subjected to residual noise equalization compensation based on the training sequence to eliminate residual multi-effect noise, ultimately achieving... x and y The polarization directions were obtained respectively N Initial quantum key of the path.

6. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 5, characterized in that, The two digital signals output by analog-to-digital converter 1 and analog-to-digital converter 2 respectively i x and i y The processing includes frequency offset estimation, bandpass filtering, quadrature downconversion, and matched filtering.

7. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 5, characterized in that, The multi-carrier demodulation process includes Fourier transform or inverse filter bank.

8. The multi-path, multi-protocol parallel continuous variable quantum key distribution method according to claim 1, characterized in that, The combined processing performed by Alice post-processing module 1 and Alice post-processing module 2 includes data negotiation, key error correction, and private key amplification.

9. A multi-path, multi-protocol parallel continuous-variable quantum key distribution system, used to implement the multi-path, multi-protocol parallel continuous-variable quantum key distribution method as described in any one of claims 1-8, characterized in that, Including Alice's side and Bob's side; The Alice terminal includes a light source, a dual-polarization IQ modulator, a dual-polarization multi-carrier quantum key generation module, an optical attenuator, a wavelength division multiplexer, a quantum random number generator 1, an Alice post-processing module 1, and an Alice post-processing module 2. The Bob terminal includes a wave demultiplexer, a polarization beam splitter 1, a local oscillator light source, a polarization beam splitter 2, a frequency shifter, an optical coupler 1, a balanced detection module 1, an analog-to-digital converter 1, an optical coupler 2, a balanced detection module 2, an analog-to-digital converter 2, a MIMO quantum key digital processing module, a quantum random number generator 2, a Bob post-processing module 1, and a Bob post-processing module 2. At the Alice end, the transmitting light source, dual-polarization IQ modulator, optical attenuator, and wavelength division multiplexer are cascaded with optical fibers. Alice post-processing module 1 and Alice post-processing module 2 are optically connected to the wavelength division multiplexer, respectively. The dual-polarization multi-carrier quantum key generation module is electrically connected to the dual-polarization IQ modulator, and data-connected to quantum random number generator 1, Alice post-processing module 1, and Alice post-processing module 2, respectively. At the Bob end, one optical fiber of the wavelength demultiplexer is connected to polarization beamsplitter 1, and the other two optical fibers are connected to Bob post-processing module 1 and Bob post-processing module 2, respectively. One optical fiber of polarization beamsplitter 1 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with optical coupler 2 and balanced detection module 1. 2; The local oscillator light source and polarization beam splitter 2 are connected by optical fiber. One optical fiber of polarization beam splitter 2 is cascaded with optical coupler 1 and balanced detection module 1, and the other optical fiber is cascaded with frequency shifter, optical coupler 2 and balanced detection module 2. Balanced detection module 1 is electrically connected to analog-to-digital converter 1, and balanced detection module 2 is electrically connected to analog-to-digital converter 2. MIMO quantum key digital signal processing module is connected to analog-to-digital converter 1, analog-to-digital converter 2, Bob post-processing module 1, and Bob post-processing module 2 for data transmission. Quantum random number generator 2 is connected to Bob post-processing module 1 and Bob post-processing module 2 for data transmission. The wavelength division multiplexer at Alice end and the wavelength demultiplexer at Bob end are connected by optical fiber through an optical fiber channel.

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