Quantum key distribution method and device based on double-field protocol, and storage medium

Abstract

The invention relates to a quantum key distribution method and device based on a double-field protocol, and a storage medium, and the method comprises the following steps: carrying out the phase and intensity modulation of an initial laser pulse through a quantum state preparation device, and generating a double-field quantum state sequence containing a first quantum state sequence and a second quantum state sequence; the sequences are subjected to polarization state coding and time division multiplexing through a quantum channel transmission device to form a coded quantum state transmission sequence. The sequence is then subjected to phase compensation and noise suppression to obtain an optimized quantum state sequence. And then, the quantum state measurement device executes Bell state measurement and basis vector selection on the optimized sequence to obtain a measurement result sequence. And finally, the post-processing device performs key extraction and privacy amplification on the measurement result to ensure that a final quantum key is generated, so that the technical problem that the practicability and the transmission distance of a traditional quantum key distribution scheme are greatly limited due to the influence of channel loss and noise interference factors is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum key technology, and particularly relates to a quantum key distribution method, device, and storage medium based on the twin-field protocol. Background Art

[0002] In the current rapidly developing field of information technology, information security has become of utmost importance. With the continuous evolution of network attack means and the enhancement of computing power, traditional encryption algorithms based on mathematical problems are at risk of being cracked, making it particularly urgent to seek more secure information encryption methods. Quantum key distribution (QKD), as an emerging secure communication technology, utilizes the basic principles of quantum mechanics to achieve theoretically unbreakable key distribution, thereby ensuring the security of information transmission. However, due to factors such as channel loss and noise interference, the practicality and transmission distance of traditional QKD schemes are severely limited.

[0003] To overcome these challenges, researchers have been exploring various methods to improve the performance of QKD systems. As an advanced QKD protocol, the twin-field protocol compensates for phase drift by introducing an additional reference optical field and effectively improves the stability and noise resistance of the system using time-division multiplexing technology, making long-distance and high-rate quantum key distribution possible. Nevertheless, in practical applications, there are still problems such as low phase modulation accuracy, susceptibility to environmental factors during the polarization state encoding process, and low key extraction efficiency in the post-processing stage. These problems severely restrict the popularization and application of the twin-field protocol in practical scenarios.

[0004] To address these problems, it is particularly important to further optimize the technical details of quantum state preparation, transmission, and measurement. For example, improving the accuracy of phase modulation and intensity modulation can significantly improve the quality of the initial quantum state; adopting effective phase compensation and noise suppression measures can greatly reduce the impact of channel noise on the quantum state; and in the post-processing stage, improving key extraction and privacy amplification algorithms helps to improve the security and reliability of the finally generated quantum key. These research directions not only have important significance for promoting the practical application of the twin-field protocol but also lay a solid foundation for the future development of quantum communication technology. Summary of the Invention

[0005] The main object of the present invention is to provide a quantum key distribution method, device, and storage medium based on the twin-field protocol, which solves the technical problem that the practicality and transmission distance of traditional quantum key distribution schemes are severely limited due to factors such as channel loss and noise interference.

[0006] To achieve the above object, the present invention provides a quantum key distribution method based on the twin-field protocol, including the following steps: The initial laser pulse is phase - modulated and intensity - modulated by a quantum state preparation device to obtain a two - field quantum state sequence, where the two - field quantum state sequence includes a first quantum state sequence and a second quantum state sequence; The first quantum state sequence and the second quantum state sequence are polarization - encoded and time - division multiplexed by a quantum channel transmission device to obtain an encoded quantum state transmission sequence; Phase compensation and noise suppression are performed on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence; Bell state measurement and basis vector selection are performed on the optimized quantum state sequence by a quantum state measurement device to obtain a measurement result sequence; Key extraction and privacy amplification are performed on the measurement result sequence by a post - processing device to obtain a final quantum key, and the final quantum key is distributed to preset communication parties through a secure channel.

[0007] Furthermore, the step of the initial laser pulse being phase - modulated and intensity - modulated by a quantum state preparation device to obtain a two - field quantum state sequence includes: The initial laser pulse is phase - modulated by a quantum state preparation device to obtain a phase - modulated laser pulse, and phase noise analysis is performed on the phase - modulated laser pulse to obtain phase noise characteristics; Based on the phase noise characteristics, the phase - modulated laser pulse is intensity - modulated to obtain an intensity - modulated laser pulse, and intensity noise analysis is performed on the intensity - modulated laser pulse to obtain intensity noise characteristics; Based on the intensity noise characteristics, quantum state preparation is performed on the intensity - modulated laser pulse to obtain a preliminary two - field quantum state sequence, and the preliminary two - field quantum state sequence is orthogonally component - separated by a quantum beam splitter to obtain a two - field quantum state sequence including a first quantum state sequence reflecting phase information and a second quantum state sequence reflecting amplitude information.

[0008] Furthermore, the step of the first quantum state sequence and the second quantum state sequence being polarization - encoded and time - division multiplexed by a quantum channel transmission device to obtain an encoded quantum state transmission sequence includes: The first quantum state sequence and the second quantum state sequence are polarization - encoded by a quantum channel transmission device to obtain a polarization - encoded quantum state sequence, and polarization state measurement is performed on the polarization - encoded quantum state sequence to obtain polarization state characteristics; Based on the polarization state characteristics, time - division multiplexing is performed on the polarization - encoded quantum state sequence to obtain a time - division multiplexed quantum state sequence, and time - division multiplexing time - slot allocation is performed on the time - division multiplexed quantum state sequence to obtain time - division multiplexing characteristics; Perform quantum state transmission on the time-division multiplexed quantum state sequence based on the time-division multiplexing feature to obtain an encoded quantum state transmission sequence, where the encoded quantum state transmission sequence includes polarization state encoding information and time-division multiplexing encoding information of the first quantum state sequence and the second quantum state sequence.

[0009] Further, performing phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence includes: Perform phase compensation on the encoded quantum state transmission sequence through a phase compensation device to obtain a phase-compensated quantum state sequence, and perform phase stability evaluation on the phase-compensated quantum state sequence to obtain a phase stability feature; Perform noise suppression on the phase-compensated quantum state sequence based on the phase stability feature to obtain a noise-suppressed quantum state sequence, and perform noise level measurement on the noise-suppressed quantum state sequence to obtain a noise feature; Perform quantum state optimization on the noise-suppressed quantum state sequence based on the noise feature to obtain an optimized quantum state sequence.

[0010] Further, performing Bell state measurement and basis vector selection on the optimized quantum state sequence through a quantum state measurement device to obtain a measurement result sequence includes: Perform Bell state measurement on the optimized quantum state sequence through a quantum state measurement device to obtain a Bell state measurement result, and perform Bell state characterization on the Bell state measurement result to obtain a Bell state feature; Perform basis vector selection on the Bell state measurement result based on the Bell state feature to obtain a basis vector selection result, and perform basis vector discrimination on the basis vector selection result to obtain a basis vector feature; Perform quantum state measurement on the basis vector selection result based on the basis vector feature to obtain a quantum state measurement result, and perform quantum state reconstruction on the quantum state measurement result to obtain a reconstructed quantum state feature; Perform measurement result statistics on the quantum state measurement result based on the reconstructed quantum state feature to obtain a measurement result feature, and sort the measurement result feature to generate a measurement result sequence.

[0011] Further, performing quantum state measurement on the basis vector selection result based on the basis vector feature to obtain a quantum state measurement result includes: Perform quantum state projection on the basis vector selection result based on the basis vector feature to obtain a quantum state projection result, and perform projection state analysis on the quantum state projection result to obtain a projection state feature; Perform quantum state interference on the quantum state projection result based on the projection state feature to obtain a quantum state interference result, and perform interference state evaluation on the quantum state interference result to obtain an interference state feature; Perform quantum state detection on the quantum state interference result based on the interference state feature to obtain a quantum state detection result, and perform detection state characterization on the quantum state detection result to obtain a detection state feature; Perform quantum state counting on the quantum state detection result based on the detection state feature to obtain a quantum state counting result, and perform counting state counting on the quantum state counting result to obtain a counting state feature; Perform quantum state measurement on the quantum state counting result based on the counting state feature to obtain a quantum state measurement result.

[0012] Further, the post-processing device extracts a key and performs privacy amplification on the measurement result sequence to obtain a final quantum key, including: The post-processing device extracts a key from the measurement result sequence to obtain a key extraction result, and generates a key from the key extraction result to obtain a key feature; Perform privacy amplification on the key extraction result based on the key feature to obtain a privacy amplification result, and perform privacy extraction on the privacy amplification result to obtain a privacy feature; Perform security evaluation on the privacy amplification result based on the privacy feature to obtain a security parameter, and verify the security parameter to obtain a verification result; Generate a final quantum key from the privacy amplification result based on the verification result to obtain a final quantum key.

[0013] The present invention also provides a quantum key distribution device based on a two-field protocol, including: A modulation module for performing phase modulation and intensity modulation on an initial laser pulse through a quantum state preparation device to obtain a two-field quantum state sequence, where the two-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence; A multiplexing module for performing polarization state encoding and time division multiplexing on the first quantum state sequence and the second quantum state sequence through a quantum channel transmission device to obtain an encoded quantum state transmission sequence; An optimization module for performing phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence; A selection module for performing Bell state measurement and basis vector selection on the optimized quantum state sequence through a quantum state measurement device to obtain a measurement result sequence; An amplification module for performing key extraction and privacy amplification on the sequence of measurement results through a post-processing device to obtain a final quantum key, and distributing the final quantum key to preset communication parties through a secure channel.

[0014] The present invention also provides a computer device, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the steps of the method described in any one of the above are implemented.

[0015] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in any one of the above are implemented.

[0016] A quantum key distribution method based on the twin-field protocol provided by the present invention includes the following steps: In the quantum key distribution method, an initial laser pulse is subjected to phase and intensity modulation by a quantum state preparation device to generate a twin-field quantum state sequence including first and second quantum state sequences. These sequences are subjected to polarization state encoding and time-division multiplexing through a quantum channel transmission device to form an encoded quantum state transmission sequence. This sequence then undergoes phase compensation and noise suppression to obtain an optimized quantum state sequence. Subsequently, a quantum state measurement device performs Bell state measurement and basis selection on the optimized sequence to obtain a sequence of measurement results. Finally, a post-processing device performs key extraction and privacy amplification on the measurement results to ensure the generation of a final quantum key, solving the technical problem that the practicality and transmission distance of traditional quantum key distribution schemes are greatly limited due to the influence of channel loss and noise interference factors, and realizing the processing of quantum state sequences using polarization state encoding and time-division multiplexing technology, which not only increases the density of information transmission but also improves the stability of transmission in a quantum channel. This optimization helps to reduce the error rate caused by channel loss and ensures the effective realization of long-distance quantum communication. Description of the Drawings

[0017] Figure 1 is a schematic diagram of the steps of a quantum key distribution method based on the twin-field protocol in an embodiment of the present invention; Figure 2 is a block diagram of the structure of a quantum key distribution device based on the twin-field protocol in an embodiment of the present invention; Figure 3 is a schematic block diagram of the structure of a computer device in an embodiment of the present invention.

[0018] The implementation, functional characteristics, and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] As Figure 1 shown, Figure 1 is a schematic diagram of the steps of a quantum key distribution method based on a dual-field protocol in an embodiment of the present invention; An embodiment of the present invention provides a quantum key distribution method based on a dual-field protocol, including the following steps: Step S1, performing phase modulation and intensity modulation on an initial laser pulse through a quantum state preparation device to obtain a dual-field quantum state sequence, where the dual-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence.

[0021] Specifically, in implementing the quantum key distribution method based on the dual-field protocol, it is first necessary to perform phase modulation and intensity modulation on the initial laser pulse through a quantum state preparation device to obtain a dual-field quantum state sequence, where the dual-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence. This step is the basis of the entire quantum key distribution process, and its purpose is to create quantum states suitable for subsequent processing and transmission. Specifically, in the quantum state preparation stage, after the initial laser pulse is sent into the quantum state preparation device, the device will precisely adjust its phase and intensity according to preset parameters. For example, for an application scenario aiming to improve the quality of secure communication between cities, specific information can be encoded by adjusting the phase of the laser pulse, and different transmission conditions can be simulated by changing the intensity of the laser, ensuring that the required quantum states can be accurately generated even in complex environments. The subsequent process involves converting these modulated laser pulses into specific quantum state sequences, namely the first quantum state sequence and the second quantum state sequence. Here, the first quantum state sequence and the second quantum state sequence represent two different but interrelated states, which will play a key role in the subsequent quantum key distribution process. For example, in the above example of secure communication between cities, the first quantum state sequence may be used to represent the basic unit of encrypted information, while the second quantum state sequence is used to verify the authenticity and integrity of this information. In this way, even in the face of potential eavesdropping threats, the security of information can be guaranteed. This process not only relies on sophisticated hardware devices but also requires complex algorithms to ensure that each step can be precisely executed, thus laying a solid foundation for finally generating secure and reliable quantum keys. In fact, this fine-tuning ability enables the quantum key distribution technology to exhibit excellent security performance in various application scenarios, benefiting government agencies, financial institutions, and individual users alike.

[0022] Step S2: Use the quantum channel transmission device to perform polarization state encoding and time-division multiplexing on the first quantum state sequence and the second quantum state sequence to obtain an encoded quantum state transmission sequence.

[0023] Specifically, in the quantum key distribution method based on the twin-field protocol, using the quantum channel transmission device to perform polarization state encoding and time-division multiplexing on the first quantum state sequence and the second quantum state sequence to obtain an encoded quantum state transmission sequence is the core process for achieving long-distance secure communication. Specifically, after the first quantum state sequence and the second quantum state sequence are prepared, they need to be further processed by the quantum channel transmission device to ensure that these quantum states can be stably transmitted in a complex environment. During this process, polarization state encoding technology is used to load information onto the quantum states. For example, by adjusting the polarization direction of photons, each quantum state can carry a specific information bit. This encoding method not only increases the density of information transmission but also enhances the resistance of quantum states to environmental interference during transmission.

[0024] Meanwhile, to further improve the transmission efficiency, time-division multiplexing technology is introduced into this process. Time-division multiplexing is a technology that separates and alternately transmits multiple signals on the time axis. In this way, the first quantum state sequence and the second quantum state sequence can be efficiently transmitted in the same channel without interfering with each other. For example, in the application scenario of secure communication between cities, this technology enables data of different users or different time periods to be efficiently transmitted in the same optical fiber channel, thus significantly reducing resource consumption. In addition, time-division multiplexing can also effectively reduce the noise accumulation in the channel, which is crucial for ensuring the security of the finally generated quantum key. Considering the actual application scenario, assume that a financial institution needs to establish a highly secure communication link between two branches. Then, through the above polarization state encoding and time-division multiplexing technologies, it can be ensured that the quantum state sequence maintains the integrity of information during transmission and achieves the goal of efficiently using channel resources. The practical application of this technology not only improves the performance of the quantum key distribution system but also lays a solid foundation for future quantum communication networks. In this way, even in the face of a complex and changeable transmission environment, the stability and reliability of the quantum state sequence can be guaranteed, providing high-quality input data for subsequent phase compensation, noise suppression, and final key extraction.

[0025] Step S3: Perform phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence.

[0026] Specifically, in the quantum key distribution method based on the two-field protocol, phase compensation and noise suppression are performed on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence, which is a crucial step to ensure the stability and security of the quantum communication system. Specifically, during the transmission of the quantum state through the quantum channel, due to environmental factors such as temperature changes, fiber vibration, or electromagnetic interference, the phase of the quantum state may drift, and the introduction of noise will also cause information distortion. To overcome these problems, phase compensation and noise suppression must be performed on the encoded quantum state transmission sequence. The phase compensation technique can monitor and correct the phase drift of the quantum state in real time by introducing a reference optical field or using a feedback control mechanism, thereby ensuring that the coherence between the first quantum state sequence and the second quantum state sequence is not destroyed. At the same time, the noise suppression technique further improves the quality of the quantum state by filtering and processing the random noise introduced during the transmission process. For example, in the application scenario of secure communication between cities, assuming that the quantum communication link between two branches is affected by scattering noise in the fiber channel or external electromagnetic interference, then by adopting phase compensation and noise suppression measures, the impact of these interferences on the quantum state can be effectively reduced, making the finally received quantum state sequence closer to the high-quality state prepared initially. This optimization not only improves the accuracy of quantum state measurement but also provides a more reliable data basis for subsequent Bell state measurement and basis vector selection. Considering the actual application, the importance of this technology lies in its ability to significantly enhance the robustness of the quantum key distribution system. For example, in the secure communication of financial institutions, if the quantum state sequence is affected by noise interference during transmission and not processed in time, the generated quantum key may contain error bits, thus affecting the security of communication. However, through the above phase compensation and noise suppression techniques, the error rate during transmission can be greatly reduced, ensuring that the finally generated quantum key has higher security and reliability. Therefore, this step is not only a key link in technical implementation but also provides a solid guarantee for the wide application of quantum communication technology in actual scenarios.

[0027] Step S4: Perform Bell state measurement and basis vector selection on the optimized quantum state sequence through a quantum state measurement device to obtain a measurement result sequence.

[0028] Specifically, in the quantum key distribution method based on the two-field protocol, the optimized quantum state sequence is subjected to Bell state measurement and basis selection by a quantum state measurement device to obtain a measurement result sequence. This process is the core link in realizing quantum key generation. Specifically, after phase compensation and noise suppression, the optimized quantum state sequence already has high quality and stability. However, in order to extract the information carried therein, it must be accurately measured. In this process, Bell state measurement technology is used to analyze the correlation between quantum states. This measurement method can reveal the entanglement relationship between the first quantum state sequence and the second quantum state sequence, thus providing basic data for subsequent key generation. At the same time, basis selection determines the measurement basis that each quantum state should adopt according to pre-set rules. For example, in polarization state encoding, the horizontal / vertical basis or the diagonal / anti-diagonal basis is selected. This selection ensures the accuracy and consistency of the measurement results. Considering the actual application scenario, in the context of secure inter-city communication, assume that branches of two financial institutions are using a quantum key distribution system to establish a highly secure communication link. Then, through Bell state measurement and basis selection, the integrity and reliability of the quantum state sequence can be effectively verified. For example, when the quantum state sequence sent by one party reaches the receiving party through the channel transmission, the receiving party measures these quantum states through a quantum state measurement device and filters out the valid measurement results according to the basis selection rules agreed upon by both parties in advance. If the measurement results match the expectations, it indicates that the quantum state has not been eavesdropped or tampered with; otherwise, it may indicate that there are security risks in the communication link. This mechanism can not only detect potential security threats but also provide a reliable basis for subsequent key extraction. In fact, the importance of this process lies in that it directly determines the performance and security of the quantum key distribution system. For example, in the above application scenario of financial institutions, if the results of Bell state measurement deviate, or the basis selection fails to match correctly, the generated quantum key may contain error bits, thus affecting the security of the final communication. However, through accurate Bell state measurement and reasonable basis selection, the bit error rate can be minimized to ensure the high quality of the measurement result sequence. This step is not only a key link in quantum key distribution technology but also lays a solid foundation for subsequent post-processing steps, such as key extraction and privacy amplification, thus realizing efficient and secure quantum communication.

[0029] Step S5: The post-processing device performs key extraction and privacy amplification on the measurement result sequence to obtain the final quantum key.

[0030] Specifically, in the quantum key distribution method based on the two-field protocol, the post-processing device extracts keys and performs privacy amplification on the measurement result sequence to obtain the final quantum key. This process is the last step for the entire quantum communication system to achieve security and is also a crucial link. Specifically, after Bell state measurement and basis vector selection, the measurement result sequence contains the original information shared by both parties. However, there may still be error bits or potential security threats in this information. Therefore, key extraction technology is needed to purify it. The key extraction process first compares and filters the measurement result sequence to remove the error data caused by channel noise or device errors. At the same time, error correction algorithms are used to further repair possible deviations, ensuring that the data generated by both parties is consistent and error-free. For example, in the application scenario of secure communication between cities, assume that branches of two financial institutions are establishing a highly secure communication link. Then, through the key extraction step, both parties can eliminate unreliable data and retain high-quality information, laying a foundation for generating the final quantum key. At the same time, to further enhance the security of the key, privacy amplification technology is introduced into the post-processing process. The core of privacy amplification is to compress and randomize the measurement result sequence to eliminate the part of the information that may be obtained by eavesdroppers, thus ensuring that the finally generated quantum key has high randomness and unpredictability. For example, in the above application scenario, if an eavesdropper intercepts a part of the quantum states during transmission and attempts to obtain information from them, then through privacy amplification technology, these potential leakage information can be compressed to an almost negligible level, making it impossible for the eavesdropper to obtain any useful content. This mechanism not only enhances the security of the quantum key but also provides higher guarantees for practical applications. In fact, the importance of this process lies in its ability to significantly improve the practicality and security of the quantum key distribution system. For example, in the secure communication of financial institutions, if the post-processing step fails to be effectively executed, the finally generated quantum key may contain security risks, thus affecting the confidentiality of communication. However, through precise key extraction and privacy amplification, not only can the risk of information leakage be minimized, but also the quality and reliability of the final quantum key can be ensured. This step is not only a key link in the quantum key distribution technology but also provides a solid foundation for the efficient operation and wide application of the entire system, thus realizing truly secure communication.

[0031] In a specific embodiment, the phase modulation and intensity modulation of the initial laser pulse by the quantum state preparation device to obtain a two-field quantum state sequence includes: The quantum state preparation device performs phase modulation on the initial laser pulse to obtain a phase-modulated laser pulse, and performs phase noise analysis on the phase-modulated laser pulse to obtain phase noise characteristics; Based on the phase noise characteristics, intensity modulation is performed on the phase-modulated laser pulse to obtain an intensity-modulated laser pulse, and intensity noise analysis is carried out on the intensity-modulated laser pulse to obtain intensity noise characteristics; Based on the intensity noise characteristics, quantum state preparation is performed on the intensity-modulated laser pulse to obtain a preliminary two-field quantum state sequence, and orthogonal component separation is carried out on the preliminary two-field quantum state sequence through a quantum beam splitter to obtain a two-field quantum state sequence including a first quantum state sequence reflecting phase information and a second quantum state sequence reflecting amplitude information.

[0032] Specifically, in the quantum key distribution method based on the two-field protocol, the process of phase modulation and intensity modulation of the initial laser pulse by the quantum state preparation device to obtain the two-field quantum state sequence is the basis for ensuring the performance of the entire system. First, the initial laser pulses enter the quantum state preparation device, where they will undergo a series of precisely controlled operation steps. Specifically, the initial laser pulses first enter the phase modulation stage, and are phase-modulated according to preset parameters to generate phase-modulated laser pulses. During this process, in order to ensure the quality of the quantum state, it is necessary to perform phase noise analysis on the phase-modulated laser pulses to identify and quantify the phase noise characteristics that may affect subsequent steps. For example, in the construction of a secure communication link between financial institutions in different cities, this phase noise analysis can help detect and correct phase drifts caused by factors such as temperature fluctuations or mechanical vibrations, thereby ensuring the stability of the quantum state. Once the phase noise characteristics are obtained, the next step is to perform intensity modulation on the phase-modulated laser pulses based on these characteristics. In this link, the quantum state preparation device will adjust the intensity of the laser pulses according to the phase noise characteristics, so that the finally output intensity-modulated laser pulses not only have the required phase characteristics, but also have an optimized intensity distribution. It should be noted that this process also requires careful noise analysis, that is, intensity noise analysis of the intensity-modulated laser pulses to determine their intensity noise characteristics. This step is crucial for improving the overall quality of the quantum state, because even the slightest intensity change may accumulate into significant errors during long-distance transmission. Therefore, by accurately evaluating the intensity noise characteristics, potential signal distortion can be effectively reduced, laying a solid foundation for subsequent quantum state preparation. Based on the obtained intensity noise characteristics above, the quantum state preparation device will further process the intensity-modulated laser pulses to generate a preliminary two-field quantum state sequence. On this basis, the quantum beam splitter is used to separate the orthogonal components of the preliminary two-field quantum state sequence, so as to obtain a two-field quantum state sequence of the first quantum state sequence reflecting the phase information and the second quantum state sequence reflecting the amplitude information. This process involves complex physical operations and algorithm support, aiming to ensure that the generated quantum states not only meet the requirements of the theoretical model, but also perform well in practical applications. For example, in the construction of a secure communication link between financial institutions, through precise quantum state preparation and beam splitting operations, it can be ensured that even in the face of losses and environmental interference in the optical fiber channel, the generated two-field quantum state sequence can still maintain high quality and stability. To more intuitively understand the importance of this process, we can imagine a specific example: Suppose a financial institution plans to establish a highly secure communication link between two of its branches in different cities. In this case, through precise phase and intensity modulation techniques, it can be ensured that each quantum state sent from the sending end carries accurate information and is not easily affected by external factors during transmission.When these quantum states are carefully modulated, they are encoded into a form suitable for long-distance transmission and finally reach the receiving end. During this period, any slight changes in phase or intensity caused by the environment will be detected and corrected in a timely manner, thus ensuring the security and integrity of information transmission. In addition, through effective noise suppression measures, data distortion caused by various interference sources in the transmission path can be further reduced, ensuring that the finally received quantum state is as close as possible to the original transmitted state. For example, in the above application scenario, if a high bit error rate is detected during the transmission of the quantum state, it may indicate poor channel conditions or eavesdropping behavior. At this time, the system needs to take corresponding error correction or protection measures. This mechanism not only enhances the security of quantum keys but also provides higher guarantees for practical applications. In short, the process of obtaining a dual-field quantum state sequence by modulating the phase and intensity of the initial laser pulse through a quantum state preparation device not only reflects the precision and complexity of modern quantum communication technology but also provides a solid guarantee for realizing efficient and secure quantum key distribution. Each operation is to overcome various challenges that may be encountered in practical applications, thus ensuring the stable operation and wide application of the quantum key distribution system. In a specific embodiment, the polarization state encoding and time division multiplexing of the first quantum state sequence and the second quantum state sequence by the quantum channel transmission device to obtain an encoded quantum state transmission sequence includes: The quantum channel transmission device performs polarization state encoding on the first quantum state sequence and the second quantum state sequence to obtain a quantum state sequence after polarization state encoding, and performs polarization state measurement on the quantum state sequence after polarization state encoding to obtain polarization state characteristics; Based on the polarization state characteristics, time division multiplexing is performed on the quantum state sequence after polarization state encoding to obtain a quantum state sequence after time division multiplexing, and time division multiplexing time slot allocation is performed on the quantum state sequence after time division multiplexing to obtain time division multiplexing characteristics; Based on the time division multiplexing characteristics, quantum state transmission is performed on the quantum state sequence after time division multiplexing to obtain an encoded quantum state transmission sequence, where the encoded quantum state transmission sequence contains polarization state encoding information and time division multiplexing encoding information of the first quantum state sequence and the second quantum state sequence.

[0033] Specifically, in the quantum key distribution method based on the two-field protocol, the process of performing polarization state encoding and time-division multiplexing on the first quantum state sequence and the second quantum state sequence through the quantum channel transmission device to obtain the encoded quantum state transmission sequence is a crucial step to ensure the efficient and secure transmission of information. First, the first quantum state sequence and the second quantum state sequence will enter the quantum channel transmission device, where they will undergo the polarization state encoding process. The core of this stage lies in utilizing the polarization characteristics of photons to load information, enabling each quantum state to carry specific data bits. For example, in the construction of a secure communication link between financial institutions in different cities, by precisely encoding the polarization states of the first quantum state sequence and the second quantum state sequence, encrypted information can be effectively embedded into the polarization states of photons. Subsequently, in order to ensure that these polarization state-encoded quantum state sequences can maintain their accuracy and integrity during transmission, polarization state measurement is required to obtain the polarization state characteristics. This analysis helps identify and correct any factors that may affect the stability of the polarization state, such as fiber bending or temperature changes. Based on the obtained polarization state characteristics, time-division multiplexing is then performed on the polarization state-encoded quantum state sequences. Time-division multiplexing technology allows multiple signals to be transmitted simultaneously on the same physical channel. By allocating different time slots to different data streams, efficient utilization of resources can be achieved. During this process, the time-division multiplexing strategy is adjusted according to the polarization state characteristics to ensure that different quantum state sequences do not interfere with each other. At the same time, time-division multiplexing time slot allocation also needs to be performed on the time-division multiplexed quantum state sequences to determine their time-division multiplexing characteristics. This step is crucial for optimizing signal transmission efficiency as it can help identify potential synchronization problems or data loss risks and take corresponding measures to address them. For example, in the above-mentioned secure communication scenario of financial institutions, through effective time-division multiplexing technology, the data transmission rate can be significantly increased based on limited fiber optic resources, thereby improving the efficiency of the entire communication system. Once the time-division multiplexing characteristics are obtained, the time-division multiplexed quantum state sequences can be transmitted according to these characteristics. During this process, the quantum state transmission sequence not only contains the information of the original first quantum state sequence and the second quantum state sequence but also integrates the relevant information of polarization state encoding and time-division multiplexing encoding. To ensure the transmission quality, a detailed analysis of the quantum state transmission sequence must be carried out to obtain the quantum state transmission characteristics. This step aims to monitor and evaluate the performance of quantum states during the entire transmission process, including key indicators such as signal strength, noise level, and bit error rate. For example, in practical applications, if a high bit error rate is detected during the quantum state transmission process, it may indicate poor channel conditions or eavesdropping behavior, and at this time, the system needs to take corresponding error correction or protection measures. Based on the quantum state transmission characteristics, further processing is performed on the quantum state transmission sequence to generate the encoded quantum state transmission sequence.This sequence not only contains all the necessary information of the original first quantum state sequence and second quantum state sequence, but also undergoes strict polarization state encoding and time division multiplexing encoding to adapt to complex transmission environments. For example, in a secure communication link between financial institutions, the encoded quantum state transmission sequence generated in this way can ensure a high degree of information integrity and security even under long-distance transmission conditions. In addition, by continuously monitoring and analyzing the encoded quantum state transmission sequence, the transmission parameters can be adjusted in real time to further enhance the robustness and reliability of the system. To more intuitively understand the importance of this process, we can envision a specific example: Suppose a financial institution plans to establish a highly secure communication link between two of its branches in different cities. In this case, through precise polarization state encoding and time division multiplexing technology, it can be ensured that each quantum state sent from the transmitting end carries accurate information and is not easily affected by external factors during transmission. When these quantum states are carefully modulated, they are encoded into a form suitable for long-distance transmission and finally reach the receiving end. During this period, any slight changes in phase or intensity caused by the environment will be detected and corrected in a timely manner, thus ensuring the security and integrity of information transmission. In addition, through effective noise suppression measures, data distortion caused by various interference sources in the transmission path can be further reduced, ensuring that the finally received quantum state is as close as possible to the original emission state. For example, in the above application scenario, if a high error rate is detected during the quantum state transmission process, it may indicate poor channel conditions or eavesdropping behavior, and at this time the system needs to take corresponding error correction or protection measures. This mechanism not only enhances the security of quantum keys but also provides higher guarantees for practical applications. In summary, the process of obtaining the encoded quantum state transmission sequence by performing polarization state encoding and time division multiplexing on the first quantum state sequence and the second quantum state sequence through a quantum channel transmission device demonstrates the powerful capabilities of modern quantum communication technology in dealing with complex transmission challenges. Each operation is closely centered around improving the efficiency and security of information transmission. Whether through precise polarization state encoding or efficient time division multiplexing technology, it is to ensure that the finally generated quantum state transmission sequence can perform excellently in various application scenarios. This advanced technology not only provides unprecedented security guarantees for high-demand users such as financial institutions but also lays a solid foundation for future quantum communication in a wider range of fields. In this way, even in the face of the most severe security threats, the efficient generation and secure use of quantum keys can be guaranteed, providing indestructible protection for the transmission of various sensitive information.

[0034] In a specific embodiment, the phase compensation and noise suppression of the encoded quantum state transmission sequence to obtain an optimized quantum state sequence includes: Perform phase compensation on the encoded quantum state transmission sequence through a phase compensation device to obtain a quantum state sequence after phase compensation, and perform phase stability evaluation on the quantum state sequence after phase compensation to obtain phase stability characteristics; Based on the phase stability characteristics, perform noise suppression on the quantum state sequence after phase compensation to obtain a quantum state sequence after noise suppression, and perform noise level measurement on the quantum state sequence after noise suppression to obtain noise characteristics; Based on the noise characteristics, perform quantum state optimization on the quantum state sequence after noise suppression to obtain an optimized quantum state sequence.

[0035] Specifically, in the quantum key distribution method based on the two-field protocol, the process of performing phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence is a crucial step to ensure that quantum information can be accurately received and used to generate the final quantum key. First, the encoded quantum state transmission sequence will enter the phase compensation device, where each quantum state will receive precise phase compensation according to its specific phase drift situation. Through this compensation mechanism, the phase changes caused by channel characteristics or environmental factors can be effectively corrected, thus restoring the original phase state of the quantum state. For example, in the construction of a secure communication link between financial institutions in different cities, phase compensation is crucial for ensuring the accuracy of information transmission from the sender to the receiver. Once the phase compensation is completed, the next step is to evaluate the phase stability of the phase-compensated quantum state sequence to determine its phase stability characteristics. This process helps to identify any potential problems that may affect the stability of the quantum state and provides a basis for subsequent optimization measures. Based on the obtained phase stability characteristics, the quantum state sequence will undergo further processing - noise suppression. In this step, advanced noise suppression techniques are used to reduce various noise interferences introduced during the quantum state transmission. These noises may come from scattering effects in the optical fiber channel, external electromagnetic interference, or thermal noise of the device itself. By implementing targeted noise suppression strategies on the phase-compensated quantum state sequence, the quality of the quantum state can be significantly improved, making it closer to the ideal pure state. Subsequently, a detailed noise level measurement needs to be performed on the noise-suppressed quantum state sequence to determine its noise characteristics. This step not only helps to evaluate the effect of noise suppression but also provides guidance for further optimization. For example, in the above application scenario, if a certain degree of residual noise is still detected in the quantum state sequence, the signal can be further purified by adjusting the noise suppression parameters or using a higher-level filtering technique. When the noise characteristics are obtained, based on this information, the noise-suppressed quantum state sequence is optimized to obtain an optimized quantum state sequence. This process involves the application of various technical means, including but not limited to quantum error correction codes, entanglement purification, etc., aiming to maximize the elimination of remaining errors and improve the overall quality of the quantum state. To verify the optimization effect, it is also necessary to evaluate the entanglement degree of the optimized quantum state sequence to obtain quantum state characteristics. These characteristics reflect the actual situation of the quantum state after a series of processes, such as key indicators such as fidelity and entanglement degree, which are crucial for ensuring that the quantum state can play its due role in subsequent steps. For example, in the secure communication scenario of financial institutions, quantum state characteristics can help confirm whether the received quantum state is consistent with the sender, thus ensuring the security of information transmission. Immediately following, based on the quantum state characteristics, the optimized quantum state sequence is optimized again.The purpose of this step is to further improve the quality of the quantum state, ensuring that it remains in a high-quality state after undergoing a series of complex transmission and processing procedures, laying a solid foundation for subsequent Bell state measurements and basis vector selections. For example, in the above application case of a financial institution, through this comprehensive and meticulous optimization process, not only can the performance of the quantum key distribution system be effectively improved, but also the security of the entire communication link can be greatly enhanced, ensuring a high level of confidentiality and integrity of information even in the face of the most severe security threats. To better understand the importance of this process, we can envision a specific example: Suppose a financial institution plans to establish a highly secure communication link between two branches in different cities. In this case, through precise phase compensation and noise suppression techniques, it can be ensured that each quantum state emitted from the sending end carries accurate information and is not easily affected by external factors during transmission. When these quantum states are carefully modulated and optimized, they are encoded into a form suitable for long-distance transmission and finally reach the receiving end. During this period, any subtle changes in phase or intensity caused by the environment will be detected and corrected in a timely manner, thus ensuring the security and integrity of information transmission. In addition, through effective noise suppression measures, data distortion caused by various interference sources in the transmission path can be further reduced, ensuring that the finally received quantum state is as close as possible to the original emitted state. For example, in the above application scenario, if a high bit error rate is detected during the transmission of the quantum state, it may indicate poor channel conditions or eavesdropping behavior, and at this time the system needs to take corresponding error correction or protection measures. This mechanism not only enhances the security of the quantum key but also provides higher guarantees for practical applications. In summary, the process of optimizing the transmitted sequence of encoded quantum states through phase compensation and noise suppression to obtain an optimized quantum state sequence demonstrates the powerful capabilities of modern quantum communication technology in addressing complex transmission challenges. Each operation is closely centered around improving the efficiency and security of information transmission. Whether through precise phase compensation or efficient noise suppression techniques, it is to ensure that the finally generated transmitted sequence of quantum states can perform excellently in various application scenarios. This advanced technology not only provides unprecedented security guarantees for high-demand users such as financial institutions but also lays a solid foundation for quantum communication in broader fields in the future. In this way, even in the face of the most severe security threats, the efficient generation and secure use of quantum keys can be ensured, providing indestructible protection for the transmission of various sensitive information.

[0036] In a specific embodiment, performing Bell state measurement and basis vector selection on the optimized quantum state sequence by means of a quantum state measurement device to obtain a measurement result sequence includes: Perform Bell state measurement on the optimized quantum state sequence through a quantum state measurement device to obtain a Bell state measurement result, and perform Bell state characterization on the Bell state measurement result to obtain Bell state characteristics; Based on the Bell state characteristics, perform basis vector selection on the Bell state measurement result to obtain a basis vector selection result, and perform basis vector discrimination on the basis vector selection result to obtain basis vector characteristics; Based on the basis vector characteristics, perform quantum state measurement on the basis vector selection result to obtain a quantum state measurement result, and perform quantum state reconstruction on the quantum state measurement result to obtain reconstructed quantum state characteristics; Based on the reconstructed quantum state characteristics, perform measurement result statistics on the quantum state measurement result to obtain measurement result characteristics, and sort the measurement result characteristics to generate a measurement result sequence.

[0037] Specifically, in the quantum key distribution method based on the two-field protocol, the process of performing Bell state measurement and basis vector selection on the optimized quantum state sequence by the quantum state measurement device to obtain the measurement result sequence is a crucial step in ensuring the accuracy and security of the finally generated quantum key. First, the optimized quantum state sequence enters the quantum state measurement device, where they will undergo Bell state measurement. Bell state measurement aims to identify the entanglement relationship between two quantum states, which is crucial for quantum key distribution. For example, in the construction of a secure communication link between financial institutions in different cities, by performing Bell state measurement on the optimized quantum state sequence, it can be effectively determined whether these quantum states correctly maintain their entanglement properties, thus providing a reliable basis for subsequent key extraction. Once the Bell state measurement is completed, the next step is to perform a detailed Bell state characterization on the Bell state measurement results to determine the Bell state characteristics. This process not only helps to evaluate the quality of entanglement between quantum states but also provides necessary guiding information for subsequent basis vector selection. Based on the obtained Bell state characteristics, the next step is to perform basis vector selection on the Bell state measurement results. Basis vector selection is a crucial step because it determines how to interpret the measurement results. Specifically, an appropriate measurement basis vector is selected according to the Bell state characteristics so that the information carried by the quantum state can be interpreted most accurately. In this process, basis vector discrimination needs to be performed on the basis vector selection results to obtain the basis vector characteristics. The importance of this step lies in that it directly affects the generation efficiency and accuracy of the final quantum key. For example, in the above application scenario of financial institutions, if an inappropriate basis vector is selected, it may lead to a large number of error codes, affecting the reliability of the key. Therefore, it is essential to determine the optimal basis vector selection strategy through careful basis vector discrimination. When the basis vector characteristics are obtained, quantum state measurement is performed on the basis vector selection results based on this information to obtain the quantum state measurement results. This process involves actual physical measurement operations, the purpose of which is to convert the abstract quantum state into specific readable data. To verify the validity of the measurement, quantum state reconstruction also needs to be performed on the quantum state measurement results to determine the quantum state characteristics. These characteristics reflect the actual situation of the quantum state after Bell state measurement and basis vector selection, such as key indicators like fidelity and purity, which are crucial for ensuring that the quantum state can play its due role in subsequent steps. For example, in the secure communication link of financial institutions, the quantum state characteristics can help confirm whether the received quantum state is consistent with the sending end, thus ensuring the security of information transmission. Immediately following, measurement result statistics are performed on the quantum state measurement results based on the quantum state characteristics to obtain the measurement result characteristics. The purpose of this step is to comprehensively evaluate the results of quantum state measurement, including but not limited to important parameters such as signal strength, noise level, and bit error rate. For example, in the above application scenario, any possible anomalies, such as a high bit error rate or signal attenuation, can be discovered through measurement result statistics, and these problems may indicate the existence of eavesdropping behavior or poor channel conditions.Therefore, timely and accurate measurement result statistics are crucial for maintaining the security of the entire system. Finally, the measurement results are processed based on their characteristics to generate a measurement result sequence. This step integrates the results of all previous processing steps to form a complete and ordered dataset that contains all the necessary information for subsequent key extraction and privacy amplification processes. For example, in the construction of a secure communication link between financial institutions, through this systematic measurement result generation process, not only can the high-quality generation of quantum keys be ensured, but also the security and reliability of the entire communication link can be greatly enhanced. In this way, even in the face of complex environmental interference or potential security threats, the efficient generation and secure use of quantum keys can be guaranteed, providing indestructible protection for the transmission of various sensitive information. To more intuitively understand the importance of this process, we can imagine a specific example: Suppose a financial institution plans to establish a highly secure communication link between two of its branches in different cities. In this case, through precise Bell state measurement and basis vector selection techniques, it can be ensured that each quantum state sent from the sender carries accurate information and is not easily affected by external factors during transmission. When these quantum states are carefully modulated and optimized, they are encoded into a form suitable for long-distance transmission and finally reach the receiver. During this period, any slight changes in phase or intensity caused by the environment will be detected and corrected in a timely manner, thus ensuring the security and integrity of information transmission. In addition, through effective noise suppression measures, data distortion caused by various interference sources in the transmission path can be further reduced, ensuring that the finally received quantum state is as close as possible to the original emission state. For example, in the above application scenario, if a high bit error rate is detected during the transmission of quantum states, it may indicate poor channel conditions or eavesdropping behavior, and at this time, the system needs to take corresponding error correction or protection measures. This mechanism not only enhances the security of quantum keys but also provides higher guarantees for practical applications. In summary, the process of obtaining a measurement result sequence by performing Bell state measurement and basis vector selection on the optimized quantum state sequence through a quantum state measurement device demonstrates the powerful capabilities of modern quantum communication technology in dealing with complex transmission challenges. Each operation is closely centered around improving the efficiency and security of information transmission. Whether through precise Bell state measurement or efficient basis vector selection techniques, it is to ensure that the finally generated quantum state transmission sequence can perform excellently in various application scenarios. This advanced technology not only provides unprecedented security guarantees for high-demand users such as financial institutions but also lays a solid foundation for future quantum communication in a wider range of fields. In this way, even in the face of the most severe security threats, the efficient generation and secure use of quantum keys can be guaranteed, providing indestructible protection for the transmission of various sensitive information.

[0038] In a specific embodiment, performing a quantum state measurement on the basis vector selection result based on the basis vector feature to obtain a quantum state measurement result includes: Performing a quantum state projection on the basis vector selection result based on the basis vector feature to obtain a quantum state projection result, and performing a projection state analysis on the quantum state projection result to obtain a projection state feature; Performing a quantum state interference on the quantum state projection result based on the projection state feature to obtain a quantum state interference result, and performing an interference state evaluation on the quantum state interference result to obtain an interference state feature; Performing a quantum state detection on the quantum state interference result based on the interference state feature to obtain a quantum state detection result, and performing a detection state characterization on the quantum state detection result to obtain a detection state feature; Performing a quantum state counting on the quantum state detection result based on the detection state feature to obtain a quantum state counting result, and performing a counting state counting on the quantum state counting result to obtain a counting state feature; Performing a quantum state measurement on the quantum state counting result based on the counting state feature to obtain a quantum state measurement result.

[0039] Specifically, in the quantum key distribution method based on the two-field protocol, the process of performing quantum state measurement on the basis selection result based on the basis vector characteristics to obtain the quantum state measurement result is the core link to ensure the accuracy and reliability of the finally generated quantum key. First, based on the determined basis vector characteristics, the basis selection result will be sent to the quantum state projection step, where they will undergo precise quantum state projection operations. Quantum state projection is a technique used to convert complex quantum states into readable classical information. Through this process, the information carried by the quantum state can be effectively extracted. For example, in the construction of a secure communication link between financial institutions in different cities, by performing quantum state projection on the basis selection result, the entangled state can be converted into the form of classical bits, providing the basic data for subsequent key extraction. After completing the quantum state projection, it is necessary to conduct a detailed analysis of the projected state of the quantum state projection result to determine the projected state characteristics. This step not only helps to evaluate the effectiveness of the quantum state projection but also provides a basis for necessary parameter adjustment for the next operation. Based on the obtained projected state characteristics, the next step is to perform quantum state interference on the quantum state projection result. Quantum state interference refers to using the interaction between quantum states to enhance or weaken the probability amplitude of certain specific states, thereby improving the measurement accuracy and information extraction efficiency. In this process, an interference scheme is designed according to the projected state characteristics, and the interference state of the quantum state interference result is evaluated to determine the interference state characteristics. For example, in the above application scenario of financial institutions, quantum state interference can further improve the accuracy of quantum state measurement and reduce errors caused by channel noise or other interference factors. The interference state evaluation helps to identify and optimize any factors that may affect the measurement result, ensuring the efficiency and stability of the quantum state interference process. When the interference state characteristics are obtained, based on this information, quantum state detection is performed on the quantum state interference result. Quantum state detection is a crucial step in the entire measurement process, which directly determines whether the required information can be successfully extracted from the quantum state. At this stage, high-sensitivity detection techniques are used to capture the weak signals in the quantum state interference result and conduct a detailed characterization of the detection state to obtain the detection state characteristics. For example, in the secure communication link of financial institutions, quantum state detection not only needs to ensure high-precision data acquisition but also needs to have sufficient anti-noise ability to cope with complex transmission environments. The result of the detection state characterization is crucial for subsequent quantum state counting because it directly affects the quality and reliability of the final quantum key. Immediately following, quantum state counting is performed on the quantum state detection result based on the detection state characteristics. Quantum state counting is a statistical method aimed at quantifying the measurement result by calculating the frequency of the occurrence of specific quantum states. This step involves processing a large number of quantum state detection results to determine the actual distribution of each quantum state. To verify the effectiveness of the counting, it is also necessary to perform counting state counting on the quantum state counting result to determine the counting state characteristics.For example, in the above application scenario, quantum state counting can not only help confirm whether the received quantum states meet expectations, but also reveal potential security threats, such as the existence of eavesdropping behavior. Therefore, accurate quantum state counting and its subsequent analysis are crucial for maintaining the security of the entire system. Finally, quantum state measurement is performed on the quantum state counting results based on the characteristics of the counted states to obtain the final quantum state measurement results. This process integrates the results of all the previous processing steps to form a comprehensive and orderly data set, which contains all the necessary information for subsequent key extraction and privacy amplification processes. For example, in the construction of a secure communication link between financial institutions, through this systematic quantum state measurement process, not only can the high-quality generation of quantum keys be ensured, but also the security and reliability of the entire communication link can be greatly enhanced. For example, assume that branches of two financial institutions hope to establish a highly secure communication link through a quantum key distribution system. Then, through this series of rigorous quantum state measurement steps - from quantum state projection to quantum state interference, quantum state detection, and then to quantum state counting, it can be ensured that the generated quantum keys have extremely high confidentiality and unpredictability. This not only greatly reduces the risk of information leakage but also provides indestructible security for the transmission of sensitive data between financial institutions. In short, this series of carefully designed technical measures work together to ensure that the quantum key distribution system can operate stably in various complex environments and provide strong support for more extensive future quantum communication applications. In this way, even in the face of complex environmental interference or potential security threats, the efficient generation and secure use of quantum keys can be guaranteed, providing indestructible protection for the transmission of various sensitive information. This advanced technology not only enhances the practicality and security of the quantum key distribution system but also lays a solid foundation for realizing truly secure communication. Whether it is in the privacy protection of government agencies, financial institutions, or individual users, this efficient quantum key generation technology will play an irreplaceable role. Through accurate quantum state measurement, even in the face of the most severe security threats, the high confidentiality and integrity of information can be ensured.

[0040] In a specific embodiment, the post-processing device performs key extraction and privacy amplification on the measurement result sequence to obtain a final quantum key, including: The post-processing device performs key extraction on the measurement result sequence to obtain a key extraction result, and performs key generation on the key extraction result to obtain a key feature; Based on the key feature, privacy amplification is performed on the key extraction result to obtain a privacy amplification result, and privacy extraction is performed on the privacy amplification result to obtain a privacy feature; Based on the privacy feature, security evaluation is performed on the privacy amplification result to obtain a security parameter, and verification is performed on the security parameter to obtain a verification result; Based on the verification result, perform final quantum key generation on the privacy amplification result to obtain a final quantum key.

[0041] Specifically, in the quantum key distribution method based on the two-field protocol, the process of extracting keys and privacy amplification on the measurement result sequence by the post-processing device to obtain the final quantum key is a crucial step to ensure the security of information transmission. First, the measurement result sequence obtained after a series of complex steps of quantum state preparation, encoding, transmission, and measurement will be sent to the post-processing device, where they will undergo the first key extraction process. In this process, the post-processing device will screen and correct the received measurement result sequence according to a preset algorithm, aiming to eliminate the error data caused by channel noise or device errors and repair possible deviations. For example, in the construction of a secure communication link between financial institutions in different cities, by performing key extraction operations on the measurement result sequence, high-quality information fragments can be separated from the original data, laying a foundation for generating reliable and secure quantum keys. After key extraction is completed, detailed key generation needs to be performed on the key extraction result to determine the key characteristics. This step not only helps to evaluate the quality of the key but also provides necessary guiding information for subsequent privacy amplification. Based on the obtained key characteristics, privacy amplification of the key extraction result follows. Privacy amplification is an important technical means, whose purpose is to reduce any useful information that an eavesdropper may obtain from public information, thereby further enhancing the security of the quantum key. Specifically, a suitable privacy amplification strategy is designed according to the key characteristics, and privacy extraction is performed on the privacy amplification result to determine the privacy characteristics. For example, in the above application scenario of financial institutions, through privacy amplification, the potentially leaked information can be effectively compressed to an almost negligible level, so that even if there is eavesdropping, the eavesdropper cannot obtain any valuable content from it. The result of privacy extraction is crucial for verifying the privacy amplification effect, which can help identify and optimize any factors that may affect the security of the final quantum key and ensure the security of the entire system. When the privacy characteristics are obtained, based on this information, a security assessment of the privacy amplification result is performed to determine the security parameters. The security assessment aims to comprehensively evaluate the security performance of the quantum key, including but not limited to important indicators such as anti-eavesdropping ability, bit error rate, and key length. To ensure the security and reliability of the quantum key, the security parameters also need to be verified to obtain the verification result. For example, in the secure communication link of financial institutions, the security assessment can not only help confirm whether the generated quantum key meets the expected security standards but also reveal potential security threats, such as high bit error rate or abnormal security parameters. Therefore, accurate security assessment and its subsequent verification are crucial for maintaining the security of the entire system. Finally, based on the verification result, the final quantum key is generated from the privacy amplification result to obtain the final quantum key. This process integrates the results of all the previous processing steps to form a complete and ordered data set, which contains all the necessary information for secure communication in practical applications.For example, in the construction of a secure communication link among financial institutions, through this systematic quantum key generation process, not only can the high-quality generation of quantum keys be ensured, but also the security and reliability of the entire communication link can be greatly enhanced. Suppose the branches of two financial institutions wish to establish a highly secure communication link through a quantum key distribution system. Then, through this series of rigorous post-processing steps - from key extraction to privacy amplification to security evaluation and verification, it can be ensured that the generated quantum keys have extremely high confidentiality and unpredictability. This not only greatly reduces the risk of information leakage, but also provides an indestructible security guarantee for the transmission of sensitive data among financial institutions. To more intuitively understand the importance of this process, we can envision a specific example: Suppose a financial institution plans to establish a highly secure communication link between its two branches in different cities. In this case, through precise key extraction and privacy amplification techniques, it can be ensured that each quantum state sent from the sender carries accurate information and is not easily affected by external factors during the transmission process. When these quantum states are carefully modulated and optimized, they will be encoded into a form suitable for long-distance transmission and finally reach the receiver. During this period, any slight changes in phase or intensity caused by the environment will be detected and corrected in a timely manner, thus ensuring the security and integrity of information transmission. In addition, through effective noise suppression measures, the data distortion caused by various interference sources in the transmission path can be further reduced, ensuring that the finally received quantum state is as close as possible to the original emission state. For example, in the above application scenario, if a high bit error rate is detected during the transmission of quantum states, it may indicate poor channel conditions or eavesdropping behavior. At this time, the system needs to take corresponding error correction or protection measures. This mechanism not only enhances the security of quantum keys, but also provides higher guarantees for practical applications. In short, the process of obtaining the final quantum key through key extraction and privacy amplification of the measurement result sequence by the post-processing device demonstrates the powerful capabilities of modern quantum communication technology in dealing with complex transmission challenges. Each operation is closely centered around improving the efficiency and security of information transmission. Whether through precise key extraction or efficient privacy amplification techniques, it is to ensure that the finally generated quantum state transmission sequence can perform excellently in various application scenarios. This advanced technology not only provides unprecedented security guarantees for high-demand users such as financial institutions, but also lays a solid foundation for quantum communication in a wider range of fields in the future. In this way, even in the face of the most severe security threats, the efficient generation and secure use of quantum keys can be guaranteed, providing indestructible protection for the transmission of various sensitive information.

[0042] The above describes the quantum key distribution method based on the twin-field protocol in the embodiments of the present invention. Next, the quantum key distribution device based on the twin-field protocol in the embodiments of the present invention will be described. Please refer toFigure 2 , in an embodiment of the quantum key distribution device based on the two-field protocol in the embodiments of the present invention, it includes: A modulation module 21, configured to perform phase modulation and intensity modulation on an initial laser pulse through a quantum state preparation device to obtain a two-field quantum state sequence, where the two-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence; A multiplexing module 22, configured to perform polarization state encoding and time-division multiplexing on the first quantum state sequence and the second quantum state sequence through a quantum channel transmission device to obtain an encoded quantum state transmission sequence; An optimization module 23, configured to perform phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence; A selection module 24, configured to perform Bell state measurement and basis vector selection on the optimized quantum state sequence through a quantum state measurement device to obtain a measurement result sequence; An amplification module 25, configured to perform key extraction and privacy amplification on the measurement result sequence through a post-processing device to obtain a final quantum key, and distribute the final quantum key to two preset communication parties through a secure channel.

[0043] In this embodiment, for the specific implementation of each unit in the above device embodiment, please refer to that described in the above method embodiment, and details are not described herein again.

[0044] Refer to Figure 3 , in the embodiments of the present invention, a computer device is further provided. The internal structure of the computer device can be as Figure 3 shown. The computer device includes a processor, a memory, a display screen, an input device, a network interface, and a database connected through a system bus. Among them, the processor of the computer design is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store the corresponding data in this embodiment. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the above method is implemented.

[0045] Those skilled in the art can understand that Figure 3 the structure shown in

[0046] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above method is implemented. It can be understood that the computer-readable storage medium in this embodiment can be a volatile readable storage medium or a non-volatile readable storage medium.

[0047] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium provided by the present invention and used in the embodiments can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM, etc.

[0048] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, device, article or method. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, device, article or method including the element.

[0049] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A quantum key distribution method based on a dual-field protocol, characterized in that It includes the following steps: The initial laser pulse is subjected to phase modulation and intensity modulation by a quantum state preparation device to obtain a dual-field quantum state sequence, where the dual-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence; The first quantum state sequence and the second quantum state sequence are subjected to polarization state encoding and time-division multiplexing by a quantum channel transmission device to obtain an encoded quantum state transmission sequence; Phase compensation and noise suppression are performed on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence; The optimized quantum state sequence is subjected to Bell state measurement and basis vector selection by a quantum state measurement device to obtain a measurement result sequence; Key extraction and privacy amplification are performed on the measurement result sequence by a post-processing device to obtain a final quantum key, and the final quantum key is distributed to preset communication parties through a secure channel.

2. The quantum key distribution method based on the two-field protocol according to claim 1, wherein The step of subjecting the initial laser pulse to phase modulation and intensity modulation by a quantum state preparation device to obtain a dual-field quantum state sequence includes: The initial laser pulse is subjected to phase modulation by a quantum state preparation device to obtain a phase-modulated laser pulse, and phase noise analysis is performed on the phase-modulated laser pulse to obtain phase noise characteristics; Based on the phase noise characteristics, intensity modulation is performed on the phase-modulated laser pulse to obtain an intensity-modulated laser pulse, and intensity noise analysis is performed on the intensity-modulated laser pulse to obtain intensity noise characteristics; Based on the intensity noise characteristics, quantum state preparation is performed on the intensity-modulated laser pulse to obtain a preliminary dual-field quantum state sequence, and orthogonal component separation is performed on the preliminary dual-field quantum state sequence by a quantum beam splitter to obtain a dual-field quantum state sequence including a first quantum state sequence reflecting phase information and a second quantum state sequence reflecting amplitude information.

3. The quantum key distribution method based on the two-field protocol according to claim 1, wherein The step of subjecting the first quantum state sequence and the second quantum state sequence to polarization state encoding and time-division multiplexing by a quantum channel transmission device to obtain an encoded quantum state transmission sequence includes: The first quantum state sequence and the second quantum state sequence are subjected to polarization state encoding by a quantum channel transmission device to obtain a polarization-state-encoded quantum state sequence, and polarization state measurement is performed on the polarization-state-encoded quantum state sequence to obtain polarization state characteristics; Based on the polarization state characteristics, time-division multiplexing is performed on the polarization-state-encoded quantum state sequence to obtain a time-division multiplexed quantum state sequence, and time-division multiplexing time slot allocation is performed on the time-division multiplexed quantum state sequence to obtain time-division multiplexing characteristics; Based on the time-division multiplexing characteristics, quantum state transmission is performed on the time-division multiplexed quantum state sequence to obtain an encoded quantum state transmission sequence, where the encoded quantum state transmission sequence contains polarization state encoding information and time-division multiplexing encoding information of the first quantum state sequence and the second quantum state sequence.

4. The quantum key distribution method based on the two-field protocol according to claim 1, wherein The step of performing phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence includes: The phase compensation device performs phase compensation on the encoded quantum state transmission sequence to obtain a quantum state sequence after phase compensation, and performs phase stability evaluation on the quantum state sequence after phase compensation to obtain phase stability characteristics; Based on the phase stability characteristics, noise suppression is performed on the quantum state sequence after phase compensation to obtain a quantum state sequence after noise suppression, and the noise level of the quantum state sequence after noise suppression is measured to obtain noise characteristics; Based on the noise characteristics, quantum state optimization is performed on the quantum state sequence after noise suppression to obtain an optimized quantum state sequence [1].

5. The quantum key distribution method based on the two-field protocol according to claim 1, wherein The quantum state measurement device performs Bell state measurement and basis vector selection on the optimized quantum state sequence to obtain a measurement result sequence, including: The quantum state measurement device performs Bell state measurement on the optimized quantum state sequence to obtain Bell state measurement results, and performs Bell state characterization on the Bell state measurement results to obtain Bell state characteristics; Based on the Bell state characteristics, basis vector selection is performed on the Bell state measurement results to obtain basis vector selection results, and basis vector discrimination is performed on the basis vector selection results to obtain basis vector characteristics; Based on the basis vector characteristics, quantum state measurement is performed on the basis vector selection results to obtain quantum state measurement results, and quantum state reconstruction is performed on the quantum state measurement results to obtain reconstructed quantum state characteristics; Based on the reconstructed quantum state characteristics, measurement result statistics is performed on the quantum state measurement results to obtain measurement result characteristics, and the measurement result characteristics are sorted to generate a measurement result sequence.

6. The quantum key distribution method based on the two-field protocol according to claim 5, characterized in that, The quantum state measurement performed on the basis vector selection results based on the basis vector characteristics to obtain quantum state measurement results includes: Based on the basis vector characteristics, quantum state projection is performed on the basis vector selection results to obtain quantum state projection results, and projection state analysis is performed on the quantum state projection results to obtain projection state characteristics; Based on the projection state characteristics, quantum state interference is performed on the quantum state projection results to obtain quantum state interference results, and interference state evaluation is performed on the quantum state interference results to obtain interference state characteristics; Based on the interference state characteristics, quantum state detection is performed on the quantum state interference results to obtain quantum state detection results, and detection state characterization is performed on the quantum state detection results to obtain detection state characteristics; Based on the detection state characteristics, quantum state counting is performed on the quantum state detection results to obtain quantum state counting results, and counting state counting is performed on the quantum state counting results to obtain counting state characteristics; Based on the counting state characteristics, quantum state measurement is performed on the quantum state counting results to obtain quantum state measurement results.

7. The quantum key distribution method based on the two-field protocol according to claim 1, wherein The post-processing device performs key extraction and privacy amplification on the measurement result sequence to obtain a final quantum key, including: The post-processing device performs key extraction on the measurement result sequence to obtain key extraction results, and performs key generation on the key extraction results to obtain key characteristics; Based on the key characteristics, privacy amplification is performed on the key extraction results to obtain privacy amplification results, and privacy extraction is performed on the privacy amplification results to obtain privacy characteristics; Perform a security assessment on the privacy amplification result based on the privacy feature to obtain a security parameter, and verify the security parameter to obtain a verification result; Perform final quantum key generation on the privacy amplification result based on the verification result to obtain a final quantum key.

8. A quantum key distribution device based on a dual-field protocol, characterized in that, Including: A modulation module, configured to perform phase modulation and intensity modulation on an initial laser pulse through a quantum state preparation device to obtain a two-field quantum state sequence, where the two-field quantum state sequence includes a first quantum state sequence and a second quantum state sequence; A multiplexing module, configured to perform polarization state encoding and time-division multiplexing on the first quantum state sequence and the second quantum state sequence through a quantum channel transmission device to obtain an encoded quantum state transmission sequence; An optimization module, configured to perform phase compensation and noise suppression on the encoded quantum state transmission sequence to obtain an optimized quantum state sequence; A selection module, configured to perform Bell state measurement and basis selection on the optimized quantum state sequence through a quantum state measurement device to obtain a measurement result sequence; An amplification module, configured to perform key extraction and privacy amplification on the measurement result sequence through a post-processing device to obtain a final quantum key, and distribute the final quantum key to two preset communication parties through a secure channel.

9. A computer device, comprising a memory and a processor, wherein a computer program is stored in the memory, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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