Quantum key distribution secure communication system based on quantum mechanics principles

Abstract

This invention relates to the field of quantum communication security technology and discloses a quantum key distribution secure communication system based on the principles of quantum mechanics. The system includes a quantum state preparation unit that manipulates a quantum emission device to output a quantum state sequence containing a photon group modulated with a preset polarization angle and phase; a quantum channel feature extraction unit that captures channel environmental interference parameters and constructs a photon polarization distribution matrix; a quantum communication security assessment unit that receives this matrix and calculates a channel security factor threshold using a quantum bit error rate analyzer; a quantum key dynamic optimization unit that combines the security factor threshold with historical key negotiation records to generate an optimized key segmentation strategy; a quantum key rotation control unit that switches quantum state modulation parameters according to the segmentation strategy and time windows; and a quantum node synchronization management unit that monitors node clock offsets and injects calibration signals to achieve key distribution time slot alignment. This system can dynamically respond to environmental interference, improving the security and adaptability of quantum key distribution.

Description

Technical Field

[0001] This invention relates to the field of quantum communication security technology, specifically to a quantum key distribution secure communication system based on the principles of quantum mechanics. Background Technology

[0002] In the information age, the security of data communication is receiving increasing attention. Traditional encryption technologies based on mathematical algorithms face potential threats from quantum computing. Once quantum computers are widely used, most existing encryption systems could be easily cracked. Against this backdrop, quantum key distribution technology based on the principles of quantum mechanics has emerged. Utilizing the no-cloning theorem and the uncertainty principle of quantum states, it can theoretically achieve unconditionally secure key distribution, becoming an important technological direction for ensuring future communication security.

[0003] Current quantum key distribution systems still face numerous unresolved issues in practical applications. During quantum state transmission, quantum channels are susceptible to environmental factors such as temperature fluctuations, vibrations, and electromagnetic interference, leading to photon polarization state drift and phase distortion, which in turn affects the accurate transmission of key information. Existing systems do not capture environmental interference parameters of quantum channels in a timely and comprehensive manner, making it difficult to construct accurate photon polarization distribution models in real time, resulting in a lag in channel state assessment.

[0004] The security assessment mechanism in the key distribution process is not dynamic and flexible enough. Most of them use fixed security thresholds for judgment and cannot adjust the assessment criteria according to the real-time channel status. This may lead to the original strategy being used when the channel quality deteriorates, increasing the risk of key leakage. On the other hand, when the channel status is good, the overly conservative strategy may reduce communication efficiency.

[0005] The key segmentation and round-robin strategies lack effective integration with historical negotiation records, often employing static segmentation methods that struggle to adapt to dynamic changes in channel characteristics, resulting in low key utilization or insufficient security. Clock synchronization accuracy between communication nodes is also a critical factor affecting key distribution performance. Existing synchronization mechanisms lack precise monitoring of clock offsets and fail to inject calibration signals in a timely manner, easily causing key distribution time slot misalignment and impacting communication stability and continuity. These issues collectively restrict the practical application effectiveness and security improvement of quantum key distribution systems. Summary of the Invention

[0006] The purpose of this invention is to provide a quantum key distribution secure communication system based on the principles of quantum mechanics to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides a quantum key distribution secure communication system based on the principles of quantum mechanics, the system comprising:

[0008] A quantum state preparation unit is configured to manipulate a quantum emission device to output a quantum state sequence carrying key information, wherein the quantum state sequence contains a photon group with a preset polarization angle and phase modulation.

[0009] The quantum channel feature extraction unit, connected to the output of the quantum state preparation unit, is used to capture environmental interference parameters during quantum channel transmission and construct a photon polarization distribution matrix.

[0010] The quantum communication security assessment unit receives the photon polarization distribution matrix generated by the quantum channel feature extraction unit and calculates the security coefficient threshold of the current quantum channel through the quantum bit error rate analyzer.

[0011] The quantum key dynamic optimization unit obtains the security coefficient threshold output by the quantum communication security assessment unit and generates an optimized quantum key segmentation strategy by combining historical quantum key negotiation records.

[0012] The quantum key rotation control unit, based on the segmentation strategy provided by the quantum key dynamic optimization unit, drives the quantum transmitter to switch quantum state modulation parameters according to time windows;

[0013] The quantum node synchronization management unit monitors the clock offset of the communication node in real time and injects a clock calibration signal into the quantum key rotation control unit to achieve time slot alignment for key distribution.

[0014] Preferably, the quantum channel feature extraction unit performs the quantum channel feature extraction operation including:

[0015] Collect data sets of polarization distortion and phase drift generated during the transmission of quantum state sequences;

[0016] The polarization distortion dataset is divided into horizontal polarization subset, vertical polarization subset, and diagonal polarization subset according to the polarization angle;

[0017] Calculate the photon count fluctuation variance of each polarization subset within a continuous time unit to generate a set of polarization stability indices.

[0018] By integrating the phase drift dataset and the polarization stability index set, a three-dimensional photon polarization distribution matrix is ​​constructed, which includes polarization angle, phase offset, and photon count weight.

[0019] Preferably, the quantum communication security assessment unit performs quantum bit error rate analysis, including:

[0020] Receive the photon polarization distribution matrix transmitted by the quantum channel feature extraction unit, and extract the photon count fluctuation variance of the polarization subset in the matrix;

[0021] The polarization mismatch difference is calculated by comparing the initial reference polarization parameters set by the quantum state preparation unit with the measured polarization parameters at the receiver.

[0022] The quantum bit error rate is derived from the polarization mismatch difference and phase drift, and a comprehensive evaluation value of the quantum bit error rate is generated by combining the channel attenuation coefficient.

[0023] When the overall quantum error rate exceeds the preset security threshold, a key discard instruction is sent to the quantum key dynamic optimization unit.

[0024] Preferably, the operation of the quantum key dynamic optimization unit in generating the quantum key segmentation strategy includes:

[0025] Analyze the comprehensive evaluation value of quantum bit error rate and key discard instructions transmitted by the quantum communication security evaluation unit;

[0026] Retrieve the duration of successful key distribution and the number of retransmissions of erroneous keys from historical quantum key negotiation records;

[0027] The length of the redundant check bits in the quantum key segment is dynamically extended based on the comprehensive evaluation value of the quantum bit error rate.

[0028] Adjust the time slot length allocation ratio of quantum key segments based on the number of erroneous key retransmissions;

[0029] The output includes a quantum key segmentation strategy table containing redundancy check bit configuration and time slot allocation parameters.

[0030] Preferably, the operation of the quantum key rotation control unit driving the switching of quantum state modulation parameters includes:

[0031] Read the length of the redundancy check bit and the time slot allocation parameters defined in the quantum key segmentation strategy table;

[0032] Generate a quantum state polarization angle rotation sequence that matches the length of the redundancy check bit;

[0033] The time window for quantum key distribution is divided according to the time slot allocation parameters, and a subset of the polarization angle rotation sequence is allocated to each time window;

[0034] The time window and polarization angle mapping table is transmitted to the quantum state preparation unit, triggering the polarization modulator of the quantum emission device to switch its working mode according to the table.

[0035] Preferably, the operation of time slot alignment implemented by the quantum node synchronization management unit includes:

[0036] Monitor the system clock pulse interval between the transmitting and receiving quantum devices;

[0037] Calculate the cumulative time offset between adjacent clock pulses and generate clock calibration compensation coefficients;

[0038] The clock calibration compensation coefficient is converted into a time slot scaling command and transmitted to the quantum key rotation control unit;

[0039] The quantum key rotation control unit adjusts the boundary position of the time window according to the time slot scaling command.

[0040] Preferably, the operation of the quantum channel feature extraction unit to update the photon polarization distribution matrix includes:

[0041] Real-time reception of the comprehensive quantum error rate assessment value fed back by the quantum communication security assessment unit;

[0042] When the overall quantum error rate assessment value is lower than the safety threshold, the resampling module of the polarization distortion dataset is activated;

[0043] The resampling module merges historical polarization distortion data according to a preset compression rate, releases storage space, and then injects newly acquired real-time polarization distortion data.

[0044] The photon polarization distribution matrix is ​​regenerated based on the updated polarization distortion dataset.

[0045] Preferably, the quantum key rotation control unit performs the quantum key rotation verification operation including:

[0046] Before the end of each time window defined in the quantum key segmentation strategy table, the preparatory round-robin verification protocol is initiated;

[0047] Obtain the comprehensive evaluation value of the quantum bit error rate for the current time window from the quantum communication security assessment unit;

[0048] If the overall quantum error rate assessment value does not meet the rotation condition, a command to extend the current polarization modulation parameters is sent to the quantum state preparation unit.

[0049] If the rotation condition is met, the rotation sequence of the polarization angle corresponding to the next time window is activated.

[0050] Preferably, the operation of the quantum communication security assessment unit to perform multiple rounds of security verification includes:

[0051] Within a single quantum key distribution cycle, at least three quantum error rate analysis processes are triggered;

[0052] Each quantum bit error rate analysis process generates an intermediate security assessment result and writes it to the verification log;

[0053] Compare the deviation values ​​of intermediate security assessment results between two adjacent quantum bit error rate analysis processes;

[0054] When the deviation value exceeds the tolerance threshold, the segmentation strategy generation process of the quantum key dynamic optimization unit is interrupted.

[0055] Preferably, the operation of the quantum node synchronization management unit in coordinating multi-node communication includes:

[0056] Receive the set of clock calibration compensation coefficients from each quantum communication node;

[0057] Calculate the arithmetic mean of the clock calibration compensation coefficients for all nodes;

[0058] The arithmetic mean is broadcast as a global time slot reference value to the quantum key rotation control unit of each node;

[0059] The quantum key rotation control unit resets the local time window boundaries based on the global time slot reference value.

[0060] Compared with the prior art, the beneficial effects of the present invention are:

[0061] This quantum key distribution secure communication system, based on the principles of quantum mechanics, forms a complete secure communication mechanism through the coordinated operation of its various units, effectively addressing many challenges in existing quantum key distribution processes. The quantum state preparation unit manipulates a quantum emission device to output a quantum state sequence carrying key information. This sequence contains a photon group with preset polarization angles and phase modulation. This design ensures that the photon group possesses stable information-carrying capabilities from the initial stage, reducing the possibility of information loss during subsequent transmission.

[0062] The quantum channel feature extraction unit is connected to the output of the quantum state preparation unit, enabling it to capture environmental interference parameters in real time during quantum channel transmission and construct a photon polarization distribution matrix. This process allows the system to dynamically monitor the real-time state of the channel and clearly understand the impact of environmental factors on photon transmission, providing a basis for subsequent security assessment and key optimization. Through precise capture of channel features, the system no longer relies on static channel assumptions but can respond to actual channel changes.

[0063] After receiving the photon polarization distribution matrix, the quantum communication security assessment unit calculates the current quantum channel security threshold using a quantum bit error rate analyzer. This dynamic generation of the threshold allows the system's assessment of channel security to better reflect real-world conditions, enabling flexible adjustments to security standards based on changes in channel quality and avoiding security redundancy or potential risks associated with fixed thresholds.

[0064] After obtaining the security coefficient threshold, the quantum key dynamic optimization unit generates an optimized quantum key segmentation strategy by combining historical quantum key negotiation records. The introduction of historical records makes the segmentation strategy adaptable and continuous, allowing it to draw on effective experience from past communications. This makes the generated segmentation strategy more in line with the actual carrying capacity and security requirements of the current channel, thereby improving the utilization efficiency of key resources.

[0065] The quantum key rotation control unit drives the quantum transmitter to switch quantum state modulation parameters according to time windows based on a segmented strategy. This dynamic adjustment according to time slots allows the quantum state modulation to respond to channel changes in real time, ensuring parameter adaptability during key distribution and reducing transmission errors caused by fixed parameters.

[0066] The quantum node synchronization management unit monitors the clock offset of communication nodes in real time and injects clock calibration signals into the quantum key distribution control unit to achieve time slot alignment for key distribution. This synchronization mechanism ensures the coordination and consistency of communication nodes in the time dimension, avoids key distribution misalignment caused by clock deviations, and guarantees the continuity and stability of the entire communication process. The organic combination of these units enables the entire system to exhibit excellent performance in dealing with environmental interference, dynamically adjusting strategies, and maintaining node coordination, thereby improving the practical effect of quantum key distribution. Attached Figure Description

[0067] Figure 1 This is a schematic diagram illustrating the working principle of the quantum key distribution secure communication system based on quantum mechanics principles described in this invention.

[0068] Figure 2 The flowchart of the operation of the quantum channel feature extraction unit;

[0069] Figure 3 An operation flowchart for generating the quantum key segmentation strategy for the quantum key dynamic optimization unit;

[0070] Figure 4 A flowchart illustrating the operation of updating the photon polarization distribution matrix for the quantum channel feature extraction unit. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0072] Please see Figure 1 The present invention provides a quantum key distribution secure communication system based on the principles of quantum mechanics. The system comprises: a quantum state preparation unit, a quantum channel feature extraction unit, a quantum communication security assessment unit, a quantum key dynamic optimization unit, a quantum key rotation control unit, and a quantum node synchronization management unit.

[0073] The quantum state preparation unit controls the quantum emission device, outputting a quantum state sequence carrying key information. This sequence contains a group of photons with preset polarization angles and phase modulations. The quantum channel feature extraction unit, connected to the output of the quantum state preparation unit, captures environmental interference parameters during quantum channel transmission and constructs a photon polarization distribution matrix. The quantum communication security assessment unit receives this matrix and calculates the current quantum channel security threshold using a quantum bit error rate analyzer. The quantum key dynamic optimization unit generates a quantum key segmentation strategy based on the security threshold and historical quantum key negotiation records. The quantum key rotation control unit drives the quantum emission device to switch quantum state modulation parameters according to the segmentation strategy, operating within time windows. The quantum node synchronization management unit monitors the clock offset of communication nodes in real time and injects a clock calibration signal into the rotation control unit to achieve key distribution time slot alignment.

[0074] Example 1: See Figure 2 After the quantum channel feature extraction unit is activated, the polarization distortion dataset captures the real-time state of the photon swarm along the transmission path using distributed fiber optic sensors. The sensor array is deployed at the physical layer interface of the quantum channel, acquiring photon polarization direction change data every millisecond. The acquisition process employs an asynchronous triggering mechanism: the polarization distortion acquisition module automatically activates when the photon detector count rate reaches a preset threshold. The raw data includes photon arrival timestamps, polarization angle offsets, and ambient temperature parameters; all parameters are temporarily stored in a high-speed cache in the form of structured data packets.

[0075] The polarization distortion dataset is classified according to a preset polarization reference axis. The selection rules for the horizontal polarization subset are: photon count data with a polarization angle offset within the range of 0°±5°; the vertical polarization subset corresponds to the range of 90°±5°; and the diagonal polarization subset covers a tolerance range of ±5° for both the 45° and 135° axes. After classification, each subset enters the time series analysis module. This module segments the data stream in 20-millisecond time units and calculates the standard deviation of photon counts within each unit. The standard deviation calculation results are labeled as polarization fluctuation indicators. Independent indicator sequences are generated for the horizontal, vertical, and diagonal polarization subsets, which together constitute a set of polarization stability indicators.

[0076] The phase drift dataset is acquired using an independent interferometer circuit, recording the phase jump amplitude of the quantum state sequence during transmission. The acquisition period is strictly synchronized with the polarization data, and each phase shift data point is associated with a corresponding timestamp. The polarization stability index set and the phase drift dataset are input to a matrix fusion processor. The processor establishes a three-dimensional coordinate mapping relationship: the X-axis represents the polarization angle classification (three types of encoding: horizontal, vertical, and diagonal), the Y-axis records the phase shift (in radians), and the Z-axis loads the photon count weight values ​​of each polarization subset. The weight values ​​are dynamically generated by the ratio of the photon count standard deviation to the baseline standard deviation. The final output structure is a row × column × depth photon polarization distribution matrix, where the matrix depth corresponds to the hierarchical index of different time units.

[0077] The quantum communication security assessment unit receives the photon polarization distribution matrix through a dedicated data channel. The matrix analysis engine extracts the fluctuation index sequence of each polarization subset and associates it with the preset reference parameters of the quantum state preparation unit. The reference parameter library stores the horizontal reference angle of 0°, the vertical reference angle of 90°, and the diagonal reference angles of 45° and 135° originally set by the transmitter. The real-time comparison process uses vector operations: the difference between the measured polarization angle at the receiver and the reference angle generates a polarization mismatch vector, and the magnitude of the vector is the polarization mismatch difference. At the same time, the phase drift data is converted into a phase angle difference in radians.

[0078] The qubit error rate derivation module establishes a dual-input calculation model: the polarization mismatch difference is input to the polarity discriminator, and the error rate increment coefficient is activated when the difference exceeds 3°; the phase drift is input to the phase tolerance window checker, and a drift exceeding π / 8 radians triggers a phase error flag. The outputs of the polarity discriminator and the phase checker are combined into a linear weighting unit with a weighting ratio of 6:4. The weighted result is input to a nonlinear conversion function, which outputs the preliminary quantum bit error rate. The channel attenuation coefficient is measured by an independent photodetector, and the measured value is converted into an attenuation compensation factor through an attenuation-bit error rate mapping table. The preliminary quantum bit error rate and the attenuation compensation factor are multiplied by a scalar in the comprehensive evaluator to generate a comprehensive quantum bit error rate evaluation value.

[0079] The security decision engine continuously monitors the comprehensive evaluation value of the quantum bit error rate. Preset security thresholds are stored in non-volatile memory, including a static threshold (0.08) and a dynamic threshold (based on 1.5 times the standard deviation of the historical bit error rate average). When the comprehensive evaluation value exceeds the static threshold or exceeds the dynamic threshold three times consecutively, the security decision engine generates a key discard instruction. The instruction is encoded as a 16-bit encrypted data packet and transmitted to the quantum key dynamic optimization unit via a quantum encryption channel. During this process, all intermediate data (including polarization mismatch difference, phase drift, preliminary bit error rate, etc.) is written to the audit log, with log entries including millisecond-level timestamps and data checksums.

[0080] The photon polarization distribution matrix update mechanism adopts an event-driven model. When the comprehensive quantum error rate assessment value is lower than the safety threshold, the matrix reconstruction trigger activates the resampling module of the polarization distortion dataset. This module initiates a two-layer processing flow: first, it scans the timestamps of the historical dataset, performs wavelet compression on old data older than 60 seconds, and sets the compression rate to 30%; the freed storage space is then used to load the newly acquired original polarization distortion data. Subsequently, the data alignment engine resynchronizes the timeline of the new dataset with the existing phase drift dataset, and the updated dataset is input into the aforementioned three-dimensional matrix construction process to generate a new version of the photon polarization distribution matrix. The matrix version number is incremented, and the old version matrix is ​​retained in the historical version library for traceability analysis. Throughout the entire process, the quantum channel feature extraction unit maintains parallel operation of real-time data acquisition.

[0081] The polarization distortion data acquisition module includes an error self-calibration function. The temperature compensation submodule acquires the ambient temperature value every 5 seconds; when the temperature change exceeds 2°C, the compensation algorithm is activated to adjust the original acquired data according to the temperature-polarization offset calibration curve. The optical intensity adaptive regulator monitors input optical power fluctuations and automatically adjusts the detector gain when the power fluctuation exceeds ±3dB. All compensation parameters are embedded in the polarization distortion dataset as metadata and participate in calculations as correction factors in subsequent processing.

[0082] The quantum communication security assessment unit incorporates a multi-level verification mechanism. After generating a comprehensive quantum bit error rate (BER) assessment value, the cross-verifier synchronously calls the original photon count record from the receiver to perform statistical inversion calculation on the polarization mismatch difference. The statistical inversion uses the Monte Carlo method to simulate 1000 transmission scenarios, and the output result is checked for consistency with the mismatch difference in the main calculation path. If the deviation exceeds 5%, the system automatically triggers a recalculation process for the assessment value. Simultaneously, before sending the key discard command, the security decision engine performs dual-signature verification: the first signature is generated by the quantum BER analyzer's private key, and the second signature is appended by the system security coprocessor's private key. The command takes effect after successful dual-signature verification; otherwise, it enters fault diagnosis mode.

[0083] Example 2: See Figure 3When the quantum key dynamic optimization unit starts, the instruction parser first receives the quantum error rate comprehensive evaluation value data packet transmitted by the quantum communication security evaluation unit. This data packet adopts a layered encryption structure: the outer layer is a 16-bit instruction header (including the evaluation value type identifier), and the inner layer contains a 32-bit floating-point evaluation value, an 8-bit key discard flag, and a 64-bit timestamp. After the decryption verification module verifies the digital signature, it extracts the evaluation value and discard flag and stores them in a real-time register. At the same time, the history record caller accesses the distributed database to retrieve historical quantum key negotiation records of the same communication node within the past 24 hours. The search criteria include node ID, quantum channel frequency band, and transmission protocol version. The returned dataset contains a sequence of the duration of successful key distribution, a sequence of the number of erroneous key retransmissions, and the corresponding time slot allocation scheme number.

[0084] The redundancy check bit extension engine dynamically adjusts based on the comprehensive quantum bit error rate (BER) assessment. The core algorithm employs a linear interpolation model: a lower BER threshold of 0.04 corresponds to a baseline BER length of 32 bits, and an upper BER threshold of 0.12 corresponds to a maximum BER length of 128 bits. Real-time assessment values ​​are input to the interpolation calculator, which outputs the target BER length. An inertia correction factor is incorporated into the interpolation process—when three consecutive assessment values ​​change in the same direction, the output bit length is increased by an additional 5 bits according to the trend. The calculation results are temporarily stored in the BER configuration buffer and output synchronously after the time slot parameters are determined.

[0085] The time slot length allocation module processes erroneous key retransmission count data in parallel. Retransmission counts in historical records are categorized by time window: each day is divided into 288 5-minute windows, and the total retransmission count within each window is calculated. The retransmission count sequence is input into a negative feedback regulator, which establishes an allocation ratio calculation formula: base time slot length (200 milliseconds) multiplied by an adjustment coefficient. The adjustment coefficient is defined as (1 + retransmission count / threshold parameter), with an initial threshold parameter value of 10. The dynamic adjustment mechanism is implemented as follows: when the retransmission count exceeds the threshold for three consecutive windows, the system automatically increases the threshold parameter by 20%; if the retransmission count returns to zero for ten consecutive windows, the threshold parameter returns to its initial value. Finally, a time slot allocation ratio table for each time window is generated.

[0086] The quantum key segmentation policy table builder receives bit length configuration and time slot length allocation ratio parameters from the redundancy check bit extension engine. The table is stored in a tree structure: the root node records the policy version number and effective time; second-level nodes are grouped by quantum communication nodes; and third-level nodes contain specific configuration parameter entries. Each parameter entry contains a quintuple data structure: time window number (32 bits), starting time slot offset (64 bits), check bit length (8 bits), time slot length scaling factor (16-bit floating-point), and hash checksum (32 bits). After construction, the policy table is transmitted via the quantum encryption channel to the policy table loading interface of the quantum key rotation control unit.

[0087] After receiving the segmented policy table, the policy parser of the quantum key distribution control unit initializes the parameter conversion process. The redundancy check bit length mapper converts the check bit length parameter into polarization angle rotation rules: every 8 check bits correspond to one polarization angle option, and the option pool contains 12 standard polarization angles (0°, 15°, 30°...165°). The rotation sequence generator uses block coding technology: based on the check bit length value N, it generates N / 8 permutations of polarization angle options to form the main template of the rotation sequence. The sequence optimizer performs compression processing on this template—removing consecutively repeated angle options—and finally outputs the polarization angle rotation sequence, which is stored in the sequence circular buffer.

[0088] The time window scheduler simultaneously processes time slot allocation parameters. A time slot length allocation scaling factor is input to the time slot calculation engine, which calculates the actual window duration based on a base time unit (200 milliseconds): the scaling factor is multiplied by the base unit value to generate the window duration. The window divider uses the system startup time as the origin and divides the key distribution period into continuous time windows according to the calculated duration parameters. Each window is assigned a unique window ID and associated with a polarization angle rotation sequence in the sequence buffer. The association rule uses a modulo operation: the window ID is modulo the rotation sequence length, and the remainder is used as the sequence start index.

[0089] The polarization assignment actuator generates a window-polarization mapping table. This table structure contains three fields: window ID (64-bit), start timestamp (64-bit), and polarization angle sequence block pointer (32-bit). The polarization angle sequence block is a subset of the rotation sequence, with a fixed length of four angle options. The pointer indicates the specific storage location in the sequence circular buffer. After the mapping table is generated, it is transmitted to the parameter configuration interface of the quantum state preparation unit via a high-speed data bus. The transmission protocol employs a two-handshake mechanism: after the rotation control unit sends a request frame, the preparation unit returns a ready signal, and then performs the parameter block atom writing operation.

[0090] After receiving the mapping table, the polarization modulation controller of the quantum state preparation unit initializes the parameter loading process. The mapping table parser extracts the polarization angle sequence block corresponding to the currently active time window and writes this data block into the modulation parameter dual buffer. The dual buffer adopts an alternating write strategy: when the modulator is executing sequence block A, the newly received sequence block B is written to the spare buffer. The buffer switch starts 10 milliseconds before the time window boundary—reading the current value of the system timer and calculating the difference to the start time of the next window. If the switch determines that new parameters need to be loaded, it sends a hardware interrupt signal to the polarization modulator.

[0091] The polarization modulator of the quantum transmitter performs a parameter switching operation upon responding to an interrupt signal. The modulator control logic consists of three stages: first, it locks the current photon emission thread and pauses the output of the quantum state sequence; then, it reads a new polarization angle sequence block from the spare buffer and loads it into the modulation angle register; finally, it activates the angle sequence execution unit, which cyclically sets the polarization modulation components according to the four angle options in the sequence block. Each angle option has an execution period of 50 milliseconds, and the sequence block is executed for a total of 200 milliseconds before an interrupt is automatically triggered to request the next sequence block. The entire photon emission pause time is controlled within 2 milliseconds, and the continuity of key distribution is maintained through the quantum channel compensation protocol.

[0092] A dynamic time slot parameter correction mechanism is embedded in the time window scheduler. The round-robin control unit receives time slot scaling commands from the quantum node synchronization management unit in real time. These commands include the scaling direction and amplitude. The scheduler adjusts the remaining duration of the active window according to the commands: when a positive scaling command (+ΔT) is received, the current window is extended by ΔT milliseconds; a negative command shortens the window duration. Simultaneously, the newly set duration parameters are automatically updated in the time window allocation table, and subsequent windows are extended sequentially. This mechanism ensures that polarization modulation parameter switching remains synchronized with system timing in clock offset scenarios.

[0093] The asynchronous parity bit monitoring loop operates continuously during key rotation. The quantum key dynamic optimization unit deploys a parity bit verifier, which obtains real-time quantum bit error rate data through the quantum communication security assessment unit. If the new bit error rate deviates from the predicted value by more than 15%, the verifier triggers a policy table revision process: sending a pause command to the rotation control unit and recalculating the redundant parity bit length. The new parity bit parameters are written to the specified field of the segmented policy table via the incremental update channel, and the rotation control unit reloads the revised policy table and continues execution. This mechanism forms a dynamic closed-loop control of the parity parameters.

[0094] The security enhancement of the polarization angle rotation sequence is achieved through a random obfuscator. After the rotation sequence generator outputs the main sequence, the sequence obfuscation module injects random angle options: a random polarization angle (uniformly distributed in the 0°-180° range) is inserted after every four standard angle options. The obfuscation rules use a quantum noise-based random number source, and each random option is appended with a time-limited label—valid only within a specified millisecond time interval. The obfuscated sequence is stored in a dedicated encrypted buffer, and the modulator automatically filters out time-expired random options during execution, ensuring that the output quantum state maintains both the policy table's regularity and randomness.

[0095] The fault tolerance handling at the time window boundaries includes dual safeguards. The boundary detector initiates a preparatory check 50 milliseconds before the window ends: if the quantum key rotation control unit does not receive a ready signal for a new polarization sequence block, it automatically extends the current window duration to the maximum tolerance threshold (500 milliseconds). The timeout manager synchronizes the timing: when the actual window duration exceeds 120% of the theoretical value, it forcibly terminates the execution of the current sequence block and switches to the default polarization angle sequence (0°, 45°, 90°, 135° cycle). Fault events are recorded in the system diagnostic log, triggering subsequent maintenance procedures.

[0096] Example 3: See Figure 4 When the quantum node synchronization management unit initiates the clock monitoring function, its hardware timer interface establishes a direct connection with the system clock of the communication node. The monitoring process employs a bidirectional timestamp comparison method: the management unit sends a set of synchronization probe pulses to both the transmitting and receiving quantum devices, each pulse containing a 64-bit precision local timestamp. The receiving device immediately returns a response pulse upon the arrival of the probe pulse, with the response data packet carrying the original timestamp and the device's local timestamp. The time offset calculator derives the cumulative offset of the clock pulse interval based on the round-trip delay and clock difference. The calculation model uses the following formula:

[0097]

[0098] in, and These represent the local transmission times of the two probe pulses sent by the management unit. and The receiving time is recorded in the response pulse returned by the corresponding receiver. This represents the final calculated cumulative clock offset, in nanoseconds. The calculation result is input to a calibration coefficient generator, which establishes a second-order filtering model: [The text then abruptly shifts to a seemingly unrelated topic about clock offset accumulation in nanoseconds.] The measured values ​​are input into a sliding window. The data within the window are averaged after removing the maximum and minimum values. The output is the clock calibration compensation coefficient. .

[0099] The conversion process for clock calibration compensation coefficients involves multiple stages of processing. The time slot stretching command encoder will... The quantization is performed as a 16-bit signed integer, with the encoding rule being: each unit value corresponds to a 50-nanosecond adjustment step at the time slot boundary. Positive coefficients indicate that the time slot length needs to be extended, while negative coefficients indicate that the time slot needs to be compressed. The encoded instructions are transmitted to the time slot adjustment interface of the quantum key distribution control unit via a dedicated control bus. The transmission protocol adopts an interrupt-driven mode—when the accumulated clock offset exceeds a set threshold (default 200 nanoseconds), the management unit immediately triggers a priority interrupt to ensure that the instructions are delivered in real time.

[0100] After receiving the time slot scaling command, the quantum key distribution control unit performs dynamic adjustments to the time window boundary adjuster. The boundary position calculator maintains the start time of the currently active window. and theoretical end time When an adjustment command value is received At that time, the new end time according to Update, in which This represents the time (50 nanoseconds) corresponding to a single instruction step. The start times of adjacent windows are then chained together, and the start times of all subsequent windows are also chained together. and Increase sequentially The adjusted new time parameters are written to a shadow copy of the time slot allocation table, and then switched to the primary copy via an atomic operation when the current window ends.

[0101] The polarization modulation timing coordinator synchronously responds to time slot adjustments. When the time window boundary changes, the coordinator recalculates the switching time points of the polarization angle sequence blocks. The sequence block execution controller maintains a countdown register, initially set to the theoretical window duration. Each time slot expansion / contraction command triggers a dynamic reload of the register value: expanding the time slot increases the countdown value, while compressing the time slot decreases it accordingly. The countdown reset event, acting as a hardware interrupt signal, directly drives the parameter switching action of the polarization modulator, ensuring strict synchronization between quantum state modulation and the adjusted time slots.

[0102] The data update process of the quantum channel feature extraction unit operates in parallel with the clock calibration process. The matrix update trigger continuously monitors the security status signal of the quantum communication security assessment unit. When the comprehensive quantum bit error rate assessment value... Below the threshold At that time, the trigger activates the resampling process for the polarization distortion dataset. The historical data compressor scans the polarization distortion records in the storage area and performs hierarchical compression on data with timestamps 60 seconds earlier than the current time: first, the data is aggregated in 5-second time blocks, and the statistical characteristics (mean, range, standard deviation) of each block are calculated; then, a discrete cosine transform is applied to the characteristic sequence, retaining the first 30% of the coefficients to achieve lossy compression. The compressed data blocks are marked as archived, and the freed storage space is filled by the real-time data collector with newly captured polarization distortion samples.

[0103] The real-time polarization distortion data injection process employs a double-buffering strategy. Newly acquired data is temporarily stored in the input buffer. After the data validator verifies its integrity, the matrix reconstruction engine performs the following operations: horizontal and vertical polarization subset data are first normalized to eliminate detector gain differences; diagonal polarization subset data is supplemented with interpolation algorithms to fill in missing points caused by environmental interference. The processed dataset is then time-aligned with the phase drift record, using 10-millisecond synchronization units to resample both data streams to a unified time grid. The aligned data is then input into a 3D matrix builder, which establishes four 2D planes based on polarization angle classification (0°, 45°, 90°, 135°). The horizontal axis of each plane represents the phase offset (divided into 16 intervals), and the vertical axis represents the photon count weight (divided into 8 levels). The final output is a photon polarization distribution matrix. have The structural dimensions.

[0104] A real-time visualization system to aid in the maintenance of the photon polarization distribution matrix. (3D matrix) Key parameters are rendered as a dynamic heatmap by a graphics processor: horizontal polarization subsets are displayed in the red channel, vertical polarization in the green channel, and diagonal polarization in the blue channel. The heatmap refreshes every second, allowing operators to visually monitor the changing trends of polarization characteristics over time. The visualization system is linked to the matrix version management module, supporting the retrospective viewing of historical version matrix rendering results and aiding in the analysis of the development patterns of polarization distortion.

[0105] The hardware accelerator for the quantum channel feature extraction unit optimizes the data processing flow. A field-programmable gate array (FPGA) chip implements parallel preprocessing of polarization distortion data, including timestamp alignment, photon count normalization, and outlier filtering. The preprocessed data is transmitted to the main processor via a direct memory access channel, reducing CPU load. The accelerator configuration registers support dynamic updates; when the matrix reconstruction algorithm version is upgraded, the main control core can remotely reload the FPGA's logic configuration, achieving hardware-level algorithm switching.

[0106] Example 4: During the final stage of time window W-7, the quantum key rotation control unit initiates the pre-rotation verification protocol when the system timer reaches 1500 milliseconds (the preset end time of the window is 1550 milliseconds). The verification trigger sends a security status query request packet to the quantum communication security evaluation unit. The request packet contains the current window identifier W-7 and the data signature. After receiving the request, the evaluation unit's status responder extracts the quantum bit error rate comprehensive evaluation value sequence for window W-7 from the real-time monitoring cache: at three time points after the start of the window, 500 milliseconds, 1000 milliseconds, and 1500 milliseconds, the values ​​are 0.062, 0.059, and 0.073, respectively. The evaluation value processor calculates the difference between the latest evaluation value of the current window (0.073) and the rotation condition threshold (0.07), and the difference comparator outputs the status flag.

[0107] The rotating decision unit executes judgment logic based on the status flag bits: if the latest evaluation value is ≤0.07, the decision unit generates a hold instruction code "HOLD_45°" (the current polarization modulation parameter is 45°); if it is >0.07, it generates a switch instruction code "SWITCH_B3" (the next window polarization sequence block number B3). In this example, 0.073 > 0.07, so the decision unit sends the "SWITCH_B3" instruction to the quantum state preparation unit through the instruction dispatcher. The instruction is encoded as an 8-bit binary control word: the high 4 bits represent the instruction type code 0010 (switch), and the low 4 bits store the sequence block index 0011 (B3). The instruction transmission adopts a redundant channel design; the main channel transmits through the fiber optic control bus, and the backup channel sends the same instruction via encrypted radio waves.

[0108] Upon receiving "SWITCH_B3", the instruction executor of the quantum state preparation unit activates the polarization sequence loading process. The sequence memory queries the index table to obtain the physical address of sequence block B3: starting address 0x7A3F, length 32 bytes. The data loader reads four polarization angle values ​​from this address: 30°, 75°, 120°, and 165°, and writes them to the modulator parameter register group. The register switching controller executes a countdown before the window boundary: when the system timer reaches 1549 milliseconds (1 millisecond before the preset boundary of 1550 milliseconds), a hardware switching pulse is issued. This pulse triggers the quantum state switching circuit of the polarization modulator: completing the electronic reconfiguration of the angle parameters within 1 microsecond, ensuring that the first angle of the new sequence block, 30°, is output starting from the 1550 millisecond mark.

[0109] The quantum communication security assessment unit synchronously performs three rounds of security verification within window W-7. The verification scheduler automatically triggers the analysis tasks according to the time nodes: the first round is in the period 300-350 milliseconds after the window starts, the second round is in the period 900-950 milliseconds, and the third round is in the period 1500-1550 milliseconds. At the start of each round of analysis, the quantum bit error rate analyzer performs the following operations: extracts the latest three sets of polarization subset variance data from the photon polarization distribution matrix; calls the reference parameter version V2.1 stored in the quantum state preparation unit; and outputs the polarization mismatch vector through the difference calculator.

[0110] The interrupt handling protocol includes a three-level response mechanism. After receiving the INT_ERR3 signal, the quantum key dynamic optimization unit first locks the current policy buffer to prevent the writing of new policy tables. The history analyzer immediately retrieves the historical data of the last five windows: it finds that windows W-5 and W-3 ​​also had similar deviation exceeding the limit. The fault diagnosis engine initiates the preset handling scheme K3: freezes the current quantum key segmentation policy generation process; sends a safe rollback command to the key rotation control unit; and activates the backup segmentation policy table B_TABLE6. The backup policy table uses fixed parameter configuration: the redundancy check bit length is fixed at 64 bits, and the time slot length ratio is fixed at 1.2 times the baseline value.

[0111] The polarization parameter switching process incorporates multiple protection measures. When the rotation control unit sends a switching command to the preparation unit, a switching confirmation mechanism is simultaneously activated: the preparation unit returns an confirmation frame after receiving the command, containing the command hash value and the receiving timestamp. After verifying the hash value matching, the rotation control unit starts a switching timer. If no parameter update flag is detected in the modulator status register within 5 milliseconds, the switching command is automatically retransmitted. If three consecutive retransmissions fail, the system switches to fault handling mode: a secure polarization sequence S-SEQ (alternating between 0° and 90°) is forcibly loaded, and a hardware maintenance alarm signal is triggered simultaneously.

[0112] The multi-round verification log management employs a chained storage structure. The verification log recorder generates a unique index code for each intermediate result entry, containing elements such as window number W-7, analysis round number 3, and timestamp 1501.3. When storing an entry, a hash pointer to the previous entry is appended: for example, the storage block for the third round result WV7-L0023 contains the hash value 0x8F3A pointing to the second round result WV7-L0017. The log verifier periodically traverses the entire chain, ensuring log data integrity by verifying the continuity of hash pointers. When a hash value mismatch is detected, the log for that period is automatically marked as suspicious, and the policy optimization unit is prohibited from accessing the relevant data.

[0113] The adaptive adjustment of the rotation condition detection is based on historical data. The rotation decision-maker has a built-in condition optimization algorithm: when parameter switching is triggered for three consecutive windows, the system automatically lowers the rotation condition threshold from 0.07 to 0.065; when parameter holding is maintained for five consecutive windows, the threshold is raised to 0.075. Threshold adjustment records are stored in the decision parameter history database, and a version record is generated for each change. The current example scenario occurs in the third window after the threshold was automatically adjusted to 0.072. After the system detects the continuous switching mode, the decision-maker restores the threshold to the default value of 0.07.

[0114] The time slot alignment mechanism ensures precise coordination at the rotation boundary. The quantum node synchronization management unit initiates time slot calibration 100 milliseconds before the window boundary: it sends a time slot scaling command of +0.3 (indicating an extension of 0.3 milliseconds) to the rotation control unit. The rotation control unit adjusts the end time of window W-7 from 1550.0 milliseconds to 1550.3 milliseconds, while simultaneously delaying the start time of subsequent windows. After calibration, the system sends a synchronization pulse to the polarization modulator, with the rising edge of the pulse aligned with the adjusted window boundary. This process ensures that the timing accuracy of quantum state sequence switching remains within ±0.05 milliseconds.

[0115] The fault isolation strategy is executed collaboratively across multiple units. When the deviation monitor detects that the third-round evaluation value exceeds the limit, the system diagnostic controller initiates a three-stage process: the first stage suspends the strategy calculation process of the quantum key dynamic optimization unit; the second stage commands the quantum channel feature extraction unit to re-acquire polarization distortion data; and the third stage switches the quantum communication security evaluation unit to diagnostic mode. In this mode, the evaluation unit performs a simplified quantum bit error rate analysis every 50 milliseconds, monitoring channel state changes until the deviation value returns to the normal range.

[0116] The activation verification of the polarization sequence block includes a parameter feedback loop. After the modulator executes the first angle of sequence block B3 (30°), the state detector reads the actual output polarization angle data. If the measured polarization angles of three consecutive photon groups deviate from the set value by more than 5°, the detector sends a correction request to the rotation control unit. Upon receiving the request, the rotation control unit initiates the sequence block retransmission process: it resends the "SWITCH_B3" command to the preparation unit, and simultaneously marks the window in the time slot allocation table as extended by 10 milliseconds for parameter reloading.

[0117] Example 5: When the quantum node synchronization management unit initiates multi-node coordination mode, its global clock synchronization module broadcasts a time calibration request to the six quantum communication nodes in the network. The request data packet is transmitted using a multicast protocol and includes the management unit's local timestamp, sequence number, and checksum. After receiving the request, each node's clock responder immediately records its local clock value at the time of arrival and returns a response packet within 2 milliseconds. The response data includes the original request sequence number, node ID, local timestamp of the request reception time, and the current clock calibration compensation coefficient. The management unit's data collector receives all valid responses within a 10-millisecond timeout window and discards delayed data packets.

[0118] The aggregation calculation of clock calibration compensation coefficients employs a distributed algorithm. The coefficient processor first verifies the signature validity of the data returned by each node, discarding responses that fail verification. The valid dataset is input into the statistical analysis engine to calculate the arithmetic mean of the six compensation coefficients. The calculation process includes outlier filtering: if a node's coefficient deviates from the median by more than 15%, that node's data is marked as suspicious and excluded from the averaging calculation. The final generated global timeslot reference value, retaining three decimal places, is written to the payload area of ​​the broadcast frame. The broadcast frame format includes a frame header, reference value, effective time window number, and cyclic redundancy check (CRC) code.

[0119] The global baseline value is distributed using a hierarchical transmission strategy. The master node of the management unit first sends the baseline value to the three regional center nodes. Upon receiving the data, the regional nodes immediately forward it to their two subordinate terminal nodes. The transmission process employs a three-way handshake protocol: after sending the baseline value, the master node waits for acknowledgment frames from the regional nodes; the regional nodes need to obtain a ready signal from the terminal nodes before forwarding. The latency of the hierarchical transmission is controlled within 5 milliseconds to ensure that all nodes complete parameter synchronization before the start of the next time window. After receiving the baseline value, the terminal nodes return a final acknowledgment frame to the management unit, forming a closed-loop verification.

[0120] The local adapter of the quantum key distribution control unit processes the global reference value. The adapter receiving module parses the reference value data in the broadcast frame, extracts the payload, and verifies the cyclic redundancy code. After successful verification, the reference value converter performs localization adjustment: calculating the weighted average of the global reference value and the local compensation coefficient, with a weighting ratio of 30% for the global value and 70% for the local value. The adjusted mixed value is input into the time slot calculation engine to re-plan the local time window boundaries. The window adjuster maintains a dynamic offset table, recording the cumulative deviation between the theoretical start time and the actual start time of each window. When the mixed reference value takes effect, the offset table performs a compensation calculation: new window start time = original theoretical time + cumulative deviation × mixed reference coefficient.

[0121] Physical synchronization at the time window boundaries is achieved through hardware signals. The clock interface module of the rotation control unit generates a synchronization pulse signal, with the rising edge of the pulse aligned with the adjusted start time of the window. This signal is transmitted to the timing controller of the quantum state preparation unit via a dedicated clock line, triggering the atomic switching of the polarization modulation parameters. The synchronization pulse is calibrated to the nanosecond level, with a fixed pulse width of 50 nanoseconds. The pulse signals of all participating nodes use the same phase reference and are uniformly driven by the reference clock source of the management unit. The pulse arrival time difference between nodes is controlled within ±1 nanosecond using fiber length compensation technology.

[0122] Global consistency checks on polarization modulation sequences are performed after each baseline update. The state monitor of the rotating control unit collects the polarization angle sequence identifiers of the currently active window and uploads them to the central database through the management unit's data channel. The database's consistency checker compares the sequence identifiers reported by all nodes. If a mismatch is found, a sequence reset command is immediately sent to the abnormal node. The reset process forces the abnormal node to load a uniform safety sequence template, which contains a cyclical arrangement of four standard polarization angles (0°, 45°, 90°, 135°). The reset command has higher priority than the local policy table, ensuring that the network quickly returns to a consistent state.

[0123] Long-term monitoring of node clock drift employs a trend prediction algorithm. The management unit's historical analysis module stores clock compensation coefficient records for each node over the past 24 hours, statistically analyzing the mean and variance by hour. When a node's coefficient is detected to exhibit a unidirectional offset trend for three consecutive time periods, the prediction engine generates a hardware calibration suggestion. The suggestion includes the predicted offset, calibration direction, and confidence score, and is transmitted to the node device management subsystem via the maintenance channel. The node automatically adjusts the voltage-controlled crystal oscillator of its local clock source based on the suggested parameters, correcting clock drift at the physical layer. The calibration process is logged, including the coefficients before calibration, the adjustment amount, and the stability test results after calibration.

[0124] The fault tolerance handling for multi-node communication interruptions employs a majority voting mechanism. When the management unit fails to collect responses from all nodes within the timeout window, the system switches to a degraded mode: only data from responding nodes is used to calculate a temporary baseline value. This temporary value is marked as pending confirmation, and its effective time window is shortened by 50%. Simultaneously, the faulty node detector initiates an automatic diagnostic process, sending a node status query command through the backup control channel. If the communication link of a confirmed node is interrupted, the management unit marks the node as offline, suspending its participation in the global synchronization process until the heartbeat signal is restored. The offline node's rotation control unit automatically switches to local clock maintenance mode, continuing operation using the most recently valid baseline value.

[0125] Backtracking analysis of the impact of baseline value updates is performed after network stabilization. The management unit's audit analyzer compares key indicators before and after the baseline value change, including time slot alignment errors of each node, polarization switching success rate, and quantum error rate fluctuations. The analysis results generate a change assessment report, recording parameters such as the baseline value version, effective period, and average network synchronization accuracy. The report data is used to optimize weight allocation ratios: if a change improves network synchronization accuracy, the system automatically increases the weight ratio of the global baseline value; if it leads to performance degradation, the weight ratio of the local compensation coefficient is increased. The weight adjustment strategy is stored in a versioned configuration file, and a new strategy version is generated each time it is modified.

[0126] Cross-node coordination in quantum key distribution relies on a global time-slot reference. When two nodes need to establish a quantum key transmission, the initiator first queries the management unit to obtain the target node's current window boundary information. The window aligner calculates the time offset between the active windows of the two nodes and dynamically adjusts the start time of key distribution. Specifically, if the target node's window is ahead of the initiator by ΔT time, the initiator delays key distribution by ΔT; if it lags, it starts key distribution earlier by ΔT. The alignment process does not require pausing the node's local round-robin sequence; time offset compensation is only inserted into the outgoing key data stream. Each data packet in cross-node key distribution carries a sending window number, and the receiver matches its local round-robin state based on the window number.

[0127] Real-time visualization of clock synchronization quality aids in operational decision-making. The management unit's human-machine interface displays a ring topology diagram of the six-node clock status: each node is represented by a colored dot, the dot's position reflects the clock offset direction, and the radius represents the offset magnitude. Real-time updated connection line colors reflect the synchronization status between nodes: green indicates synchronization error is within acceptable limits, yellow indicates it's close to the threshold, and red indicates it has exceeded limits. Operators can manually adjust the weight parameters of specific nodes or force immediate synchronization detection through the interface. All manual operations are recorded in the audit log, clearly distinguished from automatic synchronization events.

[0128] In scenarios involving dynamic node additions and deletions, baseline recalculation is event-driven. When a new node joins the network, the management unit's node registrar receives the joining request, verifies its identity, and includes it in the synchronization group. The initial baseline value of the newly added node is set to the current group's average value, and its local compensation coefficient is obtained through three consecutive measurement calibrations. A node exit event triggers the group reconstruction process: the management unit recalculates the baseline values ​​of the remaining nodes and broadcasts a group size change notification. Upon receiving the notification, each node adjusts its local weighting strategy; typically, when the size decreases, the weight of the global baseline value is appropriately increased, and vice versa, the proportion of the local coefficient is increased. A node state change event triggers a reassessment of the entire network's synchronization status, and the assessment result determines whether to immediately initiate a new round of baseline calculation.

[0129] Global consistency maintenance of polarization modulation parameters is implemented at the hardware level. After receiving the trigger signal from the rotation control unit, the physical synchronization interface of the quantum state preparation unit performs strict timing control on its optical components: the laser drive circuit begins a gradual change in polarization angle 100 nanoseconds before the window boundary, and the modulator precisely reaches the target angle at the boundary moment. This process is strictly synchronized with the system clock and is unaffected by software scheduling delays. The optical components of each node use the same hardware design, and the response curves of the crystal modulators are uniformly calibrated to ensure that different nodes output consistent quantum state characteristics under the same angle parameters. The hardware synchronization mechanism eliminates the uncertain delays introduced by the software protocol stack, enabling physical layer consistency in multi-node quantum key distribution.

[0130] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0131] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A quantum key distribution secure communication system based on the principles of quantum mechanics, characterized in that, include: A quantum state preparation unit is configured to manipulate a quantum emission device to output a quantum state sequence carrying key information, wherein the quantum state sequence contains a photon group with a preset polarization angle and phase modulation. The quantum channel feature extraction unit, connected to the output of the quantum state preparation unit, is used to capture environmental interference parameters during quantum channel transmission and construct a photon polarization distribution matrix. The quantum communication security assessment unit receives the photon polarization distribution matrix generated by the quantum channel feature extraction unit and calculates the security coefficient threshold of the current quantum channel through the quantum bit error rate analyzer. The quantum key dynamic optimization unit obtains the security coefficient threshold output by the quantum communication security assessment unit and generates an optimized quantum key segmentation strategy by combining historical quantum key negotiation records. The quantum key rotation control unit, based on the segmentation strategy provided by the quantum key dynamic optimization unit, drives the quantum transmitter to switch quantum state modulation parameters according to time windows; The quantum node synchronization management unit monitors the clock offset of the communication node in real time and injects a clock calibration signal into the quantum key rotation control unit to achieve time slot alignment for key distribution. The quantum channel feature extraction unit performs the following operations for quantum channel feature extraction: Collect data sets of polarization distortion and phase drift generated during the transmission of quantum state sequences; The polarization distortion dataset is divided into horizontal polarization subset, vertical polarization subset, and diagonal polarization subset according to the polarization angle; Calculate the variance of photon count fluctuation for each polarization subset within a continuous time unit to generate a set of polarization stability indices. By integrating the phase drift dataset and the set of polarization stability indices, a three-dimensional photon polarization distribution matrix containing polarization angle, phase offset, and photon count weights is constructed. The quantum communication security assessment unit performs quantum bit error rate analysis, including the following operations: Receive the photon polarization distribution matrix transmitted by the quantum channel feature extraction unit, and extract the photon count fluctuation variance of the polarization subset in the matrix; The polarization mismatch difference is calculated by comparing the initial reference polarization parameters set by the quantum state preparation unit with the measured polarization parameters at the receiver. The quantum bit error rate is derived from the polarization mismatch difference and phase drift, and a comprehensive evaluation value of the quantum bit error rate is generated by combining the channel attenuation coefficient. When the comprehensive evaluation value of the quantum bit error rate exceeds the preset security threshold, a key discard instruction is sent to the quantum key dynamic optimization unit. The operation of the quantum key dynamic optimization unit in generating the quantum key segmentation strategy includes: Analyze the comprehensive evaluation value of quantum bit error rate and key discard instructions transmitted by the quantum communication security evaluation unit; Retrieve the duration of successful key distribution and the number of retransmissions of erroneous keys from historical quantum key negotiation records; The length of the redundant check bits in the quantum key segment is dynamically extended based on the comprehensive evaluation value of the quantum bit error rate. Adjust the time slot length allocation ratio of quantum key segments based on the number of erroneous key retransmissions; The output includes a quantum key segmentation strategy table containing redundancy check bit configuration and time slot allocation parameters; The operation of the quantum key rotation control unit driving the switching of quantum state modulation parameters includes: Read the length of the redundancy check bit and the time slot allocation parameters defined in the quantum key segmentation strategy table; Generate a quantum state polarization angle rotation sequence that matches the length of the redundancy check bit; The time window for quantum key distribution is divided according to the time slot allocation parameters, and a subset of the polarization angle rotation sequence is allocated to each time window; The time window and polarization angle mapping table is transmitted to the quantum state preparation unit, triggering the polarization modulator of the quantum emission device to switch its working mode according to the table. The quantum node synchronization management unit performs time slot alignment operations including: Monitor the system clock pulse interval between the transmitting and receiving quantum devices; Calculate the cumulative time offset between adjacent clock pulses and generate clock calibration compensation coefficients; The clock calibration compensation coefficient is converted into a time slot scaling command and transmitted to the quantum key rotation control unit; The quantum key rotation control unit adjusts the boundary position of the time window according to the time slot scaling command.

2. The quantum key distribution secure communication system according to claim 1, characterized in that, The operation of updating the photon polarization distribution matrix by the quantum channel feature extraction unit includes: Real-time reception of the comprehensive quantum error rate assessment value fed back by the quantum communication security assessment unit; When the overall quantum error rate assessment value is lower than the safety threshold, the resampling module of the polarization distortion dataset is activated; The resampling module merges historical polarization distortion data according to a preset compression rate, releases storage space, and then injects newly acquired real-time polarization distortion data. The photon polarization distribution matrix is ​​regenerated based on the updated polarization distortion dataset.

3. The quantum key distribution secure communication system according to claim 1, characterized in that, The quantum key rotation control unit performs the following operations for quantum key rotation verification: Before the end of each time window defined in the quantum key segmentation strategy table, the preparatory round-robin verification protocol is initiated; Obtain the comprehensive evaluation value of the quantum bit error rate for the current time window from the quantum communication security assessment unit; If the overall quantum error rate assessment value does not meet the rotation condition, a command to extend the current polarization modulation parameters is sent to the quantum state preparation unit; If the rotation condition is met, the rotation sequence of the polarization angle corresponding to the next time window is activated.

4. The quantum key distribution secure communication system according to claim 1, characterized in that, The quantum communication security assessment unit performs multiple rounds of security verification, including the following operations: Within a single quantum key distribution cycle, at least three quantum bit error rate analysis processes are triggered; Each quantum bit error rate analysis process generates an intermediate security assessment result and writes it to the verification log; Compare the deviation values ​​of intermediate security assessment results between two adjacent quantum bit error rate analysis processes; When the deviation value exceeds the tolerance threshold, the segmentation strategy generation process of the quantum key dynamic optimization unit is interrupted.

5. The quantum key distribution secure communication system according to claim 1, characterized in that, The operation of the quantum node synchronization management unit in coordinating multi-node communication includes: Receive the set of clock calibration compensation coefficients from each quantum communication node; Calculate the arithmetic mean of the clock calibration compensation coefficients for all nodes; The arithmetic mean is broadcast as a global time slot reference value to the quantum key rotation control unit of each node; The quantum key rotation control unit resets the local time window boundaries based on the global time slot reference value.

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