Clock and data correction method and apparatus for quantum key distribution system

Abstract

This invention provides a clock and data correction method and apparatus for a quantum key distribution system, applicable to the field of quantum communication technology. The method includes: processing the negotiation data based on N burst frames received via a negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks; performing sliding calibration on the N mismatch data using the N mismatch clocks based on a target data sequence to obtain N correction offset parameters; performing integer correction on the sub-mismatch clocks and sub-mismatch data of any protection word period within the (n+1)th target protection interval based on the integer offset parameters between the nth target protection intervals; and performing fractional correction on the sub-mismatch clocks and sub-mismatch data of other protection word periods within the (n+1)th target protection interval, excluding any protection word period, based on the fractional phase error parameters and frequency offset parameters of the nth target protection interval, to obtain the target clock and target data.

Description

Technical Field

[0001] This invention relates to the field of quantum communication technology, and more specifically to a clock and data correction method and apparatus for a quantum key distribution system. Background Technology

[0002] The main process of quantum key distribution (QKD) protocols involves preparing and measuring quantum states encoded in carriers such as photons to achieve secure information transmission. Due to the no-cloning theorem and the uncertainty principle of quantum states, attackers cannot intercept and reconstruct quantum states without loss of data. Each end of a QKD system is equipped with an independent local clock. To ensure accuracy in QKD, clock and data synchronization is necessary between the sender and receiver. However, current QKD technologies struggle to achieve high-precision, long-term stable synchronization of clocks and data. Summary of the Invention

[0003] In view of the above problems, the present invention provides a clock and data correction method and apparatus for a quantum key distribution system.

[0004] According to a first aspect of the present invention, a clock and data correction method for a quantum key distribution system is provided, comprising: processing the negotiation data based on N burst frames received via a negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks, wherein the associated mismatch clocks and mismatch data correspond to a target protection interval including multiple protection word periods; and performing sliding calibration processing on the N mismatch data using the N mismatch clocks based on a target data sequence to obtain N correction offset parameters, wherein the correction offset parameters include an integer offset parameter, a fractional phase error parameter, and a frequency offset parameter, and the target data... The sequence includes a preset clock at the receiving end and preset data corresponding to the preset clock; based on the integer offset parameter between the nth target protection zones, the sub-mismatch clock and sub-mismatch data of any protection word period in the (n+1)th target protection zone are corrected by integer; based on the fractional phase error parameter and frequency offset parameter of the nth target protection zone, the sub-mismatch clock and sub-mismatch data of other protection word periods in the (n+1)th target protection zone are corrected by fractional, to obtain the target clock and target data. The sub-mismatch clock and sub-mismatch data are obtained by dividing the mismatch clock and mismatch data based on multiple protection word periods.

[0005] According to an embodiment of the present invention, based on a target data sequence, N mismatched data are subjected to sliding calibration processing using N mismatched clocks to obtain N correction offset parameters. This includes: for any mismatched clock among the N mismatched clocks and the mismatched data corresponding to that mismatched clock, within the time domain corresponding to that mismatched clock, fixing the mismatched data, sliding the target data sequence, and determining multiple similarities between the mismatched data and the target data sequence; determining the target similarity corresponding to the mismatched data from the multiple similarities; and determining the correction offset parameters based on the target similarity corresponding to the mismatched data.

[0006] According to an embodiment of the present invention, in the time domain corresponding to any mismatch clock, the mismatch data is fixed, the target data sequence is slid, and multiple similarities between the mismatch data and the target data sequence are determined, including: starting from the first frame of the mismatch data corresponding to any mismatch clock, the target data sequence is slid sequentially to determine multiple similarities between the mismatch data and the target data sequence.

[0007] According to an embodiment of the present invention, based on N burst frames in the negotiation data received via the negotiation optical channel, the negotiation data is processed to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks, including: for any burst frame in the N burst frames, processing the negotiation data according to any burst frame in the negotiation data to obtain a bit mismatch clock and serial mismatch data corresponding to the bit mismatch clock; performing serial-to-parallel conversion on the bit mismatch clock and the serial mismatch data to obtain a mismatch clock and mismatch data corresponding to the mismatch clock.

[0008] According to an embodiment of the present invention, performing serial-to-parallel conversion on bit mismatch clock and serial mismatch data to obtain mismatch clock and mismatch data corresponding to the mismatch clock includes: aligning bit mismatch clock and serial mismatch data based on burst frames to obtain intermediate mismatch clock and intermediate mismatch data corresponding to the intermediate mismatch clock; and performing serial-to-parallel conversion on the intermediate mismatch data based on the intermediate mismatch clock to obtain mismatch clock and mismatch data corresponding to the mismatch clock.

[0009] According to an embodiment of the present invention, the clock and data correction method of the above-mentioned quantum key distribution system further includes: determining a fusion offset parameter between the nth target protection zones based on the correction offset parameter and statistical parameters between the nth target protection zones, wherein the statistical parameters characterize the statistics obtained based on the timestamps of quantum events in the quantum channel, and the fusion offset parameter includes an integer fusion offset parameter, a fractional phase fusion error parameter, and a frequency fusion offset parameter; performing integer correction on the sub-target clock and sub-target data of any protection word period in the (n+1)th target protection zone based on the integer fusion offset parameter between the nth target protection zones, and performing fractional correction on the sub-target clock and sub-target data of other protection word periods in the (n+1)th target protection zone other than any protection word period based on the fractional phase fusion error parameter and frequency fusion offset parameter of the nth target protection zone, to obtain a first target clock and first target data.

[0010] According to an embodiment of the present invention, the mismatched clocks and mismatched data associated with each other correspond to epoch periods, and the epoch period includes a target protection interval. The clock and data correction method of the above-mentioned quantum key distribution system further includes: adjusting the epoch period and the target protection interval based on a preset security margin and target parameters to obtain the adjusted epoch period and the adjusted target protection interval. The target parameters include at least one of the following: link drift speed, frequency offset parameter or burst frame. The link drift speed characterizes the data transmission delay caused by the environment or devices in the quantum key distribution system.

[0011] According to an embodiment of the present invention, the clock and data correction method of the above-mentioned quantum key distribution system further includes: for any mismatched clock among N mismatched clocks and mismatched data corresponding to any mismatched clock, in the time domain corresponding to any mismatched clock, fixing the mismatched data, sliding the target data sequence, and determining multiple similarities between the mismatched data and the target data sequence; determining the confidence level based on the multiple similarities between the mismatched data and the target data sequence; and adjusting the correction offset parameter based on a preset amplitude when the confidence level is less than a preset confidence threshold, to obtain the adjusted correction offset parameter.

[0012] According to an embodiment of the present invention, the negotiation data includes a data frame, and the clock and data correction method of the above-mentioned quantum key distribution system further includes: between the nth target protection interval and the (n+1)th target protection interval, the target mapping relationship remains unchanged, wherein the target mapping relationship characterizes the correspondence between the quantum event corresponding to the data frame and the unit interval.

[0013] A second aspect of the present invention provides a clock and data correction apparatus for a quantum key distribution system, comprising: a first obtaining module, configured to process the negotiation data based on N burst frames received via a negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks, wherein the associated mismatch clocks and mismatch data correspond to a target protection interval including multiple protection word periods; and a second obtaining module, configured to perform sliding calibration processing on the N mismatch data using the N mismatch clocks based on a target data sequence to obtain N correction offset parameters, wherein the correction offset parameters include an integer offset parameter, a fractional phase error parameter, and a frequency offset parameter. The target data sequence includes a preset clock at the receiving end and preset data corresponding to the preset clock; the first correction module is used to perform integer correction on the sub-mismatch clock and sub-mismatch data of any protection word period in the (n+1)th target protection interval based on the integer offset parameter between the nth target protection intervals, and to perform fractional correction on the sub-mismatch clock and sub-mismatch data of other protection word periods in the (n+1)th target protection intervals other than any protection word period based on the fractional phase error parameter and frequency offset parameter of the nth target protection interval, so as to obtain the target clock and target data, wherein the sub-mismatch clock and sub-mismatch data are obtained by dividing the mismatch clock and mismatch data based on multiple protection word periods respectively.

[0014] A third aspect of the present invention provides an electronic device comprising: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0015] A fourth aspect of the present invention also provides a computer-readable storage medium having a computer program or instructions stored thereon, wherein the computer program or instructions, when executed by a processor, implement the steps of the above-described method.

[0016] A fifth aspect of the present invention also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described method.

[0017] According to the clock and data correction method of the quantum key distribution system provided by the present invention, since N burst frames are periodically inserted into the negotiation data received via the negotiation optical channel, by detecting the burst frames in the negotiation data, N mismatch clocks associated with the N burst frames and N mismatch data corresponding to the N mismatch clocks can be recovered. Then, based on the target data sequence, the N mismatch data are subjected to sliding calibration processing based on the N mismatch clocks respectively, to obtain N correction offset parameters. The correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. Based on the integer offset parameters between the nth target protection zones, the sub-mismatch clocks and sub-mismatch data of any protection word period in the (n+1)th target protection zone can be integer corrected. On this basis, based on the fractional phase error parameters of the nth target protection zone... The number and frequency offset parameters are used to perform fractional correction on the sub-mismatch clock and sub-mismatch data for all protection word periods except for any protection word period within the (n+1)th target protection interval. Integer correction can achieve coarse correction at integer multiples of the unit interval to maintain the monotonically increasing unit interval number. Fractional correction can achieve fine correction at intervals smaller than the unit interval to achieve a gradual transition of phase and frequency. The combination of integer and fractional correction within the target protection interval can improve the correction speed and accuracy, thereby enabling high-precision, low-interruption, and long-term stable clock synchronization of the quantum key distribution system under the condition of no synchronization light. At the same time, it reduces the noise interference caused by synchronization light, reduces the cost and complexity of the quantum key distribution system, and is therefore suitable for quantum key distribution deployment between metropolitan area networks, backbone networks, and data centers. Attached Figure Description

[0018] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0019] Figure 1 A diagram illustrating an application scenario of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0020] Figure 2 A flowchart of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0021] Figure 3 A schematic diagram of a sliding calibration process according to an embodiment of the present invention is shown.

[0022] Figure 4 A schematic diagram illustrating clock and data correction according to an embodiment of the present invention is shown.

[0023] Figure 5 A system architecture diagram of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0024] Figure 6 A structural block diagram of the clock and data correction device of a quantum key distribution system according to an embodiment of the present invention is shown.

[0025] Figure 7 A block diagram of an electronic device suitable for implementing a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] With cybersecurity receiving increasing attention today, quantum key distribution technology, as an emerging key communication technology, is widely used in cybersecurity work due to its unique true randomness, unbreakability, secure communication method, and traceability.

[0031] Quantum key distribution systems require the receiver's detection window to be aligned with the transmitter's clock. Related quantum key distribution systems typically use a separate synchronization optical channel to provide a continuous clock reference. However, in single-fiber co-transmission scenarios, even with pulsed synchronization optical with a low duty cycle, the peak power during the pulse can still generate transient broadband noise through Raman scattering and four-wave mixing. Furthermore, the additional optical channel and passive components increase wiring complexity and link loss. Using negotiated data-driven clock and data recovery (CDR) as a reference eliminates the need for synchronization optical, thus reducing noise interference from it.

[0032] However, continuous clock-data recovery (CDR) relies on a stable data rate to maintain lock, and is prone to instability when data characteristics change or protocol layer realignment occurs. Burst clock and data recovery (BCDR) is more suitable for segmented burst data, but it is still affected by frequency offset and environmental drift during the hold phase. It requires boundary scheduling and phase / frequency correction mechanisms to maintain the stability and continuity of the mapping between quantum events and unit interval (UI) numbers.

[0033] In view of this, embodiments of the present invention provide a clock and data correction method for a quantum key distribution system, comprising: processing the negotiation data based on N burst frames received via a negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks, wherein the associated mismatch clocks and mismatch data correspond to a target protection interval including multiple protection word periods; and performing sliding calibration processing on the N mismatch data using the N mismatch clocks based on the target data sequence to obtain N correction offset parameters, wherein the correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters, and the target data... The sequence includes a preset clock at the receiving end and preset data corresponding to the preset clock; based on the integer offset parameter between the nth target protection zones, the sub-mismatch clock and sub-mismatch data of any protection word period in the (n+1)th target protection zone are corrected by integer; based on the fractional phase error parameter and frequency offset parameter of the nth target protection zone, the sub-mismatch clock and sub-mismatch data of other protection word periods in the (n+1)th target protection zone are corrected by fractional, to obtain the target clock and target data. The sub-mismatch clock and sub-mismatch data are obtained by dividing the mismatch clock and mismatch data based on multiple protection word periods.

[0034] Figure 1 A diagram illustrating an application scenario of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0035] like Figure 1As shown, application scenario 100 according to this embodiment may include a transmitter 110 and a receiver 120. The clock and data correction method of the quantum key distribution system can be applied to the receiver 120. The transmitter 110 is used to send negotiation data with inserted burst frames to the receiver 120. The transmitter 110 and the receiver 120 realize quantum key distribution through a quantum channel and a classical auxiliary channel. The quantum channel can characterize the channel used to transmit quantum states, and the classical auxiliary channel can characterize the channel used to transmit public but non-sensitive information and to achieve timing alignment of quantum signal transmission and detection.

[0036] Figure 2 A flowchart of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0037] like Figure 2 As shown, the clock and data correction method 200 of the quantum key distribution system in this embodiment is applied to the receiving end and includes operations S210 to S230.

[0038] In operation S210, based on the N burst frames in the negotiation data received via the negotiation optical channel, the negotiation data is processed to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks.

[0039] In operation S220, based on the target data sequence, N mismatched data are calibrated using N mismatched clocks to obtain N corrected offset parameters.

[0040] In operation S230, based on the integer offset parameter between the nth target protection zones, the sub-mismatch clock and sub-mismatch data of any protection word cycle in the (n+1)th target protection zone are corrected by integer. Based on the fractional phase error parameter and frequency offset parameter of the nth target protection zone, the sub-mismatch clock and sub-mismatch data of other protection word cycles in the (n+1)th target protection zone are corrected by fractional. The target clock and target data are then obtained.

[0041] A quantum key distribution system can include a transmitter and a receiver, which achieve quantum key distribution through a quantum channel and a classical auxiliary channel. A quantum channel characterizes the channel used to transmit quantum states, while a classical auxiliary channel characterizes the channel used to transmit public but non-sensitive information and to achieve timing alignment for quantum signal transmission and detection. The classical auxiliary channel can include a negotiation optical channel and a synchronization optical channel. However, in a single-fiber co-transmission scenario, the negotiation optical channel and the synchronization optical channel can be shared based on signal multiplexing techniques. For example, the signal multiplexing techniques can be wavelength division multiplexing or time slot multiplexing.

[0042] Negotiation data can be data transmitted via a negotiation optical channel and received by the receiver. In the quantum key distribution process, negotiation data can include valid quantum events, bit decisions, etc. In one implementation, in a single-fiber co-transmission scenario, the clock and data can be recovered from the negotiation data received via the negotiation optical channel, thereby achieving clock and data synchronization without using an independent synchronization optical channel.

[0043] A burst frame can represent a frame with a known bit sequence, and N burst frames can be periodically inserted into the negotiation data. By processing the negotiation data with N burst frames inserted, N mismatch clocks associated with the N burst frames and N mismatch data corresponding to the N mismatch clocks can be obtained. In one implementation, the receiver can initiate burst clock data recovery when a burst frame is detected, thereby obtaining the N mismatch clocks associated with the N burst frames and the N mismatch data corresponding to the N mismatch clocks in a short time.

[0044] The mismatched clocks and mismatched data that are associated with each other can correspond to a target protection interval, which may include multiple protection word periods. In one implementation, the mismatched clock recovered for a burst frame and the mismatched data corresponding to the mismatched clock can correspond to a target protection interval, which may include multiple protection word periods.

[0045] The target data sequence may include a preset clock at the receiving end and preset data corresponding to the preset clock. That is, the target data sequence may be the local clock at the receiving end and known data corresponding to the local clock.

[0046] Within the time domain corresponding to each of the N mismatched clocks, by sliding the target data sequence over the N mismatched data, N correction offset parameters can be obtained. These correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. Integer offset parameters can be used to characterize unit interval offsets that are integer multiples of each other, while fractional phase error parameters and frequency offset parameters can be used to characterize phase errors and frequency offsets that are less than one unit interval offset.

[0047] In one implementation, the number of target protection intervals can be based on the same insertion period of burst frames. When the number of burst frames is N, the number of target protection intervals can also be N.

[0048] The mismatch clock and mismatch data between the next target protection zone can be corrected based on the integer offset parameters between the current target protection zones. Furthermore, the mismatch clock and mismatch data between the next target protection zones can also be corrected based on the fractional phase error parameters and frequency offset parameters of the current target protection zone, thereby obtaining the target clock and target data.

[0049] The target protection interval may include multiple protection word cycles. The sub-mismatch clock and sub-mismatch data can be obtained by dividing the mismatch clock and mismatch data based on multiple protection word cycles. In one implementation, the sub-mismatch clock and sub-mismatch data of the first protection word cycle in the (n+1)th target protection interval can be integer-corrected based on the integer offset parameter of the nth target protection interval. The sub-mismatch clock and sub-mismatch data of other protection word cycles in the (n+1)th target protection interval besides the first protection word cycle can be fractionally corrected based on the fractional phase error parameter and frequency offset parameter of the nth target protection interval to obtain the target clock and target data, where N is greater than 1, and n is greater than or equal to 1 and less than or equal to N-1.

[0050] Since N burst frames are periodically inserted into the negotiation data received via the negotiation optical channel, by detecting the burst frames in the negotiation data, N mismatch clocks associated with the N burst frames and N mismatch data corresponding to the N mismatch clocks can be recovered. Then, based on the target data sequence, the N mismatch data are calibrated by sliding based on the N mismatch clocks to obtain N correction offset parameters. The correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. Based on the integer offset parameters between the nth target protection zones, the sub-mismatch clocks and sub-mismatch data of any protection word period in the (n+1)th target protection zone can be corrected by integer. Based on this, using the fractional phase error parameter and frequency offset parameter of the nth target protection interval, fractional correction is performed on the sub-mismatch clock and sub-mismatch data of the other protection word periods in the (n+1)th target protection interval, except for any protection word period. Through integer correction, coarse correction of integer multiple unit intervals can be achieved to maintain the monotonically increasing unit interval sequence number. Through fractional correction, fine correction of smaller than unit intervals can be achieved to achieve gradual transition of phase and frequency. By combining integer and fractional correction within the target protection interval, the correction speed and accuracy can be improved. This enables high-precision, low-interruption, and long-term stable clock synchronization of the quantum key distribution system under the condition of no synchronization light, while reducing noise interference caused by synchronization light, reducing the cost and complexity of the quantum key distribution system, and thus making it suitable for quantum key distribution deployment between metropolitan area networks, backbone networks, and data centers.

[0051] In a quantum key distribution system, the transmitter can periodically insert burst frames into the negotiation data and send them to the receiver. Burst frames can include a predefined template, which may contain a preamble, a synchronization word, and a check segment. In the negotiation optical channel, the attenuation of the electrically variable optical attenuator (EVOA) is set to an initial value. The receiver performs sliding correlation on the received negotiation data, calculating the peak-to-sidelobe ratio, peak value, and arrival offset. When N burst frames reach a preset threshold for successful acquisition and the peak-to-sidelobe ratio is not lower than a preset threshold, the current preset threshold, time window center, and received power meet the requirements. If the requirements are not met, the initial attenuation value is adjusted based on the peak value and peak-to-sidelobe ratio until the above conditions are met. Simultaneously, operating parameters such as the time window center and width, the width of intermediate mismatch data, and the word clock are recorded. The word clock characterizes the intermediate mismatch clock and is used for subsequent word alignment.

[0052] Based on N burst frames in the negotiation data received via the negotiation optical channel, the negotiation data is processed to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks. This includes: for any burst frame in the N burst frames, processing the negotiation data according to any burst frame in the negotiation data to obtain a bit mismatch clock and serial mismatch data corresponding to the bit mismatch clock; and performing serial-to-parallel conversion on the bit mismatch clock and the serial mismatch data to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock.

[0053] Since the N burst frames are periodically inserted, the following will explain the process of recovering the mismatch clock and mismatch data associated with the burst frame based on any one of the N burst frames.

[0054] Upon detecting a burst frame in the negotiated data, the receiver immediately initiates clock capture, which can recover the bit mismatch clock and the serial mismatch data corresponding to the bit mismatch clock in a short time.

[0055] A serializer / deserializer (SERDES) can be used to perform word alignment and serial-to-parallel conversion on the bit mismatch clock and serial mismatch data, thereby obtaining the mismatch clock and the mismatch data corresponding to the mismatch clock.

[0056] Furthermore, performing serial-to-parallel conversion on the bit mismatch clock and serial mismatch data to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock may include: aligning the bit mismatch clock and serial mismatch data based on burst frames to obtain an intermediate mismatch clock and intermediate mismatch data corresponding to the intermediate mismatch clock; and performing serial-to-parallel conversion on the intermediate mismatch data based on the intermediate mismatch clock to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock.

[0057] Within the time domain corresponding to the bit mismatch clock, based on the burst frame, the serial mismatch data following the burst frame in the negotiation data can be word-aligned to obtain the intermediate mismatch clock and the intermediate mismatch data corresponding to the intermediate mismatch clock.

[0058] Within the time domain corresponding to the intermediate mismatch clock, serial-to-parallel conversion of the intermediate mismatch data can be performed to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock.

[0059] For burst frames in the negotiated data, the bit mismatch clock and the corresponding serial mismatch data can be recovered using BCDR. Then, word alignment processing is performed on the serial mismatch data based on the bit mismatch clock to obtain the intermediate mismatch clock and the intermediate mismatch data corresponding to the intermediate mismatch clock. On this basis, serial-to-parallel conversion is performed using a serial-to-parallel converter to obtain the mismatch clock and the corresponding mismatch data, which improves the data processing speed and is therefore suitable for high-speed data transmission scenarios.

[0060] Based on the target data sequence, N mismatched data are subjected to sliding calibration using N mismatched clocks to obtain N correction offset parameters. This includes: for any mismatched clock among the N mismatched clocks and the mismatched data corresponding to any mismatched clock, fixing the mismatched data and sliding the target data sequence within the time domain corresponding to any mismatched clock, determining multiple similarities between the mismatched data and the target data sequence; determining the target similarity corresponding to the mismatched data from the multiple similarities; and determining the correction offset parameters based on the target similarity corresponding to the mismatched data.

[0061] In some implementations, the length of the burst frames is no less than 512 unit intervals to ensure the reliability of target similarity recognition. Since burst frames are periodically inserted, the processing flow for recovering N mismatched clocks and their corresponding mismatched data from N burst frames is similar. The process of obtaining the corrected offset parameter will be explained below using any one of the N mismatched clocks and its corresponding mismatched data.

[0062] For any mismatched clock, within the time domain corresponding to that clock, the mismatched data corresponding to that clock is fixed, and the target data sequence is slid across this mismatched data to obtain multiple similarities between the mismatched data and the target data sequence. Furthermore, for any mismatched clock, within the time domain corresponding to that clock, starting from the first frame of the mismatched data corresponding to that clock, the target data sequence is slid sequentially to determine multiple similarities between the mismatched data and the target data sequence.

[0063] In one implementation, the largest similarity among multiple similarities can be used as the target similarity corresponding to the mismatched data. In another implementation, the two largest similarities among multiple similarities can be determined, and the target similarity can be obtained by processing the two largest similarities.

[0064] In one implementation, within the time domain corresponding to any mismatched clock, the peak position with the highest correlation can be obtained by sliding correlation between the target data sequence and the mismatched data. The similarity corresponding to this peak position is the target similarity. Based on the peak position, the offset of the mismatched data compared to the target data sequence by a number of unit intervals can be determined; that is, the number of unit intervals of offset is an integer offset parameter. Since the peak position may appear between two sampling points, the offset ratio of the target similarity between the two sampling points, i.e., the fractional phase error parameter, can be estimated by interpolation or fitting. Since the phase error parameter can be transformed from the frequency offset parameter over time, the frequency offset parameter can be determined based on the fractional phase error parameter.

[0065] The correction offset parameters can include integer offset parameters, fractional phase error parameters, and frequency offset parameters. Therefore, the correction offset parameters can be determined based on the similarity to the target corresponding to any mismatched clock.

[0066] For any mismatched clock among N clocks and the mismatched data corresponding to that mismatched clock, the mismatched data is fixed in the time domain corresponding to that mismatched clock. Starting from the first frame of the mismatched data, the target data sequence is slid, which can obtain multiple similarities between the mismatched data and the target data sequence. Based on the target similarity determined from the multiple similarities, the correction offset parameter is determined. Through sliding calibration, integer offset parameters with integer multiples of unit intervals and fractional phase error parameters and frequency offset parameters with fractional multiples of unit intervals can be obtained, thereby improving the correction accuracy of the mismatched clock and mismatched data.

[0067] Figure 3 A schematic diagram of a sliding calibration process according to an embodiment of the present invention is shown.

[0068] like Figure 3As shown, there are multiple burst frames, and each burst frame may include a preamble, a synchronization word, and a check segment. When the state machine detects the preamble, it recognizes the arrival of the burst frame and triggers the sliding correlator to start operation. At the same time, the sliding correlator receives the target data sequence and the mismatch data corresponding to the mismatch clock. According to the step size of unit interval, it performs sliding correlation between the mismatch data and the target data sequence. At each sliding position, the similarity between the two sequences is calculated, and two sets of data can be obtained: one set is the similarity associated with each sliding position. Multiple similarities are sent to the PSR (Peak-to-Sidelobe Ratio) peak finding and interpolation module. The other set is multiple sets of equal-length sliding splicing sequences generated by splicing frame 0 and frame 1 at unit intervals. Each set of sliding splicing sequences corresponds to a sliding position. The sliding splicing sequence is formed by splicing the latter part of the data of frame 0 and the former part of the data of frame 1. It is used to simulate the time offset of the target data sequence. Frame 0 [A0:Cn-1] represents the data of frame 0, which contains all the data from the beginning A0 to the end Cn-1. Frame 1 [A0:Cn-1] represents the complete data of frame 1.

[0069] After receiving multiple similarities, the PSR peak finding and interpolation module first performs neighborhood extremum detection on the multiple similarities to locate all candidate peaks. Then, it calculates the difference between the candidate main peak and the surrounding largest sidelobe (PSR difference) and compares it with a preset threshold to select the only valid main peak (if the difference does not meet the standard, the peak finding is determined to be unsuccessful and feedback is given to the state machine). Subsequently, interpolation fitting is performed in the neighborhood of the valid main peak to obtain the peak position, and then the integer offset parameter Δk, the fractional phase error parameter Δφ, and the frequency offset parameter Δf are obtained. At the same time, the PSR difference is used as the confidence level (the larger the difference, the higher the confidence level) and fed back to the state machine.

[0070] The alignment data generation unit performs data correction based on the received sliding splicing sequence and the integer offset parameter Δk, fractional phase error parameter Δφ, and frequency offset parameter Δf output by the PSR peak finding and interpolation module, and finally generates alignment data.

[0071] The state machine synchronously receives the frame processing completion signal and similarity sequence validity mark from the sliding correlator. Then, it combines the peak finding result, integer offset parameter Δk, fractional phase error parameter Δφ, frequency offset parameter Δf, and confidence level fed back by the PSR peak finding and interpolation module to make a logical judgment: if the peak finding is successful, the confidence level meets the standard, and the validity mark is valid, an alignment request is sent to trigger subsequent correction between target protection zones; after the deviation correction is completed and the verification segment is verified, the state machine enters the alignment locking state; if the peak finding fails, the confidence level does not meet the standard, or the validity mark is invalid, a resynchronization process is triggered, or the current frame is directly discarded, waiting for the arrival of the next frame.

[0072] Figure 4 A schematic diagram illustrating clock and data correction according to an embodiment of the present invention is shown.

[0073] like Figure 4 As shown, the mismatched clock and corresponding mismatched data associated with each burst frame can correspond to a target protection interval. For burst frame 1, the correction offset parameters of the previous target protection interval (Guard) corresponding to burst frame 1 can be obtained, specifically including the integer offset parameter Δk, the fractional phase error parameter Δφ, and the frequency offset parameter Δf. Furthermore, based on the correction offset parameters between the previous target protection intervals, the peak-to-sidelobe ratio (PSR) between the previous target protection intervals can be obtained, thus yielding the confidence level. The mismatched clock and mismatched data between the target protection intervals corresponding to burst frame 1 are corrected based on the correction offset parameters. Specifically, within the target protection interval corresponding to burst frame 1, the mismatched clock and mismatched data between the target protection intervals corresponding to burst frame 1 are corrected once based on the integer offset parameter Δk; based on the fractional phase error parameter Δφ, the mismatched clock and mismatched data between the target protection intervals corresponding to burst frame 1 are fine-tuned within S steps according to the gradually changing frequency offset parameter Δf. Specifically, each step is corrected in steps according to Δf / S, thereby completing the correction of the mismatched clock and mismatched data between the target protection intervals corresponding to burst frame 1. The monotonically increasing UI indicates that the timing reference used for correction within the target protection interval corresponding to burst frame 1 is continuous, without jumps, and increasing. The correction process for mismatched clocks and mismatched data associated with burst frame 2 is similar to that of burst frame 1, and will not be described in detail here.

[0074] The clock and data correction method of the above-mentioned quantum key distribution system may further include: determining the fusion offset parameter between the nth target protection zones based on the correction offset parameter and statistical parameters between the nth target protection zones; performing integer correction on the sub-target clock and sub-target data of any protection word period in the (n+1)th target protection zone based on the integer fusion offset parameter between the nth target protection zones; and performing fractional correction on the sub-target clock and sub-target data of other protection word periods in the (n+1)th target protection zone except for any protection word period based on the fractional phase fusion error parameter and frequency fusion offset parameter of the nth target protection zone, to obtain the first target clock and the first target data.

[0075] Statistical parameters can characterize statistics derived from the timestamps of quantum events in a quantum channel. In one implementation, a quantum event can characterize a valid event in which a single photon is captured and recorded by a detector at the receiving end; for example, a valid event can be a basis matching event, a bit error event, etc. In some implementations, statistics can be used to characterize the offset parameters of the quantum channel, which may include at least one of the following: quantum signal statistics rate, basis matching rate, quantum bit error rate, and key generation rate.

[0076] The corrected migration parameters between the nth target protected areas can be combined with statistical parameters, and the fused migration parameters between the nth target protected areas can be calculated using methods such as fixed weights, Kalman filtering, or Bayesian estimation.

[0077] In one implementation, if the corrected offset parameter between the nth target protection zones is less than the offset parameter threshold, the corrected offset parameter between the nth target protection zones can be ignored, and the fusion offset parameter between the nth target protection zones is determined based on statistical parameters. In another implementation, if the offset parameter representing the quantum channel using statistical parameters is less than the quantum offset parameter threshold, the statistical parameters can be ignored, and the fusion offset parameter between the nth target protection zones is determined based on the corrected offset parameter between the nth target protection zones. In yet another implementation, the fusion offset parameter between the nth target protection zones can be determined based on both the corrected offset parameter and the statistical parameters.

[0078] The fusion offset parameters can include integer fusion offset parameters, fractional phase fusion error parameters, and frequency fusion offset parameters.

[0079] Given a fixed fusion offset parameter, the sub-target clock and sub-target data for any protection word period within the (n+1)th target protection interval can be integer-corrected based on the integer fusion offset parameter between the nth target protection intervals. The sub-target clock and sub-target data for other protection word periods within the (n+1)th target protection intervals, excluding any protection word period, can be fractionally corrected based on the fractional phase fusion error parameter and frequency fusion offset parameter of the nth target protection interval, thus obtaining the first target clock and the first target data.

[0080] In one implementation, the sub-target clock and sub-target data of the first protection word period in the (n+1)th target protection interval can be corrected once by integer fusion offset parameters between the nth target protection intervals. For other protection word periods in the (n+1)th target protection interval besides the first protection word period, fractional phase fusion error parameters are injected into the shadow time base in S steps respectively, and the frequency is corrected based on the frequency fusion offset parameters and S steps. The number of S steps can be less than or equal to the number of protection word periods. In one implementation, the number of S steps can be equal to the number of protection word periods.

[0081] By fusing the correction offset parameters and statistical parameters between the nth target protection zones, the fusion offset parameters between the nth target protection zones can be determined. Then, based on the fusion offset parameters between the nth target protection zones, integer and fractional corrections are performed on the sub-target clocks and sub-target data of multiple word cycles between the (n+1)th target protection zones to obtain the first target clock and the first target data. This allows for further improvement of the correction accuracy based on the target clock and target data, thereby enabling high-precision, low-interruption, and long-term stable clock synchronization of the quantum key distribution system under conditions without synchronization light.

[0082] The clock and data correction method of the above quantum key distribution system may further include: adjusting the epoch period and the target protection interval based on a preset security margin and target parameters to obtain the adjusted epoch period and the adjusted target protection interval.

[0083] The negotiated data can be divided into multiple epochs in the time domain. The mismatched clocks and mismatched data that are related to each other can correspond to an epoch. A target protection interval can be set at the beginning of the epoch so that the epoch can include the target protection interval.

[0084] The target parameters may include at least one of the following: link drift speed, frequency offset parameter, or burst frame, where link drift speed characterizes the data transmission delay caused by the environment or devices in the quantum key distribution system.

[0085] In one implementation, when a burst frame is missing, the epoch period and the target protection interval can be adjusted based on a preset safety margin to obtain the adjusted epoch period and the adjusted target protection interval.

[0086] Based on the changes in the target parameters, the epoch period and target protection interval are adaptively adjusted according to the preset security margin to obtain the adjusted epoch period and adjusted target protection interval, which can realize the high-precision and long-term stable operation of the quantum key distribution system.

[0087] Link drift velocity and frequency offset parameters can be evaluated online. In one implementation, when the link drift velocity or frequency offset parameter increases, the epoch period and target protection interval can be adjusted based on a preset safety margin to obtain the adjusted epoch period and adjusted target protection interval. Adjusting the target protection interval can increase its length. Furthermore, the training period for burst frames can be shortened. When the link drift velocity characterizes a relatively stable link, the training period for burst frames can be extended to reduce the bandwidth usage of the negotiation channel. To avoid the fractional phase error parameter of the next target protection interval approaching the unit interval boundary, a safety time is used. It satisfies the following formula (1).

[0088] (1);

[0089] in, Indicates the preset safety margin. This represents the fractional phase error parameter and the frequency offset parameter. Indicates the link drift speed. This represents the frequency offset parameter. Indicates the duration of a unit interval.

[0090] The length of the target protection interval is measured in protection word cycles. In some implementations, the length of the target protection interval can be 8 to 16 protection word cycles. The number of steps is less than or equal to the number of protection word cycles. In one implementation, the number of steps can be equal to the number of protection word cycles. In the protection word cycles other than the first protection word cycle, a fractional phase error parameter is injected into the shadow time base in steps, and the frequency offset parameter is corrected based on the frequency offset parameter and the number of steps. That is, a gradual update is performed on the shadow time base parameter in each protection word cycle to achieve a gradual transition of phase and frequency. The single-step phase injection satisfies the following formula (2), and the single-step update time is... The bandwidth limit is adjusted to meet the following formula (3). The epoch period satisfies the following formula (4). The length of satisfies the following formula (5).

[0091] (2);

[0092] (3);

[0093] (4);

[0094] (5);

[0095] in, This represents the fractional phase error parameter, where S represents the number of steps. Indicates the protected word cycle, Indicates a digital clock.

[0096] The clock and data correction method of the above-mentioned quantum key distribution system further includes: for any mismatched clock among N mismatched clocks and the mismatched data corresponding to any mismatched clock, in the time domain corresponding to any mismatched clock, fixing the mismatched data, sliding the target data sequence, and determining multiple similarities between the mismatched data and the target data sequence; determining the confidence level based on the multiple similarities between the mismatched data and the target data sequence; and adjusting the correction offset parameter based on a preset amplitude when the confidence level is less than a preset confidence threshold, to obtain the adjusted correction offset parameter.

[0097] Within the time domain corresponding to any mismatched clock, by fixing the mismatched data and sliding the target data sequence over the mismatched data, multiple similarities between the mismatched data and the target data sequence can be determined. Based on the peak values ​​corresponding to the multiple similarities, the confidence level can be determined by the ratio of the peak value to the sidelobe.

[0098] If the confidence level is less than the preset confidence threshold, the correction offset parameter can be adjusted based on a preset magnitude to obtain the adjusted correction offset parameter. Furthermore, corrections between the target protection zones can be skipped.

[0099] When the confidence level is less than the preset confidence threshold, adjusting the correction offset parameter can yield the adjusted correction offset parameter, which can improve the correction accuracy and thus increase the correction flexibility.

[0100] The clock and data correction method of the above quantum key distribution system also includes: the target mapping relationship remains unchanged between the nth target protection interval and the (n+1)th target protection interval.

[0101] In addition to burst frames, the negotiation data can also include data frames, which can represent the data used by the sender and receiver to negotiate and determine the quantum key.

[0102] The target mapping relationship can characterize the correspondence between quantum events and unit intervals corresponding to data frames. The aforementioned integer and fractional corrections occur within the target protection interval. Within the target protection interval, the target mapping relationship can be changed through corrections, while outside the target protection interval, the target mapping relationship remains unchanged.

[0103] Outside the target protection zone, the target mapping relationship remains unchanged, thus ensuring the continuity of data transmission.

[0104] Based on the clock and data recovery method of the quantum key distribution system described above, it is possible to maintain the continuity and monotonicity of the correspondence between quantum events and unit interval numbers under operating conditions such as temperature changes, mechanical disturbances, and frequency maintenance errors, and maintain a low bit error rate, thus meeting the long-term stable operation requirements of the quantum key distribution system.

[0105] Figure 5 A system architecture diagram of a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0106] like Figure 5As shown, the quantum key distribution system includes a transmitter and a receiver. The transmitter periodically inserts burst frames into the negotiation data and transmits the negotiation optical signal (negotiation data) and quantum optical signal to the receiver after wavelength division multiplexing (WDM). Upon receiving the data, the receiver first performs WDM and then transmits the negotiation data in the negotiation channel, thereby recovering the mismatched clock and the corresponding mismatched data. Quantum event detection is performed in the quantum channel to obtain statistical parameters. These statistical parameters are combined with correction offset parameters to correct the clock and data, thus achieving clock and data recovery. This yields the first target clock and first target data, which are then detected and recorded.

[0107] Based on the clock and data correction method for the above-mentioned quantum key distribution system, this invention also provides a clock and data correction device for a quantum key distribution system. The following will be combined with... Figure 6 The device is described in detail.

[0108] Figure 6 A structural block diagram of the clock and data correction device of a quantum key distribution system according to an embodiment of the present invention is shown.

[0109] like Figure 6 As shown, the clock and data correction device 600 of the quantum key distribution system in this embodiment includes a first obtaining module 610, a second obtaining module 620, and a first correction module 630.

[0110] The first obtaining module 610 is used to process the negotiation data based on N burst frames in the negotiation data received via the negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks. The mismatch clocks and mismatch data associated with each other correspond to a target protection interval including multiple protection word periods. In one embodiment, the first obtaining module 610 can be used to perform the operation S210 described above, which will not be repeated here.

[0111] The second obtaining module 620 is used to perform sliding calibration processing on N mismatched data using N mismatched clocks based on the target data sequence, to obtain N corrected offset parameters. The corrected offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. The target data sequence includes a preset clock from the receiving end and preset data corresponding to the preset clock. In one embodiment, the second obtaining module 620 can be used to perform the operation S220 described above, which will not be repeated here.

[0112] The first correction module 630 is used to perform integer correction on the sub-mismatch clock and sub-mismatch data of any protection word period within the (n+1)th target protection interval based on the integer offset parameter between the nth target protection intervals, and to perform fractional correction on the sub-mismatch clock and sub-mismatch data of other protection word periods within the (n+1)th target protection interval besides any protection word period based on the fractional phase error parameter and frequency offset parameter of the nth target protection interval, to obtain the target clock and target data. The sub-mismatch clock and sub-mismatch data are obtained by dividing the mismatch clock and mismatch data based on multiple protection word periods. In one embodiment, the first correction module 630 can be used to perform the operation S230 described above, which will not be repeated here.

[0113] According to an embodiment of the present invention, the second obtaining module 620 includes: a first obtaining submodule, configured to, for any mismatched clock among N mismatched clocks and mismatched data corresponding to any mismatched clock, fix the mismatched data and slide the target data sequence within the time domain corresponding to any mismatched clock, and determine multiple similarities between the mismatched data and the target data sequence; a second obtaining submodule, configured to determine a target similarity corresponding to the mismatched data from the multiple similarities; and a third obtaining submodule, configured to determine a correction offset parameter based on the target similarity corresponding to the mismatched data.

[0114] According to an embodiment of the present invention, the first obtaining submodule includes: a first obtaining unit, configured to determine multiple similarities between the mismatched data and the target data sequence by sliding the target data sequence sequentially from the first frame of the mismatched data corresponding to the mismatched clock.

[0115] According to an embodiment of the present invention, the first obtaining module 610 includes: a fourth obtaining submodule, used for processing the negotiation data according to any one of the negotiation data for any one of the N burst frames to obtain a bit mismatch clock and serial mismatch data corresponding to the bit mismatch clock; and a fifth obtaining submodule, used for performing serial-to-parallel conversion on the bit mismatch clock and the serial mismatch data to obtain a mismatch clock and mismatch data corresponding to the mismatch clock.

[0116] According to an embodiment of the present invention, the fifth obtaining submodule includes: a second obtaining unit, configured to perform alignment processing on bit mismatch clock and serial mismatch data based on burst frames to obtain intermediate mismatch clock and intermediate mismatch data corresponding to the intermediate mismatch clock; and a third obtaining unit, configured to perform serial-to-parallel conversion on intermediate mismatch data based on the intermediate mismatch clock to obtain mismatch clock and mismatch data corresponding to the mismatch clock.

[0117] According to an embodiment of the present invention, the clock and data correction device 600 of the above-mentioned quantum key distribution system further includes: a first determining module, configured to determine a fusion offset parameter between the nth target protection zones based on the correction offset parameter and statistical parameters between the nth target protection zones, wherein the statistical parameters characterize the statistics obtained based on the timestamps of quantum events in the quantum channel, and the fusion offset parameter includes an integer fusion offset parameter, a fractional phase fusion error parameter, and a frequency fusion offset parameter; and a second correction module, configured to perform integer correction on the sub-target clock and sub-target data of any protection word period in the (n+1)th target protection zone based on the integer fusion offset parameter between the nth target protection zones, and perform fractional correction on the sub-target clock and sub-target data of other protection word periods in the (n+1)th target protection zone other than any protection word period based on the fractional phase fusion error parameter and frequency fusion offset parameter of the nth target protection zone, to obtain a first target clock and first target data.

[0118] According to an embodiment of the present invention, the mismatched clocks and mismatched data associated with each other correspond to epoch periods, and the epoch period includes a target protection interval. The clock and data correction device 600 of the quantum key distribution system further includes: a first adjustment module, used to adjust the epoch period and the target protection interval based on a preset security margin and target parameters to obtain the adjusted epoch period and the adjusted target protection interval, wherein the target parameters include at least one of the following: link drift speed, frequency offset parameter or burst frame, and the link drift speed characterizes the data transmission delay caused by the environment or devices in the quantum key distribution system.

[0119] According to an embodiment of the present invention, the clock and data correction device 600 of the quantum key distribution system further includes: a second determining module, configured to, for any mismatched clock among N mismatched clocks and mismatched data corresponding to any mismatched clock, fix the mismatched data and slide the target data sequence within the time domain corresponding to any mismatched clock, and determine multiple similarities between the mismatched data and the target data sequence; a third determining module, configured to determine a confidence level based on the multiple similarities between the mismatched data and the target data sequence; and a second adjusting module, configured to, when the confidence level is less than a preset confidence threshold, adjust the correction offset parameter based on a preset amplitude to obtain the adjusted correction offset parameter.

[0120] According to an embodiment of the present invention, the negotiation data includes a data frame, and the clock and data correction device 600 of the quantum key distribution system further includes: a holding module, used to keep the target mapping relationship unchanged between the nth target protection interval and the (n+1)th target protection interval, wherein the target mapping relationship characterizes the correspondence between the quantum event corresponding to the data frame and the unit interval.

[0121] According to embodiments of the present invention, any plurality of modules among the first obtaining module 610, the second obtaining module 620, and the first correcting module 630 may be combined into one module, or any one of these modules may be split into multiple modules. Alternatively, at least a portion of the functionality of one or more of these modules may be combined with at least a portion of the functionality of other modules and implemented in one module. According to embodiments of the present invention, at least one of the first obtaining module 610, the second obtaining module 620, and the first correcting module 630 may be at least partially implemented as a hardware circuit, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging the circuit, or implemented in software, hardware, or firmware, or in any one of the three implementation methods, or in a suitable combination of any of them. Alternatively, at least one of the first obtaining module 610, the second obtaining module 620, and the first correcting module 630 may be at least partially implemented as a computer program module, which, when run, can perform corresponding functions.

[0122] Figure 7 A block diagram of an electronic device suitable for implementing a clock and data correction method for a quantum key distribution system according to an embodiment of the present invention is shown.

[0123] like Figure 7 As shown, an electronic device 700 according to an embodiment of the present invention includes a processor 701, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 702 or a program loaded from a storage portion 708 into RAM (Random Access Memory). The processor 701 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 701 may also include onboard memory for caching purposes. The processor 701 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0124] RAM 703 stores various programs and data required for the operation of electronic device 700. Processor 701, ROM 702, and RAM 703 are interconnected via bus 704. Processor 701 executes various operations of the method flow according to embodiments of the present invention by executing programs in ROM 702 and / or RAM 703. It should be noted that the programs may also be stored in one or more memories other than ROM 702 and RAM 703. Processor 701 may also execute various operations of the method flow according to embodiments of the present invention by executing programs stored in said one or more memories.

[0125] According to an embodiment of the present invention, the electronic device 700 may further include an I / O interface 705, which is also connected to a bus 704. The electronic device 700 may also include one or more of the following components connected to the I / O interface 705: an input section 706 including a keyboard, mouse, etc.; an output section 707 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN card, modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to the I / O interface 705 as needed. A removable medium 711, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 710 as needed so that computer programs read from it can be installed into the storage section 708 as needed.

[0126] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present invention.

[0127] According to embodiments of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, RAM (Random Access Memory), ROM (Read Only Memory), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of the present invention, a computer-readable storage medium may include ROM 702 and / or RAM 703 and / or one or more memories other than ROM 702 and RAM 703 described above.

[0128] Embodiments of the present invention also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code is used to enable the computer system to implement the clock and data correction method for the quantum key distribution system provided in the embodiments of the present invention.

[0129] When the computer program is executed by the processor 701, it performs the functions defined in the system / apparatus of this invention. According to embodiments of the invention, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0130] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and may be downloaded and installed via the communication section 709, and / or installed from a removable medium 711. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0131] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 709, and / or installed from the removable medium 711. When the computer program is executed by the processor 701, it performs the functions defined in the system of this embodiment of the invention. According to embodiments of the invention, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0132] According to embodiments of the present invention, program code for executing the computer programs provided in the embodiments of the present invention can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0133] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0134] Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention can be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0135] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A clock and data correction method for a quantum key distribution system, characterized in that, include: Based on N burst frames in the negotiation data received via the negotiation optical channel, the negotiation data is processed to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks. The mismatch clocks and mismatch data associated with each other correspond to a target protection interval including multiple protection word periods. Based on the target data sequence, N mismatched data are calibrated by N mismatched clocks to obtain N correction offset parameters. The correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. The target data sequence includes a preset clock at the receiving end and preset data corresponding to the preset clock. Based on the integer offset parameter between the nth target protection zones, the sub-mismatch clock and sub-mismatch data of any protection word cycle within the (n+1)th target protection zone are corrected by integer. Based on the fractional phase error parameter and frequency offset parameter of the nth target protection zone, the sub-mismatch clock and sub-mismatch data of other protection word cycles within the (n+1)th target protection zone (excluding the aforementioned protection word cycle) are corrected by fractional. This yields the target clock and target data. The sub-mismatch clock and sub-mismatch data are obtained by dividing the mismatch clock and mismatch data based on the multiple protection word cycles.

2. The method according to claim 1, characterized in that, The process involves using N mismatched clocks to perform sliding calibration on N mismatched data based on the target data sequence, resulting in N corrected offset parameters, including: For any one of the N mismatched clocks and the mismatched data corresponding to that mismatched clock, Within the time domain corresponding to any of the mismatched clocks, the mismatched data is fixed, the target data sequence is slid, and multiple similarities between the mismatched data and the target data sequence are determined. Determine the target similarity corresponding to the mismatched data from the plurality of similarities; The correction offset parameter is determined based on the target similarity corresponding to the mismatched data.

3. The method according to claim 2, characterized in that, Within the time domain corresponding to any mismatched clock, fixing the mismatched data, sliding the target data sequence, and determining multiple similarities between the mismatched data and the target data sequence includes: Starting from the first frame of the mismatched data corresponding to any of the mismatched clocks, the target data sequence is slid sequentially to determine multiple similarities between the mismatched data and the target data sequence.

4. The method according to claim 1, characterized in that, The process involves processing the negotiation data based on N burst frames received via the negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks, including: For any one of the N burst frames, Based on any burst frame in the negotiation data, the negotiation data is processed to obtain a bit mismatch clock and serial mismatch data corresponding to the bit mismatch clock; The bit mismatch clock and the serial mismatch data are converted from serial to parallel to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock.

5. The method according to claim 4, characterized in that, The step of performing serial-to-parallel conversion on the bit mismatch clock and the serial mismatch data to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock includes: Based on the burst frame, the bit mismatch clock and the serial mismatch data are aligned to obtain the intermediate mismatch clock and the intermediate mismatch data corresponding to the intermediate mismatch clock. Based on the intermediate mismatch clock, the intermediate mismatch data is converted from serial to parallel to obtain the mismatch clock and the mismatch data corresponding to the mismatch clock.

6. The method according to claim 1, characterized in that, The method further includes: Based on the corrected offset parameters and statistical parameters between the nth target protection zones, the fusion offset parameters between the nth target protection zones are determined. The statistical parameters characterize the statistics obtained from the timestamps of quantum events in the quantum channel. The fusion offset parameters include integer fusion offset parameters, fractional phase fusion error parameters, and frequency fusion offset parameters. Based on the integer fusion offset parameter between the nth target protection zones, the sub-target clock and sub-target data of any protection word period in the (n+1)th target protection zone are corrected by integer. Based on the fractional phase fusion error parameter and frequency fusion offset parameter of the nth target protection zone, the sub-target clock and sub-target data of other protection word periods in the (n+1)th target protection zone, excluding the aforementioned protection word period, are corrected by fractional. This yields the first target clock and the first target data.

7. The method according to claim 1, characterized in that, The mismatched clocks and mismatched data, which are associated with each other, correspond to epoch periods, the epoch periods including the target protection interval. The method further includes: Based on a preset security margin and target parameters, the epoch period and the target protection interval are adjusted to obtain the adjusted epoch period and the adjusted target protection interval. The target parameters include at least one of the following: link drift speed, the frequency offset parameter, or the burst frame. The link drift speed characterizes the data transmission delay caused by the environment or devices in the quantum key distribution system.

8. The method according to claim 1, characterized in that, The method further includes: For any one of the N mismatched clocks and the mismatched data corresponding to that mismatched clock, Within the time domain corresponding to any of the mismatched clocks, the mismatched data is fixed, the target data sequence is slid, and multiple similarities between the mismatched data and the target data sequence are determined. The confidence level is determined based on multiple similarities between the mismatched data and the target data sequence; If the confidence level is less than a preset confidence threshold, the correction offset parameter is adjusted based on a preset amplitude to obtain the adjusted correction offset parameter.

9. The method according to claim 6, characterized in that, The negotiated data includes data frames, and the method further includes: Between the nth target protection interval and the (n+1)th target protection interval, the target mapping relationship remains unchanged, wherein the target mapping relationship characterizes the correspondence between the quantum event and the unit interval corresponding to the data frame.

10. A clock and data correction device for a quantum key distribution system, characterized in that, include: The first obtaining module is used to process the negotiation data based on N burst frames in the negotiation data received via the negotiation optical channel to obtain N mismatch clocks and N mismatch data corresponding to the N mismatch clocks. The mismatch clocks and mismatch data associated with each other correspond to a target protection interval including multiple protection word periods. The second obtaining module is used to perform sliding calibration processing on N mismatched data using N mismatched clocks based on the target data sequence to obtain N correction offset parameters. The correction offset parameters include integer offset parameters, fractional phase error parameters, and frequency offset parameters. The target data sequence includes a preset clock of the receiving end and preset data corresponding to the preset clock. The first correction module is used to perform integer correction on the sub-mismatch clock and sub-mismatch data of any protection word period in the (n+1)th target protection interval based on the integer offset parameter between the nth target protection intervals, and to perform fractional correction on the sub-mismatch clock and sub-mismatch data of other protection word periods in the (n+1)th target protection intervals other than the aforementioned protection word period based on the fractional phase error parameter and frequency offset parameter of the nth target protection interval, to obtain the target clock and target data. The sub-mismatch clock and the sub-mismatch data are obtained by dividing the mismatch clock and the mismatch data based on the multiple protection word periods respectively.

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