A CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging

Abstract

The application discloses a CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging, wherein the sending signal sent by the sending end contains repeated frames, and the repeated frames contain multiple quantum key frames which are repeated identically, so that the receiving end can obtain multiple corresponding receiving frames to construct an average frame, the signal-to-noise ratio of the average frame is significantly higher than that of a single receiving frame, accordingly, the correlation coefficient between the average frame received by the receiving end and the quantum key frame to be sent by the sending end is also significantly higher than the correlation coefficient between a single receiving frame received by the receiving end and the quantum key frame to be sent by the sending end. The correlation coefficient of the average frame is significantly improved, and the transmission performance of the signal is effectively enhanced, therefore, the quantum key distribution is carried out by adopting the repeated frame method, a longer transmission distance can be achieved, the accuracy of signal demodulation is effectively improved, the system performance is enhanced, and the communication security is ensured. The application is widely applied to the technical field of quantum communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum communication, and particularly relates to a CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging. BACKGROUND

[0002] With the rapid development of quantum communication technology, continuous variable quantum key distribution (CVQKD) system as an effective means to achieve quantum secure communication has attracted attention. The CVQKD system uses the principles of quantum mechanics to generate keys by encoding and transmitting quantum states, thereby realizing secure communication between two communicating parties. However, due to the weak characteristics of quantum signals, the CVQKD system is easily affected by noise and other interference factors in practical application, and is limited by transmission distance and bandwidth, which seriously restricts its communication rate and signal quality. SUMMARY

[0003] In view of the technical problems that the current continuous variable quantum key distribution process is easily affected by noise and other interference factors, and is limited by transmission distance and bandwidth, the purpose of the present application is to provide a CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging.

[0004] In one aspect, the present application embodiment includes a CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging, applied to a sending end, the CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging comprising:

[0005] Obtaining a quantum key frame;

[0006] Generating a repeated frame; the repeated frame includes a plurality of repeated quantum key frames;

[0007] Sending the repeated frame to a receiving end.

[0008] Further, the obtaining of the quantum key frame comprises:

[0009] Generating a quantum random number;

[0010] Generating the quantum key frame according to the quantum random number.

[0011] Further, the generating of the repeated frame comprises:

[0012] Determining a repetition number;

[0013] According to the repetition number, copying the quantum key frame to obtain a plurality of identical quantum key frames;

[0014] Generating a synchronization sequence;

[0015] Arranging each quantum key frame in turn after the synchronization sequence to form the repeated frame.

[0016] Further, the determining the repetition number comprises:

[0017] Obtaining a correlation coefficient of the feedback from the receiving end;

[0018] According to the correlation coefficient, dynamically adjusting the size of the repetition number.

[0019] Further, the repetition number is negatively correlated with the correlation coefficient.

[0020] Further, the sending the repetition frame to the receiving end comprises:

[0021] Generating a single frequency laser;

[0022] Using the repetition frame to modulate the single frequency laser to obtain a sending signal;

[0023] Sending the sending signal to the receiving end through an optical fiber channel.

[0024] In another aspect, the embodiments of the present application also include a CVQKD signal-to-noise ratio enhancement method based on repetition frame averaging, applied to a receiving end, the CVQKD signal-to-noise ratio enhancement method based on repetition frame averaging comprising:

[0025] Receiving a receiving signal from a sending end;

[0026] Obtaining a plurality of receiving frames from the receiving signal;

[0027] Performing average processing on each of the receiving frames to obtain an average frame;

[0028] Determining a quantum key according to the average frame.

[0029] Further, the obtaining a plurality of receiving frames from the receiving signal comprises:

[0030] Obtaining a synchronization sequence from the receiving signal;

[0031] Performing frame synchronization on the receiving signal according to the synchronization sequence;

[0032] From the receiving signal after frame synchronization, sequentially segmenting out each of the receiving frames.

[0033] Further, the CVQKD signal-to-noise ratio enhancement method based on repetition frame averaging further comprises:

[0034] Obtaining a quantum key frame of the sending end from a lossless channel;

[0035] Determining a correlation coefficient according to the quantum key frame and the average frame.

[0036] Further, the CVQKD SNR enhancement method based on repeated frame averaging further comprises:

[0037] The correlation coefficient is fed back to the sending end.

[0038] In another aspect, the embodiments of the present application further include a computer device comprising a memory and a processor, the memory being used to store at least one program, and the processor being used to load the at least one program to execute the CVQKD SNR enhancement method based on repeated frame averaging in the embodiments.

[0039] In another aspect, the embodiments of the present application further include a computer readable storage medium having stored therein a program executable by a processor, the program executable by the processor when executed by the processor being used to execute the CVQKD SNR enhancement method based on repeated frame averaging in the embodiments.

[0040] The CVQKD SNR enhancement method based on repeated frame averaging in the embodiments has the following beneficial effects: the sending signal sent by the sending end contains repeated frames, and the repeated frames contain multiple quantum key frames that are the same in repetition, so that the receiving end can obtain multiple corresponding receiving frames to construct an average frame; since the average frame is constructed by averaging multiple receiving frames, the SNR of the average frame is significantly higher than that of a single receiving frame, and accordingly, the correlation coefficient between the average frame received by the receiving end and the quantum key frame to be sent by the sending end is also significantly higher than the correlation coefficient between a single receiving frame received by the receiving end and the quantum key frame to be sent by the sending end. The correlation coefficient of the average frame is significantly improved, effectively enhancing the transmission performance of the signal, and therefore, the method of quantum key distribution using repeated frames can achieve a longer transmission distance, effectively improve the accuracy of signal demodulation, enhance system performance, and thus ensure communication security. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A structure diagram of a quantum communication system to which the CVQKD SNR enhancement method based on repeated frame averaging in the embodiments can be applied;

[0042] Figure 2 A step diagram of the CVQKD SNR enhancement method based on repeated frame averaging executed by the sending end in the embodiments;

[0043] Figure 3 A data structure diagram of a sending signal and a receiving signal in the embodiments;

[0044] Figure 4 A step diagram of the CVQKD SNR enhancement method based on repeated frame averaging executed by the receiving end in the embodiments;

[0045] Figure 5This is a schematic diagram illustrating the effect of the CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging in the embodiment. Detailed Implementation

[0046] The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging in this embodiment can be applied to... Figure 1 The quantum communication system shown. (Refer to...) Figure 1 The quantum communication system includes a transmitter, a receiver, and an optical fiber channel. The transmitter needs to send information to the receiver through the optical fiber channel. The information to be sent is mainly presented in the form of quantum transmission signals. The content of the information to be sent can be a dual-polarization quantum key, thereby realizing dual-polarization quantum key distribution from the transmitter to the receiver (also known as continuous variable quantum key distribution, CVQKD).

[0047] In this embodiment, the complete CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging includes steps S1A-S3A performed by the transmitter and steps S1B-S4B performed by the receiver.

[0048] Reference Figure 1 The transmitting end includes a laser source, a frame repetition module, and a signal modulation module. Specifically, steps S1A-S3A can be executed by the frame repetition module.

[0049] Reference Figure 2 The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging, executed by the transmitter, includes the following steps:

[0050] S1A. Obtain the quantum key frame;

[0051] S2A. Generate repeating frames;

[0052] S3A. Sends duplicate frames to the receiving end.

[0053] In step S1A, the quantum key frame can be a quantum key that needs to be distributed to terminals such as receivers. Quantum random numbers can be used as the quantum key. Specifically, quantum random numbers can be generated and then packaged to obtain the quantum key frame. In this embodiment, it is assumed that the quantum key frame contains only quantum random numbers.

[0054] In this embodiment, when the sending end performs step S2A, which is the step of generating duplicate frames, it can specifically perform the following steps:

[0055] S201A. Determine the number of repetitions;

[0056] S202A. Copy the quantum key frame according to the number of repetitions to obtain multiple identical quantum key frames;

[0057] S203A. Generating a synchronization sequence;

[0058] S204A. Arranging the quantum key frames in sequence after the synchronization sequence to form a repeated frame.

[0059] In step S201A, the sending end determines the number of repetitions N, which is an integer greater than 1. Specifically, N can be a fixed value, for example, N = 10.

[0060] In step S202A, the sending end replicates the quantum key frame according to the number of repetitions to obtain quantum key frame 1, quantum key frame 2, …, and quantum key frame N. The N quantum key frames are exactly the same as the original quantum key frame.

[0061] In step S203A, the sending end generates a synchronization sequence, which can contain specific marker information, so that each device can identify the repeated frame according to the synchronization sequence and perform frame synchronization and other processing.

[0062] In step S204A, as shown in FIG. 2A, the frame repetition module in the sending end arranges the quantum key frames in sequence after the synchronization sequence to form a large repeated frame. Referring to FIG. 2A, the repeated frame sequentially includes the synchronization sequence, quantum key frame 1, quantum key frame 2, …, and quantum key frame N. Figure 3 Figure 3

[0063] In this embodiment, when the sending end performs step S3A, that is, sends the repeated frame to the receiving end, the following steps can be performed:

[0064] S301A. Generating a single-frequency laser;

[0065] S302A. Modulating the single-frequency laser with the repeated frame to obtain a sending signal;

[0066] S303A. Sending the sending signal to the receiving end through an optical fiber channel.

[0067] In step S301A, a single-frequency laser is generated by a laser light source in the sending end, and the laser is input into a signal modulation module. In step S302A, the frame repetition module inputs the repeated frame obtained by performing steps S201A-S204A into the signal modulation module, and the signal modulation module modulates the single-frequency laser with the repeated frame to obtain a sending signal, that is, a laser-form repeated frame. The signal modulation module sends the modulated single-frequency laser, that is, the sending signal, to the optical fiber channel, and the single-frequency laser carrying the repeated frame information is transmitted along the optical fiber channel to the receiving end.

[0068] ​​Since the transmission of the sending signal in the fiber channel will be affected by physical effects such as noise, the form of the signal received by the receiving end from the fiber channel may be different from the communication signal sent by the sending end in terms of spectrum and signal-to-noise ratio, and therefore in the embodiment, the signal received by the receiving end from the fiber channel is referred to as a received signal to distinguish it from the sending signal sent by the sending end.

[0069] In the embodiment, since the signal is carried by laser, the sending signal itself and the laser beam carrying the sending signal can not be distinguished without special instructions, and the received signal itself and the laser beam carrying the received signal can also not be distinguished.

[0070] With reference to Figure 1 , the receiving end includes a signal receiving module, a digital signal processing module, and a correlation coefficient calculation module.

[0071] In the embodiment, with reference to Figure 4 The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging executed by the receiving end includes the following steps:

[0072] S1B. receiving a received signal from the sending end;

[0073] S2B. obtaining a plurality of received frames from the received signal;

[0074] S3B. performing average processing on each received frame to obtain an average frame;

[0075] S4B. determining a quantum key according to the average frame.

[0076] In step S1B, the signal receiving module in the receiving end receives a laser beam from the fiber channel, thereby obtaining a received signal. In an ideal case without noise and fiber channel dispersion, the received signal is the same as the sending signal and contains the same information.

[0077] The signal receiving module sends the received signal to the digital signal processing module, and the digital signal processing module performs digital signal processing on the received signal. Specifically, in step S1B, the digital signal processing module performs down-conversion processing on the received signal.

[0078] In the embodiment, when the receiving end executes step S2B, that is, obtains a plurality of received frames from the received signal, the following steps can be executed:

[0079] S201B. obtaining a synchronization sequence from the received signal;

[0080] S202B. performing frame synchronization on the received signal according to the synchronization sequence;

[0081] S203B. From the frame-synchronized received signal, each received frame is sequentially segmented.

[0082] Steps S201B-S203B can be processed by the digital signal processing module. In step S201B, the digital signal processing module extracts the synchronization sequence from the received signal, performs step S202B to frame-synchronize the received signal according to the synchronization sequence, and then performs step S203B.

[0083] In step S203B, referring to Figure 3 , the digital signal processing module can segment the received signal according to the same frame length of the quantum key frame negotiated with the sending end, thereby sequentially segmenting the received frame 1, the received frame 2,..., and the received frame N. Among them, the received frame 1 corresponds to the quantum key frame 1, that is, in an ideal case, the received frame 1 is the same as the quantum key frame 1 and contains the same information; similarly, the received frame 2 corresponds to the quantum key frame 2,..., and the received frame N corresponds to the quantum key frame N.

[0084] After the digital signal processing module performs steps S201B-S203B, it performs step S3B to average process each received frame. In this embodiment, the digital signal processing module can average process all N received frames after obtaining the received frame 1, the received frame 2,..., and the received frame N. In this embodiment, assuming that a single received frame is represented as x1[i], i = 1, 2,..., N, then the average frame x

[0085]

[0086] is obtained by calculating average [N] from the following formula:

[0087] In step S4B, the digital signal processing module can perform matching filtering and phase recovery on the average frame x average [N], and the obtained data is determined as the quantum key assigned by the sending end, thereby realizing the allocation of the quantum key.

[0088] The principle of the CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging in this embodiment is that the sending signal sent by the sending end contains repeated frames, and the repeated frames contain multiple quantum key frames that are the same. This can enable the receiving end to obtain multiple corresponding received frames to construct an average frame. Referring to Figure 5Since the average frame is constructed by averaging a plurality of received frames (corresponding to quantum key frames), the signal-to-noise ratio (SNR) of the average frame is significantly higher than that of a single received frame. Accordingly, the correlation coefficient between the average frame received by the receiving end and the quantum key frame to be sent by the sending end is also significantly higher than the correlation coefficient between a single received frame received by the receiving end and the quantum key frame to be sent by the sending end. The correlation coefficient of the average frame is significantly improved, effectively enhancing the transmission performance of the signal. Therefore, quantum key distribution using the repeated frame method can achieve a longer transmission distance.

[0089] In this embodiment, with reference to Figure 1 , the receiving end also calculates the correlation coefficient during the reception and processing of the received signal, controls the reception process according to the correlation coefficient, and feeds back the correlation coefficient to the sending end through the optical fiber channel.

[0090] Specifically, when sending the repeated frame, the sending end can send in the order of the synchronization sequence, the quantum key frame 1, the quantum key frame 2, and so on. In this way, when performing step S2B, the receiving end can immediately segment the received data without waiting for the complete repeated frame to be received and segmented. In this way, the receiving end can synchronously receive the synchronization sequence, the received frame 1, the received frame 2, and so on in turn.

[0091] In this embodiment, the receiving end can also calculate the total average frame x average [N] after receiving N received frames, that is, after receiving data equivalent to a complete repeated frame. Then, the receiving end can feed back the correlation coefficient correlation average [N] between the average frame x N and the quantum key frame to the sending end through the optical fiber channel. N The correlation coefficient correlation N is defined as an index for measuring the strength of the linear relationship between the data related to the quantum random key received by the receiving end and the quantum key frame of the sending end. The value of the correlation coefficient correlation N is between -1 and 1, where 1 represents complete positive correlation, -1 represents complete negative correlation, and 0 represents no linear relationship. In the communication process, it is desirable for the correlation coefficient correlation

[0092] In this embodiment, the receiving end can feed back the correlation coefficient correlation N to the sending end. The sending end receives the correlation coefficient correlation N fed back by the receiving end.After that, the number of repetitions can be dynamically adjusted according to the correlation coefficient when performing step S201A, i.e., the step of determining the number of repetitions. Specifically, the number of repetitions is positively correlated with the correlation coefficient correlation N and negatively correlated with the correlation coefficient correlation

[0093] For example, if the sending end receives the correlation coefficient correlation N , the sending end will increase the number of repetitions N accordingly, so that the sending end will send a longer repeated frame when sending the next repeated frame (a new repeated frame generated by a new quantum random number); the larger the correlation coefficient correlation N , the smaller the number of repetitions N will be adjusted accordingly, so that the sending end will send a shorter repeated frame when sending the next repeated frame (a new repeated frame generated by a new quantum random number). N

[0094] In this embodiment, the receiving end feeds back the correlation coefficient to the sending end, and the principle of the sending end adjusting the number of repetitions according to the correlation coefficient is that if x1[i] represents a quantum key frame in a repeated frame, then x1[i] can be regarded as the addition of signal s1[i] and noise n1[i], i.e.

[0095] x1[i] = s1[i] + n1[i], 1≤i≤,

[0096] where N is the number of samples. A repeated frame contains N quantum key frames, so the repeated frame x N [i] can be represented as the addition of the N quantum key frames, i.e.

[0097]

[0098] where ​represents N-frame noise addition. Since the mean of the random noise n[i] is 0, when N approaches infinity, the N-frame noise addition also approaches 0. The correlation coefficient in the embodiment is an index for measuring the strength of the linear relationship between two data frames, wherein the value of the correlation coefficient is between -1 and 1, wherein 1 represents a complete positive correlation, -1 represents a complete negative correlation, and 0 represents no linear relationship. Therefore, the correlation coefficient of the signal frame obtained by averaging the N-frame quantum key frames approaches 1. Since the repetition number N cannot be infinite in the actual system, the specific value of the repetition number N will affect the noise size in the received signal. Specifically, the larger the repetition number N is, the smaller the noise is, but the larger the repetition number N is, the lower the communication efficiency is. In the case of a larger correlation coefficient, a smaller repetition number N is required. Therefore, the sender can reduce the number of quantum key frames remaining in the transmission of the same repeated frame or reduce the length of the transmission of the next repeated frame, so as to obtain a higher communication efficiency while ensuring the transmission of accurate quantum keys. Conversely, in the case of a smaller correlation coefficient, a larger repetition number N is required. Therefore, the sender can increase the number of quantum key frames remaining in the transmission of the same repeated frame or increase the length of the transmission of the next repeated frame, so as to ensure the transmission of accurate quantum keys.

[0099] In the embodiment, when the receiver performs step S2B, that is, when the receiver obtains a plurality of received frames from the received signal, the receiver can further perform the following steps:

[0100] S204B. When the number of the segmented received frames is equal to or greater than the number threshold, performing an average processing on each of the received frames other than the last received frame among all the segmented received frames to obtain an average intermediate frame;

[0101] S205B. Determining a correlation coefficient according to the last received frame among all the segmented received frames and the average intermediate frame;

[0102] S206B. When the correlation coefficient is equal to or greater than the coefficient threshold, interrupting the receiving process of the received signal;

[0103] S207B. When the correlation coefficient is less than the coefficient threshold, continuing the receiving process of the received signal.

[0104] Suppose that before performing steps S204B-S207B, the receiver has segmented received frame 1, received frame 2, …, received frame M (M is an integer and 1

[0105]

[0106] The calculation is performed so as to obtain the average intermediate frame x average [M-1], that is, the average value of the first M-1 received frames that have been received.

[0107] In step S205B, a correlation coefficient is determined according to the last received frame among all the divided received frames and the average intermediate frame;

[0108] S206B. When the correlation coefficient is equal to or greater than the coefficient threshold value, the receiving process of the received signal is interrupted;

[0109] S207B. When the correlation coefficient is less than the coefficient threshold value, the receiving process of the received signal is continued.

[0110] In step S205B, the digital signal processing module can calculate the correlation coefficient correlation average between the last received frame, that is, the received frame M and the average intermediate frame x M，averageM-1 ; if the correlation coefficient correlation M，averageM-1 is equal to or greater than the coefficient threshold value, it can be determined that the correlation coefficient correlation M，averageM-1 is relatively large, and the receiving end can execute step S206B to interrupt the receiving process of the received signal, that is, to no longer receive the received frame M+1 (corresponding to the quantum key frame M+1), the received frame M+2 (corresponding to the quantum key frame M+2), …, the received frame N (corresponding to the quantum key frame N), etc.; if the correlation coefficient correlation M，averageM-1 is less than the coefficient threshold value, it can be determined that the correlation coefficient correlation M，averageM-1 is relatively small, and the receiving end can execute step S207B to continue the receiving process of the received signal, so as to continue to receive the received frame M+1 (corresponding to the quantum key frame M+1), the received frame M+2 (corresponding to the quantum key frame M+2), …, the received frame N (corresponding to the quantum key frame N), etc.

[0111] In this embodiment, the principle of executing steps S204B-S207B is that the correlation coefficient correlation M，averageM-1 represents the correlation coefficient between the multiple received frames that have been received by the receiving end at present, if the correlation coefficient is relatively large, it indicates that the received frames that have been received at present can accurately recover the quantum key, so as to end the receiving process of the received signal in advance; on the contrary, if the correlation coefficient is relatively small, the receiving process of the received signal needs to be continued, so as to obtain more received frames.

[0112] In this embodiment, steps S204B-S207B constitute a loop body, and the receiving end can execute steps S204B-S207B once every time a new receiving frame is segmented, thereby guaranteeing the transmission rate and accuracy of the quantum key.

[0113] For example, in this embodiment, the receiving end can feed back the correlation coefficient correlation M，averageM-1 to the sending end. After receiving the correlation coefficient correlation M，averageM-1 , the sending end correspondingly adjusts the repetition number N. If the correlation coefficient correlation M，averageM-1 is smaller, the sending end correspondingly increases the repetition number N, so that the sending end transmits more quantum key frames when transmitting the next quantum key frame M+1, quantum key frame M+2,..., quantum key frame N in the current repetition frame. If the correlation coefficient correlation M，averageM-1 is larger, the sending end correspondingly decreases the repetition number N, so that the sending end transmits fewer quantum key frames when transmitting the next quantum key frame M+1, quantum key frame M+2,..., quantum key frame N in the current repetition frame.

[0114] It should be noted that, unless otherwise specified, when a certain feature is referred to as being “fixed” or “connected” to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. In addition, the up, down, left, right, and the like used in the present disclosure are merely relative to the positional relationship between the components of the present disclosure in the drawings. The singular forms “a”, “an” and “the” used in the present disclosure are also intended to include the plural forms, unless the context clearly indicates otherwise. In addition, unless otherwise defined, all technical and scientific terms used in the present embodiment have the same meaning as generally understood by those skilled in the art. The terms used in the present embodiment are only used to describe the specific embodiments and are not intended to limit the present application. The term “and / or” used in the present embodiment includes any combination of one or more related listed items.

[0115] It should be understood that although the terms first, second, third, etc. can be used in the present disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish one type of element from another type of element. For example, without departing from the scope of the present disclosure, a first element can also be referred to as a second element, and similarly, a second element can also be referred to as a first element. The use of any and all examples or exemplary language (e.g., “for example”, “as such”, etc.) provided in the present embodiment is only intended to better illustrate the embodiments of the present application, and unless otherwise required, does not impose a limitation on the scope of the present application.

[0116] It should be appreciated that embodiments of the present application can be implemented or realized in a computing hardware, a combination of hardware and software, or by computer instructions stored on a non-transitory computer readable storage medium. The methods can be implemented using standard programming techniques - including the configuration of a non-transitory computer readable storage medium with computer program instructions stored thereon, wherein the storage medium is configured such that it causes a computer to operate in a specific and predefined manner as described in the various embodiments and figures according to the methods described in the various embodiments. Each program can be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the programs can be implemented in assembly or machine language, if desired. In any case, the language can be a compiled or interpreted language. Furthermore, the programs can be able to operate with a specific dedicated integrated circuit that is programmed to perform the methods described in the various embodiments.

[0117] Further, the operations of the processes described in the embodiments can be performed in any suitable order, unless otherwise indicated herein or otherwise clearly contradicted by context. The processes described in the embodiments (or variations and / or combinations thereof) can be implemented under the control of one or more computer systems configured with executable instructions (e.g., computer programs, one or more computer programs, or one or more applications), and can be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) executing collectively on one or more processors, by hardware, or combinations thereof. The computer programs include a plurality of instructions executable by one or more processors.

[0118] Further, the methods can be implemented in any suitable type of computing platform operably connected to, including but not limited to, a personal computer, a mini-computer, a mainframe, a workstation, a network or distributed computing environment, a stand-alone or integrated computer platform, or in communication with a charged particle tool or other imaging device, and the like. Aspects of the present application can be implemented in machine readable code stored on a non-transitory storage medium or device, whether removable or integrated to the computing platform, such as a hard disk, an optical read and / or write storage medium, RAM, ROM, and the like, such that it is readable by a programmable computer and, when the storage medium or device is read by the computer, is used to configure and operate the computer to perform the processes described herein. Further, the machine readable code, or portions thereof, can be transmitted over a wired or wireless network. The present application includes these and other different types of non-transitory computer readable storage media when the instructions or programs implementing the above steps are included in conjunction with a microprocessor or other data processor. The present application also includes the computer itself when programmed according to the methods and techniques of the present application.

[0119] The computer program can be applied to input data to perform the functions of the present embodiments to transform the input data to generate output data that is stored to non-volatile memory. The output information can also be applied to one or more output devices such as a display. In a preferred embodiment of the present application, the transformed data represents a physical and tangible object, including a particular visual depiction of the physical and tangible object produced on a display.

[0120] The above merely preferred embodiments of the present application and are not intended to limit the present application. The present application can be implemented in various ways without departing from the spirit and principles of the present application. The technical solutions and / or embodiments of the present application can be variously modified and changed within the scope of the present application.

Claims

1. A CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging, characterized in that, The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging includes steps applied at the transmitting end and steps applied at the receiving end; The steps applied to the sending end include: Obtain the quantum key frame; Generate repeating frames; the repeating frames include multiple repeating quantum key frames; Send the repeated frame to the receiving end; The steps applied at the receiving end include: The received signal is received from the transmitting end; Multiple received frames are obtained from the received signal; each received frame corresponds to a quantum key frame. The received frames are averaged to obtain an average frame. The quantum key is determined based on the average frame. The process of obtaining multiple received frames from the received signal includes: Obtain the synchronization sequence from the received signal; The received signal is frame-synchronized according to the synchronization sequence; Each received frame is sequentially segmented from the received signal after frame synchronization; When the number of segmented received frames is equal to or greater than the number threshold, the average of all received frames except the last received frame is performed to obtain the average intermediate frame. The correlation coefficient is determined based on the last received frame among all the segmented received frames and the average intermediate frame. When the correlation coefficient is equal to or greater than the coefficient threshold, the reception process of the received signal is interrupted. When the correlation coefficient is less than the coefficient threshold, the receiving process of the received signal continues.

2. The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging according to claim 1, characterized in that, The acquisition of the quantum key frame includes: Generate quantum random numbers; The quantum key frame is generated based on the quantum random number.

3. The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging according to claim 1, characterized in that, The generation of repeating frames includes: Determine the number of repetitions; The quantum key frame is copied according to the number of repetitions to obtain multiple identical quantum key frames; Generate a synchronization sequence; Each of the quantum key frames is arranged sequentially after the synchronization sequence to form the repeating frame.

4. The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging according to any one of claims 1-3, characterized in that, Sending the repeated frame to the receiving end includes: Generate a single-frequency laser; The single-frequency laser is modulated using the repeated frames to obtain a transmitted signal; The transmitted signal is sent to the receiving end via an optical fiber channel.

5. The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging according to claim 1, characterized in that, The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging also includes: Obtain the quantum key frame from the transmitter via a lossless channel; The correlation coefficient is determined based on the quantum key frame and the average frame.

6. The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging according to claim 5, characterized in that, The CVQKD signal-to-noise ratio enhancement method based on repeated frame averaging also includes: The correlation coefficient is fed back to the sending end.

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