A code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution

Abstract

The present invention proposes a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution. The system implementing the method mainly includes continuous laser sources at Alice and Bob ends, a pulse modulation module, a Gaussian modulation module, an optical attenuator, and a polarization multiplexing module. The polarization demultiplexing module, an optical collimator, and a balanced homodyne detector at Charlie end. The steps of the method are: Step 1: Alice and Bob ends prepare Gaussian coherent states; Step 2: Charlie end performs Bell measurement; Step 3: Shot noise normalization of measurement data; Step 4: Phase compensation of measurement data; Step 5: Measurement angle error estimation; Step 6: Measurement angle error compensation. Step 7: Calculate and generate a security key. In practical applications, due to the non-ideality of the phase modulator, non-ideal Bell detection at the Charlie end will occur, resulting in a reduction in the system code rate. The present invention can compensate for the angle error during measurement, achieve ideal Bell detection, and improve the security code rate of the system.

Description

Technical Field

[0001] The present invention relates to the field of quantum secure communication, and in particular to a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution. Background Art

[0002] Information plays an important role in the development of human history. In the 21st century, it is an era of information explosion. It is particularly important to ensure the security of information. With the emergence of quantum computers, traditional encryption methods, such as RSA, face the risk of being cracked. In order to solve this potential risk, people proposed the encryption method of quantum key distribution (QKD) based on the quantum no-cloning theorem and the uncertainty principle, which has absolute security in theory. QKD includes discrete variable quantum key distribution (DV-QKD) and continuous variable quantum key distribution (CV-QKD). Among them, CV-QKD has received widespread attention due to its simple equipment, low price, and strong compatibility with existing communication systems.

[0003] Although CV-QKD is absolutely secure in theory, in practical applications, due to many factors such as device imperfections, it will not be consistent with the theoretical model, resulting in security issues, such as saturation attacks against detector imperfections. In response to this situation, people proposed continuous variable measurement device-independent quantum key distribution (CV-MDI ​​QKD), which effectively eliminates side channel attacks on the measurement device by introducing an untrusted third party Charlie between the communicating parties through Bell measurement.

[0004] In recent years, research on CV-MDI ​​QKD schemes has made significant progress. Coherent state CV-MDI ​​QKD in space and optical fiber has been theoretically studied and experimentally verified.

[0005] In coherent CV-MDI ​​QKD, the signals at Alice and Bob are Bell detected at Charlie. Due to the non-ideality of the phase modulator, the detection of the P component cannot accurately rotate the phase by 90°. This introduces a measurement angle error into the measurement, resulting in non-ideal Bell detection, which will reduce the code rate of the system. Therefore, compensation for the measurement angle error and code rate analysis are very important. Summary of the invention

[0006] The purpose of the present invention is to solve the non-ideal Bell problem caused by the imperfection of the phase modulator during Bell detection in a continuous variable measurement device independent quantum key distribution system, and to propose a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device independent quantum key distribution, which improves the security code rate of the system.

[0007] A system for implementing a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution is as follows:

[0008] The Alice end is composed of a first continuous laser source, a first pulse modulation module, an optical beam splitter 1, a first Gaussian modulation module, a first delay module, an optical attenuator 1, and a first polarization multiplexing module.

[0009] At Alice's end, the first continuous laser source generates continuous coherent light. After the coherent light passes through the first pulse modulation module, it becomes a pulse light with a certain repetition frequency and duty cycle. This pulse light is divided into quantum signal pulse light and reference signal pulse light by the optical beam splitter 1. The reference signal pulse light directly enters the first polarization multiplexer, and the quantum signal pulse light passes through the first Gaussian modulation module to modulate the key information on the quantum signal pulse light. The quantum signal pulse light is then attenuated to the required modulation variance level by the optical attenuator 1, and then the quantum signal pulse light and the reference signal pulse light are multiplexed in the time domain by the first delay module. Finally, it enters the first polarization multiplexer to multiplex the polarization of the reference signal pulse light and the quantum signal pulse light, and transmits them together to the quantum channel 1.

[0010] The Bob end is composed of a second continuous laser source, a second pulse modulation module, an optical beam splitter 2, a second Gaussian modulation module, a second delay module, an optical attenuator 2, and a second polarization multiplexing module.

[0011] At Bob's end, the second continuous laser source generates continuous coherent light. After the coherent light passes through the second pulse modulation module, it becomes a pulse light with a certain repetition frequency and duty cycle. This pulse light is divided into quantum signal pulse light and local oscillator pulse light by optical beam splitter 2, wherein the local oscillator signal pulse light directly enters the second polarization multiplexer, and the quantum signal pulse light passes through the second Gaussian modulation module to modulate the key information on the quantum signal pulse light, and then the quantum signal pulse light is attenuated to the required modulation variance level through the optical attenuator 2, and then the quantum signal pulse light and the local oscillator pulse light are multiplexed in the time domain through the second delay module, and finally enter the second polarization multiplexer to multiplex the polarization of the local oscillator pulse light and the quantum signal pulse light, and transmit them together to quantum channel 2.

[0012] The Charlie end comprises a first polarization demultiplexing module, a third delay module, an optical beam splitter, a second polarization demultiplexing module, a fourth delay module, an optical collimator, and a balanced homodyne detector.

[0013] At the Charlie end, the pulse light transmitted through the quantum channel 1 is demultiplexed by the first polarization demultiplexing module into reference signal pulse light and quantum signal pulse light, wherein the reference signal pulse light passes through the third delay module to achieve balancing on the optical path, and after passing through the optical beam splitter 7, it is equally divided into the optical beam splitter 10. In the optical beam splitter 11, the signal pulse light is coupled into space through the optical collimator 2 and enters the optical beam splitter 5. The pulse light transmitted through the quantum channel 2 is demultiplexed by the second polarization demultiplexing module into local oscillator pulse light and quantum signal pulse light, wherein the local oscillator pulse light passes through the fourth delay module to balance the optical path, and then is divided into two beams through the optical beam splitter 3. One part of the local oscillator pulse light is divided into two beams through the optical beam splitter 6, and one part passes through the phase modulator 2 and enters the optical beam splitters 10 and 11 with the other beam to interfere with the reference signal pulse light and enter the balanced homodyne detectors 3 and 4 for detection. The other local oscillator pulse light is divided into two beams by the optical beam splitter 4, and both pass through the optical collimator 3, the optical collimator 4, one beam passes through the phase modulator 1 and the other beam enters the optical beam splitter 8, 9. The signal pulse light is coupled into the space by the optical collimator 1, enters the beam splitter 5 to interfere with the other signal light, and then interferes with the local oscillator light in the optical collimators 3, 4 to enter the balanced homodyne detectors 1, 2 for detection.

[0014] Preferably, the data obtained by detection by the balanced homodyne detector in the above system is used for phase compensation.

[0015] Preferably, the data measured by the balanced homodyne detectors 1 and 2 in the above system are used for subsequent measurement angle error estimation and compensation to generate a key.

[0016] The steps of a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution provided by the present invention are as follows:

[0017] Step 1: After balanced homodyne detection modules 1 and 2, Bell detection is completed to obtain two sets of data (x i ,p i ), i=1,2,3...。

[0018] Step 2: After balanced homodyne detection modules 3 and 4, heterodyne coherent detection is completed to obtain two sets of data (x j ,p j ), j=1,2,3...。

[0019] Step 3: Transform the data (x i ,p i ), (x j ,pj ) The data shot noise is normalized to obtain the data (x' i ,p' i ), (x' j ,p' j )

[0020] Step 4: Based on the data obtained in step 3 (x' i ,p' i ), for data (x' j ,p' j ) to perform phase compensation and obtain two new sets of data (x k ,p k ), k=1,2,3...。

[0021] Step 5: According to the new data (x obtained in step 4 k ,p k ), and estimate the measurement angle error.

[0022] Step 6: Based on the estimation results in step 5, perform data p k Measure angle error compensation and obtain data p m , m=1,2,3...。

[0023] Step 7: Calculate and analyze the security code rate and generate the key.

[0024] Preferably, the measurement angle error estimation method described in step 5 is:

[0025] The formula for calculating the measurement angle error is:

[0026]

[0027] Where θ is the measurement angle error, <x k ,p k > is the covariance between the two sets of data, V A , V B Prepare the modulation variance of the Gaussian state for the data Alice, Bob.

[0028] Preferably, the measurement angle error compensation method in step 6 is:

[0029] The formula for compensating the measurement angle error is:

[0030]

[0031] Among them, P m is the P component after compensation.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] In the Bell detection process of the continuous variable measurement device-independent quantum key distribution system, when measuring the P component, the phase of the local oscillator light needs to be rotated 90°, but due to the non-ideality of the phase modulator, the measurement of the P component will be inaccurate, resulting in non-ideal Bell, which reduces the security code rate. The present invention provides a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution, which compensates for the measurement angle error, realizes ideal Bell measurement, and improves the code rate of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a specific implementation system of the present invention

[0035] Figure 2 Flow chart of the method of the present invention

[0036] Figure 3 The equivalent entanglement model diagram corresponding to the system of the present invention is

[0037] Figure 4 This is a comparison diagram of the simulation effect after the implementation of the present invention Specific implementation methods

[0038] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail and in depth below with reference to the accompanying drawings.

[0039] The present invention provides a code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution, such as Figure 1 As shown, the system includes Alice, Bob, and Charlie.

[0040] The Alice end is composed of a first continuous laser source, a first pulse modulation module, an optical beam splitter 1, a first Gaussian modulation module, a first delay module, an optical attenuator 1, and a first polarization multiplexing module.

[0041] At Alice's end, the first continuous laser source generates continuous coherent light. After the coherent light passes through the first pulse modulation module, the module is composed of two cascaded intensity modulators, which modulate the coherent light into a pulse light with a certain repetition frequency and duty cycle. This pulse light is divided into quantum signal pulse light and reference signal pulse light by a 99:1 optical beam splitter 1, wherein the reference signal pulse light directly enters the first polarization multiplexer, and the quantum signal pulse light passes through the first Gaussian modulation module to modulate the key information on the quantum signal pulse light. In this process, the phase information is loaded on the phase modulator and obeys the uniform distribution of [0, 2π], and the intensity information is loaded on the intensity modulator and obeys the Rayleigh distribution. Then, the quantum signal pulse light is attenuated to the level of the required modulation variance through the optical attenuator 1, and then the quantum signal pulse light and the reference signal pulse light are multiplexed in the time domain through the first delay module. Finally, it enters the first polarization multiplexer to multiplex the polarization of the reference signal pulse light and the quantum signal pulse light, and transmit them together to the quantum channel 1.

[0042] The Bob end is composed of a second continuous laser source, a second pulse modulation module, an optical beam splitter 2, a second Gaussian modulation module, a second delay module, an optical attenuator 2, and a second polarization multiplexing module.

[0043] At Bob's end, the second continuous laser source generates continuous coherent light. After the coherent light passes through the second pulse modulation module, which is composed of two cascaded intensity modulators, the coherent light becomes a pulse light with a certain repetition frequency and duty cycle. This pulse light is divided into quantum signal pulse light and local oscillator pulse light by a 99:1 optical beam splitter 2, wherein the local oscillator signal pulse light directly enters the second polarization multiplexer, and the quantum signal pulse light passes through the second Gaussian modulation module to modulate the key information on the quantum signal pulse light. In this process, the phase information is loaded on the phase modulator and obeys the uniform distribution of [0, 2π], and the intensity information is loaded on the intensity modulator and obeys the Rayleigh distribution. Then, the quantum signal pulse light is attenuated to the level of the required modulation variance through the optical attenuator 2, and then the quantum signal pulse light and the local oscillator pulse light are multiplexed in the time domain through the second delay module. Finally, it enters the second polarization multiplexer to multiplex the polarization of the local oscillator pulse light and the quantum signal pulse light, and transmits them together to the quantum channel 2.

[0044] The Charlie end comprises a first polarization demultiplexing module, a third delay module, an optical beam splitter, a second polarization demultiplexing module, a fourth delay module, an optical collimator, and a balanced homodyne detector.

[0045] The Charlie end comprises a first polarization demultiplexing module, a third delay module, an optical beam splitter, a second polarization demultiplexing module, a fourth delay module, an optical collimator, and a balanced homodyne detector.

[0046] At the Charlie end, the pulse light transmitted through the quantum channel 1 is demultiplexed by the first polarization demultiplexing module into reference signal pulse light and quantum signal pulse light, wherein the reference signal pulse light passes through the third delay module to achieve balancing on the optical path, and after passing through the optical beam splitter 7, it is equally divided into the optical beam splitter 10. In the optical beam splitter 11, the signal pulse light is coupled into space through the optical collimator 2 and enters the optical beam splitter 5. The pulse light transmitted through the quantum channel 2 is demultiplexed by the second polarization demultiplexing module into local oscillator pulse light and quantum signal pulse light, wherein the local oscillator pulse light passes through the fourth delay module to balance the optical path, and then is divided into two beams through the optical beam splitter 3. One part of the local oscillator pulse light is divided into two beams through the optical beam splitter 6, and one part passes through the phase modulator 2 and enters the optical beam splitters 10 and 11 with the other beam to interfere with the reference signal pulse light and enter the balanced homodyne detectors 3 and 4 for detection. The other local oscillator pulse light is divided into two beams by the optical beam splitter 4, and both pass through the optical collimator 3, the optical collimator 4, one beam passes through the phase modulator 1 and the other beam enters the optical beam splitter 8, 9. The signal pulse light is coupled into the space by the optical collimator 1, enters the beam splitter 5 to interfere with the other signal light, and then interferes with the local oscillator light in the optical collimators 3, 4 to enter the balanced homodyne detectors 1, 2 for detection.

[0047] In the module, the reference pulse light and the local oscillator pulse light interfere with each other, and the x and p components (x j ,p j ), used as phase compensation, the signal pulse light from Alice and Bob interferes with the local oscillator pulse light and is detected by balanced homodyne detectors 1 and 2 to obtain the required data (x i ,p i ).

[0048] The measurement angle error compensation method for continuous variable measurement device-independent quantum key distribution is as follows: Figure 2 As shown, the specific steps are as follows:

[0049] Step 1: Alice and Bob prepare Gaussian coherent states, whose X and P components are:

[0050] X A =A sigA cos(φ sigA ) (3)

[0051] P A =A sigA sin(φ sigA ) (4)

[0052] X B =A sigB cos(φ sigB ) (5)

[0053] P B =A sigB sin(φ sigB ) (6)

[0054] Among them A sigA , A sigB Obeys Rayleigh distribution, φ sigA ,φ sigB Obeys uniform distribution in [0,2π]

[0055] Step 2: Perform Bell measurement at Charlie end to get data

[0056]

[0057]

[0058]

[0059] Among them, A Lo is the intensity of the local oscillator light, R is the responsivity of the detector, and η is the detection efficiency of the detector. shiftA ,φ shiftB is the phase drift between Alice and Bob

[0060] However, due to the imperfection of the phase modulator in the second heterodyne detection module, the phase is not rotated by 90°, so the actual P component is:

[0061]

[0062] φ ps is the angle error when measuring the phase modulator.

[0063] Step 3, normalize the data shot noise obtained in step 2, the result is:

[0064]

[0065]

[0066] Step 4: Use the data from the balanced homodyne detectors 3 and 4 to perform phase compensation. The result is:

[0067]

[0068]

[0069] Step 5: Use the data from step 4 to estimate the measurement angle error

[0070]

[0071] in, is the covariance of the two, V Ax , V Bx Prepare the modulation variance of the Gaussian states for Alcie and Bob.

[0072] Step 6: Measure the compensation of the angle error. The P component after compensation is

[0073]

[0074]

[0075] in, is the P component after compensation.

[0076] Step 7: Calculate and analyze the security code rate and generate the key.

[0077] according to Figure 3 For the model shown, the security code rate calculation method of non-ideal Bell detection CV-MDI ​​QKD is as follows:

[0078] The covariance matrix of Alice and Bob's end sources can be described as:

[0079]

[0080] in, μ A , μ B Prepare the variance of the data for Alice and Bob.

[0081] After passing through the channel, under Eve's dual-mode attack, we take the optimal attack:

[0082]

[0083] Where g = -φ, g' = φ

[0084] Under certain physical conditions, we set:

[0085]

[0086]

[0087] T A(B) is the channel transmittance between Charlie and Alice and Bob, ε A(B) is the excess noise introduced between Charlie, Alice and Bob.

[0088] Under Bell detection at Charlie end, there are

[0089]

[0090]

[0091] Since there is an angle error in the measurement of the P component, this error is expressed by the phase rotation matrix

[0092]

[0093] θ is the measurement angle error. So the actual P component expression is:

[0094]

[0095] After Charlie published his measurement results, Bob modified mode B2 according to his published results:

[0096]

[0097] g x(p) is the gain factor related to channel attenuation.

[0098] We use the idea of ​​entanglement exchange to estimate the code rate. This method only needs to use the covariance matrix to complete the calculation of the code rate. Therefore, we combine the X and P component expressions derived from the above formula to obtain the covariance matrix describing the system state:

[0099]

[0100] In the Matrix T x(p) represents the equivalent transmittance between Alice and Bob, T A is the channel transmittance between Alice and Charlie, and the equivalent excess noise of the system ε x(p) for:

[0101]

[0102]

[0103] In the bit rate analysis, in order to make ε x(p) To obtain the optimal value, we take

[0104] At this time, the equivalent excess noise we get is:

[0105]

[0106]

[0107] With the above matrix, we can calculate the security code rate as:

[0108] K=βI(A:B)-S(E:B) (26)

[0109] β is the coordination efficiency, and I(A:B) is the mutual information between Alice and Bob:

[0110] I(A:B)=I x (A:B)+I p (A:B) (27)

[0111]

[0112]

[0113] is the variance of the X, P components of mode B2

[0114] S(E:B)=S(E)-S(E|B) (30)

[0115] In the case of Eve's ability to purify the system, we can obtain S(E) = S(A2B'2). For a covariance matrix, we can use the symplectic eigenvalues ​​of the matrix to calculate its von Neumann entropy:

[0116]

[0117]

[0118] For any mode covariance matrix, we can use To calculate the symplectic eigenvalues ​​of the matrix, where:

[0119]

[0120] After heterodyning mode B'2, mode A2 is projected onto a new Gaussian state:

[0121]

[0122]

[0123] Then, the von Neumann entropy is solved according to the method of calculating the symplectic eigenvalues.

[0124] like Figure 4 As shown, the code rate analysis method of the present invention is used to simulate the change of the security code rate of the extreme asymmetric structure CV-MDI-QKD before and after the measurement angle error compensation. It can be seen from the figure that as the measurement angle error increases, the security code rate will seriously drop and the transmission distance will also become shorter. After compensation, the code rate and distance can be significantly improved, indicating that the method proposed in the present invention has a very significant effect.

[0125] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution, characterized in that: The system for implementing the method includes an Alice end, a Bob end, and a Charlie end, wherein: the Alice end is composed of a first continuous laser source, a first pulse modulation module, an optical beam splitter 1, a first Gaussian modulation module, a first delay module, an optical attenuator 1, and a first polarization multiplexing module; At Alice's end, the first continuous laser source generates continuous coherent light. After the coherent light passes through the first pulse modulation module, it becomes a pulse light with a certain repetition frequency and duty cycle. The pulse light is divided into quantum signal pulse light and reference signal pulse light by the optical beam splitter 1, wherein the reference signal pulse light directly enters the first polarization multiplexer, and the quantum signal pulse light passes through the first Gaussian modulation module to modulate the key information on the quantum signal pulse light, and then the quantum signal pulse light is attenuated to the required modulation variance level by the optical attenuator 1, and then the quantum signal pulse light and the reference signal pulse light are multiplexed in the time domain by the first delay module, and finally enter the first polarization multiplexer to multiplex the polarization of the reference signal pulse light and the quantum signal pulse light, and transmit them together to the quantum channel 1; The Bob end is composed of a second continuous laser source, a second pulse modulation module, an optical beam splitter 2, a second Gaussian modulation module, a second delay module, an optical attenuator 2, and a second polarization multiplexing module; At Bob's end, the second continuous laser source generates continuous coherent light. After the coherent light passes through the second pulse modulation module, it becomes a pulse light with a certain repetition frequency and duty cycle. This pulse light is divided into quantum signal pulse light and local oscillator pulse light by the optical beam splitter 2, wherein the local oscillator signal pulse light directly enters the second polarization multiplexer, and the quantum signal pulse light passes through the second Gaussian modulation module to modulate the key information on the quantum signal pulse light, and then the quantum signal pulse light is attenuated to the required modulation variance level through the optical attenuator 2, and then the quantum signal pulse light and the local oscillator pulse light are multiplexed in the time domain through the second delay module, and finally enter the second polarization multiplexer to multiplex the polarization of the local oscillator pulse light and the quantum signal pulse light, and transmit them together to the quantum channel 2; Charlie end consists of a first polarization demultiplexing module, a third delay module, an optical beam splitter, a second polarization demultiplexing module, a fourth delay module, an optical collimator, and a balanced homodyne detector; At Charlie's end, the pulse light transmitted through quantum channel 1 is demultiplexed by the first polarization demultiplexing module into reference signal pulse light and quantum signal pulse light, wherein the reference signal pulse light passes through the third delay module to achieve balancing on the optical path, passes through the optical beam splitter 7, and then enters the optical beam splitter 10 in equal parts. In the optical beam splitter 11, the signal pulse light is coupled into space through the optical collimator 2 and enters the optical beam splitter 5. The pulse light transmitted through quantum channel 2 is demultiplexed by the second polarization demultiplexing module into local oscillator pulse light and quantum signal pulse light, wherein the local oscillator pulse light passes through the fourth delay module to balance the optical path, and then passes through the optical beam splitter 3. Divided into two beams, one local oscillator pulse light is divided into two beams by optical beam splitter 6, one beam passes through phase modulator 2 and enters optical beam splitters 10, 11 with the other beam to interfere with reference signal pulse light and enter balanced homodyne detectors 3, 4 for detection, and the other local oscillator pulse light is divided into two beams by optical beam splitter 4, and both pass through optical collimator 3, optical collimator 4, one beam passes through phase modulator 1 and enters optical beam splitters 8, 9 with the other beam, the signal pulse light is coupled into space by optical collimator 1, enters beam splitter 5 to interfere with another signal light, and interferes with the local oscillator light in optical collimators 3, 4 to enter balanced homodyne detectors 1, 2 for detection; The detection results of balanced homodyne detectors 1 and 2 are recorded as (x i ,p i ), where x i represents the detection result of the reference signal light X component, p i represents the detection result of the reference signal light P component, where i = 1, 2, 3, ..., and the result after shot noise normalization is recorded as (x i ',p i '), the detection results of the balanced homodyne detectors 3 and 4 are recorded as (x j ,p j ), where x j represents the detection result of the X component of the quantum signal light, p j represents the detection result of the quantum signal light P component, where j = 1, 2, 3, ..., and the result after shot noise normalization is recorded as (x' j ,p' j ), according to the normalized result of the reference signal light (x i ',p i ') can calculate the phase drift angle θ caused by the channel i for Since the quantum signal light and the reference signal light pass through the same channel, the phase drift θ i After that, the quantum signal light phase is compensated, and the compensated data is (x k ,p k ), whose expression is x k =x' j cosθ i +p' j sinθ i , (2) p k =-x' j sinθ i +p' j cosθ i , (3) After compensating for the channel phase drift, it is necessary to compensate for the measurement angle error caused by the actual device. Since the angles between the X and P components are relative, the measurement angle errors of the X and P components can be attributed to a certain component. Here, it is assumed that there is a measurement angle error in the P component, and its measurement angle error θ is estimated to be in<xk,pk> represents the covariance between the phase-compensated data (xk, pk), V A and V B They represent the variance of the Gaussian data prepared by Alice and Bob, respectively. The data is corrected according to the estimated measurement angle error θ. The corrected data p m Expressed as At this point, the correction of the measurement angle error is completed.

2. A code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution according to claim 1, characterized in that: The data detected by the balanced homodyne detectors 3 and 4 in the system are used for phase compensation.

3. A code rate analysis method based on non-ideal Bell detection in continuous variable measurement device-independent quantum key distribution according to claim 1, characterized in that: The balanced homodyne detectors 1 and 2 in the system detect the measured data for subsequent measurement angle error estimation and compensation to generate a key.

4. A method for compensating measurement angle errors for continuous variable measurement device-independent quantum key distribution, characterized in that: The steps are as follows: Step 1: After the balanced homodyne detectors 1 and 2, Bell detection is completed to obtain the data x of the X component of the reference signal light respectively. i and the data p of the P component of the reference signal light i , i=1,2,3,...; Step 2: After balanced homodyne detectors 3 and 4, heterodyne coherent detection is completed to obtain data x of the X component of the quantum signal light respectively. j and the data p of the P component of the quantum signal light j , j = 1, 2, 3, ...; Step 3: The X component and P component data (x i ,p i ) and the X-component and P-component data of the quantum signal light (x j ,p j ) shot noise is normalized, and the normalized data is (x i ',p i ') and (x' j ,p' j ); Step 4: According to the normalized data (x i ',p i ') can estimate the phase drift of the channel θ i for Since the reference signal and the quantum signal are transmitted simultaneously, through θ i The phase drift compensation is performed on the normalized data (x'j, p'j) of the quantum signal. The compensated data (x k ,p k )for x k =x' j cosθ i +p' j sinθ i , (7) p k =-x' j sinθ i +p' j cosθ i , (8) Where k = 1, 2, 3, ...; Step 5: Based on the data of the X and P components after phase compensation of the quantum signal light obtained in step 4 (x k ,p k ), the angle error of the measurement is estimated. Since the angles between the X and P components are relative, the angle errors of the X and P components can be attributed to a certain component. Here, it is assumed that there is an angle error in the P component, and its angle error θ is estimated to be in<xk,pk> represents the covariance between the phase-compensated data (xk, pk), V A and V B They represent the variance of the Gaussian data prepared by Alice and Bob respectively. At this time, the data of the P component is corrected for the angle error. m for Step 6: According to the measurement angle error estimation and compensation process in step 5, the P component data p with measurement angle error is k Perform measurement angle error compensation to obtain corrected data p m , the data x of the quantum signal light component X k constant; Step 7: Calculate and analyze the security code rate and generate a security key.

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