Quantum communication system quantum state polarization and intensity relevance detection method and device

Abstract

A quantum communication system quantum state polarization and intensity relevance detection method comprises a source end, a measurement end and a data processing device. The source end comprises a laser, a waveform generator and a source end modulator, the measurement end comprises a light intensity measurement device and a polarization measurement device, and polarization-to-intensity correlation detection: setting an average photon number of intensity modulation in the source end system device of the quantum communication system; the waveform generator is controlled by an upper computer at a source end and is used for applying bias voltage to the source end modulation device for direct control; phase-randomized weak coherent light pulses are prepared at the source end of the quantum communication system; the quantum communication system performs polarization modulation through a polarization modulator of a modulation source end modulator; the measuring end measures the single photon detector under the current polarization modulation parameter; the modulation voltage of the polarization modulator is changed, and the process of source end polarization modulation and measurement end measurement reading is repeated k times; the measured voltage and the measured average photon number image.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum secure communication, and in particular relates to a method and device for detecting the correlation between polarization and intensity of quantum states in a quantum communication system. Background Art

[0002] Information security is very important to both individuals and countries. Ensuring the security of information transmitted by both parties in communication has always been a research focus in the field of information security. In order to ensure the security of information transmitted through channels, people usually use encryption. However, with the development of quantum computers, the parallel computing capabilities of quantum computers have caused major security risks in a series of encryption systems based on computational complexity, including the RSA algorithm. In order to cope with the security threat of quantum computers to the basic system of classical cryptography, replacing the existing classical cryptography system with "quantum-safe" encryption has become a major strategic measure for various countries to ensure communication security. Quantum cryptography is based on the basic physical theories such as the no-cloning theorem and the superposition principle of quantum mechanics, rather than the computational difficulty problem of traditional public key cryptography. Therefore, quantum cryptography can resist quantum attacks from quantum computers and has been proven to achieve information-theoretic provable security, which is usually referred to as unconditional security.

[0003] Quantum communication systems (such as Figure 1 (as shown) is one of the most typical technologies in quantum cryptography. This technology solves the important problem of key pair distribution in classical cryptography, so that symmetric key pairs can be safely distributed to both parties of legitimate communication on an insecure channel. The quantum communication system uses the principle of non-cloning in quantum physics to ensure that the key carried by the quantum state cannot be eavesdropped on insecure channels. And because this technology is not based on any mathematical assumptions, it can resist the security threats brought by the development of quantum computers, which is exactly the problem that classical encryption algorithms based on mathematical assumptions cannot solve. Due to the significant advantages of quantum communication system technology over classical cryptography in terms of security, quantum communication system technology has gradually become a hot topic of research and has been rapidly developed in all aspects in the quantum information technology revolution.

[0004] With the in-depth study of quantum communication systems, researchers have found that there are still many differences between the technical theory and practical application of quantum communication systems. Specifically, this is because the security proof contains a series of assumptions that the quantum cryptographic system needs to meet and an abstract mathematical model of the actual device, but these assumptions and models are likely to not match the actual device. For example, the mathematical model established in the theoretical proof cannot describe the actual system well; or, the system in actual application still cannot meet the assumptions in the security proof model of the quantum communication system under the existing technology; or, due to the crosstalk effect and imperfection of the modulation device in the system, the polarization modulation and intensity modulation of the system will affect each other in the process of modulating the quantum state pulse, and the intensity and polarization of the output quantum state pulse have certain correlation problems. It is precisely because of the existence of these differences that quantum hackers can create security vulnerabilities based on the specific differences between theory and practice, thereby threatening the security of information transmitted by both communicating parties.

[0005] In quantum communication systems, the integration and high speed of source-end modulation devices are the current research focus. Integrated source-end modulators can reduce the size of the source, reduce the manufacturing cost and use cost of the source; high-speed source-end modulators can improve the security code rate of quantum communication systems and effectively improve the performance indicators of quantum communication systems. Both play an important role in the large-scale application of quantum communication systems. Therefore, quantum communication systems often use silicon-based processes that are compatible with traditional large-scale integrated circuits to manufacture high-speed integrated modulation chips as modulation devices for quantum communication systems.

[0006] At present, the security analysis of quantum communication systems usually assumes that the pulses emitted by the source are independent and identically distributed, which means that the intensity of each pulse should fully comply with the theoretical intensity setting, and its output intensity should be completely independent of polarization, and its output polarization should be completely independent of intensity. However, in actual quantum communication systems, silicon-based high-speed modulation modules are used in both the intensity modulator and polarization modulator actually used. On the one hand, the optical loss of the module shows polarization dependence during polarization modulation, that is, the optical loss of the module is different under different polarization modulation parameters. This makes the average number of photons of the photon pulses finally prepared by the source end inconsistent under different polarization modulation settings due to the change in the optical loss of the high-speed modulation module of the polarization modulator, making the polarization-intensity correlation inevitable. On the other hand, the polarization modulation result of the module shows intensity dependence during high-speed modulation, that is, the polarization modulation results of the module are different under different intensity modulation parameters and the same polarization modulation parameters. This makes the final polarization state of the photon pulses finally prepared by the source end inconsistent under different intensity modulation settings due to the change in the modulation result of the high-speed modulation module of the polarization modulator, making the intensity-polarization modulation correlation inevitable.

[0007] The above two phenomena are inconsistent with the assumption of independent and identically distributed pulses based on the security analysis of quantum communication systems, and may become security vulnerabilities of the system. If the widely used quantum communication system cannot eliminate the correlation between polarization and intensity modulation in the system, then the secure communication of the existing quantum communication system may have security risks of key leakage. In order to deal with the security risks caused by the correlation between polarization and intensity modulation of quantum states in quantum communication systems, we design a method and device for detecting the correlation between polarization and intensity of quantum states in quantum communication systems.

[0008] CN111585747A proposes a transmitting end for realizing six polarization state encoding, comprising a light source (1), a phase modulation module (2) and an optical path return module (3), wherein the light source (1) is used to provide signal light to be encoded; the phase modulation module (2) comprises a first phase modulation unit (211) and a polarization beam splitting unit (212), and is configured to: split the signal light to be encoded into a first signal light component and a second signal light component, and form a first phase difference θ between the first and second signal light components through the first phase modulation unit (211). 1 , and causing the first and second signal light components to interfere with each other to output a first interference light signal; the optical path return module (3) is configured to receive the first interference light signal and return the first interference light signal, and includes a second phase adjustment unit for adjusting the phase of the first interference light signal; and the phase modulation module (2) receives the returned first interference light signal, and is further configured to: cause the returned first interference light signal to interfere with each other to form a second interference light signal, and cause the second interference light signal to be output through the polarization beam splitting unit (212); or, divide the returned first interference light signal into first and second returned light signal components, and form a second phase difference θ between the first and second returned light signal components through the first phase modulation unit (211). 2 , and couple the first and second reflected light signal components out through the polarization beam splitting unit (212). Summary of the invention

[0009] Purpose of the invention: In view of the fact that in existing quantum communication systems, the generation of correlation between the polarization and intensity modulation of quantum state pulses is inevitable. In particular, quantum communication systems based on high-speed modulation may have security vulnerabilities caused by correlation. The present invention provides a method and device for detecting the correlation between the polarization and intensity of quantum state in a quantum communication system. When analyzing the correlation between polarization and intensity, the intensity of quantum state pulses with different polarizations can be analyzed to test the intensity correlation between quantum state pulses with different polarization modulations. When analyzing the correlation between intensity and polarization, the polarization of quantum state pulses with different intensities can be analyzed to test the polarization correlation between quantum state pulses with different intensities. The present invention realizes the inspection and analysis of the correlation between the polarization and intensity modulation of quantum state light pulses generated by the quantum communication system in the original key distribution process, realizes an objective evaluation of the security of the system, and provides a guarantee for the actual security of the quantum communication system.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] A method and device for detecting the correlation between polarization and intensity of quantum states in a quantum communication system, based on the following device, including a source end, a measuring end, and a data processing device; the source end includes a laser, a waveform generator, and a source end modulator (intensity modulator and polarization modulator); the measuring end includes a light intensity measuring device (single photon detector or optical power meter) and a polarization measuring device (polarization analyzer or polarization decoder), etc.; the data processing device includes a host computer hardware device and data analysis software; based on the above device, the method includes the following steps:

[0012] (1) Polarization-intensity correlation test method:

[0013] Step 1) Set the average number of photons with intensity modulation in the source-end device of the quantum communication system; the source end of the quantum communication system mainly includes a laser, a waveform generator, and a source-end modulation device (such as Figure 2 As shown); the waveform generator is controlled by the host computer at the source end, and is mainly used to apply bias voltage to the source end modulation device for direct control; the source end modulation device mainly includes intensity modulator and polarization modulator; firstly, the quantum communication system only modulates the light intensity output by the laser, so that the average number of photons output by it should be as close or consistent as possible with the average number of photons used in the actual operation of the quantum communication system; it should be noted that the polarization modulator is not working at this time, and one or more average photon numbers can be determined before the test, such as the decoy state and the signal state for multiple tests under different modulation parameters;

[0014] Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses; the quantum communication system performs polarization modulation by modulating the polarization modulator of the source end modulation device; in the process of modulating the specific polarization parameters by the source end polarization modulator, it is necessary to record the voltage applied to the polarization modulator, which is recorded as V p It should be noted that the voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable.

[0015] Step 3) The measuring end measures the average number of photons / average optical power displayed by the single photon detector / optical power meter under the current polarization modulation parameters, and the reading is recorded as N p ; If a single-photon detector is used in this process, it is necessary to ensure that the response rate of the single-photon detector is linearly related to the input light intensity, and to ensure that the detection efficiency of the single-photon detector does not change in the time dimension;

[0016] Step 4) changing the modulation voltage of the polarization modulator in step 2), repeating the process of polarization modulation at the source end in step 2) and measuring the reading at the measurement end in step 3) for k times;

[0017] Step 5) According to the voltage measured in step 4), the measured average photon number / measured average optical power image is obtained; after arranging the data, a set of measurement data is obtained.

[0018] Step 6): Compare the experimental data. If the test voltage V is different But the average number of photons / average optical power obtained by the test is the same When , it can be proved that the quantum state polarization and intensity of the measured quantum communication system are unrelated; otherwise, there is a correlation;

[0019] (2) Intensity-polarization correlation test method:

[0020] Step 1) Setting the polarization of intensity modulation in the source-end device of the quantum communication system; the source end of the quantum communication system mainly includes a laser, a waveform generator and a source-end modulation device (such as Figure 2 As shown); the waveform generator can be controlled by the host computer at the source end, and is mainly used to apply a bias voltage to the source end modulation device for direct control; the source end modulation device mainly includes an intensity modulator and a polarization modulator; first, the quantum communication system only modulates the polarization output of the laser, so that the polarization state of its output should be as close to or consistent as possible with the polarization state used in the actual operation of the quantum communication system; it should be noted that the intensity modulator does not work at this time, and one or more polarization states can be determined before the test, such as horizontal polarization H, vertical polarization V, +45° polarization D and -45° polarization A, etc., to perform multiple tests under different modulation parameters;

[0021] Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses; the quantum communication system performs intensity modulation by modulating the intensity modulator of the source end modulation device; in the process of modulating the specific intensity parameter by the source end intensity modulator, it is necessary to record the voltage applied to the intensity modulator, which is recorded as V i It should be noted that the voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable.

[0022] Step 3) The measurement end uses a polarization analyzer or a polarization decoder to measure the polarization state under the current intensity modulation parameters, which is recorded as P i ; In this process, multiple measurements can be taken to obtain the average value to avoid the influence of single measurement error on the measurement result;

[0023] Step 4) Step 4) changes the modulation voltage of the polarization modulator in step 2), and repeats the process of intensity modulation at the source end in step 2) and measurement reading at the measurement end in step 3) for k times;

[0024] Step 5) Correlation test method A: According to the voltage measured in step 4) and the measured polarization state image; after arranging the data, a set of measurement data is obtained Compare the experimental data, if the test voltage V is different But the polarization state results obtained by the test are the same When , it can be proved that the quantum state polarization and intensity of the measured quantum communication system are unrelated; otherwise, there is a correlation;

[0025] Correlation test method B: Use polarization P to represent the physical quantity X and obtain the voltage V i Relationship with physical quantity X, in step 6) compare different voltages V i The correlation between intensity and polarization can be determined by looking at whether the physical quantity X under the condition changes. Since the vertical axis polarization is difficult to express as a scalar, we can use V i = 0 when the polarization measurement result P i (V i =0) as the reference, calculate the polarization state P under other intensity modulation voltages i (V i ) and P i (V i =0), plot the voltage V i The image with angle θ is calculated as follows

[0026]

[0027] if This means that the polarization state results are the same It can be proved that there is no correlation between the polarization and intensity of the quantum state of the measured quantum communication system; otherwise, there is a correlation.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention can characterize the potential polarization and intensity correlation of the optical pulses emitted by the source module under test, aiming to detect a common assumption in quantum communication systems, that is, the intensity of each expected intensity of the emitted pulse is independent of its polarization. The present invention proposes for the first time a set of polarization and intensity correlation detection methods for quantum communication systems for single-photon detectors. The present invention can be easily extended to any intensity emitted by the tested transmission module, and is suitable for quantum communication protocols that emit optical pulses with different polarization modulation parameters; and provides two correlation test methods. The present invention analyzes and detects the correlation between the polarization and intensity of the optical quantum pulses prepared by the quantum communication system, thereby avoiding the security risks caused by information leakage, and providing direct protection for the actual security of the quantum communication system. The present invention has important guiding significance for promoting the research on security and reliability in quantum secure communications, and has important scientific significance and practical value for promoting the practical application of quantum communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a simplified schematic diagram of a quantum communication system.

[0031] Figure 2 This is a diagram of the general equipment setup at the source end of a quantum communication system.

[0032] Figure 3 This is a device for analyzing and detecting the correlation between the polarization and intensity modulation of quantum state pulses in quantum communication systems. The solid line and hollow line represent the optical signal and the measurement data stream, respectively;

[0033] Figure 4 For different Down, Different, the simulated curve proves that there is polarization-intensity correlation in this quantum communication system.

[0034] Figure 5 For different Down, Different, the simulated curve proves that there is polarization-intensity correlation in this quantum communication system. DETAILED DESCRIPTION

[0035] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0036] A method and device for detecting correlation between polarization and intensity of quantum states in a quantum communication system, including a source end, a measurement end and a data processing device, comprises the following steps:

[0037] 1. Polarization to intensity correlation test method:

[0038] Step 1) Set the average number of photons with intensity modulation in the source-end device of the quantum communication system. The source end of the quantum communication system mainly includes a laser (typical models such as Lingyunguang 1550nm single-frequency fiber laser), a waveform generator (typical models such as Arb Rider AWG-4000Arbitrary Waveform Generator) and a source-end modulation device (such as Figure 2 As shown). The waveform generator can be controlled by the host computer at the source end, and is mainly used to apply bias voltage to the source end modulation device for direct control. The source end modulation device mainly includes intensity modulator (typical models such as KG-AM-15-40G) and polarization modulator (Shanghai Hanyu EPC-300). First of all, the quantum communication system only modulates the light intensity output by the laser, so that the average number of photons output by it should be as close or consistent as possible with the average number of photons used in the actual operation of the quantum communication system. It should be noted that the polarization modulator is not working at this time, and one or more average photon numbers can be determined before the test, such as the decoy state and signal state for multiple tests under different modulation parameters.

[0039] Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses. The quantum communication system performs polarization modulation by modulating the polarization modulator of the source end modulation device. In the process of modulating specific polarization parameters by the source end polarization modulator, it is necessary to record the voltage applied to the polarization modulator, which is recorded as V p It should be noted that the voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable.

[0040] Step 3) The measuring end measures the average number of photons / average optical power displayed by the single photon detector / optical power meter under the current polarization modulation parameters, and the reading is recorded as N p If a single-photon detector is used in this process, it is necessary to ensure that the response rate of the single-photon detector is linearly related to the input light intensity, and to ensure that the detection efficiency of the single-photon detector does not change in the time dimension.

[0041] Step 4) changing the modulation voltage of the polarization modulator in step 2), repeating k times the process of polarization modulation at the source end in step 2) and measuring the reading at the measurement end in step 3).

[0042] Step 5) The voltage measured in step 4) is compared with the measured average photon number / measured average optical power image. After sorting the data, a set of measurement data is obtained.

[0043] Step 6): Compare the experimental data. If the test voltage V is different But the average number of photons / average optical power obtained by the test is the same When , it can be proved that the quantum state polarization and intensity of the measured quantum communication system are unrelated. Otherwise, there is a correlation, such as Figure 4 , in different Down, The difference proves that there is polarization intensity correlation in this quantum communication system.

[0044] 2. Intensity-polarization correlation test method:

[0045] Step 1) Set the polarization of intensity modulation in the source-end device of the quantum communication system. The source end of the quantum communication system mainly includes a laser, a waveform generator, and a source-end modulation device (such as Figure 2 As shown). The waveform generator can be controlled by the host computer at the source end, and is mainly used to apply bias voltage to the source end modulation device for direct control. The source end modulation device mainly includes intensity modulator and polarization modulator. First of all, the quantum communication system only modulates the polarization output of the laser, so that the polarization state of its output should be as close or consistent as possible with the polarization state used in the actual operation of the quantum communication system. It should be noted that the intensity modulator is not working at this time, and one or more polarization states can be determined before the test, such as horizontal polarization H, vertical polarization V, +45° polarization D and -45° polarization A, etc., to perform multiple tests under different modulation parameters.

[0046] Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses. The quantum communication system performs intensity modulation by modulating the intensity modulator of the source end modulation device. In the process of modulating a specific intensity parameter by the source end intensity modulator, it is necessary to record the voltage applied to the intensity modulator, which is recorded as V i It should be noted that the voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable.

[0047] Step 3) The measurement end uses a polarization analyzer or a polarization decoder to measure the polarization state under the current intensity modulation parameters, which is recorded as P i In this process, multiple measurements can be taken to obtain an average value to avoid the influence of a single measurement error on the measurement result.

[0048] Step 4) Step 4) changes the modulation voltage of the polarization modulator in step 2), and repeats the process of intensity modulation at the source end in step 2) and measurement reading at the measurement end in step 3) for k times.

[0049] Step 5) Correlation test method A: According to the voltage measured in step 4) and the measured polarization state image. After sorting the data, a set of measurement data is obtained. Compare the experimental data, if the test voltage V is different But the polarization state results obtained by the test are the same When , it can be proved that there is no correlation between the polarization and intensity of the quantum state of the measured quantum communication system. On the contrary, there is a correlation.

[0050] Correlation test method B: Use polarization P to represent the physical quantity X and obtain the voltage V i Relationship with physical quantity X, in step 6) compare different voltages V i The correlation between intensity and polarization can be determined by looking at whether the physical quantity X under the condition changes. Since the vertical axis polarization is difficult to express in scalar form, we can use V i = 0 when the polarization measurement result P i (V i =0) as the reference, calculate the polarization state P under other intensity modulation voltages i (V i ) and P i (V i =0), plot the voltage V i The image with angle θ is calculated as follows

[0051]

[0052] if This means that the polarization state results are the same It can be proved that the quantum state polarization and intensity of the measured quantum communication system are unrelated. On the contrary, there is a correlation, such as Figure 5 , in different Down, The difference proves that there is polarization intensity correlation in this quantum communication system.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting the correlation between polarization and intensity of quantum states in a quantum communication system, based on the following devices, including a source end, a measuring end, and a data processing device; the source end includes a laser, a waveform generator, and a source end modulator, including an intensity modulator and a polarization modulator; the measuring end includes a light intensity measuring device and a polarization measuring device, including a polarization analyzer or a polarization decoder; the data processing device includes a host computer hardware device and a data analysis program; based on the above-mentioned devices, it is characterized in that, The steps include: (1) Polarization-intensity correlation test method: Step 1) setting the average number of photons of intensity modulation in the source-end control device of the quantum communication system; the source-end waveform generator of the quantum communication system is controlled by the host computer of the source end, and is used to apply a bias voltage to the source-end modulation device for direct control; the source-end modulation device includes an intensity modulator and a polarization modulator; first, the quantum communication system only modulates the light intensity output by the laser, so that the average number of photons output by the laser is as close as possible to or consistent with the average number of photons used in the actual operation of the quantum communication system; at this time, the polarization modulator does not work, and one or more average photon numbers can be determined before the test; Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses; the quantum communication system performs polarization modulation by modulating the polarization modulator of the source end modulation device; in the process of modulating the specific polarization parameters by the source end polarization modulator, it is necessary to record the voltage applied to the polarization modulator, which is recorded as V p ; The voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable; Step 3) The measuring end measures the average number of photons / average optical power displayed by the single photon detector / optical power meter under the current polarization modulation parameters, and the reading is recorded as N p ; If a single-photon detector is used in this process, ensure that the response rate of the single-photon detector is linearly related to the input light intensity, and ensure that the detection efficiency of the single-photon detector does not change in the time dimension; Step 4) changing the modulation voltage of the polarization modulator in step 2), repeating the process of polarization modulation at the source end in step 2) and measuring the reading at the measurement end in step 3) for k times; Step 5) According to the voltage measured in step 4), the measured average photon number / measured average optical power image is obtained; after arranging the data, a set of measurement data is obtained. Step 6): Compare the experimental data. If the test voltage V is different But the average number of photons / average optical power obtained by the test is the same When , it proves that the quantum state polarization and intensity of the measured quantum communication system are unrelated; otherwise, there is a correlation; (2) Intensity-polarization correlation test method: Step 1) setting the polarization of intensity modulation in the source-end control device of the quantum communication system; the source end of the quantum communication system mainly includes a laser, a waveform generator and a source-end modulation device; the waveform generator can be controlled by the host computer of the source end, and is used to apply a bias voltage to the source-end modulation device for direct control; the source-end modulation device includes an intensity modulator and a polarization modulator; first, the quantum communication system only modulates the polarization output of the laser, so that the polarization state of its output should be as close to or consistent as possible with the polarization state used in the actual operation of the quantum communication system; the intensity modulator does not work at this time, and one or more polarization states are determined before the test; Step 2) The source end of the quantum communication system prepares phase-randomized weakly coherent optical pulses; the quantum communication system performs intensity modulation by modulating the intensity modulator of the source end modulation device; in the process of modulating the specific intensity parameter by the source end intensity modulator, it is necessary to record the voltage applied to the intensity modulator, which is recorded as V i ; The voltage application time needs to be long enough (more than 2 seconds) so that the average value of the measurement result at the measuring end is stable; Step 3) The measurement end uses a polarization analyzer or a polarization decoder to measure the polarization state under the current intensity modulation parameters, which is recorded as P i ; In this process, multiple measurements can be taken to obtain the average value to avoid the influence of single measurement error on the measurement result; Step 4) Step 4) changes the modulation voltage of the polarization modulator in step 2), and repeats the process of intensity modulation at the source end in step 2) and measurement reading at the measurement end in step 3) for k times; Step 5) Correlation test method A: According to the voltage measured in step 4) and the measured polarization state image; after arranging the data, a set of measurement data is obtained Comparing the experimental data, if the test voltage V is different But the polarization state results obtained by the test are the same When , it proves that the quantum state polarization and intensity of the measured quantum communication system are uncorrelated; otherwise, there is a correlation.

2. The method for detecting the correlation between polarization and intensity of quantum states in a quantum communication system according to claim 1, characterized in that: Determining one or more average photon numbers before testing refers to performing multiple tests under different modulation parameters on the decoy state and the signal state; One or more polarization states are determined before testing, such as horizontal polarization H, vertical polarization V, +45° polarization D, and -45° polarization A, and multiple tests are performed under different modulation parameters.

3. The method for detecting the correlation between polarization and intensity of quantum states in a quantum communication system according to claim 1, characterized in that: Or adopt the following correlation test method B: Use polarization P to represent the physical quantity X and get the voltage V i Relationship with physical quantity X, in step 6) compare different voltages V i The correlation between intensity and polarization can be determined by looking at whether the physical quantity X under the condition changes. Since the vertical axis polarization is difficult to express as a scalar, we can use V i = 0 when the polarization measurement result P i (V i =0) as the reference, calculate the polarization state P under other intensity modulation voltages i (V i ) and P i (V i =0), plot the voltage V i The image with angle θ is calculated as follows if This means that the polarization state results are the same It can be proved that there is no correlation between the polarization and intensity of the quantum state of the measured quantum communication system; otherwise, there is a correlation.

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