Improved randomness evaluation method and system for continuous variable source independent quantum random number generator based on heterodyne detection

Abstract

The invention provides an improved randomness evaluation method and system for a continuous variable source independent quantum random number generator based on heterodyne detection, and relates to the technical field of quantum information communication. According to the method, the influence of non-perfect ideal characteristics of an actual device at a measuring end is considered, and the safety problems of non-equilibrium heterodyne detection and the like caused by non-ideal characteristics of local oscillation light intensity fluctuation, the beam splitting ratio of a beam splitter and the detection efficiency of a detector are solved; the above imperfect characteristics are associated with the estimation of the measurement accuracy of the orthogonal component in the calibration process, and the measurement accuracy estimation formula of the orthogonal component is corrected, so that the randomness evaluation is corrected, the problem of security vulnerabilities introduced by local oscillation light intensity fluctuation under unbalanced heterodyne detection can be solved, and the accuracy of the measurement accuracy of the orthogonal component is improved. And the actual safety of the system is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum information communication structures, and in particular to an improved randomness evaluation method and system for a continuous variable source-independent quantum random number generator based on heterodyne detection. Background Art

[0002] As an important random resource, random numbers play a vital role in modern science and business. Random numbers generated using the uncertainty principle of quantum mechanics are called quantum random numbers. They meet the properties of true random numbers such as unpredictability, non-replicability, and non-repeatability, and have received widespread attention and research. In the past two decades, quantum random number generators have developed rapidly, forming discrete variable quantum random number generators with single photons, entangled photons, etc. as quantum entropy sources and continuous variable quantum random number generators with vacuum fluctuation noise, laser phase noise, amplified spontaneous emission noise, etc. as quantum entropy sources. Continuous variable quantum random number generators use high-speed photodetectors to measure signals, and their random number generation rate can reach hundreds of Gbps, which has become a research focus.

[0003] The quantum entropy source is the source of the entire randomness. When the source is unreliable, an eavesdropper can control or monitor the random source to obtain information about random numbers, affecting the actual security of the quantum random number generator system. In order to further improve the actual performance, the researchers proposed a continuous variable source-independent quantum random number generation protocol that does not require trust in the quantum entropy source. It can be divided into two methods: based on homodyne detection and based on heterodyne detection. Among them, the continuous variable source-independent quantum random number generation protocol based on heterodyne detection does not require random modulation phase modulation devices, nor does it require additional input of random numbers. The device is simpler and easier to implement.

[0004] Although the continuous variable source-independent quantum random number generation protocol based on heterodyne detection can generate secure random numbers under the condition that the source is untrustworthy, it requires precise characterization of the measurement equipment, etc. The non-ideal characteristics of actual devices inevitably introduce security vulnerabilities. Eavesdroppers can use these actual non-ideal factors to carry out corresponding attacks and threaten the security of random numbers. In the continuous variable source-independent quantum random number generator based on heterodyne detection, the intensity of the quantum random signal input from the unknown source is weak. In order to effectively detect the unknown quantum signal, a strong local oscillator light is usually introduced to coherently amplify it. However, it cannot be guaranteed that the intensity of the local oscillator light is always stable, and its intensity fluctuation may introduce related security vulnerabilities; in addition, actual optical beam splitters, detectors, etc. may also have non-perfect characteristics, deviate from the ideal situation, and cause unbalanced heterodyne detection. Therefore, considering the security vulnerabilities introduced by non-ideal factors such as local oscillator light intensity fluctuations is of great significance to improving the actual security of the continuous variable source-independent quantum random number generator based on heterodyne detection.

[0005] In the security analysis of continuous variable source-independent quantum random numbers based on heterodyne detection proposed so far, firstly, it is usually assumed that the intensity of the local oscillator light is constant, and the security issues introduced by the fluctuation of the intensity of the local oscillator light are not considered; secondly, it is assumed that the heterodyne detection is ideal, and the impact of unbalanced heterodyne detection caused by non-ideal factors of actual devices such as optical beam splitters and detectors on the continuous variable source-independent quantum random number generator is not considered. Therefore, how to ensure the security of generating random numbers under the conditions of fluctuation of the intensity of the local oscillator light and unbalanced heterodyne detection, and to provide a randomness evaluation method under such conditions still need to be studied and analyzed. Summary of the invention

[0006] In order to accurately evaluate and improve the actual security of a continuous variable source-independent quantum random number generator under the conditions of local oscillator light intensity fluctuation and unbalanced heterodyne detection, the present invention provides an improved randomness evaluation method and system for a continuous variable source-independent quantum random number generator based on heterodyne detection.

[0007] In a first aspect, the present invention provides an improved randomness evaluation method for a continuous variable source-independent quantum random number generator based on heterodyne detection, characterized in that, for an unknown quantum state input, under the non-ideal characteristics of the local oscillator light intensity fluctuation, the beam splitting ratio of the beam splitter and the detection efficiency of the detector, the measurement resolution δ of the X orthogonal component and the P orthogonal component of the unknown quantum state in the vacuum state phase space is X and δ P A correction is made to the lower bound of the random number content that can be extracted from the measurement result based on the corrected measurement resolution.

[0008] Furthermore, the measurement resolution δ of the estimated X and P quadrature components of the unknown quantum state in the vacuum phase space is X and δ P Make corrections, including:

[0009] Calibrate the unbalance parameter △ of the beam splitter and the detection efficiency η of each detector i and the parameter l of the initial variance of the local oscillator light intensity fluctuation noise relative to the variance of the vacuum fluctuation noise, and estimate m according to the following formula 1,X(P) and m 2,X(P) ;

[0010]

[0011]

[0012] Among them, m 1,X(P) and m 2,X(P) They represent the ratio of the variance of vacuum noise and the variance of local oscillator light intensity fluctuation noise to the power of local oscillator light respectively; η 1(3)represents the detection efficiency of the first detector or the third detector, η 2(4) represents the detection efficiency of the second detector or the fourth detector, wherein the first detector and the second detector belong to one homodyne detector module, and the third detector and the fourth detector belong to another homodyne detector module; D(δX(P) L (t)) represents the initial variance of the local oscillator light intensity fluctuation noise, l = D(δX(P) L (t)) / D(δX(P) QV (t)).

[0013] By changing the input LO light power P LO , record the total variance of the measurement results Thus, we can get P LO and The relationship between:

[0014]

[0015] Among them, m X(P) and c X(P) Respectively represent the slope and intercept of the relationship, and m X(P) Meet m X(P) =m 1,X(P) +m 2,X(P) ;

[0016] Considering the influence of the local oscillator light intensity fluctuation noise, according to the estimated m 1,X(P) and m 2,X(P) And the intercept c obtained by fitting X(P) , and correct the variance of the measurement results to:

[0017]

[0018] in, represents the variance of the corrected measurement results;

[0019] According to the corrected standard deviation σ with,X(P) The estimated corrected measurement resolution is δ with,X(P) =δ ADC σ with,X(P) / σ t,X(P) ; Among them, δ ADC is the measurement resolution of the analog-to-digital converter ADC.

[0020] Furthermore, considering the quantum side information ε that can be obtained by the eavesdropper, the modified extractable random number content H min (M δ The lower bound of |ε) is:

[0021]

[0022] In a second aspect, the present invention provides an improved continuous variable source-independent quantum random number generator system based on heterodyne detection, comprising:

[0023] A randomness evaluation module, used to calculate a lower bound of the modified extractable random number content using the randomness evaluation method according to any one of claims 1 to 3;

[0024] The post-processing module is used to use the lower bound of the modified extractable random number content as a constraint condition to perform random extraction operations on the original data using a post-processing method to obtain secure true random numbers.

[0025] Beneficial effects of the present invention:

[0026] (1) In the improved randomness evaluation method proposed in the present invention, the influence of the local oscillator light intensity fluctuation on the randomness evaluation under unbalanced heterodyne detection is considered, and the measurement accuracy δ of the orthogonal component is corrected. X and δ P , so that the random number content that can be extracted from the measurement results can be correctly estimated.

[0027] (2) In the existing continuous variable source-independent quantum random number generator system based on heterodyne detection, the influence of the imperfect ideal characteristics of the actual device at the measurement end is not considered, including the security issues such as unbalanced heterodyne detection caused by the non-ideal characteristics of the local oscillator light intensity fluctuation, the beam splitting ratio of the beam splitter and the detection efficiency of the detector. In the random number generator system proposed in the present invention, the influence of the local oscillator light intensity fluctuation on the measurement accuracy of the orthogonal component under unbalanced heterodyne detection is considered, the above-mentioned imperfect characteristics are linked to the estimation of the measurement accuracy of the orthogonal component during the calibration process, and the measurement accuracy estimation formula of the orthogonal component is corrected, thereby correcting the randomness evaluation, which can solve the security vulnerability problem introduced by the local oscillator light intensity fluctuation under unbalanced heterodyne detection, and further improve the actual security of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a continuous variable source-independent quantum random number generator device based on heterodyne detection provided by an embodiment of the present invention;

[0029] Figure 2 A schematic flow chart of an improved randomness evaluation method for a continuous variable source-independent quantum random number generator based on heterodyne detection provided in an embodiment of the present invention;

[0030] Figure 3 The embodiment of the present invention provides the following example: the imbalance degree △ of the beam splitter is proportional to the minimum entropy H of the quantum condition under the two conditions of considering the fluctuation of the intensity of the local oscillator light and not considering the fluctuation of the intensity of the local oscillator light. min (M δ|ε)

[0031] Figure 4 A schematic structural diagram of an improved continuous variable source-independent quantum random number generator system based on heterodyne detection provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] In the continuous variable source-independent quantum random number generator based on heterodyne detection, the quantum state ρ of the unknown quantum source input is considered A is unreliable and may be completely controlled by the eavesdropper Eve. The measuring end device is reliable. Heterodyne detection technology can simultaneously measure the unknown quantum state ρ A The X and P components of the heterodyne detection technology solve the disadvantage that the homodyne detection technology requires additional random numbers to actively select the measurement basis. Figure 1 As shown, BS represents an optical beam splitter, PD represents a detector, and ADC represents an analog-to-digital converter. The light output by the continuous laser is used as the local oscillator light. The local oscillator light first passes through a beam splitter BS0 with a splitting ratio of 1:99. 1% of the local oscillator light is measured by an optical power meter to monitor the intensity of the local oscillator light and the magnitude of the intensity fluctuation; the remaining 99% of the local oscillator light enters BS1 and is coherently amplified with the weak unknown quantum signal. The local oscillator light and the unknown quantum signal light pass through optical beam splitters BS1 and BS2 respectively to form two beams of light respectively; the local oscillator light of the upper arm is not phase modulated, and after passing through the optical beam splitter BS3 with the unknown quantum signal light, it is measured by a homodyne detector composed of detectors PD1, PD2 and a differential amplifier, thereby realizing the measurement of the X component of the unknown quantum state; the local oscillator light of the lower arm is modulated by the phase modulator, and the phase shift is π / 2. After passing through the optical beam splitter BS4 with the unknown quantum signal light, it is measured by a homodyne detector composed of detectors PD3, PD4 and a differential amplifier, thereby realizing the measurement of the P component of the unknown quantum state. The measurement results of the X component and the P component can be obtained after being discretely sampled by an analog-to-digital converter, and the original data can be obtained by estimating the extractable random number content in the original data and using a post-processing method to finally obtain unpredictable and secure true random numbers.

[0035] Consider the attack capability of the eavesdropper Eve, who can obtain quantum side information ε from the discrete measurement results M δ The lower bound of the random number content that can be extracted is the quantum conditional minimum entropy H min (M δ |ε) lower bound;

[0036]

[0037] where δ X and δ P They represent the measurement resolution of the X-quadrature component measurement and the P-quadrature component measurement in the vacuum phase space, respectively. X and δ P The value of can determine the lower bound of the quantum conditional minimum entropy.

[0038] In actual situations, the local oscillator light may have intensity fluctuations, and the beam splitting ratio of the beam splitter and the detection efficiency of the detector may be imperfect, resulting in unbalanced heterodyne detection. Considering the above imperfect characteristics, the embodiment of the present invention corrects the measurement resolution of the X quadrature component and the P quadrature component, thereby correcting the lower bound of the quantum conditional minimum entropy, such as Figure 2 As shown, the specific steps include:

[0039] S101: For the unknown quantum state input, under the non-ideal characteristics of the local oscillator light intensity fluctuation, the beam splitting ratio of the beam splitter and the detection efficiency of the detector, the measurement resolution δ of the X and P quadrature components of the unknown quantum state in the vacuum phase space X and δ P make corrections;

[0040] S102: Correcting a lower limit of the random number content that can be extracted from the measurement result based on the corrected measurement resolution.

[0041] Specifically, assuming that the electric fields of the local oscillator light and the unknown quantum signal are represented by E L (t) = E L +δX L (t)+iδP L (t) and E s (t) = E s +δX s (t)+iδP s (t). The actual input untrusted quantum state can be any state such as vacuum state, thermal state, compressed state, etc. The mean of these quantum states is 0 and symmetric in any direction, so E scan be regarded as 0. In the heterodyne detection system, the local oscillator light signal and the unknown quantum signal are respectively divided into two beams by the beam splitter, and then coupled into the two input ports of the beam splitter BS3 and BS4 respectively and interfere with each other. The interference output signal is converted into a current signal by the two photodiodes of the balanced zero-beat detector of the upper arm and the lower arm respectively, and finally outputs a voltage signal after differential amplification. Assume that the transmission coefficients of the beam splitters BS1, BS2, BS3 and BS4 are The photoelectric conversion gain coefficients of detectors PD1, PD2, PD3, and PD4 are η1, η2, η3, and η4, respectively, so the two output voltage signals are

[0042]

[0043] The voltage signal v1(t) is the measurement result of the X quadrature component, and v2(t) is the measurement result of the P quadrature component.

[0044] In order to simplify the analysis, two cases are discussed. One is that beam splitters BS1 and BS2 are ideal, while BS3 and BS4 have imperfect characteristics; the other is that beam splitters BS1 and BS2 have defects, while BS3 and BS4 are ideal.

[0045] Case 1: Assume that the transmission coefficients of imperfect BS3 and BS4 are the same, and the imbalance parameters △ of the two are the same, that is, Correspondingly, the variance of the local oscillator light intensity fluctuation noise in the X(P) component measurement is

[0046]

[0047] The variance of the quantum noise in the X(P) component measurement is

[0048]

[0049] Among them, P LO represents the optical power of the local oscillator light entering BS1, D(δX(P) L (t)) represents the initial variance of the local oscillator light intensity fluctuation noise, D(δX(P) s (t)) = D(δX(P) QV (t))+D(δX(P) QN (t)) indicates that the variance of the measured quantum signal noise consists of two parts, one of which is the variance of the vacuum fluctuation noise D(δX(P) QV (t)), and the other part is the variance D(δX(P) of the quantum side information noise owned by the eavesdropper Eve QN (t)). The multiple of the initial variance of the local oscillator light fluctuation noise relative to the variance of the vacuum fluctuation noise is l, l = D(δX(P) L(t)) / D(δX(P) QV (t)). The larger l is, the larger the initial variance of the local oscillator light fluctuation noise is. In addition, the experimental device will inevitably introduce electronic noise, and the variance of the electronic noise is denoted by The total variance of the measurement results is

[0050]

[0051] The second case: Assume that the transmission coefficients of the imperfect BS1 and BS2 are the same, and the imbalance parameters △ of the two are the same, that is, Correspondingly, the variance of the local oscillator light fluctuation noise in the X(P) component measurement is

[0052]

[0053] The variance of the quantum noise in the X(P) component measurement is

[0054]

[0055] The total variance of the measurement results is

[0056]

[0057] To further simplify the analysis, assuming that the photoelectric conversion gain coefficients of the detectors are all equal η1=η2=η3=η4=η, for the second case, according to formula (7), the corresponding variance of the local oscillator light fluctuation noise is 0, that is, the influence of the local oscillator light intensity fluctuation noise is eliminated; for the first case, according to formula (4), the corresponding influence of the local oscillator light intensity fluctuation noise cannot be eliminated, and the total variance of the final output signal noise will include the variance of the local oscillator light intensity fluctuation noise. If the influence of the local oscillator light intensity fluctuation noise is not considered in the randomness analysis, it will affect the estimation of the final quantum conditional minimum entropy. Therefore, the present invention mainly analyzes the first case, that is, imperfect BS3 and BS4, and ideal BS1 and BS2.

[0058] In order to estimate the extractable random number content, a calibration procedure is performed before generating random numbers to estimate the resolution δ of the X-component and P-component measurements. X and δ P During the calibration process, the signal port of the heterodyne detector is blocked, the input quantum state is pure vacuum state, and the power P of the input local oscillator light is changed. LO , records the total variance of the measured signal Finally, a straight line can be fitted and the relationship can be obtained:

[0059]

[0060] Among them, m X(P) and cX(P) represent the slope and intercept of the relationship respectively;

[0061] In the case where beam splitters BS3 and BS4 are non-ideal, the total variance of the measured signal is

[0062]

[0063] Among them, the variance of vacuum fluctuation noise is The variance of the noise of the local oscillator light intensity fluctuation The variance of vacuum noise and the variance of local oscillator light intensity fluctuation noise are both proportional to the power of the local oscillator light. The slope of the fitting line is m X(P) Meet m X(P) =m 1,X(P) +m 2,X(P) For convenience, the variance of the orthogonal measurement of the vacuum state is given in vacuum units by

[0064] If the influence of local oscillator light fluctuation is ignored, the variance of the measured signal can be expressed in units of vacuum noise as

[0065]

[0066] The estimated measurement resolution δ X and δ P is δ without,X(P) =δ ADC σ without,X(P) / σ t,X(P) , where δ ADC =N / 2 n-1 It represents the measurement resolution of the analog-to-digital converter. Its measurement accuracy is n and its measurement range is [-N+δ ADC / 2,N-3δ ADC / 2],N=kσ t,X(P) , k is an integer; the local oscillator light intensity fluctuation noise is mistakenly regarded as vacuum fluctuation noise, resulting in a measurement resolution of δ X and δ P Estimation error.

[0067] Considering the influence of the local oscillator light intensity fluctuation noise, the variance of the measured signal is corrected in units of vacuum noise to

[0068]

[0069] Among them, t X(P) Represents the slope of the fitted line.

[0070] Measurement resolution δ X and δ P It can be expressed as δ with,X(P) =δ ADC σ with,X(P) / σt,X(P) Therefore, in order to correctly estimate the lower bound of the extractable random number content, it is important to correctly estimate the measurement resolution δ X and δ P , that is, to estimate the slope m 1,X(P) and m 2,X(P) According to formula (4) and formula (5),

[0071]

[0072] As long as the unbalance parameter △ of the beam splitter and the detection efficiency η of each detector are calibrated i The slope parameter m can be estimated by using the parameter l of the initial variance of the local oscillator light intensity fluctuation noise relative to the variance of the vacuum fluctuation noise. 1,X(P) and m 2,X(P) The value of .

[0073] In this way, formula (1) can be corrected as follows:

[0074]

[0075] Example 2

[0076] Based on the above embodiments, Figure 1 The experimental device is given. On the basis of the above embodiment, the embodiment of the present invention carries out the following simulation process to verify the effectiveness of the solution of the present invention.

[0077] Assume that the detection efficiency of the detectors is all equal η1=η2=η3=η4=1, and the electronic noise follows a Gaussian distribution with a variance of Local oscillator optical power P LO = 1, the initial variance of vacuum fluctuation noise D(δX QV (t)) = D(δP QV (t)) = 0.5, the sampling range of the analog-to-digital converter N = kσ t,X(P) =3σ t,X(P) , sampling accuracy n=8.

[0078] Figure 3 The effect of the beam splitter imbalance △ on the quantum conditional minimum entropy H is shown under the two conditions of considering the local oscillator light intensity fluctuation and ignoring the local oscillator light intensity fluctuation. min (M δ |ε). Figure 3 It can be clearly seen that if the influence of the local oscillator light intensity fluctuation is not considered, the estimated quantum conditional minimum entropy H min (M δ|ε) will be overestimated, affecting the security of the output quantum random number. The larger the initial variance of the local oscillator light intensity fluctuation, the greater the overestimated extractable random number content. Therefore, in the continuous variable source-independent quantum random number generator based on heterodyne detection, the impact of the local oscillator light intensity fluctuation on the randomness evaluation cannot be ignored.

[0079] In the improved randomness evaluation method of the continuous variable source-independent quantum random number generator based on heterodyne detection proposed in the present invention, the influence of the local oscillator light intensity fluctuation on the randomness evaluation under unbalanced heterodyne detection is considered, and the measurement accuracy δ of the orthogonal component is corrected. X and δ P , so that the random number content that can be extracted from the measurement results can be correctly estimated, which can solve the security vulnerability problem introduced by the fluctuation of local oscillator light intensity under unbalanced heterodyne detection, and further improve the actual security of the system.

[0080] Example 3

[0081] like Figure 4 As shown, an embodiment of the present invention provides an improved continuous variable source-independent quantum random number generator system based on heterodyne detection, including: a randomness evaluation module and a post-processing module.

[0082] Among them, the randomness evaluation module is used to calculate the lower bound of the corrected extractable random number content using the randomness evaluation method as mentioned above; the post-processing module is used to use the lower bound of the corrected extractable random number content as a constraint condition and use the post-processing method to perform randomness extraction operations on the original data to obtain secure true random numbers.

[0083] In the existing continuous variable source-independent quantum random number generator system based on heterodyne detection, the influence of the imperfect ideal characteristics of the actual device at the measurement end is not considered, including the security issues such as unbalanced heterodyne detection caused by the non-ideal characteristics of the local oscillator light intensity fluctuation, the beam splitting ratio of the beam splitter and the detection efficiency of the detector. In the quantum random number generator system proposed in the present invention, the influence of the local oscillator light intensity fluctuation on the measurement accuracy of the orthogonal component under unbalanced heterodyne detection is considered, the above-mentioned imperfect characteristics are linked to the estimation of the measurement accuracy of the orthogonal component during the calibration process, and the measurement accuracy estimation formula of the orthogonal component is corrected, thereby correcting the randomness evaluation, which can solve the security vulnerability problem introduced by the local oscillator light intensity fluctuation under unbalanced heterodyne detection, and further improve the actual security of the system.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An improved randomness evaluation method for a continuous variable source-independent quantum random number generator based on heterodyne detection, characterized in that: For the unknown quantum state input, under the non-ideal characteristics of the local oscillator light intensity fluctuation, the beam splitting ratio of the beam splitter and the detection efficiency of the detector, the measurement resolution δ of the X-quadrature component and the P-quadrature component of the unknown quantum state in the vacuum state phase space is X and δ P A correction is made to the lower bound of the random number content that can be extracted from the measurement result based on the corrected measurement resolution.

2. According to claim 1, the improved randomness evaluation method of the continuous variable source-independent quantum random number generator based on heterodyne detection is characterized in that: The measurement resolution δ of estimating the X and P quadrature components of the unknown quantum state in the vacuum phase space is X and δ P Make corrections, including: Calibrate the unbalance parameter △ of the beam splitter and the detection efficiency η of each detector i and the parameter l of the initial variance of the local oscillator light intensity fluctuation noise relative to the variance of the vacuum fluctuation noise, and estimate m according to the following formula 1,X(P) and m 2,X(P) ; Among them, m 1,X(P) and m 2,X(P) They represent the ratio of the variance of vacuum noise and the variance of local oscillator light intensity fluctuation noise to the power of local oscillator light respectively; η 1(3) represents the detection efficiency of the first detector or the third detector, η 2(4) represents the detection efficiency of the second detector or the fourth detector, wherein the first detector and the second detector belong to one homodyne detector module, and the third detector and the fourth detector belong to another homodyne detector module; D(δX(P) L (t)) represents the initial variance of the local oscillator light intensity fluctuation noise, l = D(δX(P) L (t)) / D(δX(P) QV (t)). By changing the input LO light power P LO , record the total variance of the measurement results Thus, we can get P LO and The relationship between: Among them, m X(P) and c X(P) Respectively represent the slope and intercept of the relationship, and m X(P) Meet m X(P) =m 1,X(P) +m 2,X(P) ; Considering the influence of the local oscillator light intensity fluctuation noise, according to the estimated m 1,X(P) and m 2,X(P) And the intercept c obtained by fitting X(P) , and correct the variance of the measurement results to: in, represents the variance of the corrected measurement results; According to the corrected standard deviation σ with,X(P) The estimated corrected measurement resolution is δ with,X(P) =δ ADC σ with,X(P) / σ t,X(P) ; Among them, δ ADC is the measurement resolution of the analog-to-digital converter ADC.

3. The method for evaluating randomness of an improved continuous variable source-independent quantum random number generator based on heterodyne detection according to claim 2, characterized in that: Considering the quantum side information ε that can be obtained by the eavesdropper, the modified extractable random number content H min (M δ The lower bound of |ε) is:

4. An improved continuous variable source-independent quantum random number generator system based on heterodyne detection, characterized in that: include: A randomness evaluation module, used for calculating a lower bound of a modified extractable random number content using the randomness evaluation method according to any one of claims 1 to 3; The post-processing module is used to use the lower bound of the modified extractable random number content as a constraint condition to perform random extraction operations on the original data using a post-processing method to obtain secure true random numbers.

Images