Basic selection proportion detection method and device for QKD (quantum key distribution) equipment

Abstract

According to the base selection proportion detection method and device for the QKD equipment, consistency analysis is carried out on a decoding end beam splitter and a detector in the time domain and the frequency domain, and testing and safety evaluation of the base selection proportion of the detected QKD equipment can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of quantum technology, and more particularly to a method and device for detecting the basis selection ratio of a QKD device. Background Art

[0002] In the actual implementation of quantum key distribution (QKD) devices, the devices are imperfect, which may deviate from the theoretical model, thus violating the security assumption and causing actual security risks in QKD. An attacker can exploit the vulnerabilities in the actual device to attack QKD and undermine its actual security. For the Bob side, the imperfections of its device are mainly reflected in the beam splitter and detector at the decoding end. The existing evaluation methods are relatively one-sided, only performing wavelength-related efficiency consistency tests on the detector, and finally incorporating this parameter into the correction of the key generation rate. Although the current method considers the situation of device imperfections, its evaluation of device imperfections is not comprehensive and lacks a comprehensive evaluation. Summary of the Invention

[0003] In view of the above-mentioned defects of the prior art, the present invention proposes a method and device for detecting the basis selection ratio of a QKD device, which can realize the test and security evaluation of the basis selection ratio of the QKD device to be measured by performing consistency analysis on the beam splitter and detector at the decoding end in the time domain and frequency domain.

[0004] Specifically, the first aspect of the present invention relates to a method for detecting the basis selection ratio of a QKD device, which includes a frequency domain consistency test process of the beam splitter at the decoding end, a frequency domain consistency test process of the detector, and an evaluation step;

[0005] The frequency domain consistency test process of the beam splitter at the decoding end is used to obtain the frequency domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter and the frequency domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter according to the first basis vector selection probability P i (i) and the second basis vector selection probability P BS1 (i) of the beam splitter at the decoding end under multiple optical signal center wavelengths λ, where i = 1,..., n; BS2 (i), i = 1,..., n;

[0006] The frequency domain consistency test process of the detector is used to obtain the frequency domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the frequency domain fluctuation coefficient K_det2_w of the second basis vector of the detector according to the first basis vector detection probability P j det1 w (j) and the second basis vector detection probability P(j) of the detector under multiple optical signal center wavelengths λ, where j = 1,..., m; det2 w (j), j = 1,..., m;

[0007] The evaluation step is used to perform a security evaluation based on the beam splitter first basis vector frequency-domain fluctuation coefficient K_bs1_w, the beam splitter second basis vector frequency-domain fluctuation coefficient K_bs2_w, the detector first basis vector frequency-domain fluctuation coefficient K_det1_w, and the detector second basis vector frequency-domain fluctuation coefficient K_det2_w.

[0008] Further, the beam splitter frequency-domain consistency test process at the decoding end includes the following steps:

[0009] Optical signals with different central wavelengths λ i are respectively input into the QKD device receiver, and corresponding to each central wavelength λ i , the counts C BS1 (i) and C BS2 (i) at the output ends corresponding to the first and second basis vectors in the beam splitter at the decoding end are acquired and recorded;

[0010] According to , the first basis vector selection probability is calculated, and according to , the second basis vector selection probability is calculated;

[0011] From the n first basis vector selection probabilities P BS1 (i), its maximum value P BS1max and minimum value P BS1min are statistically obtained, and from the n second basis vector selection probabilities P BS2 (i), its maximum value P BS2max and minimum value P BS2min are statistically obtained;

[0012] According to , the beam splitter first basis vector frequency-domain fluctuation coefficient is calculated, and according to , the beam splitter second basis vector frequency-domain fluctuation coefficient is calculated, where

[0013]

[0014]

[0015] Further, the detector frequency-domain consistency test process includes the following steps:

[0016] Optical signals with different central wavelengths λ j are respectively input into the QKD device receiver, and corresponding to each central wavelength λ j , the detection counts C det1 w (j) and C det2 w (j) of the detectors corresponding to the first and second basis vectors are acquired and recorded;

[0017] According to , the first basis vector detection probability is calculated, and according to Calculate the detection probability of the second basis vector;

[0018] Statistically obtain its maximum value \(P_{max}\) from the \(m\) detection probabilities \(P(j)\) of the first basis vectors det1 w (j), and its minimum value \(P_{min}\), and statistically obtain its maximum value \(P_{max}\) from the \(m\) detection probabilities \(P(j)\) of the second basis vectors det1 wmax and its minimum value \(P_{min}\); det1 wmin (j), det2 w (j), det2 wmax and its minimum value \(P_{min}\); det2 wmin ;

[0019] According to calculate the frequency-domain fluctuation coefficient of the first basis vector of the detector, and according to calculate the frequency-domain fluctuation coefficient of the second basis vector of the detector, where

[0020]

[0021]

[0022] Furthermore, in the evaluation step, use the sum of the frequency-domain fluctuation coefficient \(K_{bs1\_w}\) of the first basis vector of the beam splitter and the frequency-domain fluctuation coefficient \(K_{det1\_w}\) of the first basis vector of the detector, and / or the sum of the frequency-domain fluctuation coefficient \(K_{bs2\_w}\) of the second basis vector of the beam splitter and the frequency-domain fluctuation coefficient \(K_{det2\_w}\) of the second basis vector of the detector for security evaluation.

[0023] Furthermore, the basis selection ratio detection method of the present invention may further include a detector time-domain consistency test process for obtaining the time-domain fluctuation coefficient \(K_{det1\_t}\) of the first basis vector of the detector and the time-domain fluctuation coefficient \(K_{det2\_t}\) of the second basis vector of the detector according to the detection probabilities \(P(k)\) of the first basis vector and the detection probabilities \(P(k)\) of the second basis vector corresponding to a plurality of delays \(T\) applied to the signal light, where \(k = 1,\cdots,q\). k corresponding to the first basis vector and the detection probabilities \(P(k)\) of the second basis vector det1 t (k), det2 t (k).

[0024] Furthermore, the detector time-domain consistency test process includes the following steps:

[0025] Input the signal light and the synchronization light into the receiver of the QKD device, apply different delays \(T\) to the signal light respectively k , and corresponding to each delay \(T\) k , obtain and record the detection counts \(C(k)\) and \(C(k)\) of the detector corresponding to the first and second basis vectors respectively det1 t (k) and \(C\) det2 t (k);

[0026] According to calculate the detection probability of the first basis vector, and according to calculate the detection probability of the second basis vector;

[0027] From the detection probabilities P det1 t (k) of q first basis vectors, the maximum value P det1 tmax and the minimum value P det1 tmin are statistically obtained, and from the detection probabilities P det2 t (k) of q second basis vectors, the maximum value P det2 tmax and the minimum value P det2 tmin are statistically obtained;

[0028] According to calculate the time-domain fluctuation coefficient of the first basis vector of the detector, and according to calculate the time-domain fluctuation coefficient of the second basis vector of the detector, where

[0029]

[0030]

[0031] Furthermore, in the evaluation step, use the sum of the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the time-domain fluctuation coefficient K_det1_t of the first basis vector of the detector and / or the sum of the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector and the time-domain fluctuation coefficient K_det2_t of the second basis vector of the detector for security evaluation.

[0032] Further, in the process of the frequency-domain consistency test of the beam splitter at the decoding end, use a power meter to obtain the power value Power at the output end of the beam splitter at the decoding end, and calculate the count C at the output end according to C = 10 Power / 10

[0033] Optionally, the first basis vector is the Z basis vector and the second basis vector is the X basis vector.

[0034] The second aspect of the present invention relates to a basis selection ratio detection device for a QKD device, which includes a wavelength tunable laser, a first optical power meter, a second optical power meter and a basis selection ratio detection module;

[0035] The wavelength tunable laser is configured to provide optical signals with different central wavelengths to the receiver of the QKD device under test;

[0036] The first optical power meter is configured to obtain the count at the output end corresponding to the first basis vector of the beam splitter at the decoding end in the receiver of the QKD device under test;

[0037] The second optical power meter is configured to obtain the count at the output end corresponding to the second basis vector of the beam splitter at the decoding end in the receiver of the QKD device under test;

[0038] ​The selected basis ratio detection module is configured to adjust the central wavelength of the wavelength-tunable laser and detect the selected basis ratio of the receiver of the QKD device under test according to the above-mentioned selected basis ratio detection method.

[0039] Furthermore, the selected basis ratio detection device of the present invention may further include a weak coherent light source and an adjustable optical delay line;

[0040] The weak coherent light source is configured to provide signal light and synchronization light to the receiver of the QKD device under test;

[0041] The adjustable optical delay line is configured to apply a delay T to the signal light k ;

[0042] The selected basis ratio detection module is further configured to adjust the delay T of the adjustable optical delay line k and detect the selected basis ratio of the receiver of the QKD device under test according to the above-mentioned selected basis ratio detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematically shows a component connection diagram of the selected basis ratio detection device according to the present invention for the frequency domain consistency test process of the decoder beam splitter;

[0044] Figure 2 Schematically shows a component connection diagram of the selected basis ratio detection device according to the present invention for the frequency domain consistency test process of the detector;

[0045] Figure 3 Schematically shows a component connection diagram of the selected basis ratio detection device according to the present invention for the time domain consistency test process of the detector;

[0046] Figure 4 Schematically shows a flowchart of an example of the selected basis ratio detection method according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] Hereinafter, the exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so as to fully convey the spirit of the present invention to those skilled in the art to which the present invention pertains. Therefore, the present invention is not limited to the embodiments disclosed herein.

[0048] In the present invention, in order to comprehensively evaluate the imperfections of the components at the decoding end, a solution for comprehensive evaluation based on the consistency of the decoder beam splitter and the detector is proposed. Therefore, in the selected basis ratio detection method for the QKD device of the present invention, it includes the frequency domain consistency test process of the decoder beam splitter, the frequency domain consistency test process of the detector, and the evaluation step.

[0049] Figure 1Schematically shown is a component connection diagram of the basis selection ratio detection device according to the present invention for the frequency-domain consistency test process of the decoding end beam splitter.

[0050] As Figure 1 shown, the basis selection ratio detection device may include a wavelength tunable laser, a first optical power meter, a second optical power meter, and a basis selection ratio detection module.

[0051] When using the basis selection ratio detection device to implement the frequency-domain consistency test process of the decoding end beam splitter, the wavelength tunable laser can be connected to the input end of the QKD device receiver under test, so as to allow, for example, under the control of the basis selection ratio detection module, by changing its central wavelength λ, to provide an optical signal with different central wavelengths to the QKD device receiver under test.

[0052] The first optical power meter and the second optical power meter are respectively connected to the two output ends of the decoding end beam splitter in the QKD device receiver under test to obtain the power outputs of the two output ends.

[0053] Therefore, the basis selection ratio detection module can, within a preset wavelength range, control the wavelength tunable laser to provide optical signals with different central wavelengths λ i (i = 1,..., n) to the QKD device receiver under test, and record the optical signals corresponding to each central wavelength λ i ; with the help of the first optical power meter and the second optical power meter, measure the power outputs of the two output ends of the decoding end beam splitter; based on these two power outputs, calculate the selection probabilities of the two basis vectors respectively corresponding to the two output ends, that is, the first basis vector selection probability P BS1 (i) and the second basis vector selection probability P BS2 (i), and further obtain the frequency-domain fluctuation coefficients of the two basis vectors at the decoding end beam splitter, that is, the beam splitter first basis vector frequency-domain fluctuation coefficient K_bs1_w and the beam splitter second basis vector frequency-domain fluctuation coefficient K_bs2_w, so as to perform frequency-domain consistency analysis of the decoding end beam splitter.

[0054] Here, those skilled in the art can understand that, for example, in a QKD device based on a time-phase encoding protocol, the first and second basis vectors can be the Z basis vector and the X basis vector.

[0055] Figure 4 Schematically shown is a flowchart of an example of the basis selection ratio detection method of the present invention. The frequency-domain consistency test process of the decoding end beam splitter of the present invention will be specifically described below with reference to Figure 4 Specifically describe the frequency-domain consistency test process of the decoding end beam splitter of the present invention.

[0056] As Figure 4 shown, during the frequency-domain consistency test process of the decoding end beam splitter, the central wavelength λ of the wavelength tunable laser can be set with the help of the basis selection ratio detection module i, and correspondingly count and record the optical signal input corresponding to the center wavelength λ i The counts C BS1 (i) and C Bs2 (i) at the output terminals corresponding to the first (e.g., Z basis vector) and the second basis vector (e.g., X basis vector) in the decoder beam splitter.

[0057] As an example, the power value Power at the output terminal of the decoder beam splitter can be obtained with the help of a power meter, and then the energy value (count) C at the output terminal can be calculated according to C = 10 Power / 10 .

[0058] By changing the center wavelength λ i (i = 1,..., n) multiple times, for example, traversing all wavelengths within a preset wavelength range with a preset step value, and counting and recording the corresponding counts C BS1 (i) and C BS2 (i), n groups of center wavelengths λ i and their corresponding counts C BS1 (i) and C BS2 (i) are obtained. Then, the basis selection ratio detection module can use these counts to obtain the corresponding first basis vector selection probability P BS1 (i) and the second basis vector selection probability P BS2 (i), and further obtain the beam splitter first basis vector frequency domain fluctuation coefficient K_bs1_w and the beam splitter second basis vector frequency domain fluctuation coefficient K_bs2_w.

[0059] As an example, the basis selection ratio detection module can calculate and obtain the first basis vector selection probability P and corresponding to the center wavelength λ i respectively according to the relational expressions BS1 (i) and the second basis vector selection probability P BS2 (i).

[0060] Subsequently, the maximum value P BS1 (i) and the minimum value P BS1max are statistically obtained from the n first basis vector selection probabilities P BS1min , and the maximum value P BS2 (i) and the minimum value P ES2max are statistically obtained from the n second basis vector selection probabilities P BS2min .

[0061] Therefore, the beam splitter first basis vector frequency domain fluctuation coefficient K_bs1_w and the beam splitter second basis vector frequency domain fluctuation coefficient K_bs2_w can be calculated respectively according to the relational expressions and , where:

[0062]

[0063]

[0064]

[0065]

[0066] Preferably, the beam splitter first basis vector frequency domain fluctuation coefficient K_bs1_w and the beam splitter second basis vector frequency domain fluctuation coefficient K_bs2_w can also be converted into logarithmic coordinate values, so as to facilitate subsequent security evaluation using these fluctuation coefficients in the evaluation step.

[0067] Table 1 below shows an example of the frequency domain consistency test process of the decoder beam splitter, where the first basis vector is the Z basis vector and the second basis vector is the X basis vector.

[0068]

[0069] (Table 1)

[0070] Table 2 shows an example of the frequency domain consistency analysis result of the decoder beam splitter corresponding to Table 1.

[0071] <![CDATA[max(R BS2 )]]> <![CDATA[R BS2m > K_bs1_w K_bs1_w (dB) 1.008092 0.982429 1.026121 0.111987 <![CDATA[max(R BS1 )]]> <![CDATA[R BS1m > K_bs2_w K_bs2_w (dB) 1.044480 1.017885 1.026127 0.112013

[0072] (Table 2)

[0073] Figure 2 Schematically shows the component connection diagram of the basis selection ratio detection device of the present invention for the detector frequency domain consistency test process.

[0074] As Figure 2 shown, when realizing the detector frequency domain consistency test process by using the basis selection ratio detection device, the wavelength tunable laser can be connected to the input end of the QKD device receiver under test, so as to allow, for example, under the control of the basis selection ratio detection module, by changing its central wavelength λ, to provide an optical signal with different central wavelengths to the QKD device receiver under test.

[0075] Therefore, the basis selection ratio detection module can control the wavelength tunable laser to provide optical signals with different central wavelengths λ j (j = 1,..., m) within a preset wavelength range to the QKD device receiver under test, and record the detection counts of the detectors in the QKD device receiver under test respectively used for the first basis vector and the second basis vector corresponding to each central wavelength λ j ; and calculate the detection probabilities of the two detectors based on these two detection counts, that is, the first basis vector detection probability P det1 w (j) and the second basis vector detection probability P det2 w(j), and then obtain the frequency-domain fluctuation coefficients corresponding to the two detectors, namely the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector, so as to perform the frequency-domain consistency analysis of the detectors.

[0076] Next, the frequency-domain consistency test process of the detector of the present invention will be specifically described with reference to Figure 4 the following.

[0077] As shown in Figure 4 , in the frequency-domain consistency test process of the detector, the central wavelength λ of the wavelength-tunable laser can be set by means of the basis selection ratio detection module j , and the detection counts C j corresponding to the input of the optical signal with this central wavelength λ det1 w output by the detectors corresponding to the first basis vector (for example, the Z basis vector) and the second basis vector (for example, the X basis vector) are respectively statistically recorded det2 w (j) and C

[0078] By changing the central wavelength λ j (j = 1,..., m) multiple times, for example, traversing all wavelengths within a preset wavelength range with a certain step value, and statistically recording the corresponding counts C det1 w (j) and C det2 w (j), m groups of central wavelengths λ j and their corresponding counts C det1 w (j) and C det2 w (j) are obtained. Then, the basis selection ratio detection module can calculate the detection probability P det1 w of the first basis vector and the detection probability P det2 w of the second basis vector by using these counts, and further obtain the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector.

[0079] As an example, the basis selection ratio detection module can calculate the detection probability P of the first basis vector and the detection probability P corresponding to the central wavelength λ j respectively according to the relational expressions det1 w (j) and the detection probability P det2 w (j) of the second basis vector.

[0080] Subsequently, the maximum value P det1 w and the minimum value P det1 wmax are statistically obtained from the m detection probabilities P det1 wmin of the first basis vector, and the maximum value P det2 w and the minimum value P det2 wmax are statistically obtained from the m detection probabilities Pdet2 wmin .

[0081] Therefore, according to the relational expressions and the detector first basis vector frequency domain fluctuation coefficient K_det1_w and the detector second basis vector frequency domain fluctuation coefficient K_det2_w can be calculated respectively, where:

[0082]

[0083]

[0084]

[0085]

[0086] Preferably, the detector first basis vector frequency domain fluctuation coefficient K_det1_w and the detector second basis vector frequency domain fluctuation coefficient K_det2_w can also be converted into logarithmic coordinate values, so as to facilitate subsequent safety assessment using these fluctuation coefficients in the evaluation step.

[0087] Table III below shows an example of the detector frequency domain consistency test process, where the first basis vector is the Z basis vector and the second basis vector is the X basis vector.

[0088]

[0089] (Table III)

[0090] Table IV shows an example of the detector frequency domain consistency test analysis results corresponding to Table III.

[0091] <![CDATA[max(R det2 w )]]> <![CDATA[R det2 wm > K_det1_w K_det1_w (dB) 0.936 0.913144882 1.025206181 0.108112157 <![CDATA[max(R det1 w )]]> <![CDATA[R det1 wm > K_det2_w K_det2_w (dB) 1.123 1.095116471 1.025235058 0.108234485

[0092] (Table IV)

[0093] When the beam splitter first basis vector frequency domain fluctuation coefficient K_bs1_w, the beam splitter second basis vector frequency domain fluctuation coefficient K_bs2_w, the detector first basis vector frequency domain fluctuation coefficient K_det1_w and the detector second basis vector frequency domain fluctuation coefficient K_det2_w are obtained through the above test process, then the safety assessment can be carried out using the above coefficients with the help of the evaluation step.

[0094] As an example, the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter and the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector can be added, and the sum of the two can be compared with a preset safety threshold, and / or the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter and the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector can be added, and the sum of the two can be compared with a preset safety threshold. When the sum of the coefficients does not exceed the safety threshold, it is determined that the current basis selection ratio parameter is normal; otherwise, it is determined that the current basis selection ratio parameter is abnormal, and a corresponding test report is output.

[0095] To more comprehensively evaluate the imperfections of the devices at the decoding end, the basis selection ratio detection method of the present invention may further include a detector time-domain consistency test process to statistically analyze the efficiency consistency of different detectors at different time positions.

[0096] For this purpose, a weak coherent light source and an adjustable optical delay line may also be provided in the basis selection ratio detection device of the present invention, and their connection relationship during the detector time-domain consistency test process is shown in Figure 3 shown.

[0097] As Figure 3 shown, when implementing the detector time-domain consistency test process using the basis selection ratio detection device, the weak coherent light source can be connected to the input end of the receiver of the QKD device under test to provide signal light and synchronization light thereto.

[0098] The adjustable optical delay line can, for example, under the control of the basis selection ratio detection module, change its delay amount T k , so as to apply different delays T k , k = 1,..., q, to the signal light.

[0099] Therefore, the basis selection ratio detection module can control the adjustable optical delay line to provide different delays T k to the signal light within a preset delay range, and record the detection counts of the detectors respectively used for the first basis vector and the second basis vector in the receiver of the QKD device under test corresponding to each delay T k ; and calculate the detection probabilities of the two detectors based on these two detection counts, that is, the first basis vector detection probability P det1 t (k) and the second basis vector detection probability P det2 t (k), and further obtain the time-domain fluctuation coefficients corresponding to the two detectors, that is, the detector first basis vector time-domain fluctuation coefficient K_det1_t and the detector second basis vector time-domain fluctuation coefficient K_det2_t, so as to perform detector time-domain consistency analysis.

[0100] Next, the detector time-domain consistency test process of the present invention will be specifically described with reference to Figure 4 this.

[0101] As shown Figure 4 in the detector time-domain consistency test, the delay T applied to the signal light can be set by means of the basis selection ratio detection module k , and the counts C k corresponding to the optical signal input with the delay T det1 t (k) and C det2 t (k) of the detector outputs corresponding to the first basis vector (e.g., Z basis vector) and the second basis vector (e.g., X basis vector) are statistically recorded respectively

[0102] By changing the delay T k (k = 1,..., q) multiple times, for example, traversing all delays within a preset delay amount range with a certain step value, and statistically recording the corresponding counts C det1 t (k) and C det2 t (k), q groups of delays T k and their corresponding counts C det1 t (k) and C det2 t (k) are obtained. Then, the basis selection ratio detection module can use these counts to obtain the corresponding first basis vector detection probability P det1 t (k) and the second basis vector detection probability P det2 t (k), and further obtain the detector first basis vector time-domain fluctuation coefficient K_det1_t and the detector second basis vector time-domain fluctuation coefficient K_det2_t

[0103] As an example, the basis selection ratio detection module can calculate and obtain the first basis vector detection probability P and corresponding to the delay T k respectively according to the relational expressions det1 t (k) and the second basis vector detection probability P det2 t (k)

[0104] Subsequently, the maximum value P det1 t (k) and the minimum value P det1 tmax are statistically obtained from the q first basis vector detection probabilities P det1 tmin , and the maximum value P det2 t (k) and the minimum value P det2 tmax are statistically obtained from the q second basis vector detection probabilities P det2 tmin

[0105] Therefore, the detector first basis vector time-domain fluctuation coefficient K_det1_t and the detector second basis vector time-domain fluctuation coefficient K_det2_t can be calculated respectively according to the relational expressions and , where

[0106] ​

[0107]

[0108]

[0109]

[0110] Preferably, the detector first basis vector time-domain fluctuation coefficient K_det1_t and the detector second basis vector time-domain fluctuation coefficient K_det2_t can also be converted into logarithmic coordinate values, so as to facilitate subsequent security evaluation using these fluctuation coefficients in the evaluation step.

[0111] Table V below shows an example of the detector time-domain consistency test process, where the first basis vector is the Z basis vector and the second basis vector is the X basis vector.

[0112]

[0113] (Table V)

[0114] Table VI shows an example of the detector time-domain consistency test analysis results corresponding to Table V.

[0115] <![CDATA[max(R det2 t )]]> <![CDATA[R det2 tm > K_det1_t K_det1_t (dB) 1.066618 0.999770 1.066864 0.281089 <![CDATA[max(R det1 t )]]> <![CDATA[R det1 tm > K_det2_t K_det2_t (dB) 1.067110 1.000230 1.066864 0.281091

[0116] Accordingly, in the evaluation step, the beam splitter first basis vector frequency-domain fluctuation coefficient K_bs1_w, the detector first basis vector frequency-domain fluctuation coefficient K_det1_w, and the detector first basis vector time-domain fluctuation coefficient K_det1_t can be added together, and the sum of the three is compared with a preset security threshold, and / or the beam splitter second basis vector frequency-domain fluctuation coefficient K_bs2_w, the detector second basis vector frequency-domain fluctuation coefficient K_det2_w, and the detector second basis vector time-domain fluctuation coefficient K_det2_t are added together, and the sum of the three is compared with the preset security threshold. When the sum of the coefficients does not exceed the security threshold, it is determined that the current basis selection ratio parameter is normal, otherwise it is determined that the current basis selection ratio parameter is abnormal, and a corresponding test report is output.

[0117] In summary, the present invention provides a method and device for detecting the basis selection ratio of a QKD device, which can realize the test and security evaluation of the basis selection ratio of the QKD device to be measured by performing consistency analysis on the beam splitter and detector at the decoding end in the time domain and frequency domain, and provide the function of generating and outputting a test report.

[0118] Although the present invention has been described by way of specific embodiments in conjunction with the accompanying drawings, it is readily appreciated by those skilled in the art that the above embodiments are merely exemplary and are used to illustrate the principles of the present invention, which will not limit the scope of the present invention. Those skilled in the art can make various combinations, modifications and equivalent substitutions to the above embodiments without departing from the spirit and scope of the present invention.

Claims

1. A method for detecting the basis selection ratio of a QKD device, which includes the frequency-domain consistency test process of the decoder beam splitter, the frequency-domain consistency test process of the detector, and the evaluation step; The frequency-domain consistency test process of the decoding end beam splitter is used to obtain the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter and the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter according to the first basis vector selection probability P i at the central wavelengths λ of multiple optical signals, and the second basis vector selection probability P BS1 (i). Here, i = 1, …, n; BS2 (i), The detector frequency domain consistency test process is used to obtain the detector first basis vector frequency domain fluctuation coefficient K_det1_w and the detector second basis vector frequency domain fluctuation coefficient K_det2_w according to the first basis vector detection probability P j (j) and the second basis vector detection probability P det1_w (j) at multiple optical signal center wavelengths λ, where j = 1, …, m; j The first basis vector detection probability P det1_w (j) and the second basis vector detection probability P det2_w (j); The evaluation step is used to perform a security evaluation based on the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector, and the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector.

2. The base selection ratio detection method according to claim 1, wherein The frequency-domain consistency test process of the decoder beam splitter includes the following steps: Optical signals with different central wavelengths λ are respectively input into the receiver of the QKD device i , and corresponding to each central wavelength λ i , the counts C BS1 (i) and C BS2 (i) at the output ends corresponding to the first and second basis vectors in the beam splitter at the decoding end are obtained and recorded; According to calculate the first basis vector selection probability, and according to calculate the second basis vector selection probability; Probability \(P\) of selecting from \(n\) first basis vectors BS1 The maximum value \(P\) is obtained by statistics in (i) BS1max and the minimum value \(P\) BS1min , Probability \(P\) of selecting from \(n\) second basis vectors BS2 The maximum value \(P\) is obtained by statistics in (i) BS2max and the minimum value \(P\) BS2min ; According to calculate the frequency-domain fluctuation coefficient of the first basis vector of the beam splitter, and according to calculate the frequency-domain fluctuation coefficient of the second basis vector of the beam splitter, where 3. The base selection ratio detection method according to claim 1, wherein, The frequency-domain consistency test process of the detector includes the following steps: Input optical signals with different central wavelengths λ into the receiver of the QKD device respectively j and, corresponding to each central wavelength λ j , obtain and record the detection counts C det1_w (j) and C det2_w (j) of the detectors corresponding to the first and second basis vectors respectively; According to calculate the detection probability of the first basis vector, and according to calculate the detection probability of the second basis vector; From the detection probabilities \(P\) of \(m\) first basis vectors det1_w (j), its maximum value \(P\) det1_wmax and minimum value \(P\) det1_wmin are statistically obtained. From the detection probabilities \(P\) of \(m\) second basis vectors det2_e (j), its maximum value \(P\) det2_wmax and minimum value \(P\) det2_wmin ; According to calculate the first basis vector frequency domain fluctuation coefficient of the detector. According to calculate the second basis vector frequency domain fluctuation coefficient of the detector, where 4. The base selection ratio detection method according to claim 1, wherein, In the evaluation step, the sum of the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter and the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector, and / or the sum of the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter and the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector are used for security evaluation.

5. The basis selection ratio detection method according to claim 1 further includes a detector time-domain consistency test process for obtaining a detector first basis vector time-domain fluctuation coefficient K_det1_t and a detector second basis vector time-domain fluctuation coefficient K_det2_t based on a first basis vector detection probability P k (k) and a second basis vector detection probability P det1_t (k) corresponding to a delay T applied to the signal light, where k = 1, …, q. k corresponding to the first basis vector detection probability P det1_t (k) and the second basis vector detection probability P det2_t (k), where k = 1, …, q.

6. The base selection ratio detection method according to claim 5, wherein, The time-domain consistency test process of the detector includes the following steps: Input signal light and synchronization light into the receiver of the QKD device, and apply different time delays T to the signal light respectively k , and corresponding to each time delay T k , obtain and record the detection counts C det1_t (k) and C det2_t (k) of the detectors corresponding to the first and second base vectors respectively; According to calculate the detection probability of the first basis vector, and according to calculate the detection probability of the second basis vector; From the detection probabilities \(P\) of \(q\) first basis vectors det1_t (k), the maximum value \(P\) det1_tmax and the minimum value \(P\) det1_tmin are statistically obtained, and from the detection probabilities \(P\) of \(q\) second basis vectors det2_t (k), the maximum value \(P\) det2_tmax and the minimum value \(P\) det2_tmin are obtained; According to calculate the time-domain fluctuation coefficient of the first basis vector of the detector, and according to calculate the time-domain fluctuation coefficient of the second basis vector of the detector, where 7. The base selection ratio detection method according to claim 5, wherein, In the evaluation step, the sum of the frequency-domain fluctuation coefficient K_bs1_w of the first basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the time-domain fluctuation coefficient K_det1_t of the first basis vector of the detector, and / or the sum of the frequency-domain fluctuation coefficient K_bs2_w of the second basis vector of the beam splitter, the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector and the time-domain fluctuation coefficient K_det2_t of the second basis vector of the detector are used for security evaluation.

8. The base selection ratio detection method according to claim 2, wherein, During the frequency domain consistency test of the decoder beam splitter, the power value Power at the output end of the decoder beam splitter is obtained with the help of a power meter, and according to C = 10 Power / 10 calculate the count C at the output end.

9. The base selection ratio detection method according to claim 1, wherein The first basis vector is the Z basis vector, and the second basis vector is the X basis vector.

10. A device for detecting the basis selection ratio of a QKD device, which includes a wavelength-tunable laser, a first optical power meter, a second optical power meter, and a basis selection ratio detection module; The wavelength-tunable laser is configured to provide optical signals with different central wavelengths to the receiver of the QKD device under test; The first optical power meter is configured to obtain the count of the output end corresponding to the first basis vector of the decoder beam splitter in the receiver of the QKD device under test; The second optical power meter is configured to obtain the count of the output end corresponding to the second basis vector of the decoder beam splitter in the receiver of the QKD device under test; The basis selection ratio detection module is configured to adjust the central wavelength of the wavelength-tunable laser and detect the basis selection ratio of the receiver of the QKD device under test according to the basis selection ratio detection method described in any one of claims 1-4, 8, and 9.

11. The basis selection ratio detection device according to claim 10, which further includes a weak coherent light source and an adjustable optical delay line; The weak coherent light source is configured to provide signal light and synchronization light to the receiver of the QKD device under test; The adjustable optical delay device is configured to impose a delay T on the signal light k ; The selected basis ratio detection module is further configured to adjust the delay T of the adjustable optical delay line k , and detect the selected basis ratio of the receiver of the QKD device under test according to the selected basis ratio detection method according to any one of claims 1-9.

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