Quantum key distribution (QKD) equipment base selection proportion detection method and device based on detector consistency

Abstract

The invention provides the method and the device for detecting the base selection proportion of the QKD equipment based on consistency analysis carried out on the detector from the time domain and the frequency domain at the same time, and the test and the safety evaluation of the base selection proportion of the detected QKD equipment are comprehensively realized.

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 based on detector consistency. 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 potential 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 devices 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 case 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 based on the consistency analysis of the detector carried out simultaneously in the time domain and the frequency domain, which more comprehensively realizes the test and security evaluation of the basis selection ratio of the measured QKD device.

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

[0005] 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) under multiple optical signal central wavelengths λ det2 w , where j = 1,..., m;

[0006] The detector time domain consistency test process is used to 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 according to the first basis vector detection probability P k corresponding to multiple delays T det1 t acting on the signal light and the second basis vector detection probability P det2 t (k), where k = 1,..., q;

[0007] The evaluation step is used to perform a security evaluation based on the detector's first basis vector frequency-domain fluctuation coefficient \(K_{det1\_w}\), the detector's second basis vector frequency-domain fluctuation coefficient \(K_{det2\_w}\), the detector's first basis vector time-domain fluctuation coefficient \(K_{det1\_t}\), and the detector's second basis vector time-domain fluctuation coefficient \(K_{det2\_t}\).

[0008] Further, the detector frequency-domain consistency test process includes the following steps:

[0009] Optical signals with different central wavelengths \(\lambda\) j are respectively input into the QKD device receiver, and corresponding to each central wavelength \(\lambda\) 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 obtained and recorded;

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

[0011] From the \(m\) detection probabilities \(P\) det1 w (j) of the first basis vector, its maximum value \(P\) det1 wmax and minimum value \(P\) det1 wmin are statistically obtained. From the \(m\) detection probabilities \(P\) det2 w (j) of the second basis vector, its maximum value \(P\) det2 wmax and minimum value \(P\) det2 wmin are statistically obtained;

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

[0013]

[0014]

[0015]

[0016]

[0017] Further, the detector time-domain consistency test process includes the following steps:

[0018] An optical signal and a synchronization optical signal are input into the QKD device receiver, and different delays \(T\) k are respectively applied to the optical signal, and corresponding to each delay \(T\) k , the detection counts \(C\) det1 t (k) and \(C\)det2 t (k);

[0019] According to calculate the detection probability P det1 t (k) of the first basis vector, and according to calculate the detection probability P det2 t (k) of the second basis vector;

[0020] Among the q detection probabilities P det1 t (k) of the first basis vector, statistically obtain its maximum value P det1 tmax and minimum value P det1 tmin , and among the q detection probabilities P det2 t (k) of the second basis vector, statistically obtain its maximum value P det2 tmax and minimum value P det2 tmin ;

[0021] 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

[0022]

[0023]

[0024]

[0025]

[0026] Furthermore, in the evaluation step, use the sum of 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_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.

[0027] Furthermore, in the evaluation step, when the sum of the logarithmic coordinate values of the frequency-domain fluctuation coefficient K_det1_w of the first basis vector of the detector and the logarithmic coordinate value of the time-domain fluctuation coefficient K_det1_t of the first basis vector of the detector exceeds the preset security threshold, evaluate that the basis selection ratio parameter is abnormal, and / or when the sum of the logarithmic coordinate values of the frequency-domain fluctuation coefficient K_det2_w of the second basis vector of the detector and the logarithmic coordinate value of the time-domain fluctuation coefficient K_det2_t of the second basis vector of the detector exceeds the preset security threshold, evaluate that the basis selection ratio parameter is abnormal.

[0028] Optionally, in the evaluation step, also output a test report according to the security evaluation result.

[0029] Optionally, during the detector frequency-domain consistency test, m central wavelengths λ are determined within a preset wavelength range according to a preset step value j 。

[0030] Optionally, during the detector time-domain consistency test, q delays T are determined within a preset delay range according to a preset step value k 。

[0031] Optionally, the first basis vector is the Z basis vector and the second basis vector is the X basis vector.

[0032] The second aspect of the present invention relates to a basis selection ratio detection device for a QKD device based on detector consistency, which includes a wavelength tunable laser, a weak coherent light source, an adjustable optical delay line, and a basis selection ratio detection module;

[0033] The wavelength tunable laser is configured to provide an optical signal with different central wavelengths to the receiver of the QKD device under test;

[0034] The weak coherent light source is configured to provide signal light and synchronization light to the receiver of the QKD device under test;

[0035] The adjustable optical delay line is configured to apply a delay T to the signal light k ;

[0036] The basis selection ratio detection module is configured to adjust the central wavelength of the wavelength tunable laser, adjust the delay T of the adjustable optical delay line k , and detect the basis selection ratio of the receiver of the QKD device under test according to the above-mentioned basis selection ratio detection method. Description of the Drawings

[0037] Figure 1 Schematically shows a component connection diagram of the basis selection ratio detection device according to the present invention for the detector frequency-domain consistency test process;

[0038] Figure 2 Schematically shows a component connection diagram of the basis selection ratio detection device according to the present invention for the detector time-domain consistency test process;

[0039] Figure 3 Schematically shows a flowchart of an example of the basis selection ratio detection method according to the present invention. Detailed Embodiments

[0040] Hereinafter, the exemplary embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example 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.

[0041] In the present invention, to comprehensively evaluate the imperfections of the devices at the decoding end, a solution for comprehensive evaluation based on the consistency of detectors is proposed. Therefore, in the method for detecting the basis selection ratio of the QKD device of the present invention, it includes a detector frequency-domain consistency test process, a detector time-domain consistency test process, and an evaluation step.

[0042] Figure 1 Schematically shows a component connection diagram of the basis selection ratio detection device of the present invention for the detector frequency-domain consistency test process.

[0043] As Figure 1 shown, the basis selection ratio detection device may include a wavelength tunable laser and a basis selection ratio detection module.

[0044] When implementing the detector frequency-domain consistency test process using this basis selection ratio detection device, the wavelength tunable laser can be connected to the input end of the receiver of the QKD device 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 receiver of the QKD device under test.

[0045] Therefore, the basis selection ratio detection module can control the wavelength tunable laser to provide different central wavelengths λ j (j = 1,..., m) of optical signals within a preset wavelength 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 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 further obtain the frequency-domain fluctuation coefficients corresponding to the two detectors, that is, 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, so as to perform detector frequency-domain consistency analysis.

[0046] Figure 3 Schematically shows a flowchart of an example of the basis selection ratio detection method of the present invention, and the detector frequency-domain consistency test process of the present invention will be specifically described below with reference to Figure 3 this.

[0047] As Figure 3 shown, in the detector frequency-domain consistency test process, the central wavelength λ of the wavelength tunable laser can be set with the help of the basis selection ratio detection module j , and the detection counts corresponding to the optical signal with this central wavelength λ jThe detection counts C det1 w (j) and C det2 w (j) output by the detectors corresponding to the first basis vector (e.g., the Z basis vector) and the second basis vector (e.g., the X basis vector) respectively for the input of the optical signal.

[0048] 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 first basis vector detection probability P det1 w (j) and the second basis vector detection probability P det2 w (j) using these counts, and further 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.

[0049] As an example, the basis selection ratio detection module can calculate the first basis vector detection probability P and corresponding to the central wavelength λ j respectively according to the relational expressions det1 w (j) and the second basis vector detection probability P det2 w (j).

[0050] Subsequently, the maximum value P det1 w (j) and the minimum value P det1 wmax are statistically obtained from the m first basis vector detection probabilities P det1 wmin , and the maximum value P det2 w (j) and the minimum value P det2 wmax are statistically obtained from the m second basis vector detection probabilities P det2 wmin .

[0051] Therefore, 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 according to the relational expressions and , where:

[0052]

[0053]

[0054]

[0055]

[0056] 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 security evaluation using these fluctuation coefficients in the evaluation step.

[0057] Table 1 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.

[0058]

[0059]

[0060] (Table 1)

[0061] Table 2 shows an example of the detector frequency-domain consistency test analysis results corresponding to Table 1.

[0062] <![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

[0063] (Table 2)

[0064] The detector time-domain consistency test process is used to statistically analyze the efficiency consistency of different detectors at different time positions.

[0065] For this purpose, a weak coherent light source and an adjustable optical delay line can also be provided in the basis selection ratio detection device of the present invention, and their connection relationship in the detector time-domain consistency test process is shown in Figure 2 shown.

[0066] As Figure 2 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 to it.

[0067] The adjustable optical delay line can, for example, change its delay amount T under the control of the basis selection ratio detection module k so as to apply different delays T to the signal light k , k = 1,..., q.

[0068] Therefore, the basis selection ratio detection module can control the adjustable optical delay line to provide different delays T to the signal light within a preset delay range k and record the detection counts of the detectors for the first basis vector and the second basis vector respectively 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 Pdet1 t (k) and the second basis vector detection probability P det2 t (k), and then obtain the time-domain fluctuation coefficients corresponding to the two detectors, namely the first basis vector time-domain fluctuation coefficient K_det1_t of the detector and the second basis vector time-domain fluctuation coefficient K_det2_t of the detector, so as to perform the time-domain consistency analysis of the detector.

[0069] Next, the time-domain consistency test process of the detector of the present invention will be specifically described with reference to Figure 3 the following.

[0070] As shown in Figure 3 , during the time-domain consistency test process of the detector, 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 are respectively recorded, which are the outputs of the detectors corresponding to the first basis vector (such as the Z basis vector) and the second basis vector (such as the X basis vector) det2 t (k) and C

[0071] By changing the delay T k multiple times (k = 1,..., q), for example, traversing all delays within the preset delay 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 then obtain the first basis vector time-domain fluctuation coefficient K_det1_t of the detector and the second basis vector time-domain fluctuation coefficient K_det2_t of the detector.

[0072] As an example, the basis selection ratio detection module can calculate 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).

[0073] Subsequently, the maximum value P det1 t and the minimum value P det1 tmax are statistically obtained from the q first basis vector detection probabilities P det1 tmin , and from the q second basis vector detection probabilities P det2 t(k), the maximum value P is obtained through statistics det2 tmax and the minimum value P det2 tmin .

[0074] Therefore, according to the relational expressions and 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, where:

[0075]

[0076]

[0077]

[0078]

[0079] Table III 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.

[0080]

[0081] (Table III)

[0082] Table IV shows an example of the detector time-domain consistency test analysis result corresponding to Table III.

[0083] <![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

[0084] Correspondingly, in the evaluation step, 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, and the sum is compared with a preset safety threshold, and / or 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, and the sum is compared with the 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.

[0085] Preferably, the detector first basis vector frequency domain fluctuation coefficient K_det1_w, the detector second basis vector frequency domain fluctuation coefficient K_det2_w, 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. The sum of the logarithmic coordinate value of the detector first basis vector frequency domain fluctuation coefficient K_det1_w and the logarithmic coordinate value of the detector first basis vector time domain fluctuation coefficient K_det1_t is compared with a preset safety threshold, and / or the sum of the logarithmic coordinate value of the detector second basis vector frequency domain fluctuation coefficient K_det2_w and the logarithmic coordinate value of the detector second basis vector time domain fluctuation coefficient K_det2_t is compared with the preset safety threshold. When the sum of the logarithmic coordinate values 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.

[0086] In summary, the present invention provides a method and device for detecting the basis selection ratio of a QKD device based on a comprehensive analysis of the detector consistency simultaneously from the frequency domain and the time domain, which can more comprehensively implement the test and safety assessment of the basis selection ratio of the QKD device to be measured, and provide the function of generating and outputting a test report.

[0087] Although the present invention has been described above with reference to specific embodiments in conjunction with the accompanying drawings, it is easy for those skilled in the art to recognize that the above embodiments are merely exemplary and are used to illustrate the principle 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 replacements 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 based on detector consistency, which includes a detector frequency-domain consistency test process, a detector time-domain consistency test process, and an evaluation step; 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 central wavelengths λ, where j = 1, …, m; det2_w (j), The detector time-domain consistency test process is used to obtain the detector first basis vector time-domain fluctuation coefficient \(K_{det1\_t}\) and the detector second basis vector time-domain fluctuation coefficient \(K_{det2\_t}\) according to the first basis vector detection probability \(P^{(k)}_{\langle0000004\rangle}\) and the second basis vector detection probability \(P^{(k)}_{\langle0000005\rangle}\) corresponding to a plurality of delays \(T\) applied to the signal light, where \(k = 1,\cdots,q\). k \(P^{(k)}_{\langle0000004\rangle}\) det1_t \(P^{(k)}_{\langle0000005\rangle}\) det2_t where \(k = 1,\cdots,q\). The evaluation step is used to perform a security evaluation based on the detector first basis vector frequency-domain fluctuation coefficient K_det1_w, the detector second basis vector frequency-domain fluctuation coefficient K_det2_w, 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.

2. The method for detecting the basis selection ratio of the QKD device according to claim 1, wherein, The detector frequency-domain consistency test process includes the following steps: Optical signals with different central wavelengths λ are respectively input into the receiver of the QKD device, j and corresponding to each central wavelength λ, j the detection counts C of the detectors corresponding to the first and second basis vectors are obtained and recorded respectively, de+1_w (j) and C det2_w (j); 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), the maximum value \(P\) det1_wmax and the minimum value \(P\) det1_wmin are statistically obtained. From the detection probabilities \(P\) of \(m\) second basis vectors det2_w (j), the maximum value \(P\) det2_wmax and the minimum value \(P\) det2_wmin are statistically obtained; 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 3. The QKD device basis ratio detection method according to claim 1, wherein, The detector time-domain consistency test process includes the following steps: Input signal light and synchronization light into the receiver of the QKD device, and apply different delays T to the signal light respectively k , and corresponding to each delay T k , obtain and record the detection counts C det1_t (k) and C de+2_t (k) of the detectors corresponding to the first and second basis vectors respectively; According to calculate the first basis vector detection probability P det1_t (k), and according to calculate the second basis vector detection probability P det2_t (k); From the q first basis vector detection probabilities P det1_t (k), the maximum value P det1_tmax and the minimum value P det1_tmin are statistically obtained, and from the q second basis vector detection probabilities P det2_t (k), the maximum value P det2_tmax and the minimum value P det2_+min 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 4. The QKD device basis selection ratio detection method according to claim 1, wherein, In the evaluation step, a security evaluation is performed using the sum of 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 and / or the sum of 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.

5. The method for detecting the basis selection ratio of the QKD device according to claim 1, wherein, In the evaluation step, when the sum of the logarithmic coordinate values of 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 exceeds a preset security threshold, the basis selection ratio parameter is evaluated as abnormal, and / or when the sum of the logarithmic coordinate values of 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 exceeds a preset security threshold, the basis selection ratio parameter is evaluated as abnormal.

6. The method for detecting the basis selection ratio of the QKD device as described in claim 5, wherein, In the evaluation step, a test report is also output according to the security evaluation result.

7. The QKD device basis ratio detection method according to claim 1, wherein, During the frequency domain consistency test of the detector, m central wavelengths λ are determined within a preset wavelength range according to a preset step value j .

8. The QKD device basis selection ratio detection method according to claim 1, wherein, During the time-domain consistency test of the detector, q delays T are determined according to a preset step value within a preset delay range k .

9. The QKD device basis 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 based on detector consistency, which includes a wavelength tunable laser, a weak coherent light source, an adjustable optical delay line, 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 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 is set to apply a delay T to the signal light k ; The selected basis ratio detection module is configured to adjust the central wavelength of the wavelength tunable laser and adjust the delay T of the tunable 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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