An independent and identically distributed detection device and method for an optical beam splitter

Abstract

The application provides an independent and identical distribution detection device and method of an optical beam splitter, wherein a test light source is used to generate a test light signal; an adjustable optical attenuator attenuates the received test light signal; a signal source is used to trigger the test light source and a time-to-digital conversion module; a measured device is used to divide the received attenuated light signal into two beams and then input the two beams into first and second polarization controllers; the first and second polarization controllers are used to adjust the polarization state of the received light; a low-noise detector receives light output by the first polarization controller after time delay and light directly output by the second polarization controller; the time-to-digital conversion module is used to receive an electrical signal output by the low-noise detector, measure the electrical signal, and then output the measured electrical signal to an upper computer; and the upper computer performs independent and identical distribution detection. The application has the advantages that the probability of the data of two output paths is collected in real time, the published standard is used for testing, the test scheme and the test standard are both reliable, and therefore the safety evaluation is more comprehensive.

Description

Technical Field

[0001] This invention relates to quantum key distribution technology, and in particular to independent and identically distributed detection of optical beam splitters. Background Technology

[0002] Quantum key distribution devices must ensure the randomness of both transmission and detection during design. Currently, there are two schemes for achieving random detection: active modulation and passive modulation. Active modulation obtains random numbers (binary digits composed of 0s and 1s) from the receiver's random number generator and uses these digits to randomly probe the received light. Therefore, the key to active modulation lies in the randomness of the digits 0 and 1. Passive modulation uses a beam splitter to divide the received light into two beams. Each beam is probed using a set of orthogonal bases. After a photon passes through the beam splitter, one output is arbitrarily selected, and its orthogonal base is used for detection. At the detector, the orthogonal base used depends on which output was selected after beam splitting. To perform random detection on the received photon (using different bases), the probabilities of the two outputs after passing through the beam splitter should be equal. Therefore, the key to passive modulation lies in the randomness of the two outputs of the optical beam splitter. A 1:1 optical beamsplitter is typically used for modulation. Currently, there is no direct testing method for the randomness of this 1:1 optical beamsplitter. It is generally converted to testing the beam splitting ratio of the device under test (DUT). This involves using a single-photon detector to collect two counts of the beam splitter's output, calculating the beam splitting ratio based on the two counts, and comparing it to a preset threshold. A test connection diagram is shown below. Figure 1 As shown.

[0003] The randomness of a beam splitter manifests as the probability of its two outputs. Current testing methods calculate the splitting ratio by counting the two outputs. The underlying principle is that if the probabilities of the two outputs are the same, the counts should be consistent. This testing method cannot directly measure the probabilities of the two outputs; instead, it converts the probabilities of the two outputs into the splitting ratio for measurement. The randomness of the beam splitter is indirectly evaluated by the magnitude of the splitting ratio. However, there are currently no clear specifications or standards explaining the correspondence between the magnitude of the splitting ratio and the randomness of the beam splitter.

[0004] Furthermore, there is no clear specification or standard defining the threshold value for the beam splitting ratio calculated by this test scheme. This means that the currently used test scheme cannot directly test the randomness of the beam splitter, and there are no corresponding standards for reference in the converted test results. Therefore, this test scheme provides a rather one-sided assessment of the randomness of the beam splitter. Combined with the random detection process of the passive modulation scheme mentioned earlier, its essence lies in the randomness of the optical beam splitter. If the randomness of the optical beam splitter cannot be fully assessed, it will pose a risk to the decoding security of the detection end. Therefore, it is necessary to directly measure the randomness of the optical beam splitter. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to directly test the randomness of an optical beam splitter.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] An independent co-distribution detection device for an optical beam splitter, comprising:

[0008] Test light source, used to generate test light signals for independent and identically distributed detection;

[0009] An adjustable optical attenuator is used to attenuate the received test optical signal and output the attenuated optical signal to the device under test.

[0010] The signal source is used to trigger the test light source and the time-to-digital conversion module;

[0011] The first and second polarization controllers are used to adjust the polarization state of the received light split from the device under test.

[0012] A low-noise detector is used to receive light output from the first polarization controller via the first channel after a delay, and light directly output from the second polarization controller via the second channel.

[0013] The time-to-digital converter module is used to receive the electrical signal output by the low-noise detector, and after measurement, output the detection count to the host computer. The time-to-digital converter module records the detection counts of the first channel and the second channel as bit0 and bit1, respectively.

[0014] The host computer is used to store bit0 and bit1 recorded by the aforementioned time-to-digital conversion module in binary files and to perform independent identical distribution detection.

[0015] As an optimized technical solution, the independent and co-distributed detection device for the optical beam splitter also includes an optical beam combiner. The light output from the delayed first polarization controller and the light directly output from the second polarization controller are input to the low-noise detector after passing through the optical beam combiner. The low-noise detector is a single-channel low-noise detector.

[0016] As another optimized technical solution, the low-noise detector has at least two channels, and the light output by the delayed first polarization controller and the light directly output by the second polarization controller enter the two input ports of the low-noise detector respectively.

[0017] As an optimized technical solution, the test light source is a single-photon light source or a weakly coherent light source.

[0018] As an optimized technical solution, the first polarization controller is connected to the low-noise detector via an optical fiber jumper to achieve a delay.

[0019] As an optimized technical solution, the low-noise detector is a superconducting detector.

[0020] As an optimized technical solution, the host computer controls the light emission of the test light source, controls the attenuation of the adjustable light attenuator, sets the parameters of the signal source, and controls the time-to-digital conversion module.

[0021] As an optimized technical solution, the host computer assesses the safety of the device under test based on the results of independent and identically distributed detection, combined with the safety threshold of independent and identically distributed detection in the NIST SP800-90B standard.

[0022] The present invention also provides a method for detection using the optical beam splitter independent co-distributed detection device described in any of the above-described schemes, comprising the following steps:

[0023] Step 1: Hardware setup: According to the connection structure of the independent and co-distributed detection device for the optical beam splitter, establish the hardware connection relationship between each component. Connect the input end of the device under test to the output end of the adjustable optical attenuator, and connect the input ends of the first polarization controller and the second polarization controller to the two output ports of the device under test, respectively.

[0024] Step 2, Data Acquisition: Establish the data connection between the built-in software in the host computer and the connected components;

[0025] Step 3: After the test environment is set up, start the independent identical distribution test through the host computer software, including the following steps:

[0026] Step 1: Start independent same-distribution detection. The host computer software will automatically connect to the test light source, signal source, adjustable light attenuator and time-to-digital converter module, and then proceed to Step 2;

[0027] Step 2: Control the signal source to output a trigger signal through the host computer software. The trigger signal provides the same trigger signal to the test light source and the time-to-digital converter module. Then proceed to Step 3.

[0028] Step 3: Control the test light source to emit light through the host computer software, and then proceed to Step 4;

[0029] Step 4: Adjust the adjustable optical attenuator to reduce the intensity of the output optical signal, then proceed to step 5;

[0030] Step 5: Measure the output light intensity to determine if it is in a single-photon state. If not, proceed to step 4; if yes, proceed to step 6.

[0031] Step 6: Adjust the first polarization controller, then proceed to step 7;

[0032] Step 7: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, the peak count will be displayed. Repeat step 6 to adjust and find the maximum value of the changing peak count. Then stop the adjustment in step 6 and proceed to step 8.

[0033] Step 8: Adjust the second polarization controller, then proceed to step 9;

[0034] Step 9: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, the peak count will be displayed. Repeat step 8 to adjust and find the maximum value of the changing peak count. Then stop the adjustment in step 8 and proceed to step 10.

[0035] Step 10: After the above adjustments are completed, the data of the two output channels of the device under test measured by the time-to-digital converter module are collected by the host computer software and automatically saved as a binary file. Then proceed to step 11.

[0036] Step 11: The host computer software loads the data from step 10, performs independent identically distributed (ICD) tests on randomness, and outputs the test results.

[0037] As an optimized technical solution, the detection method further includes the following steps:

[0038] Step 12: Based on the results of Step 11, the host computer software assesses the safety of the device under test by combining the safety threshold of independent identically distributed detection in the NIST SP 800-90B standard, and then proceeds to Step 13.

[0039] Step 13: The host computer software summarizes the above test data, outputs a test report, and the test ends.

[0040] The advantages of this invention are as follows: This invention proposes an independent and identically distributed detection method and device for optical beamsplitters, realizing direct randomness testing of optical beamsplitters. In this scheme, data from the two output channels of the optical beamsplitter are acquired in real time, and the data passing through the two channels are recorded as 0 and 1 respectively. During the real-time acquisition process, the numbers 0 and 1 will appear alternately. The numbers 0 and 1 are saved as binary files for independent and identically distributed detection of randomness (see the relevant content in the NISTSP 800-90B standard for details). Finally, based on the test results and security thresholds, a security assessment is given. This security assessment is based on the probability of acquiring data from the two output channels in real time, and is verified using the published NIST SP800-90B standard. From the test scheme to the test standard, there are reliable sources, so the security assessment given is relatively comprehensive. In addition, it also has the function of generating and outputting test reports. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the randomness test connection of an existing optical beam splitter;

[0042] Figure 2 This is a schematic diagram of the independent and co-distributed detection connection of the optical beam splitter in Embodiment 1 of the present invention;

[0043] Figure 3 This is a flowchart of the independent and identically distributed detection method of Embodiment 1 of the present invention;

[0044] Figure 4 This is a schematic diagram of the independent and co-distributed detection connection of the optical beam splitter in Embodiment 2 of the present invention;

[0045] Figure 5 This is a flowchart of the independent and identically distributed detection method of Embodiment 2 of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This invention provides a method and apparatus for detecting independent and identical distribution of optical beam splitters, including two embodiments, as detailed below.

[0048]

Example 1

[0049] This embodiment provides an independent and identically distributed detection device for optical beam splitters. See [link to relevant documentation]. Figure 2 This device is used to perform independent and identically distributed testing on the device under test (DUT). Its components include a signal source, a test light source, an adjustable optical attenuator, a first polarization controller, fiber optic patch cords, a second polarization controller, an optical beam combiner, a low-noise detector, a time-to-digital converter, and a host computer. The DUT is an optical beam splitter, and the preferred low-noise detector is a superconducting detector because it has lower noise; lower noise introduces less measurement error.

[0050] The test light source is connected to an adjustable optical attenuator. The inputs of the first and second polarization controllers are respectively connected to the two output ports of the device under test. The output of the first polarization controller is connected to one input port of the optical combiner via the fiber optic patch cord, and the output of the second polarization controller is connected to the other input port of the optical combiner. The output port of the optical combiner is connected to the time-to-digital converter module via the low-noise detector. The output of the signal source is simultaneously connected to both the test light source and the time-to-digital converter module. The host computer is connected to the signal source, the test light source, the adjustable optical attenuator, and the time-to-digital converter module.

[0051] The test light source is used to generate test light signals for independent and identically distributed detection. This test light source must be a single-photon source or a weakly coherent source.

[0052] The adjustable optical attenuator attenuates the received test optical signal and outputs the attenuated optical signal to the device under test.

[0053] The signal source is used to trigger the test light source and the time-to-digital conversion module;

[0054] The device under test is used to split the received light into two beams, which are then input to the first polarization controller and the second polarization controller, respectively.

[0055] The first polarization controller is used to adjust the polarization state of the received light and output the polarization-adjusted light.

[0056] The second polarization controller is used to adjust the polarization state of the received light and output the polarization-adjusted light.

[0057] The fiber optic patch cord is used to add a delay to the light received from the first polarization controller and output it to the optical combiner;

[0058] The optical beam combiner is used to receive light whose delay is changed by the fiber optic jumper and the light output by the second polarization controller, combine them, and then output the beam to a single-channel low-noise detector.

[0059] The low-noise detector is used to detect the received optical signal and output one electrical signal to the time-to-digital converter module;

[0060] The time-to-digital converter module is used to receive the electrical signal output by the low-noise detector, and after measurement, output the detection count to the host computer; wherein, the time-to-digital converter module records the detection count of channel 1 (on the link of the first polarization controller + fiber optic patch cord) as bit0, and records the detection count of channel 2 (on the link of the second polarization controller) as bit1.

[0061] The host computer controls the light emission of the test light source, controls the attenuation of the adjustable light attenuator, sets the parameters of the signal source, controls the time-to-digital converter module, and stores bit0 and bit1 recorded by the time-to-digital converter module in a binary file. It also has an independent same-distribution detection function.

[0062] This embodiment also proposes a detection method based on the above-mentioned independent and co-distributed detection device for optical beam splitters. Using the above-mentioned device, hardware environment setup and test data acquisition can be realized, including the following steps:

[0063] Step 1: Hardware Environment Setup: Based on the connection structure of the independent and co-distributed optical beam splitter detection device described above, establish the hardware connection relationship between the test light source, adjustable optical attenuator, signal source, device under test, first polarization controller, fiber optic patch cord, second polarization controller, optical beam combiner, low-noise detector, time-to-digital converter module, and host computer.

[0064] Step 2, Data Acquisition: Establish the data connection between the built-in software in the host computer and the test light source, signal source, adjustable light attenuator, and time-to-digital converter module;

[0065] Step 3: After the test environment is set up, start the independent same-distribution test through the host computer software. This will enable the functions of test light source modulation, test data recording, and test report output. The specific test process is as follows: Figure 3 As shown, it includes the following steps:

[0066] Step 1: Start independent same-distribution detection. The host computer software will automatically connect to the test light source, signal source, adjustable light attenuator and time-to-digital converter module, and then proceed to Step 2;

[0067] Step 2: Control the signal source to output a trigger signal through the host computer software. The trigger signal provides the same trigger signal for the test light source and the time-to-digital converter module. The trigger frequency can be flexibly set according to the trigger frequency supported by the test light source and the time-to-digital converter module. Then proceed to Step 3.

[0068] Step 3: Control the test light source to emit light through the host computer software, and then proceed to Step 4;

[0069] Step 4: Adjust the adjustable optical attenuator to reduce the intensity of the output optical signal, then proceed to step 5;

[0070] Step 5: Measure the output light intensity to determine if it is in a single-photon state. If not, proceed to step 4; if yes, proceed to step 6.

[0071] Step 6: Adjust the first polarization controller, then proceed to step 7;

[0072] Step 7: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, two peak counts (bit0 and bit1) that are staggered in time will be displayed. Repeat step 6 to adjust. At this time, one of the peak counts (bit0) will change. Find the maximum value of this peak count, then stop adjusting in step 6 and proceed to step 8.

[0073] Step 8: Adjust the second polarization controller, then proceed to step 9;

[0074] Step 9: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, two peak counts (bit0 and bit1) that are staggered in time will be displayed. Repeat step 8 to adjust. At this time, the other peak count (bit1) will change. Find the maximum value of this peak count, then stop the adjustment in step 8 and proceed to step 10.

[0075] Step 10: After the above adjustments are completed, the data of the two output channels of the device under test measured by the time-to-digital converter module (i.e., the probability data of the two outputs of the beam splitter directly acquired) are collected by the host computer software and automatically saved as a binary file. Then proceed to step 11.

[0076] Step 11: The host computer software loads the data from step 10, performs independent identically distributed detection on randomness, outputs the test results, and then proceeds to step 12;

[0077] Step 12: Based on the results of Step 11, the host computer software assesses the safety of the device under test by combining the safety threshold of independent identically distributed detection in the NIST SP 800-90B standard, and then proceeds to Step 13.

[0078] Step 13: The host computer software summarizes the above test data, outputs a test report, and the test ends.

[0079]

Example 2

[0080] This embodiment provides an independent and identically distributed detection device for optical beam splitters. See [link to relevant documentation]. Figure 4 This device is used to perform independent and identically distributed testing on the device under test (DUT). Its components include a signal source, a test light source, an adjustable optical attenuator, a first polarization controller, fiber optic patch cords, a second polarization controller, a low-noise detector, a time-to-digital converter module, and a host computer. The DUT is an optical beamsplitter, and the low-noise detector is preferably a superconducting detector with at least two channels.

[0081] The test light source is connected to an adjustable optical attenuator. The inputs of the first and second polarization controllers are respectively connected to the two output ports of the device under test. The output of the first polarization controller is connected to one input port of the low-noise detector via the fiber optic patch cord, and the output of the second polarization controller is connected to the other input port of the low-noise detector. The output of the low-noise detector is connected to the time-to-digital converter module. The output of the signal source is simultaneously connected to both the test light source and the time-to-digital converter module. The host computer software is connected to the signal source, the test light source, the adjustable optical attenuator, and the time-to-digital converter module.

[0082] The test light source is used to generate test light signals for independent and identically distributed detection;

[0083] The adjustable optical attenuator attenuates the received test optical signal and outputs the attenuated optical signal to the device under test.

[0084] The signal source is used to trigger the test light source and the time-to-digital conversion module;

[0085] The device under test is used to split the received light into two beams, which are then input to the first polarization controller and the second polarization controller, respectively.

[0086] The first polarization controller is used to adjust the polarization state of the received light and output the polarization-adjusted light.

[0087] The fiber optic patch cord is used to add a delay to the received light and output the delayed optical signal to one of the channels of the dual-channel low-noise detector.

[0088] The second polarization controller is used to adjust the polarization state of the received light and output the polarization-adjusted light to the other channel of the dual-channel low-noise detector;

[0089] The low-noise detector is used to detect the received optical signal and output two electrical signals to the time-to-digital converter module;

[0090] The time-to-digital converter module is used to receive the electrical signal output by the low-noise detector, and after measurement, output the detection count to the host computer; wherein, the time-to-digital converter module records the detection count of channel 1 (on the link of the first polarization controller + fiber optic patch cord) as bit0, and records the detection count of channel 2 (on the link of the second polarization controller) as bit1.

[0091] The host computer controls the light emission of the test light source, controls the attenuation of the adjustable light attenuator, sets the parameters of the signal source, controls the time-to-digital converter module, and stores bit0 and bit1 recorded by the time-to-digital converter module in a binary file. It also has an independent same-distribution detection function.

[0092] This embodiment also proposes a method for detecting independent and co-distributed optical beam splitters. Using the above-mentioned device, hardware environment setup and test data acquisition can be achieved, including the following steps:

[0093] Step 1: Hardware Environment: Establish the hardware connection relationship between the test light source, adjustable optical attenuator, signal source, device under test (optical beam splitter), first polarization controller, fiber optic patch cord, second polarization controller, low noise detector (superconducting detector), time-to-digital converter module, and host computer software.

[0094] Step 2: Data Acquisition: Establish data connection between the host computer software and the test light source, signal source, adjustable light attenuator, and time-to-digital converter module.

[0095] Step 3: After the test environment is set up, start the independent same-distribution test through the host computer software. This will enable the functions of test light source modulation, test data recording, and test report output. The specific test process is as follows: Figure 5 As shown, it includes the following steps:

[0096] Step 1: Start independent same-distribution detection. The host computer software will automatically connect to the test light source, signal source, adjustable light attenuator and time-to-digital converter module, and then proceed to Step 2;

[0097] Step 2: Control the signal source to output a trigger signal through the host computer software. The trigger signal provides the same trigger signal for the test light source and the time-to-digital converter module. The trigger frequency can be flexibly set according to the trigger frequency supported by the test light source and the time-to-digital converter module. Then proceed to Step 3.

[0098] Step 3: Control the test light source to emit light through the host computer software, and then proceed to Step 4;

[0099] Step 4: Adjust the adjustable optical attenuator to reduce the intensity of the output optical signal, then proceed to step 5;

[0100] Step 5: Measure the output light intensity to determine if it is in a single-photon state. If not, proceed to step 4; if yes, proceed to step 6.

[0101] Step 6: Adjust the first polarization controller, then proceed to step 7;

[0102] Step 7: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, a peak count (bit0) will be displayed, which is the detection count of channel 1 of the low noise detector. Repeat step 6 to adjust and find the maximum value of this peak count. Then stop adjusting in step 6 and proceed to step 8.

[0103] Step 8: Adjust the second polarization controller, then proceed to step 9;

[0104] Step 9: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, another peak count (bit1) will be displayed, which is the detection count of channel 2 of the low noise detector. Repeat step 8 to adjust and find the maximum value of this peak count. Then stop the adjustment in step 8 and proceed to step 10.

[0105] Step 10: After the above adjustments are completed, the data of the two output channels of the device under test measured by the low noise detector (i.e., the probability data of the two outputs of the beam splitter directly acquired) are collected by the host computer software and automatically saved as a binary file. Then proceed to step 11.

[0106] Step 11: The host computer software loads the data from step 10, performs independent identically distributed detection on randomness, outputs the test results, and then proceeds to step 12;

[0107] Step 12: Based on the results of Step 11, the host computer software assesses the safety of the device under test (optical beam splitter) in conjunction with the safety threshold of independent and identically distributed detection in the NIST SP 800-90B standard, and then proceeds to Step 13.

[0108] Step 13: The host computer software summarizes the above test data, outputs a test report, and the test ends.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A detection device for independent co-distribution of optical beam splitters, characterized in that: include: Test light source, used to generate test light signals for independent and identically distributed detection; An adjustable optical attenuator is used to attenuate the received test optical signal and output the attenuated optical signal to the device under test. The signal source is used to trigger the test light source and the time-to-digital conversion module; The first and second polarization controllers are used to adjust the polarization state of the received light split from the device under test. A low-noise detector is used to receive light output from the first polarization controller via the first channel after a delay, and light directly output from the second polarization controller via the second channel. The time-to-digital converter module is used to receive the electrical signal output by the low-noise detector, and after measurement, output the detection count to the host computer. The time-to-digital converter module records the detection counts of the first channel and the second channel as bit0 and bit1, respectively. The host computer is used to store bit0 and bit1 recorded by the aforementioned time-to-digital conversion module in binary files and to perform independent identical distribution detection.

2. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: It also includes an optical beam combiner, wherein the light output from the delayed first polarization controller and the light directly output from the second polarization controller are input to the low-noise detector after passing through the optical beam combiner, and the low-noise detector is a single-channel low-noise detector.

3. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The low-noise detector has at least two channels, and the light output by the delayed first polarization controller and the light directly output by the second polarization controller enter the two input ports of the low-noise detector respectively.

4. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The test light source is a single-photon light source or a weakly coherent light source.

5. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The first polarization controller is connected to the low-noise detector via an optical fiber patch cord to achieve a delay.

6. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The low-noise detector is a superconducting detector.

7. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The host computer controls the light emission of the test light source, controls the attenuation of the adjustable light attenuator, sets the parameters of the signal source, and controls the time-to-digital conversion module.

8. The optical beam splitter independent co-distribution detection device according to claim 1, characterized in that: The host computer assesses the safety of the device under test based on the results of independent identically distributed detection, combined with the safety threshold of independent identically distributed detection in the NIST SP 800-90B standard.

9. A method for detection using the independent and co-distributed detection device for optical beam splitters according to any one of claims 1 to 8, characterized in that: Includes the following steps: Step 1: Hardware setup: According to the connection structure of the independent and co-distributed detection device for the optical beam splitter, establish the hardware connection relationship between each component. Connect the input end of the device under test to the output end of the adjustable optical attenuator, and connect the input ends of the first polarization controller and the second polarization controller to the two output ports of the device under test, respectively. Step 2, Data Acquisition: Establish the data connection between the built-in software in the host computer and the connected components; Step 3: After the test environment is set up, start the independent identical distribution test through the host computer software, including the following steps: Step 1: Start independent same-distribution detection. The host computer software will automatically connect to the test light source, signal source, adjustable light attenuator and time-to-digital converter module, and then proceed to Step 2; Step 2: Control the signal source to output a trigger signal through the host computer software. The trigger signal provides the same trigger signal to the test light source and the time-to-digital converter module. Then proceed to Step 3. Step 3: Control the test light source to emit light through the host computer software, and then proceed to Step 4; Step 4: Adjust the adjustable optical attenuator to reduce the intensity of the output optical signal, then proceed to step 5; Step 5: Measure the output light intensity to determine if it is in a single-photon state. If not, proceed to step 4; if yes, proceed to step 6. Step 6: Adjust the first polarization controller, then proceed to step 7; Step 7: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, the peak count will be displayed. Repeat step 6 to adjust and find the maximum value of the changing peak count. Then stop the adjustment in step 6 and proceed to step 8. Step 8: Adjust the second polarization controller, then proceed to step 9; Step 9: Control the time-to-digital converter module to perform the measurement through the host computer software. At this time, the peak count will be displayed. Repeat step 8 to adjust and find the maximum value of the changing peak count. Then stop the adjustment in step 8 and proceed to step 10. Step 10: After the above adjustments are completed, the data of the two output channels of the device under test measured by the time-to-digital converter module are collected by the host computer software and automatically saved as a binary file. Then proceed to step 11. Step 11: The host computer software loads the data from step 10, performs independent identically distributed (ICD) detection on randomness, and outputs the test results.

10. The detection method as described in claim 9, characterized in that: It also includes the following steps: Step 12: Based on the results of Step 11, the host computer software assesses the safety of the device under test by combining the safety threshold of independent identically distributed detection in the NIST SP 800-90B standard, and then proceeds to Step 13. Step 13: The host computer software summarizes the data and test results from the two output channels, outputs a test report, and the test ends.

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