An automatic calibration device and method for system operating point of phase fluctuation QRNG

Abstract

The invention discloses an automatic calibration device and method for a system working point of a phase fluctuation QRNG, comprising a logic control module, a driving current module, a light source adjustment module, a sampling and measuring module and a human-computer interaction module, wherein the human-computer interaction module is connected to the logic control module, and the logic control module is respectively connected to the driving current module, the light source adjustment module and the sampling and measuring module; the driving current module is connected to a laser of a QRNG to be measured, the light source adjustment module is respectively connected to a laser and an interferometer of the QRNG to be measured, and the sampling and measuring module is connected to a photoelectric conversion module of the QRNG to be measured; the light source adjustment module is built with a light switching unit, a light attenuation unit, a photosynthetic unit and a light intensity measurement unit, and the light switching unit, the light attenuation unit and the light intensity measurement unit are respectively connected to the logic control module; according to the automatic calibration method of the invention, there is no need to use an external general detection instrument, the entire calibration process is automatically completed without manual participation, saving labor costs and avoiding manual errors.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum random number generator (QRNG), and in particular relates to an automatic calibration device and method for a system operating point of a phase fluctuation QRNG. Background Art

[0002] The randomness of the phase fluctuation-based QRNG comes from the random phase fluctuations caused by the spontaneous radiation of the medium inside the laser. The atomic energy level transitions of the working medium inside the laser will produce two types of radiation, stimulated radiation and spontaneous radiation. The latter is caused by vacuum fluctuations, and the phase of the emitted photons is highly random. In the phase fluctuation quantum random number generator, the purpose of the entire device is to extract the random phase of spontaneous radiation to generate random numbers. There is a threshold relationship between the pump current of the laser and the laser gain medium and the resonant cavity. Below this threshold, there is only weak spontaneous radiation inside the laser and no laser output. Only when it is above this threshold will there be laser output, and stimulated radiation is dominant. When the quantum random number generator is working, the pump current intensity is set to be slightly higher than the threshold, so that the proportion of spontaneous radiation can be as high as possible under the condition of laser output.

[0003] The QRNG scheme based on phase fluctuations requires converting the phase fluctuations that cannot be directly measured into measurable light intensity fluctuations through an interferometer, and then converting them into randomly fluctuating electrical signals through a high-speed photodetector, which are then collected and quantized into quantum random numbers.

[0004] In actual systems, the measured signal includes not only quantum phase noise contributed by spontaneous radiation, but also classical noise caused by various factors. These classical noises are partly derived from the classical physical process in the laser, and also include the dark current of the photodetector, the thermal noise of the acquisition circuit, and the electromagnetic noise in the environment. Improving the ratio of quantum phase noise to classical noise in the laser means that the extracted original random number has higher quantum randomness. By reducing the laser output power to increase the proportion of quantum phase noise in the laser, the influence of classical noise in the laser can be reduced. However, it should be noted that there must be a certain limit to reducing the laser output power. Although the classical noise level in the laser is reduced, the proportion of relatively fixed classical noise such as the dark current of the detector and the thermal noise of the acquisition circuit will increase, so the optimal operating point of the laser should be determined through theoretical analysis and experiments.

[0005] Theoretical literature shows that the electrical signal output by a photodetector contains both quantum phase noise and classical noise:

[0006] V 2 =AQP+ACP 2 +F

[0007] Where V2 It is the variance of the electrical signal, which is a statistic that can be calculated through a large number of samples. AQP is quantum phase noise, ACP is 2 and F are classical noises, and P is the laser output power. The above formula shows that both quantum phase noise and classical noise are related to the laser power P. It can be seen that the variance of the classical noise electrical signal is a quadratic function of P, and each system AQ, AC, and F are constants that can be calculated by fitting. By changing the value of P, the ratio of quantum phase noise to classical noise can be changed. Setting an appropriate P value can maximize the ratio of quantum phase noise.

[0008] Define γ as the ratio of the quantum phase noise variance to the classical noise variance, that is:

[0009] γ=AQP / (ACP 2 +F)

[0010] The goal of calibrating the optimal operating point of the laser is to find the appropriate laser output power to maximize γ, that is, to maximize the proportion of quantum phase noise.

[0011] One of the mainstream methods for calibrating the system operating point of phase fluctuation QRNG is the direct measurement method, that is, by measuring the classical part and the quantum part of the variance of the electrical signal output by the photodetector of the laser at different output powers, the ratio γ of the two parts is directly obtained. The specific process is as follows:

[0012] 1) When the output power of the light source is large, as the power increases, the proportion of the quantum part becomes lower and lower. Therefore, it can be assumed that when the laser output power is large enough, the contribution of the quantum part to the laser phase fluctuation can be ignored, so it can be considered that the variance of the photodetector output signal at this time all comes from the classical part.

[0013] 2) During calibration, the laser output power can be adjusted to the maximum, and then the light intensity input to the interferometer can be adjusted to the same as the output power of the aforementioned light source by adding an adjustable optical attenuator. In this way, the output fluctuations of the measured photodetector are all the classical parts at this power.

[0014] 3) By combining the variance of the photodetector output voltage under different laser luminescence intensities, the variance value of the quantum part can be calculated, and thus the γ value under this power can be directly calculated.

[0015] The traditional method for calibrating the system operating point of phase fluctuation QRNG is manual calibration, which faces the following three problems:

[0016] a) Manual calibration takes too long

[0017] Because the intensity adjustment step of the laser and the attenuation adjustment step of the variable optical attenuator can be made very small, when manually adjusting the parameters, it may be necessary to test the corresponding test data for tens of thousands of steps. The calibration of a QRNG is incredibly time-consuming and inefficient.

[0018] b) The calibration personnel are required to have a high level of mastery of the testing instruments

[0019] During the calibration process, the intensity of the laser light source can be adjusted by adjusting the external driving current; the intensity of the laser through the optical attenuator can be adjusted by adjusting the attenuation of the adjustable optical attenuator; the variance of the photodetector is measured and analyzed by a real-time oscilloscope. There are certain professional and technical requirements for the calibration personnel, and it is not directly available.

[0020] c) The sampling rate of the oscilloscope does not match the ADC sampling rate of the QRNG being tested

[0021] The tool used to measure the output signal of the photodetector is a real-time oscilloscope, and the sampling rate of the oscilloscope needs to be consistent with the ADC (analog-to-digital converter) sampling rate of the QRNG being measured, otherwise it may cause oversampling or undersampling. However, the sampling rate of oscilloscopes on the market now only supports setting to a few fixed values, and the coverage range is limited. In addition, the sampling rate of the ADC of the high-speed QRNG itself will be very high, and for the oscilloscope, a high sampling rate means an improvement in the grade of the oscilloscope when selecting it. The price of a high-end oscilloscope is as high as four or five million, which is also a considerable expense for the calibration personnel (unit). Summary of the invention

[0022] The present invention aims at the various problems faced by the manual calibration of the system operating point of the phase fluctuation QRNG mentioned above, makes up for the deficiencies of the prior art, and provides an automatic calibration device and method for the system operating point of the phase fluctuation QRNG. According to the automatic calibration device and method provided by the present invention, there is no need to use an external general detection instrument (such as an adjustable optical attenuator, an oscilloscope, etc.), and the entire calibration process is automatically completed without manual participation.

[0023] To achieve the above object, the present invention adopts the following technical solution.

[0024] The present invention provides an automatic calibration device for the system operating point of a phase fluctuation QRNG, which realizes the automatic calibration of the system operating point of the QRNG under test based on phase fluctuation. The QRNG under test includes a laser, an interferometer, a photoelectric conversion module, a data acquisition module, and a post-processing module connected in sequence; the calibration device includes a logic control module, a driving current module, a light source adjustment module, a sampling and measurement module, and a human-computer interaction module, the human-computer interaction module is connected to the logic control module, and the logic control module is respectively connected to the driving current module, the light source adjustment module, and the sampling and measurement module; the driving current module is connected to the laser of the QRNG under test, and the light source adjustment module They are respectively connected to the laser and interferometer of the QRNG under test, and the sampling measurement module is connected to the photoelectric conversion module of the QRNG under test; the light source adjustment module is equipped with an optical switching unit, an optical attenuation unit, a photosynthesis unit, and a light intensity measurement unit, the optical switching unit is respectively connected to the optical attenuation unit, the photosynthesis unit, and the light intensity measurement unit, the optical attenuation unit is connected to the photosynthesis unit, the optical switching unit, the optical attenuation unit, and the light intensity measurement unit are respectively connected to the logic control module, the optical signal output end of the laser of the QRNG under test is connected to the optical signal input end of the optical switching unit of the light source adjustment module, and the optical signal output end of the photosynthesis unit is connected to the optical signal input end of the interferometer of the QRNG under test.

[0025] Furthermore, the driving current module includes a DAC digital-to-analog converter and a constant current source, the signal output end of the DAC digital-to-analog converter is connected to the signal input end of the constant current source, the signal input end of the DAC digital-to-analog converter is connected to the signal output end of the logic control module, and the signal output end of the constant current source is connected to the laser of the QRNG under test.

[0026] Furthermore, the optical switching unit is composed of a "1-input 3-output" optical switch, the optical attenuation unit is composed of an electrically controlled adjustable optical attenuator, the photosynthesis unit is composed of a photosynthesis device, and the light intensity measurement unit is composed of a PIN photodiode.

[0027] Furthermore, the sampling and measuring module is equipped with an ADC analog-to-digital converter.

[0028] The present invention provides an automatic calibration method for a phase fluctuation QRNG system operating point, which uses the calibration device to complete the automatic calibration method, including the following steps:

[0029] Step 1: The user conveys the driving current range and step parameters of the laser of the QRNG under test and the sampling rate parameters of the photoelectric conversion module of the QRNG under test to the logic control module of the calibration device through the human-computer interaction module of the calibration device;

[0030] Step 2: The logic control module of the calibration device sets the sampling rate of the sampling measurement module of the calibration device according to the sampling rate parameter in step 1;

[0031] Step 3: The logic control module of the calibration device controls the driving current module to output the maximum driving current according to the upper limit of the driving current range in step 1, so that the laser output light intensity of the QRNG under test reaches the maximum;

[0032] Step 4: The logic control module of the calibration device determines whether the driving current at this time reaches the lower limit of the range. If not, continue to execute step 5; if it has reached, jump to execute step 12;

[0033] Step 5: The logic control module of the calibration device controls the driving current module to reduce the driving current output by one step, and uses this driving current to control the laser output light intensity of the QRNG under test;

[0034] Step 6: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module, so that the output optical signal of the QRNG laser under test is input to the light intensity measurement unit through the output light of the optical switching unit, and the output light intensity of the QRNG laser under test is measured to be P;

[0035] Step 7: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output light of the optical switching unit is output to the interferometer of the QRNG under test through the photosynthetic unit;

[0036] Step 8: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, which is the sum of the classical noise and quantum phase noise under the P laser luminescence intensity;

[0037] Step 9: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output optical signal of the QRNG laser under test is input to the optical attenuation unit through the output light of the optical switching unit;

[0038] Step 10: The logic control module of the calibration device first controls the driving current of the driving current module to the upper limit value, so that the output light intensity of the QRNG laser under test reaches the maximum; then controls the light attenuation unit of the light source adjustment module, and sets a certain attenuation so that the light intensity output to the interferometer of the QRNG under test through the photosynthesis unit is also P;

[0039] Step 11: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, i.e., the classical noise under the laser luminescence intensity P; the logic control module of the calibration device can calculate the ratio Y of the quantum phase noise to the classical noise under the laser luminescence intensity in combination with the calculated value of step 8, and record it; after completion, jump to step 4;

[0040] Step 12: The logic control module of the calibration device finds the laser luminous intensity value when the ratio of quantum phase noise to classical noise is maximum according to the records, and transmits it to the human-computer interaction module, which outputs the calibration result to the user.

[0041] Beneficial effects of the present invention:

[0042] 1) The automatic calibration device of the system working point of the phase fluctuation QRNG of the present invention is constituted by the cooperation of the human-computer interaction module and the logic control module, the driving current module, the light source adjustment module, and the sampling measurement module, which can realize one-key automatic calibration. The calibration process does not require human participation, saving labor costs and avoiding human errors.

[0043] 2) No need to prepare additional calibration instruments and tools, a set of automatic calibration device can meet the QRNG calibration needs; saving the cost of calibration environment and tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The schematic block diagram of the system structure of the QRNG under test.

[0045] Figure 2 It is a schematic block diagram of the structure of the automatic calibration device of the system operating point of the phase fluctuation QRNG of the present invention.

[0046] Figure 3 It is a schematic block diagram of the structure of the driving current module of the present invention.

[0047] Figure 4 It is a schematic block diagram of the structure in which the automatic calibration device of the present invention is connected with the QRNG to be tested.

[0048] Figure 5 The present invention is a flow chart of the automatic calibration device for the system operating point of the phase fluctuation QRNG. DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Example 1

[0051] Combination Figures 1 to 4 As shown, an automatic calibration device for the system operating point of a phase fluctuation QRNG, the calibration device realizes the automatic calibration of the system operating point of the QRNG under test based on phase fluctuation, the QRNG under test includes a laser, an interferometer, a photoelectric conversion module, a data acquisition module, and a post-processing module connected in sequence; the calibration device includes a logic control module, a driving current module, a light source adjustment module, a sampling measurement module and a human-computer interaction module, the human-computer interaction module is connected to the logic control module, the logic control module is respectively connected to the driving current module, the light source adjustment module, and the sampling measurement module; the driving current module is connected to the laser of the QRNG under test, and the light source adjustment module is respectively The sampling and measuring module is connected to the laser and interferometer of the QRNG under test, and the sampling and measuring module is connected to the photoelectric conversion module of the QRNG under test; the light source adjustment module is equipped with an optical switching unit, an optical attenuation unit, a photosynthetic unit, and a light intensity measurement unit, the optical switching unit is respectively connected to the optical attenuation unit, the photosynthetic unit, and the light intensity measurement unit, the optical attenuation unit is connected to the photosynthetic unit, the optical switching unit, the optical attenuation unit, and the light intensity measurement unit are respectively connected to the logic control module, the optical signal output end of the laser of the QRNG under test is connected to the optical signal input end of the optical switching unit of the light source adjustment module, and the optical signal output end of the photosynthetic unit is connected to the optical signal input end of the interferometer of the QRNG under test.

[0052] The driving current module includes a DAC digital analog converter and a constant current source. The signal output end of the DAC digital analog converter is connected to the signal input end of the constant current source, the signal input end of the DAC digital analog converter is connected to the signal output end of the logic control module, and the signal output end of the constant current source is connected to the laser of the QRNG under test. Specifically, the function of the driving current module is to provide a driving current to the laser of the QRNG under test, so as to adjust the output light intensity of the laser; the intensity of the driving current is controlled by the logic control module, and the adjustment range and step length of the driving current are input by the user on the human-computer interaction module before the automatic calibration begins. The logic control module sends instructions to the DAC digital analog converter, and the output of the DAC digital analog converter is used as the input voltage of the constant current source to control the output current of the constant current source; thereby providing different DC driving currents to the laser of the QRNG under test, thereby controlling the output power of the light source emitted by the laser.

[0053] Specifically, the function of the light source adjustment module is: it receives the optical signal output by the laser of the QRNG under test, and the output optical signal is input to the interferometer of the QRNG under test; the light source adjustment module is equipped with an optical switching unit, an optical attenuation unit, a photosynthetic unit, and a light intensity measurement unit, and can switch the received light to three different optical signal processing channel modes according to the needs of the calibration process, namely, attenuating the light intensity through the optical attenuation unit and then outputting it to the interferometer of the QRNG under test, directly outputting it to the interferometer of the QRNG under test, and outputting it to the built-in light intensity measurement unit for light intensity measurement.

[0054] Specifically, the optical switching unit adopts a "1-input 3-output" optical switch. The optical switching unit is controlled by a logic control module and can switch the optical path of the received optical signal output by the QRNG laser under test to one of three different optical path channels. The three optical path channels are: channel 1, output to the photosynthesis unit, directly output to the interferometer of the QRNG under test through the photosynthesis unit; channel 2, output to the optical attenuation unit for light intensity attenuation, then output to the photosynthesis unit, and output to the interferometer of the QRNG under test through the photosynthesis unit; channel 3, output to the light intensity measurement unit for optical power measurement.

[0055] Specifically, the optical attenuation unit adopts an electrically controlled adjustable optical attenuator, and the optical attenuation unit is controlled by the logic control module to attenuate the optical signal output from the optical switching unit. The optical beam combining unit adopts an optical beam combiner, which is used to output the optical signal of channel 1 or channel 2 passing through the optical switching unit to the interferometer of the QRNG under test. The light intensity measurement unit adopts a PIN photodiode, which is used to measure the optical power (intensity) of the optical signal input from the laser of the QRNG under test, and feed back the measurement result to the logic control module.

[0056] Specifically, the sampling and measuring module is equipped with an ADC analog-to-digital converter. The function of the sampling and measuring module is to receive the electrical signal output by the photoelectric conversion module of the QRNG under test, and to measure and collect the amplitude of the electrical signal at a specified sampling rate. The sampling rate is input by the user in the human-computer interaction module before the automatic calibration starts. The sampling and measuring module can sample and measure the input electrical signal at a specified time interval (sampling rate), and convert it into a digital signal (digital quantity) for output; that is, it realizes the amplitude measurement of the electrical signal output by the photoelectric conversion module of the QRNG under test at a specified sampling rate, and outputs the measured data to the logic control module for data calculation and analysis. The sampling rate is input by the user in the human-computer interaction module before the automatic calibration starts.

[0057] In the automatic calibration device of the present invention, the logic control module plays three roles in control signal sending, data collection and data analysis. The functions of control signal sending include: the logic control module controls the driving current of the driving current module according to the pre-calibrated process logic, switches the internal optical path of the optical switching unit of the light source adjustment module, adjusts the attenuation of the optical attenuation unit in the light source adjustment module, and controls the sampling rate of the sampling measurement module. The functions of data collection include: the logic control module collects the current optical power value P of the laser of the QRNG under test from the light intensity measurement unit in the light source adjustment module, and the logic control module also obtains the amplitude measurement value from the sampling measurement module for further data analysis. The functions of data analysis and processing include: the logic control module collects the current optical power value P of the laser of the QRNG under test according to the light intensity measurement unit in the light source adjustment module, and then adjusts the light attenuation unit in the light source adjustment module according to the value, so that the maximum output light intensity Pmax of the laser of the QRNG under test is also attenuated to P through the light attenuation unit in the light source adjustment module; the logic control module also completes the variance calculation of the amplitude measurement value obtained from the sampling measurement module, and calculates the variance value of the quantum part in combination with the variance of the output voltage of the photoelectric conversion module under different laser luminous intensities, so that the γ value under the power can be directly calculated; the final system operating point value is input into the human-computer interaction module.

[0058] The user inputs the following pre-calibration parameters into the human-machine interaction module of the automatic calibration device: the driving current range and step size of the laser of the QRNG under test; the sampling rate of the photoelectric conversion module of the QRNG under test. The human-machine interaction module of the automatic calibration device of the present invention receives the calibration result of the logic control module and displays the system working point data to the user.

[0059] Example 2

[0060] like Figure 5 As shown, a method for automatically calibrating the system operating point of a phase fluctuation QRNG is provided. The method for automatically calibrating the system operating point of the phase fluctuation QRNG is completed by using the above-mentioned calibration device, and includes the following steps:

[0061] Step 1: The user conveys the driving current range and step parameters of the laser of the QRNG under test and the sampling rate parameters of the photoelectric conversion module of the QRNG under test to the logic control module of the calibration device through the human-computer interaction module of the calibration device;

[0062] Step 2: The logic control module of the calibration device sets the sampling rate of the sampling measurement module of the calibration device according to the sampling rate parameter in step 1;

[0063] Step 3: The logic control module of the calibration device controls the driving current module to output the maximum driving current according to the upper limit of the driving current range in step 1, so that the laser output light intensity of the QRNG under test reaches the maximum;

[0064] Step 4: The logic control module of the calibration device determines whether the driving current at this time reaches the lower limit of the range. If not, continue to execute step 5; if it has reached, jump to execute step 12;

[0065] Step 5: The logic control module of the calibration device controls the driving current module to reduce the driving current output by one step, and uses this driving current to control the laser output light intensity of the QRNG under test;

[0066] Step 6: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module, so that the output optical signal of the QRNG laser under test is input to the light intensity measurement unit through the output light of the optical switching unit, and the output light intensity of the QRNG laser under test is measured to be P;

[0067] Step 7: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output light of the optical switching unit is output to the interferometer of the QRNG under test through the photosynthetic unit;

[0068] Step 8: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, which is the sum of the classical noise and quantum phase noise under the P laser luminescence intensity;

[0069] Step 9: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output optical signal of the QRNG laser under test is input to the optical attenuation unit through the output light of the optical switching unit;

[0070] Step 10: The logic control module of the calibration device first controls the driving current of the driving current module to the upper limit value, so that the output light intensity of the laser of the QRNG under test reaches the maximum; then controls the light attenuation unit of the light source adjustment module, and sets a certain attenuation so that the light intensity output to the interferometer of the QRNG under test through the photosynthetic unit is also P;

[0071] Step 11: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, i.e., the classical noise under the laser luminescence intensity P; the logic control module of the calibration device can calculate the ratio Y of the quantum phase noise to the classical noise under the laser luminescence intensity in combination with the calculated value of step 8, and record it; after completion, jump to step 4;

[0072] Step 12: The logic control module of the calibration device finds the laser luminous intensity value when the ratio of quantum phase noise to classical noise is maximum according to the records, and transmits it to the human-computer interaction module, which outputs the calibration result to the user.

[0073] Example 3

[0074] An automatic calibration method for a phase fluctuation QRNG system operating point is provided, wherein the automatic calibration method is completed by using the above-mentioned calibration device, and specifically comprises the following steps:

[0075] Step 1. The driving current range of the laser of the QRNG under test is 0.01A to 0.1A, and the adjustment step is 0.01A; the sampling rate of the photoelectric conversion module of the QRNG under test is 500M.

[0076] Step 2. The user inputs the driving current range and step size of the laser of the QRNG under test, the sampling rate of the photoelectric conversion module of the QRNG under test and other parameters in the human-computer interaction module of the calibration device.

[0077] Step 3. The logic control module of the calibration device controls the driving current module to output a driving current that is reduced by one step, namely 0.09A, based on the maximum driving current, and loads it on the laser of the QRNG under test.

[0078] Step 4. The logic control module of the calibration device controls the light switching unit of the light source adjustment module so that the output light intensity of the laser of the QRNG under test is input to the light intensity measurement unit. The output power of the laser of the QRNG under test is measured to be 9 mW (driving current 0.09 A).

[0079] Step 5. The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output optical signal of the laser of the QRNG under test is output to the interferometer of the QRNG under test through the photosynthesis unit.

[0080] Step 6. The sampling and measurement module of the calibration device samples and measures the amplitude of the electrical signal output by the interferometer of the QRNG under test at a sampling rate of 500M.

[0081] Step 7. The logic control module of the calibration device obtains 10,000 amplitude measurement values ​​from the sampling measurement module and calculates its variance as 5; that is, the sum of the classical noise and the quantum phase noise at 9 mW laser intensity is 5.

[0082] Step 8. The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output light of the QRNG under test is input to the optical attenuation unit.

[0083] Step 9. The logic control module of the calibration device first controls the driving current of the driving current module to 0.1A, so that the output light intensity of the laser of the QRNG under test is maximized at this time; then, the light attenuation unit of the light source adjustment module is controlled to set the attenuation value to 0.46dB (after 0.46dB attenuation of the 10mW input light, the light intensity will be attenuated to 9mW); so that the light intensity output to the interferometer of the QRNG under test through the photosynthetic unit is also 9mW.

[0084] Step 10. The sampling and measurement module of the calibration device samples and measures the amplitude of the electrical signal output by the interferometer of the QRNG under test at a sampling rate of 500M. The logic control module of the calibration device obtains 10,000 amplitude measurement values ​​from the sampling and measurement module and calculates its variance to be 4.9, that is, the classical noise at 9mW laser intensity is 4.9.

[0085] Step 11. The logic control module of the calibration device calculates the ratio of the quantum phase noise to the classical noise at this time as (5-4.9) / 4.9=0.02, and records the ratio (0.02) at the current light intensity (9 mW).

[0086] Step 12. The logic control module of the calibration device determines that the driving current at this time is not the lower limit value (0.1A) of the measured QRNG driving current range, and then continues to execute steps 3 to 11; until the logic control module of the calibration device determines that the driving current at this time is the lower limit value of the measured QRNG driving current range, then executes step 13.

[0087] Step 13. The logic control module of the calibration device analyzes the ratio of quantum phase noise to classical noise at each light intensity and finds that the ratio is the largest when the light intensity is 1 mW, and the maximum ratio is 6.8.

[0088] Step 14. The logic control module of the calibration device transmits the determination result to the human-computer interaction module, and the human-computer interaction module displays the detection result to the user; that is, the automatic calibration process of the system operating point has been completed, and the optimal system operating point is 1mW.

[0089] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.

Claims

1. A method for automatically calibrating a system operating point of a phase fluctuation QRNG, using an automatic calibration device for the system operating point of a phase fluctuation QRNG, the calibration device realizes automatic calibration of the system operating point of a QRNG under test based on phase fluctuation, the QRNG under test comprises a laser, an interferometer, a photoelectric conversion module, a data acquisition module, and a post-processing module connected in sequence; characterized in that: The calibration device includes a logic control module, a driving current module, a light source adjustment module, a sampling and measuring module and a human-computer interaction module, wherein the human-computer interaction module is connected to the logic control module, and the logic control module is respectively connected to the driving current module, the light source adjustment module and the sampling and measuring module; The driving current module is connected to the laser of the QRNG under test, the light source adjustment module is respectively connected to the laser and the interferometer of the QRNG under test, and the sampling and measuring module is connected to the photoelectric conversion module of the QRNG under test; The light source adjustment module is built with an optical switching unit, an optical attenuation unit, a photosynthetic unit, and a light intensity measurement unit. The optical switching unit is connected to the optical attenuation unit, the photosynthetic unit, and the light intensity measurement unit respectively. The optical attenuation unit is connected to the photosynthetic unit. The optical switching unit, the optical attenuation unit, and the light intensity measurement unit are connected to the logic control module respectively. The optical signal output end of the laser of the QRNG under test is connected to the optical signal input end of the optical switching unit of the light source adjustment module, and the optical signal output end of the photosynthetic unit is connected to the optical signal input end of the interferometer of the QRNG under test. The automatic calibration method of the system operating point of the phase fluctuation QRNG comprises the following steps: Step 1: The user conveys the driving current range and step parameters of the laser of the QRNG under test and the sampling rate parameters of the photoelectric conversion module of the QRNG under test to the logic control module of the calibration device through the human-computer interaction module of the calibration device; Step 2: The logic control module of the calibration device sets the sampling rate of the sampling measurement module of the calibration device according to the sampling rate parameter in step 1; Step 3: The logic control module of the calibration device controls the driving current module to output the maximum driving current according to the upper limit of the driving current range in step 1, so that the laser output light intensity of the QRNG under test reaches the maximum; Step 4: The logic control module of the calibration device determines whether the driving current at this time reaches the lower limit of the range. If not, continue to execute step 5; if it has reached, jump to execute step 12; Step 5: The logic control module of the calibration device controls the driving current module to reduce the driving current output by one step, and uses this driving current to control the laser output light intensity of the QRNG under test; Step 6: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module, so that the output optical signal of the QRNG laser under test is input to the light intensity measurement unit through the output light of the optical switching unit, and the output light intensity of the QRNG laser under test is measured to be P; Step 7: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output light of the optical switching unit is output to the interferometer of the QRNG under test through the photosynthetic unit; Step 8: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, which is the sum of the classical noise and quantum phase noise under the P laser luminescence intensity; Step 9: The logic control module of the calibration device controls the optical switching unit of the light source adjustment module so that the output optical signal of the QRNG laser under test is input to the optical attenuation unit through the output light of the optical switching unit; Step 10: The logic control module of the calibration device first controls the driving current of the driving current module to the upper limit value, so that the output light intensity of the QRNG laser under test reaches the maximum; then controls the light attenuation unit of the light source adjustment module, and sets a certain attenuation so that the light intensity output to the interferometer of the QRNG under test through the photosynthesis unit is also P; Step 11: The logic control module of the calibration device controls the sampling and measuring module to measure the amplitude of the electrical signal output by the photoelectric conversion module of the QRNG under test, obtains the measurement data from the sampling and measuring module, and calculates its variance, i.e., the classical noise under the laser luminescence intensity P; the logic control module of the calibration device can calculate the ratio Y of the quantum phase noise to the classical noise under the laser luminescence intensity in combination with the calculated value of step 8, and record it; after completion, jump to step 4; Step 12: The logic control module of the calibration device finds the laser luminous intensity value when the ratio of quantum phase noise to classical noise is maximum according to the records, and transmits it to the human-computer interaction module, which outputs the calibration result to the user.

2. The automatic calibration method of the system operating point of a phase fluctuation QRNG according to claim 1 is characterized by: The driving current module includes a DAC digital analog converter and a constant current source. The signal output end of the DAC digital analog converter is connected to the signal input end of the constant current source. The signal input end of the DAC digital analog converter is connected to the signal output end of the logic control module. The signal output end of the constant current source is connected to the laser of the QRNG under test.

3. The automatic calibration method of the system operating point of a phase fluctuation QRNG according to claim 1 is characterized by: The optical switching unit is composed of a "1-input 3-output" optical switch, the optical attenuation unit is composed of an electrically controlled adjustable optical attenuator, the photosynthetic unit is composed of a photosynthetic device, and the light intensity measurement unit is composed of a PIN photodiode.

4. The method for automatically calibrating the system operating point of a phase fluctuation QRNG according to claim 1, characterized in that: The sampling and measuring module is equipped with an ADC analog-to-digital converter.

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