Single photon detector gating circuitry and detection method

Abstract

The application discloses a kind of single-photon detector gate circuit system and detection method, including first circuit branch, second circuit branch, avalanche diode, band-stop filter, low-noise amplifier and counter;Sinusoidal signal A' output by first circuit branch is input to the avalanche diode with sinusoidal signal B' output by second circuit branch, so that avalanche diode repeatedly is in Geiger mode and generates pulse signal when receiving photon and inputs into band-stop filter, band-stop filter outputs pulse signal into low-noise amplifier and outputs amplified pulse signal after amplification, after amplified pulse signal enters the counter, the counter carries out counting processing.The application uses the interaction of two sinusoidal signals to make avalanche diode in Geiger mode, greatly shorten the dead time of avalanche diode, improve single-photon detection efficiency.

Description

Technical Field

[0001] This invention relates to the field of single-photon detection technology, specifically to a single-photon detector gating circuit system and detection method. Background Technology

[0002] Quantum secure communication involves transmitting single photons or entangled photons to transfer quantum states, thus achieving secure communication. Quantum communication technology based on single photons typically refers to quantum key distribution (QKD), and single-photon detection technology is an indispensable and crucial element in this process. Single-photon detection technology is widely used in quantum key distribution, fiber optic communication, fiber optic sensing, lidar, and fluorescence imaging. Single-photon avalanche diodes (SPDBs) are currently one of the most commonly used single-photon detectors. However, current single-photon detector gating circuits input the gate signal directly to the avalanche diode after passing through a capacitor. This clearly lacks processing for the DC component and other frequency components of the gate signal. Furthermore, this gating circuit requires the arrival time of the gate pulse to detect the photon, limiting its application to scenarios where the photon arrival time is known in advance, resulting in a narrow application range and low detection efficiency.

[0003] The efficiency of a single-photon detector is also related to the restart time of the single-photon avalanche diode, also known as the dead time. An avalanche diode is a single-photon detection device using Geiger mode. Once triggered, it requires a period of time to restart before it can detect the next photon event. Currently, single-photon detectors use active quenching circuits and passive quenching circuits. Active quenching circuits can precisely control the dead time, but their structure is relatively complex, placing higher demands on some integrated circuits, and resulting in a larger overall area and higher power consumption, making them less suitable for array detector applications. Passive quenching circuits utilize the principle of resistor voltage division. After each quenching of the avalanche diode, a longer time is required for the bias voltage to charge the diode. Therefore, passive quenching circuits have a long dead time and high dark count noise, affecting detection efficiency.

[0004] There is room for improvement on the shortcomings of existing technologies. A gated quenching mode circuit is proposed to shorten the dead time of the gated quenching mode circuit, reduce dark counting noise, and improve the detection efficiency of single photons. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the technology and solve the problem of single-photon detection efficiency by proposing a single-photon detector gating circuit system and detection method.

[0006] The method of this invention is achieved through the following technical solution:

[0007] A single-photon detector gating circuit system, the system comprising a first circuit branch, a second circuit branch, an avalanche diode, a band-stop filter, a low-noise amplifier, and a counter;

[0008] The output terminal of the first circuit branch is connected to the cathode of the avalanche diode, the output terminal of the second circuit branch is connected to the cathode of the avalanche diode, the anode of the avalanche diode is connected to one end of the band-stop filter, the other end of the band-stop filter is connected to the input terminal of the low-noise amplifier, and the output terminal of the low-noise amplifier is connected to the counter.

[0009] The first circuit branch is used to generate a sine wave signal A', and the second circuit branch is used to generate a sine wave signal B';

[0010] The avalanche diode is used to receive optical signals and generate pulse signals;

[0011] The band-stop filter is used to filter gate signals;

[0012] The low-noise amplifier is used to amplify pulse signals;

[0013] The counter is used to count the incoming photons;

[0014] The sinusoidal signal A' output from the first circuit branch and the sinusoidal signal B' output from the second circuit branch are superimposed to form a superposition gate signal, which is input to the avalanche diode. The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that the avalanche diode generates a pulse signal when it receives a photon. The pulse signal and the superposition gate signal are input to the band-stop filter to filter out the superposition gate signal. The pulse signal output from the band-stop filter enters the low-noise amplifier for amplification and outputs an amplified pulse signal. The amplified pulse signal enters the counter for counting processing.

[0015] Furthermore, the cathode of the avalanche diode is connected in series with one end of a resistor R1, and the other end of R1 is connected to a voltage VCC, the voltage of which is less than the avalanche voltage of the avalanche diode.

[0016] Furthermore, the first circuit branch includes a sinusoidal signal source A, an amplifier A, a bandpass filter A, a capacitor C1, and a unidirectional conducting diode D1 connected in sequence.

[0017] Furthermore, one end of the capacitor C1 is connected to the unidirectional conducting diode D1, and the other end of the capacitor C1 is grounded through a resistor.

[0018] Furthermore, the steps for the first circuit branch to generate the sinusoidal signal A' are as follows:

[0019] Step A: The sinusoidal signal source A outputs a sinusoidal signal A, which is then amplified by the amplifier A.

[0020] Step B: The amplifier A outputs an amplified sine wave signal A, which then enters the bandpass filter A;

[0021] Step C: After the bandpass filter A filters out the interference frequency signals of the amplified sine signal A, it outputs a single-frequency sine signal A and enters the capacitor C1;

[0022] Step D: After removing the DC component of the single-frequency sinusoidal signal A, the capacitor C1 outputs a sinusoidal signal A with only AC flux and inputs it to the unidirectional conducting diode D1;

[0023] Step E: The unidirectional diode D1 performs half-wave rectification on the sinusoidal signal A with only AC flux, and finally outputs a sinusoidal signal A'.

[0024] Furthermore, the second circuit branch includes a sinusoidal signal source B, an amplifier B, a bandpass filter B, a capacitor C2, and a unidirectional conducting diode D2 connected in sequence.

[0025] Furthermore, one end of the capacitor C2 is connected to the unidirectional conducting diode D2, and the other end of the capacitor C2 is grounded through a resistor.

[0026] Furthermore, the steps for the second circuit branch to output a sinusoidal signal B' are as follows:

[0027] Step a: The sinusoidal signal source B outputs a sinusoidal signal B which is then amplified by the amplifier B.

[0028] Step b: The amplifier B outputs an amplified sine signal B, which then enters the bandpass filter B;

[0029] Step c: After the bandpass filter B filters out the interference frequency signals of the amplified sine signal B, it outputs a single-frequency sine signal B and enters the capacitor C2.

[0030] Step d: After removing the DC component of the single-frequency sinusoidal signal B, the capacitor C2 outputs a sinusoidal signal B with only AC flux and inputs it to the unidirectional conducting diode D1;

[0031] Step e: The unidirectional diode D2 performs half-wave rectification on the sinusoidal signal B with only AC flux, and the unidirectional diode D2 finally outputs a sinusoidal signal B'.

[0032] A detection method using a single-photon detector gating circuit, employing the aforementioned single-photon detector gating circuit system, includes the following steps:

[0033] Step 1: The sinusoidal signal source A outputs a sinusoidal signal A; the sinusoidal signal A enters the amplifier A for signal amplification.

[0034] Simultaneously, the sinusoidal signal source B outputs a sinusoidal signal B; the sinusoidal signal B enters the amplifier B for signal amplification.

[0035] Step 2: The amplifier A outputs an amplified sine wave signal A, which enters the bandpass filter A. The bandpass filter A filters out the interference frequency components of the amplified sine wave signal A and then outputs the signal into the capacitor C1.

[0036] Simultaneously, the amplifier B outputs an amplified sine signal B, which enters the bandpass filter B. The bandpass filter A filters out the interference frequency components of the amplified sine signal B and then outputs a signal that enters the capacitor C2.

[0037] Step 3: After removing the DC component of the sinusoidal signal A, the capacitor C1 inputs the sinusoidal signal A with only AC flux to the unidirectional conducting diode D1;

[0038] Meanwhile, after removing the DC component of the sinusoidal signal B, the capacitor C2 inputs the sinusoidal signal B with only AC flux to the unidirectional conducting diode D2.

[0039] Step 4: After the unidirectional conducting diode D1 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal A'.

[0040] Meanwhile, after the unidirectional conducting diode D2 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal B'.

[0041] Step 5: The sinusoidal signals A' and B' from Step 4 are superimposed to form a superposition gate signal, which is then input to the avalanche diode;

[0042] Step 6: The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that when the avalanche diode receives a photon, it generates a pulse signal and inputs the pulse signal together with the superimposed gate signal into the band-stop filter;

[0043] Step 7: The band-stop filter filters out the superposition gate signal and outputs a pulse signal, which is then amplified by the low-noise amplifier.

[0044] Step 8: The amplified pulse signal output by the low-noise amplifier is fed into the counter for calculation and processing;

[0045] Furthermore, when the superimposed gate signal is input to the avalanche diode in step 5, the voltage across the avalanche diode is greater than the avalanche voltage, that is, the avalanche diode is in Geiger mode.

[0046] The beneficial effects of this invention are as follows:

[0047] This invention discloses a single-photon detector gating circuit system and detection method, which employs two gate signals: signal A' and signal B'. When the gate pulse of gate signal A' passes, the gate pulse of gate signal B' arrives just in time, and the switching time between the two signals is relatively short. When the voltage of signal A' is lower than V1, the avalanche diode is quenched. Within a very short time, the voltage of signal B' rises to a voltage higher than V1, and the quenching of the avalanche diode ends, thereby putting the avalanche diode into Geiger mode. This greatly reduces the dead time of the avalanche diode and improves the single-photon detection efficiency. Attached Figure Description

[0048] Figure 1 This is a system block diagram of the present invention;

[0049] Figure 2 The waveforms of the sinusoidal signals A' and B', as well as the superimposed waveform, are shown in the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. However, the scope of protection of this invention is not limited to the specific embodiments described below.

[0051] like Figure 1 As shown, a single-photon detector gating circuit system includes a first circuit branch, a second circuit branch, an avalanche diode, a band-stop filter, a low-noise amplifier, and a counter.

[0052] The output terminal of the first circuit branch is connected to the cathode of the avalanche diode, the output terminal of the second circuit branch is connected to the cathode of the avalanche diode, the anode of the avalanche diode is connected to one end of the band-stop filter, the other end of the band-stop filter is connected to the input terminal of the low-noise amplifier, and the output terminal of the low-noise amplifier is connected to the counter.

[0053] The first circuit branch is used to generate a sine wave signal A', and the second circuit branch is used to generate a sine wave signal B';

[0054] The avalanche diode is used to receive optical signals and generate pulse signals;

[0055] The band-stop filter is used to filter gate signals;

[0056] The low-noise amplifier is used to amplify pulse signals;

[0057] The counter is used to count the number of times photons are injected;

[0058] The sinusoidal signal A' output from the first circuit branch and the sinusoidal signal B' output from the second circuit branch are superimposed to form a superposition gate signal, which is input to the avalanche diode. The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that the avalanche diode generates a pulse signal when it receives a photon. The pulse signal and the superposition gate signal are input to the band-stop filter to filter out the superposition gate signal. The pulse signal output from the band-stop filter enters the low-noise amplifier for amplification and outputs an amplified pulse signal. The amplified pulse signal enters the counter and the counter performs counting processing.

[0059] The first circuit branch is used to output a sinusoidal signal A'. The first circuit branch includes a sinusoidal signal source A, an amplifier A, a bandpass filter A, a capacitor C1, and a unidirectional conducting diode D1 connected in sequence.

[0060] The steps for the first circuit branch to output a sinusoidal signal A' are as follows:

[0061] Step A: The sinusoidal signal source A outputs a sinusoidal signal A, which is then amplified by the amplifier A.

[0062] Step B: The amplifier A outputs an amplified sine wave signal A, which then enters the bandpass filter A;

[0063] The signal frequency that can pass through bandpass filter A is exactly the frequency of the sinusoidal signal A. Bandpass filter A consists of a low-pass filter cascading with a high-pass filter, and the cutoff frequency f2 of the low-pass filter is greater than the cutoff frequency f1 of the high-pass filter. The frequency range that the bandpass filter passes through is f2-f1, and the optimal value is (f2-f1) / 2. The values ​​of f1 and f2 are calculated using the cutoff frequency formula, as follows:

[0064] f = 1 / (2*Pi*R*C),

[0065] Pi represents pi (circular diameter), R represents the resistance, and C represents the capacitance.

[0066] Step C: After the bandpass filter A filters out the interference frequency signals of the sinusoidal signal A, it outputs a sinusoidal signal A with a single frequency and enters the capacitor C1;

[0067] One end of the capacitor C1 is connected to the unidirectional diode D1, and the other end of the capacitor C1 is connected to one end of the resistor R4, with the other end of the resistor R4 grounded.

[0068] Since the sinusoidal signal A coming from the bandpass filter A has a DC component, and the capacitor has the characteristic of passing AC and blocking DC, the DC component of the sinusoidal signal A cannot pass through the capacitor C1. However, the DC component will charge the capacitor C1, thus causing the capacitor to generate a DC component. Therefore, after connecting a resistor R4 to one end of the capacitor C1, the other end of R4 is grounded, so that the DC component is diverted to ground through the resistor R4, thereby preventing the DC component from charging the capacitor C1.

[0069] Step D: After removing the DC component of the single-frequency sinusoidal signal A, the capacitor C1 outputs a sinusoidal signal A with only AC flux and inputs it to the unidirectional conducting diode D1;

[0070] Step E: The unidirectional diode D1 performs half-wave rectification on the sinusoidal signal A with only AC flux, and the unidirectional diode finally outputs a sinusoidal signal A'.

[0071] Half-wave rectification is the most commonly used circuit that uses the unidirectional conductivity of diodes for rectification. It is often used to convert alternating current into direct current. When the input is a standard sine wave, the positive half of the output sine wave is used, and the negative half is discarded.

[0072] The second circuit branch includes a sinusoidal signal source B, an amplifier B, a bandpass filter B, a capacitor C2, and a unidirectional diode D2 connected in sequence.

[0073] The steps for the second circuit branch to output a sinusoidal signal B' are as follows:

[0074] Step a: The sinusoidal signal source B outputs a sinusoidal signal B which is then amplified by the amplifier B.

[0075] Step b: The amplifier B outputs an amplified sine signal B, which then enters the bandpass filter B;

[0076] The signal frequency that can pass through bandpass filter B is exactly the frequency of the sinusoidal signal B. Bandpass filter B consists of a low-pass filter cascading with a high-pass filter, and the cutoff frequency f2 of the low-pass filter is greater than the cutoff frequency f1 of the high-pass filter. The frequency range that this bandpass filter passes through is f2-f1, and the optimal value is (f2-f1) / 2. The values ​​of f1 and f2 are calculated using the cutoff frequency formula, as follows:

[0077] f = 1 / (2*Pi*R*C),

[0078] Pi represents pi (circular diameter), R represents the resistance, and C represents the capacitance.

[0079] Step c: After the bandpass filter B filters out frequencies different from the sinusoidal signal B in step b, it outputs a single-frequency sinusoidal signal B and enters the capacitor C2.

[0080] One end of capacitor C2 is connected to unidirectional diode D2, and the other end of capacitor C2 is connected to one end of resistor R3, with the other end of resistor R3 grounded.

[0081] Since the sinusoidal signal B coming out of the bandpass filter B has a DC component, and the capacitor has the characteristic of passing AC and blocking DC, the DC component of the sinusoidal signal B cannot pass through the capacitor C2. However, this DC component will charge the capacitor C2, thus causing the capacitor to generate a DC component. Therefore, after connecting a resistor R3 to one end of the capacitor C2, the other end of R3 is grounded, so that the DC component is diverted to ground through the resistor R3, thereby preventing the DC component from charging the capacitor C2.

[0082] Step d: After removing the DC component of the single-frequency sinusoidal signal B, the capacitor C2 outputs a sinusoidal signal B with only AC flux and inputs it to the unidirectional conducting diode D1;

[0083] Step e: The unidirectional diode D2 performs half-wave rectification on the sinusoidal signal B with only AC flux, and the unidirectional diode D2 finally outputs a sinusoidal signal B'.

[0084] Half-wave rectification is the most commonly used circuit that uses the unidirectional conductivity of diodes for rectification. It is often used to convert alternating current into direct current. When the input is a standard sine wave, the positive half of the output sine wave is used, and the negative half is discarded.

[0085] The sinusoidal signal A' output from the first circuit branch and the sinusoidal signal B' output from the second circuit branch both enter the avalanche diode. The anode of the avalanche diode is connected to the band-stop filter, and the cathode of the avalanche diode is connected in series with the resistor R1 and the voltage VCC. The voltage VCC is less than the avalanche voltage of the avalanche diode, that is, when it is not connected to one end of the band-stop filter, the voltage across the avalanche diode will not exceed the avalanche breakdown voltage.

[0086] Specifically, sinusoidal signals A' and B' enter the avalanche diode almost simultaneously. When sinusoidal signal A' arrives at the avalanche diode, the voltage across the avalanche diode is greater than its avalanche voltage, thus putting the avalanche diode into Geiger mode. At this time, as long as a photon hits the avalanche diode, it can generate a pulse signal, thereby enabling the counter to count. When the voltage across the avalanche diode is less than its avalanche voltage, the avalanche diode is quenched. The arrival of sinusoidal signal B' in a very short time makes the voltage across the avalanche diode greater than its avalanche voltage, ending the quenching and putting the avalanche diode back into Geiger mode, continuing to receive photons and enabling the counter to count. The gating circuit of this invention has two gate signals: sinusoidal signal A' and sinusoidal signal B'. When sinusoidal signal A' passes, sinusoidal signal B' arrives just in time.

[0087] The arrival time difference between the sinusoidal signal B' and the sinusoidal signal A' is in the range of 8ns to 12ns, and the preferred value in this embodiment is 10ns.

[0088] The aforementioned gated circuit overcomes the limitations of traditional gated circuits, which can only be applied to detection methods where the arrival time of photons is known in advance. This invention significantly reduces the restart time (i.e., dead time) of avalanche diodes and improves photon detection efficiency.

[0089] After the avalanche diode receives a photon, the anode output pulse signal of the avalanche diode and the superposition signal of the sine signal A' and the sine signal B' enter the band-stop filter. The band-stop filter is used to filter the superposition signal of the sine signal A' and the sine signal B', retain the pulse signal and output it.

[0090] The pulse signal output from the band-stop filter needs to be amplified by a low-noise amplifier, which is used to amplify the pulse signal.

[0091] Furthermore, the counter is used to count the number of times photons are injected; the amplified pulse signal output by the low-noise amplifier is fed into the counter for calculation and processing, and the counter automatically increments by 1 for each pulse signal received.

[0092] A detection method using a single-photon detector gating circuit, employing the aforementioned single-photon detector gating circuit system, includes the following steps:

[0093] Step 1: The sinusoidal signal source A outputs a sinusoidal signal A; the sinusoidal signal A enters the amplifier A for signal amplification.

[0094] Simultaneously, the sinusoidal signal source B outputs a sinusoidal signal B; the sinusoidal signal B enters the amplifier B for signal amplification.

[0095] Step 2: The amplifier A outputs an amplified sine wave signal A, which enters the bandpass filter A. The bandpass filter A filters out the interference frequency components of the amplified sine wave signal A and then outputs the signal into the capacitor C1.

[0096] Simultaneously, the amplifier B outputs an amplified sine signal B, which enters the bandpass filter B. The bandpass filter A filters out the interference frequency components of the amplified sine signal B and then outputs a signal that enters the capacitor C2.

[0097] Step 3: After removing the DC component of the sinusoidal signal A, the capacitor C1 inputs the sinusoidal signal A with only AC flux to the unidirectional conducting diode D1;

[0098] Meanwhile, after removing the DC component of the sinusoidal signal B, the capacitor C2 inputs the sinusoidal signal B with only AC flux to the unidirectional conducting diode D2.

[0099] Step 4: After the unidirectional conducting diode D1 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal A'.

[0100] Meanwhile, after the unidirectional conducting diode D2 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal B'.

[0101] Step 5: The sinusoidal signals A' and B' from Step 4 are superimposed to form a superposition gate signal, which is then input to the avalanche diode; the waveforms of the sinusoidal signals A' and B' and the superposition gate signal are shown below. Figure 2 As shown;

[0102] In this process, the sinusoidal signal A' and the sinusoidal signal B' enter the avalanche diode almost simultaneously. When the sinusoidal signal A' reaches the avalanche diode, the voltage across the avalanche diode is greater than the avalanche voltage of the avalanche diode, thereby putting the avalanche diode into Geiger mode.

[0103] The arrival time difference between the sinusoidal signal B' and the sinusoidal signal A' is in the range of 8ns to 12ns, and the preferred value in this embodiment is 10ns.

[0104] Step 6: The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that when the avalanche diode receives a photon, it generates a pulse signal and inputs the pulse signal together with the superimposed gate signal into the band-stop filter;

[0105] When the sinusoidal signal A' arrives at the avalanche diode, the voltage across the avalanche diode is greater than its avalanche voltage, thus putting the avalanche diode into Geiger mode. At this time, as long as a photon hits the avalanche diode, it can generate a pulse signal, thereby enabling the counter to count. When the voltage across the avalanche diode is less than its avalanche voltage, the avalanche diode is quenched. The arrival of the sinusoidal signal B' in a very short time makes the voltage across the avalanche diode greater than its avalanche voltage, ending the quenching of the avalanche diode and putting it back into Geiger mode, allowing it to continue receiving photons and enabling the counter to count.

[0106] Step 7: The band-stop filter filters out the superposition gate signal and outputs a pulse signal, which is then amplified by the low-noise amplifier.

[0107] Step 8: The amplified pulse signal output by the low-noise amplifier enters the counter, and the value of the counter is incremented by 1.

[0108] The single-photon detector gate circuit structure disclosed in this invention can not only reduce the interference of DC components generated by the system, but also put the avalanche diode in Geiger mode through the interaction of two sinusoidal signals, shortening the dead time and greatly improving the efficiency of photon detection.

[0109] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the invention.

Claims

1. A single-photon detector gating circuit system, characterized in that, The system includes a first circuit branch, a second circuit branch, an avalanche diode, a band-stop filter, a low-noise amplifier, and a counter; The output terminal of the first circuit branch is connected to the cathode of the avalanche diode, the output terminal of the second circuit branch is connected to the cathode of the avalanche diode, the anode of the avalanche diode is connected to one end of the band-stop filter, the other end of the band-stop filter is connected to the input terminal of the low-noise amplifier, and the output terminal of the low-noise amplifier is connected to the counter. The first circuit branch is used to generate a sine wave signal A', and the second circuit branch is used to generate a sine wave signal B'; The avalanche diode is used to receive optical signals and generate pulse signals; The band-stop filter is used to filter gate signals; The low-noise amplifier is used to amplify pulse signals; The counter is used to count the incoming photons; The sinusoidal signal A' output from the first circuit branch and the sinusoidal signal B' output from the second circuit branch are superimposed to form a superposition gate signal, which is input to the avalanche diode. The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that the avalanche diode generates a pulse signal when it receives a photon. The pulse signal and the superposition gate signal are input to the band-stop filter to filter out the superposition gate signal. The pulse signal output from the band-stop filter enters the low-noise amplifier for amplification and outputs an amplified pulse signal. The amplified pulse signal enters the counter for counting processing.

2. The single-photon detector gating circuit system according to claim 1, characterized in that, The cathode of the avalanche diode is connected in series with one end of a resistor R1, and the other end of R1 is connected to a voltage VCC, which is less than the avalanche voltage of the avalanche diode.

3. The single-photon detector gating circuit system according to claim 1, characterized in that, The first circuit branch includes a sinusoidal signal source A, an amplifier A, a bandpass filter A, a capacitor C1, and a unidirectional diode D1 connected in sequence.

4. The single-photon detector gating circuit system according to claim 3, characterized in that, One end of the capacitor C1 is connected to the unidirectional diode D1, and the other end of the capacitor C1 is grounded through a resistor.

5. A single-photon detector gating circuit system according to claim 3, characterized in that, The steps for the first circuit branch to generate a sinusoidal signal A' are as follows: Step A: The sinusoidal signal source A outputs a sinusoidal signal A, which is then amplified by the amplifier A. Step B: The amplifier A outputs an amplified sine wave signal A, which then enters the bandpass filter A; Step C: After the bandpass filter A filters out the interference frequency signals of the amplified sine signal A, it outputs a single-frequency sine signal A and enters the capacitor C1; Step D: After removing the DC component of the single-frequency sinusoidal signal A, the capacitor C1 outputs a sinusoidal signal A with only AC flux and inputs it to the unidirectional conducting diode D1; Step E: The unidirectional diode D1 performs half-wave rectification on the sinusoidal signal A with only AC flux, and finally outputs a sinusoidal signal A'.

6. The single-photon detector gating circuit system according to claim 1, characterized in that, The second circuit branch includes a sinusoidal signal source B, an amplifier B, a bandpass filter B, a capacitor C2, and a unidirectional diode D2 connected in sequence.

7. A single-photon detector gating circuit system according to claim 6, characterized in that, One end of the capacitor C2 is connected to the unidirectional diode D2, and the other end of the capacitor C2 is grounded through a resistor.

8. A single-photon detector gating circuit system according to claim 6, characterized in that, The steps for the second circuit branch to output a sinusoidal signal B' are as follows: Step a: The sinusoidal signal source B outputs a sinusoidal signal B which is then amplified by the amplifier B. Step b: The amplifier B outputs an amplified sine signal B, which then enters the bandpass filter B; Step c: After the bandpass filter B filters out the interference frequency signals of the amplified sine signal B, it outputs a single-frequency sine signal B and enters the capacitor C2. Step d: After removing the DC component of the single-frequency sinusoidal signal B, the capacitor C2 outputs a sinusoidal signal B with only AC flux and inputs it to the unidirectional conducting diode D1; Step e: The unidirectional diode D2 performs half-wave rectification on the sinusoidal signal B with only AC flux, and the unidirectional diode D2 finally outputs a sinusoidal signal B'.

9. A detection method using a gated circuit of a single-photon detector, characterized in that, The method, which employs a single-photon detector gating circuit system as described in any one of claims 1-8, comprises the following steps: Step 1: The sinusoidal signal source A outputs a sinusoidal signal A; the sinusoidal signal A enters the amplifier A for signal amplification. Simultaneously, the sinusoidal signal source B outputs a sinusoidal signal B; the sinusoidal signal B enters the amplifier B for signal amplification. Step 2: The amplifier A outputs an amplified sine wave signal A, which enters a bandpass filter A. The bandpass filter A filters out the interference frequency components of the amplified sine wave signal A and then outputs the signal into capacitor C1. Meanwhile, the amplifier B outputs an amplified sine signal B and enters the bandpass filter B. The bandpass filter A filters out the interference frequency components of the amplified sine signal B and then outputs the signal into capacitor C2. Step 3: After removing the DC component of the sinusoidal signal A, the capacitor C1 inputs the sinusoidal signal A with only AC flux to the unidirectional conducting diode D1; Meanwhile, after removing the DC component of the sinusoidal signal B, the capacitor C2 inputs the sinusoidal signal B with only AC flux to the unidirectional conducting diode D2. Step 4: After the unidirectional conducting diode D1 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal A'. Meanwhile, after the unidirectional conducting diode D2 performs half-wave rectification on the input signal, the unidirectional conducting diode outputs a sinusoidal signal B'. Step 5: The sinusoidal signals A' and B' from Step 4 are superimposed to form a superposition gate signal, which is then input to the avalanche diode; Step 6: The gate signal causes the avalanche diode to repeatedly enter Geiger mode, so that when the avalanche diode receives a photon, it generates a pulse signal and inputs the pulse signal together with the superimposed gate signal into the band-stop filter; Step 7: The band-stop filter filters out the superposition gate signal and outputs a pulse signal, which is then amplified by the low-noise amplifier. Step 8: The amplified pulse signal output by the low-noise amplifier is fed into the counter for calculation and processing.

10. The detection method of a single-photon detector gated circuit according to claim 9, characterized in that, In step 5, when the superimposed gate signal is input to the avalanche diode, the voltage across the avalanche diode is greater than the avalanche voltage, meaning the avalanche diode is in Geiger mode.

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