Single-photon detection device and single-photon detection method

Abstract

A single photon detection device (200) including an interference unit (100), the interference unit (100) including: a signal distribution module (110) arranged to split an input signal into a first signal and a second signal; a first signal path (120) coupled to the signal distribution module (110) and arranged to receive and transmit the first signal; a second signal path (130) coupled to the signal distribution module (110) and arranged to receive the second signal and filter and transmit a signal of a preset frequency component; a phase shift module (140) installed in the first signal path (120) or the second signal path (130) and arranged to shift the phase of the transmission signal by 180°; and a combination module (150) coupled to the first signal path (120) and the second signal path (130) and arranged to receive, combine, and output output signals of the first signal path (120) and the second signal path (130).

Description

Technical Field

[0001] The present invention relates to the field of weak light detection technology, and particularly to a single photon detection device including an interference unit and a single photon detection method using the single photon detection device.

Background Art

[0002] Due to the demand for weak light sensing and detection in fields such as quantum key distribution, optical fiber sensing, optical fiber communication, lidar, high energy physics, semiconductor device characteristic analysis, and biological imaging, single photon detection devices based on semiconductor avalanche photodiodes (APDs) are widely used. Among them, APDs used in the optical fiber communication wavelength bands (1310 nanometers and 1550 nanometers) are mainly based on indium gallium arsenide (InGaAs) materials.

[0003] In order to suppress the afterpulse noise of a single photon detection device based on an indium gallium arsenide APD and increase the photon counting rate of the single photon detection device, a gate drive method is adopted for the avalanche photodiode to reduce the avalanche charge and the recovery time after avalanche. The gate drive method may also be adopted for silicon-based APDs. However, due to the parasitic capacitance of the avalanche photodiode and the circuit, the capacitive response of the gate signal will cover the avalanche signal caused by photons. Therefore, the capacitive response of the gate signal must be effectively removed.

[0004] Conventional technologies include active noise cancellation, band-stop filtering, low-pass filtering, and self-differential filtering. Of these, active noise cancellation can effectively remove the fundamental and harmonic frequencies of the capacitance response of the gate signal at the APD output terminal, and can process narrow avalanche pulse signals by passing through a wider and more continuous frequency domain. However, when the temperature and bias voltage of the APD change, the capacitance response of the gate signal at the APD output terminal also changes. In this case, active noise cancellation requires readjustment to remove the capacitance response signal of the gate signal at the APD output terminal, which limits its practicality.

[0005] Bandstop filter technology utilizes bandstop filters across multiple radio frequencies to suppress the fundamental and harmonic frequencies of the capacitive response of the gate signal at the APD output terminal. The typical stopband bandwidth of bandstop filters is on the order of 100-300 MHz, with a constant transition bandwidth. This method can process narrow avalanche pulse signals with a wider frequency domain passband, but it introduces significant frequency domain discontinuities near the fundamental and harmonic frequency points of the gate signal. This reduces the signal-to-noise ratio of the narrow avalanche pulse signal, resulting in a certain degree of spread and distortion in the pulse waveform and increased jitter.

[0006] Low-pass filtering methods have a smaller frequency-domain passband for processing narrow avalanche pulse signals, generally not exceeding 90% of the gate signal frequency. A smaller frequency-domain processing bandwidth reduces the signal-to-noise ratio of narrow avalanche pulse signals, causing broadening and distortion in the pulse waveform and increasing jitter.

[0007] Self-differential technology requires two differential signal channels to transmit and process broadband signals, resulting in high demands on the device's broadband performance. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In view of at least one drawback of the prior art, the present invention provides a single-photon detection device including an interference unit. [Means for solving the problem]

[0009] The aforementioned interference unit is A signal distribution module is arranged to split the input signal into a first signal and a second signal, A first signal path, coupled to the signal distribution module and arranged to receive and transmit the first signal, A second signal path is coupled to the signal distribution module and is arranged to receive the second signal, filter the preset frequency component signal from the second signal, and transmit it; A phase shift module installed in the first signal path or the second signal path and arranged to shift the phase of the transmitted signal by 180°, The system includes a coupling module that is coupled to the first signal path and the second signal path, and is arranged to receive, combine, and output the output signals of the first signal path and the second signal path.

[0010] According to one aspect of the present invention, the difference in transmission distance between the first signal path and the second signal path is smaller than the first preset value.

[0011] According to one aspect of the present invention, the second signal path includes a narrowband filter module, The passband of the aforementioned narrowband filter module has preset frequency components.

[0012] According to one aspect of the present invention, the passband of the narrowband filter module is 10 MHz. Z The following applies:

[0013] According to one aspect of the present invention, the narrowband filter module includes one or more of a surface acoustic wave filter, a bulk acoustic wave filter, and a dielectric filter.

[0014] According to one aspect of the present invention, the first signal path includes a power attenuation module, The power attenuation module is positioned to adjust the power of the first signal so that the power difference between the output signals of the first signal path and the second signal path is less than a second preset value.

[0015] According to one aspect of the present invention, the power attenuation module includes one or more of an analog voltage-controlled attenuator, a digitally controlled step attenuator, and a resistance network attenuator.

[0016] According to one aspect of the present invention, the phase shift module is installed in the second signal path.

[0017] According to one aspect of the present invention, the phase shift module includes one or more of the following: a radio frequency transmission line, an analog voltage-controlled phase shifter, a digitally controlled step phase shifter, a capacitive network phase shifter, an inductance network phase shifter, and a capacitive-inductance hybrid network phase shifter.

[0018] According to one aspect of the present invention, the signal distribution module and the coupling module each include a 3-port radio frequency matching element having a first port, a second port, and a third port, and the 3-port radio frequency matching element of the signal distribution module is arranged as follows: The first port is coupled to a single-photon inductor and is arranged to receive the input signal. The second port is coupled to the first signal path and is arranged to output the first signal. The third port is coupled to the second signal path and is arranged to output the second signal. The three-port radio frequency matching elements of the coupling module are arranged as follows: The second port is coupled to the second signal path and is arranged to receive the output signal of the second signal path. The third port is coupled to the first signal path and is arranged to receive the output signal of the first signal path. The first port outputs a signal obtained by combining the output signal of the first signal path and the output signal of the second signal path.

[0019] According to one aspect of the present invention, the three-port radio frequency matching element includes a directional coupler, and the second port and the third port of the directional coupler have a preset signal isolation degree.

[0020] According to one aspect of the present invention, the single photon detection device a single photon induction element arranged to receive an optical signal, convert it into an electrical signal, and output the electrical signal; a DC voltage source coupled to the single photon induction element and arranged to provide a DC bias voltage to the single photon induction element to bring the single photon induction element into a critical breakdown state; a gate signal generator coupled to the single photon induction element and arranged to provide a gate signal to the single photon induction element, and further includes: The input signal includes an interference signal due to the capacitive response of the electrical signal and the gate signal.

[0021] According to one aspect of the present invention, the gate signal includes a periodic signal, and the preset frequency component includes one of the frequency components of the gate signal.

[0022] According to one aspect of the present invention, the single photon detection device includes a plurality of the interference units, the plurality of interference units are connected in cascade, and the second signal path of each interference unit filters an interference signal corresponding to one of the frequency components of the gate signal.

[0023] According to one aspect of the present invention, the single photon detection device further includes a plurality of signal amplification units, each signal amplification unit is installed in front of one of the interference units along the transmission direction of the input signal and is arranged to amplify the input signal. '

[0024] According to one aspect of the present invention, the single photon detection device The system further includes a low-pass filter unit, which is installed after a plurality of interference units along the transmission direction of the input signal and is configured to perform low-pass filtering on the output signal filtered by the plurality of interference units.

[0025] Furthermore, the present invention provides a chip that integrates the single-photon detection device described above.

[0026] Furthermore, the present invention provides a method for performing single-photon detection using the single-photon detection device described above. The DC voltage source provides a DC bias voltage to the single-photon inductor, causing the single-photon inductor to enter a critical breakdown state. The gate signal generator provides a gate signal to the single-photon inductor, The single-photon inductor receives an optical signal and converts it into an electrical signal, The signal distribution module divides the input signal, which includes the electrical signal and the interference signal due to the capacitive response of the gate signal, into a first signal and a second signal. The first signal is received and transmitted via the first signal path, The second signal is received via the second signal path, and the preset frequency components of the signal are filtered from the second signal and transmitted. The phase shift module shifts the phase of the transmitted signal by 180°, The coupling module includes receiving the output signals from the first signal path and the second signal path, coupling them, and outputting them.

[0027] According to one aspect of the present invention, the difference in transmission distance between the first signal path and the second signal path is smaller than the first preset value.

[0028] According to one aspect of the present invention, the second signal path includes a narrowband filter module, the passband of the narrowband filter module includes the preset frequency components, and the passband of the narrowband filter module is 10 MHz. zThe method is as follows: The process further includes filtering the second signal using the narrowband filter module.

[0029] According to one aspect of the present invention, the first signal path includes a power attenuation module, and the method is The power attenuation module further includes adjusting the power of the first signal to make the power difference between the output signals of the first signal path and the second signal path less than a second preset value.

[0030] According to one aspect of the present invention, the signal distribution module and the coupling module each include a 3-port radio frequency matching element having a first port, a second port, and a third port, wherein the 3-port radio frequency matching element of the signal distribution module is arranged such that the first port is coupled to a single-photon inductor, the second port is coupled to the first signal path, and the third port is coupled to the second signal path, and the 3-port radio frequency matching element of the coupling module is arranged such that the second port is coupled to the second signal path and the third port is coupled to the first signal path, and the method is as follows: The input signal is received by the first port of the three-port radio frequency matching element of the signal distribution module, The first signal is output by the second port of the three-port radio frequency matching element of the signal distribution module, The second signal is output by the third port of the three-port radio frequency matching element of the signal distribution module, The output signal of the second signal path is received by the second port of the three-port radio frequency matching element of the coupling module, The output signal of the first signal path is received by the third port of the three-port radio frequency matching element of the coupling module, The coupling module further includes outputting a signal obtained by combining the output signal of the first signal path and the output signal of the second signal path through the first port of the three-port radio frequency matching element of the coupling module.

[0031] According to one aspect of the present invention, the single-photon detection device includes a plurality of interference units, the plurality of interference units are cascaded, the preset frequency component includes one of the frequency components of the gate signal, and the method is The second signal path of each interference unit further includes filtering an interference signal corresponding to one of the frequency components of the gate signal.

[0032] According to one aspect of the present invention, the single-photon detection apparatus further includes a plurality of signal amplification units installed in front of one of the interference units along the transmission direction of the input signal, and the method The process further includes amplifying the input signal using the plurality of signal amplification units.

[0033] According to one aspect of the present invention, the single-photon detection device further includes a low-pass filter unit installed after a plurality of interference units along the transmission direction of the input signal, and the method is The process further includes performing low-pass filtering on the output signal filtered by the plurality of interference units using the low-pass filter unit.

[0034] Furthermore, the present invention provides a non-instantaneous computer-readable storage medium in which computer-readable instructions are stored, and when the instructions are executed by a processor, the processor causes the processor to perform the method. [Effects of the Invention]

[0035] This invention provides a single-photon detection device including an interference unit, an electrical chip, and a method for single-photon detection. The gate interference signal is filtered by an ultra-narrowband bandpass filter to obtain the fundamental or harmonic signal frequency components, which are then interfered with by a coupling module (including the electrical signal after photoelectric conversion and the gate interference signal). Since the interference phenomenon occurs only within the passband and transition band of the ultra-narrowband bandpass filter when viewed from the entire frequency domain, the impact on the main transmission signal is small. Multi-stage filtering effectively removes a large amount of gate interference signals and stably provides a wider and continuous frequency domain passband, enabling processing of narrow avalanche pulse signals. The signal-to-noise ratio, pulse waveform, and jitter effects of narrow avalanche pulse signals are small, resulting in a clear optimization effect on the detection efficiency, after-pulse effect, and time resolution of the single-photon detector. [Brief explanation of the drawing]

[0036] To more clearly describe the invention according to the embodiments of this application, the drawings necessary for describing the embodiments are briefly described below. Clearly, the drawings in the following description are only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without exceeding the scope for which this application seeks protection. [Figure 1] This figure shows a detection device including an avalanche photodiode and its voltammetry curve. [Figure 2] This figure shows the gate voltage signal waveform applied to an avalanche photodiode. [Figure 3] This figure shows the output signal waveform of a conventional single-photon detector. [Figure 4] This figure shows an interference unit for a single-photon detection device according to one embodiment of the present invention. [Figure 5] This figure shows an interference unit for a single-photon detection device according to one embodiment of the present invention. [Figure 6] This figure shows the frequency response curve of an ultra-narrowband bandpass filter in a single-photon detection device according to one embodiment of the present invention. [Figure 7] This figure shows an interference unit for a single-photon detection device according to one embodiment of the present invention. [Figure 8] This figure shows an interference unit for a single-photon detection device according to one embodiment of the present invention. [Figure 9] This figure shows a single-photon detection device including an interference unit according to one embodiment of the present invention. [Figure 10A] This figure shows the frequency response curve of the interference unit of a single-photon detection device according to one embodiment of the present invention. [Figure 10B] This figure shows the frequency response curve of the interference unit of a single-photon detection device according to one embodiment of the present invention. [Figure 11] This figure shows a single-photon detection device including an interference unit according to one embodiment of the present invention. [Figure 12] This figure shows the output signal waveform of a single-photon detection device including an interference unit according to one embodiment of the present invention. [Figure 13] This figure shows a single-photon detection device including an interference unit according to one embodiment of the present invention. [Figure 14] This figure shows a single-photon detection device including an interference unit according to one embodiment of the present invention. [Figure 15] This figure shows a single-photon detection method according to one embodiment of the present invention. [Figure 16A] This figure shows a device configuration diagram of a single-photon detection device according to one embodiment of the present invention. [Figure 16B] This figure shows a time distribution histogram of detection events in a single-photon detection device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0037] Hereinafter, the invention according to the embodiments of the present application will be described clearly and completely with reference to the drawings of the embodiments of the present application. Clearly, the embodiments described are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person skilled in the art without creative work based on the embodiments of the present application are within the scope of the protection of the present application.

[0038] The embodiments of this application have been described in detail above, and the principles and embodiments of this application are described using specific examples. The above description of embodiments is used solely to aid in understanding the methods and spirit of this application. At the same time, those skilled in the art will know that any modifications or alterations made based on the ideas of this application and based on the specific embodiments and scope of application of this application fall within the scope of protection of this application. Thus, the contents of this specification should not be understood as limitations on this application.

[0039] Single-photon detection devices generally utilize an avalanche photodiode (APD) as a photoelectric sensor. The avalanche photodiode operates under the action of a reverse bias voltage, and its operating curve is shown in Figure 1 (Figure 1 shows a detection device including an avalanche photodiode and its operating curve). When no photon is incident, the reverse current is very weak and is called the dark current. When a photon is incident, the carriers (electron-hole pairs) generated by light absorption are separated by the electric field, generating a reverse current called the photocurrent. In the linear operating region, i.e., when the APD reverse bias voltage is lower than the breakdown voltage, the photocurrent and light intensity are proportional, and in this case, the APD does not have single-photon detection capabilities. However, when the APD bias is higher than its breakdown voltage, the carriers generated by the single photon are accelerated to sufficient energy by the electric field, generating new electron-hole pairs through collisional ionization, achieving a sustained carrier multiplication effect (i.e., the avalanche effect), thereby generating a detectable macrocurrent signal. Under high bias voltages, avalanche photodiodes can sense single-photon level optical signals, making them suitable for single-photon detection devices required in fields such as quantum key distribution and quantum direct communication.

[0040] Avalanche photodiodes exhibit an afterpulse effect. That is, within a certain period after an avalanche is generated, even without photon incidence, the avalanche photodiode randomly generates secondary avalanches. Afterpulses are a type of detector noise and should be suppressed as much as possible. There is a correlation between afterpulses and avalanche current. The larger the avalanche current, i.e., the higher the APD reverse bias voltage, the more pronounced the afterpulse becomes. To suppress afterpulses, the APD reverse bias voltage cannot be set too high, which affects the single-photon detection efficiency of the APD. At the same time, APD detectors typically introduce a long dead time. That is, after successfully detecting a single single-photon avalanche signal, photon counting is not performed for a long period afterward, reducing the detection counting rate of the single-photon detector. To improve the photon counting rate and detection efficiency of a single-photon detector, a gate-driven method is typically used for avalanche photodiodes. As shown in Figure 1, a DC bias is applied to the avalanche photodiode to induce a critical breakdown state, and a periodically changing gate signal is applied to the avalanche photodiode while the DC bias is still in place. As shown in Figure 2, or as shown in Figure 2, the gate signal applied to the avalanche photodiode includes one or more periodic signals from, for example, a sine wave signal, a square wave signal, or a triangular wave signal (Figure 2 shows the waveforms of two gate signals). Within a certain time of the gate signal, the avalanche photodiode is in an avalanche breakdown state, and when it receives a single-photon level optical signal, an avalanche occurs, and it can output an avalanche current. Within the remaining time of the gate signal, since the reverse bias voltage is lower than the breakdown voltage, the avalanche current is quenched, reducing the avalanche charge and the recovery time after the avalanche. By applying a gate voltage signal, the afterpulse of the avalanche photodiode is effectively suppressed, improving the photon counting rate and detection efficiency of the single-photon detector.

[0041] However, the parasitic capacitance of the avalanche photodiode and its connection circuit, as well as the capacitance response due to gate signal injection, mask the avalanche signal induced by the photon. As shown in Figure 3, the output signal of the avalanche photodiode contains numerous interference signals due to the capacitance response of the gate signal, making it difficult to read the electrical signal generated by the optical signal injection conversion. Therefore, the interference signals introduced by the capacitance response of the gate signal must be effectively removed.

[0042] The present invention provides a single-photon detection device including an interference unit, which uses an ultra-narrowband interference circuit to remove the fundamental and harmonic frequency components of the interference signal due to the capacitance response of the gate signal at the output terminal of an avalanche photodiode (APD). The passband of the ultra-narrowband interference circuit generally does not exceed 10 MHz, the transition band is generally less than 20 MHz, and it is not affected by the operating state of the APD device itself, providing a stable and wider continuous frequency domain passband to process narrow avalanche pulse signals. The impact on the signal-to-noise ratio, pulse waveform, and jitter of the avalanche narrow pulse signal is small, and there is a clear optimization effect on the detection efficiency, after-pulse effect, and temporal resolution of the single-photon detector.

[0043] According to one embodiment of the present invention, the present invention provides a single-photon detection device including an interference unit 100, as shown in Figure 4, the interference unit 100 includes a signal distribution module 110, a first signal path 120, a second signal path 130, a phase shift module 140, and a coupling module 150.

[0044] The signal distribution module 110 is configured to split the input signal into a first signal and a second signal. Alternatively, the signal distribution module 110 receives a signal from the avalanche photodiode input, which includes an electrical signal generated by the avalanche photodiode in response to incident photons, and also includes an interference signal due to the capacitive response of the gate signal, the frequency of which the interference signal matches that of the gate signal. The signal distribution module 110 splits the input signal into a first signal and a second signal and transmits them along the first signal path 120 and the second signal path 130, respectively.

[0045] The first signal path 120 is coupled to the signal distribution module 110 and is configured to receive and transmit the first signal. Alternatively, the signal distribution module 110 splits the input signal into a first signal and a second signal with approximately equal power, and both the first and second signals output from the signal distribution module 110 include an electrical signal generated by the avalanche photodiode in response to an incident photon and an interference signal due to the capacitive response of the gate signal, with the first signal being transmitted along the first signal path 120.

[0046] The second signal path 130 is coupled to the signal distribution module 110 and is configured to receive the second signal, filter the signal for preset frequency components, and transmit it. The second signal output from the signal distribution module 110 is transmitted along the second signal path 130. Alternatively, the second signal path 130 includes a narrowband filter module, which filters the signal for preset frequency components in the input signal and transmits it. This preset frequency component signal is one of the frequency components of the interference signal due to the capacitive response of the gate signal (hereinafter simply referred to as the "gate interference signal"). For example, if the gate signal is a sine wave signal, the gate interference signal has one frequency component. Also, for example, if the gate signal is a square wave signal, the gate interference signal has multiple frequency components (the Fourier expansion of a square wave signal contains signal components of multiple frequencies).

[0047] The phase shift module 140 is installed in the first signal path 120 or the second signal path 130 and is positioned to shift the phase of the transmitted signal by 180°. Figure 4 shows one embodiment in which the phase shift module 140 is installed in the second signal path 130, although the phase shift module 140 may also be installed in the first signal path 120. All of these embodiments are within the scope of the present invention. In the embodiment shown in Figure 4, the phase shift module 140 shifts the phase of the transmitted signal in the second signal path 130, i.e., the signal of the preset frequency components, by 180°, and the phase-shifted signal continues to be transmitted along the second signal path 130.

[0048] The coupling module 150 is coupled to the first signal path 120 and the second signal path 130, and is configured to receive, combine, and output the output signals from the first signal path 120 and the second signal path 130. The first signal path 120 receives and transmits a first signal, which includes an electrical signal generated by the avalanche photodiode in response to an incident photon and an interference signal due to the capacitive response of the gate signal. Therefore, the transmitted signal of the first signal path 120 includes all frequency components of the electrical signal generated by the avalanche photodiode in response to an incident photon and the gate interference signal. The second signal path 130 receives a second signal, filters the signal for preset frequency components, and transmits it. Since these preset frequency components are one of the frequency components of the interference signal due to the capacitive response of the gate signal, the transmitted signal of the second signal path 130 includes one of the frequency components of the gate interference signal. The phase shift module 140 shifts the phase of the transmission signal by 180°. When the phase shift module 140 is installed in the second signal path 130, the signal output by the second signal path 130 is one of the frequency components of the gate interference signal, which is the frequency signal after a 180° phase shift. The output signal of the first signal path 120 and the output signal of the second signal path 130 are combined and cancel each other out with the preset frequency component signal with a phase difference of 180°. The coupling module 150 outputs the full frequency domain signal with the preset frequency component canceled out. That is, the coupling module 150 outputs the electrical signal generated by the avalanche photodiode in response to the incident photon, and the remaining gate interference signal after filtering out the preset frequency component signal. Alternatively, if the gate signal is a sine wave signal and the gate interference signal contains only one frequency component, the entire gate interference signal can be filtered out by a single filtering by the interference unit 100.

[0049] According to one embodiment of the present invention, in the interference unit 100 of a single-photon detector, the difference in transmission distance between the first signal path 120 and the second signal path 130 is smaller than a first preset value. The signal distribution module 110 splits the input signal into a first signal and a second signal, transmitting the first signal along the first signal path 120 and the second signal along the second signal path 130. When output from the signal distribution module 110, the initial phases of the first signal and the second signal are the same, and during transmission, the phase change of the first signal and the second signal depends on the module control which has a signal transmission time and phase shift function, and the transmission distances of the first signal path 120 and the second signal path 130 can be set to be equal, that is, the time required to transmit the first signal along the first signal path 120 and the time required to transmit the second signal along the second signal path 130 can be set to be the same. Alternatively, a narrowband filter module can filter the preset frequency component signal from the second signal, and a phase shift module 140 can phase shift the preset frequency component signal by 180°, so that both the output signals of the first signal path 120 and the second signal path 130 include the preset frequency component signal, and the phase difference between the output of the first signal path and the output of the second signal path is exactly 180°, so that the preset frequency component signal can be completely canceled out. The difference in transmission distance between the first signal path 120 and the second signal path 130 is set to be smaller than a first preset value, and the smaller the first preset value, the greater the cancellation effect of the output signals, for example, when the signal transmission distances of the first signal path 120 and the second signal path 130 are exactly equal.

[0050] According to one embodiment of the present invention, as shown in Figure 5, in the interference unit 100 of the single-photon detection device, the second signal path 130 further includes a narrowband filter module 131.

[0051] The passband of the narrowband filter module 131 is 10 MHz or less, and the passband of the narrowband filter module 131 includes the preset frequency components.

[0052] According to one embodiment of the present invention, the narrowband filter module 131 includes one or more of a surface acoustic wave filter, a bulk acoustic wave filter, and a dielectric filter.

[0053] A single-photon detection device including the interference unit 100 according to the above-described multiple embodiments of the present invention filters the signal using an ultra-narrowband bandpass filter to obtain the fundamental or harmonic signal frequency components of the gate interference signal, and further interferes with the main transmission signal (including the electrical signal after photoelectric conversion and the gate interference signal) using a coupling module. Since the interference phenomenon occurs only within the passband and transition band of the ultra-narrowband bandpass filter when viewed from the entire frequency domain, the impact on the main transmission signal is small. Figure 6 shows the frequency response curve of the ultra-narrowband bandpass filter.

[0054] According to one embodiment of the present invention, as shown in Figure 7, in the interference unit 100 of the single-photon detection device, the first signal path 120 further includes a power attenuation module 121.

[0055] The power attenuation module 121 adjusts the power of the first signal and is positioned to make the power difference between the output signals of the first signal path 120 and the second signal path 130 smaller than a second preset value.

[0056] The narrowband filter module 131 is installed in the second signal path 130, causing power loss in the transmitted signal of the second signal path 130. By installing a power attenuation module 121 in the first signal path 120, the power loss caused by the narrowband filter module 131 during narrowband filtering is compensated for. The first signal is transmitted via the first signal path 120, adjusted by the power attenuation module 121, and attenuated by a certain amount of power. The second signal is transmitted via the second signal path 130, filtered by the narrowband filter module 131 for preset frequency components, and the filtered signal is similarly attenuated by a certain amount of power. By adjusting the operating range of the power attenuation module 121, the power difference between the output signals of the first signal path 120 and the second signal path 130 can be made smaller than the second preset value. The smaller the power difference between the output signals of the first signal path 120 and the second signal path 130, the greater the effect on filtering interference signals of the preset frequency components. For example, if the power of the output signals from the first signal path 120 and the second signal path 130 are equal, the signal power of the preset frequency components will be equal, their phases will be opposite, and they can effectively cancel each other out.

[0057] According to one embodiment of the present invention, the power attenuation module 121 of the interference unit 100 includes one or more of the following: an analog voltage-controlled attenuator (VCA), a digitally controlled step attenuator (DSA), and a resistor network attenuator (the attenuation value can be adjusted by selecting a resistor parameter). The power attenuation module 121 has a wide operating frequency bandwidth and is installed in the first signal path 120 to effectively attenuate the signal in the frequency domain of the first signal (which includes an electrical signal generated by an avalanche photodiode in response to an incident photon and an interference signal due to the capacitive response of the gate signal).

[0058] According to one embodiment of the present invention, in the interference unit 100 of a single-photon detection device, the phase shift module 140 is installed on the second signal path 130.

[0059] According to one embodiment of the present invention, the phase shift module 140 in the interference unit 100 includes one or more of the following: a radio frequency transmission line, an analog voltage-controlled phase shifter, a digitally controlled step phase shifter, a capacitive network phase shifter, an inductance network phase shifter, and a capacitive-inductance hybrid network phase shifter.

[0060] The phase shift module 140 of the interference unit 100 changes the phase by adjusting the physical length or propagation coefficient of the radio frequency transmission path, modulates the phase by selecting capacitance / inductance parameters, or modulates the attenuation value with an analog voltage-controlled capacitor or a digitally controlled step capacitor. The phase shift module 140 includes a capacitance or inductance element, or a radio frequency transmission path where the phase shift amount depends on the frequency. Therefore, the phase shift module 140 is installed at the output terminal of the narrowband filter module 131 of the second signal path 130, and the operating bandwidth of the phase shift module 140 only needs to cover the operating bandwidth of the narrowband filter module 131.

[0061] According to one embodiment of the present invention, as shown in Figure 8, the signal distribution module 110 and the coupling module 150 each include a 3-port radio frequency matching element having a first port, a second port, and a third port (Figure 8 shows the 3-port radio frequency matching element 111 and the 3-port radio frequency matching element 151), The three-port radio frequency matching elements 111 of the signal distribution module 110 are arranged as follows: The first port is coupled to a single-photon inductor and is arranged to receive the input signal. The third port is connected to the first signal path 120 and is arranged to output the first signal. The second port is connected to the second signal path 130 and is arranged to output the second signal. The three-port radio frequency matching elements 151 of the coupling module 150 are arranged as follows: The third port is connected to the second signal path 130 and is configured to receive the output signal of the second signal path 130. The second port is connected to the first signal path 120 and is configured to receive the output signal of the first signal path 120. The output signals of the first signal path 120 and the second signal path 130 are coupled within the 3-port radio frequency matching element 151 to cancel out signal interference of the preset frequency components, and the first port of the 3-port radio frequency matching element 151 outputs the coupled signal.

[0062] The 3-port radio frequency matching elements of the signal distribution module 110 and the coupling module 150 employ a symmetrical usage method to eliminate the differences that imbalance between ports brings to the two signal paths. For example, the second port of the 3-port radio frequency matching element 111 of the signal distribution module 110 is coupled to the first signal path 120 and is configured to output the first signal, while the third port is coupled to the second signal path 130 and is configured to output the second signal. Because there is a difference between the second and third ports of the 3-port radio frequency matching element 111, there is also a difference in the power of the first and second signals output by the signal distribution module 110. In the coupling module 150, the coupling method of the 3-port radio frequency matching element 151 and the coupling method of the 3-port radio frequency matching element 111 are interchangeable. In other words, the second port of the 3-port radio frequency matching element 151 is coupled to the second signal path 130 and is positioned to receive the output signal of the second signal path 130, and the third port is coupled to the first signal path 120 to receive the output signal of the first signal path 120. Since the second and third ports of the 3-port radio frequency matching element 151 have the same difference, power correction can be obtained between the signal transmitted by the first signal path 120 and the signal transmitted by the second signal path 130 before coupling. The power difference between the signal transmitted by the first signal path 120 and the signal transmitted by the second signal path 130 becomes smaller than the preset value, and furthermore, after passing through the interference unit 100, a large proportion of the interference signal of the preset frequency components can be removed.

[0063] According to one embodiment of the present invention, in the interference unit 100, the three-port radio frequency matching element includes a directional coupler, the second and third ports of the directional coupler having a preset signal isolation degree. The second port of the directional coupler of the signal distribution module 110 is coupled to a first signal path 120 and is configured to output the first signal, the third port is coupled to a second signal path 130 and is configured to output the second signal, the second port of the directional coupler of the coupling module 150 is coupled to a second signal path 130 and is configured to receive the output signal of the second signal path 130, and the third port is coupled to the first signal path 120 to receive the output signal of the first signal path 120. The second and third ports of the directional coupler have a preset isolation degree to reduce the reflection of signals transmitted in the first signal path 120 or the second signal path 130 back to the second signal path 130 or the first signal path 120.

[0064] According to one embodiment of the present invention, as shown in Figure 9, the present invention provides a single-photon detection device 200 including the above-described interference unit 100, the single-photon detection device 200 further including a single-photon inductor 210, a DC voltage source 220, and a gate signal generator 230.

[0065] The single-photon inductor 210 is configured to receive an optical signal, convert it into an electrical signal, and output it. Alternatively, the single-photon inductor 210 includes an avalanche photodiode, which operates under the influence of a reverse bias voltage. When there is no photon incidence, the reverse current is extremely weak and is called the dark current. When there is a photon incidence, the reverse current increases rapidly and is called the photocurrent. The greater the light intensity, the greater the reverse current, meaning the avalanche photodiode converts the optical signal into an electrical signal and outputs it.

[0066] The DC voltage source 220 is coupled to the single-photon inductor 210 and is positioned to provide the single-photon inductor 210 with a DC bias voltage. The DC voltage source 220 applies a DC bias voltage to the single-photon inductor 210, bringing it into a critical breakdown state.

[0067] The gate signal generator 230 is coupled to the single-photon inductor 210 and is positioned to provide a gate signal to the single-photon inductor 210. After applying a DC bias voltage, the gate signal generator 230 applies a periodically changing gate signal to the single-photon inductor 210. Alternatively, the gate signal applied by the gate signal generator 230 to the single-photon inductor 210 includes one or more periodic signals such as a sine wave signal, a square wave signal, or a triangular wave signal. Within half a period of the gate signal, the single-photon inductor 210 is in an avalanche breakdown state and can generate an avalanche and output an avalanche current when it receives a single-photon level optical signal. Within the other half a period of the gate signal, the single-photon inductor 210 is unable to respond to the incident optical signal, thus reducing the avalanche charge and the recovery time after the avalanche.

[0068] The interference unit 100 receives an input signal, which includes an electrical signal generated after photoelectric conversion by the single-photon inductor 210 and an interference signal due to the capacitive response of the gate signal.

[0069] According to one embodiment of the present invention, the gate signal described above includes a periodic signal, for example, one or more of a sine wave signal, a square wave signal, or a triangular wave signal, and the second signal path 130 transmits the signal of a preset frequency component in the input signal filtered by the narrowband filter module 131, and the signal of the preset frequency component is one of the frequency components of the interference signal due to the capacitance response of the gate signal. For example, if the gate signal is a sine wave signal, the gate interference signal has one frequency component, and if the gate signal is a square wave signal, for example, the gate interference signal has multiple frequency components (the Fourier expansion of a square wave signal includes signal components of multiple frequencies).

[0070] Figures 10A and 10B show typical frequency response curves of the interference unit 100 of the single-photon detection device according to the above-described multiple embodiments of the present invention. Here, Figure 10B shows the effect of the adjustment coordinate axis amplification (Zoom In) in Figure 10A, and it can be seen that the interference phenomenon occurs within the passband and transition band of the ultra-narrowband bandpass filter, and that the effect on the output signal is small when viewed from the entire frequency domain.

[0071] According to one embodiment of the present invention, as shown in Figure 11, the present invention provides a single-photon detection device 200 including a plurality of interference units 100.

[0072] Multiple interference units 100 are cascaded, and the second signal path 130 of each interference unit 100 filters a signal corresponding to one of the frequency components of the gate signal.

[0073] The present invention makes it possible to filter out multiple frequency components in a gate interference signal one by one by installing a multi-stage interference unit 100.

[0074] Regardless of whether the gate signal is a periodic signal waveform such as a sine wave, square wave, or triangular wave, it is always a linear combination of its fundamental frequency component and harmonic frequency components. By arranging the operating frequencies and number of interference units 100, for example, by having two interference units 100 operate at the fundamental frequency of the gate signal, one interference unit 100 operate at the second harmonic frequency of the gate signal, and one interference unit 100 operate at the third harmonic frequency of the gate signal, most of the signal of the gate interference signal can be filtered.

[0075] Figure 12 shows the signal waveform output by a single-photon detection device 200, which includes an interference unit 100 according to the present invention, after filtering the gate interference signal by the multi-stage interference unit 100. Compared with the signal waveform in Figure 3, the single-photon inductor 210 allows for easy reading of the electrical signal generated in response to photon incidence.

[0076] According to one embodiment of the present invention, as shown in Figure 13, the single-photon detection device 200 according to the present invention further includes a plurality of signal amplification units 240, Each signal amplification unit 240 is positioned before one of the interference units 100 along the transmission direction of the input signal and is configured to amplify the input signal. The signal input to the interference unit 100 is preprocessed in preparation for subsequent narrowband filtering. Figure 13 shows that the single-photon detector 200 includes a two-stage interference unit 100, with one amplification unit 240 positioned before each stage of the interference unit 100 along the transmission direction of the input signal. As will be readily apparent to those skilled in the art, the single-photon detector 200 may further include more or fewer interference units 100 and more or fewer amplification units 240, and the single-photon detector 200 may also include a single-stage interference unit 100 and an amplification unit 240 positioned before the single-stage interference unit 100 along the transmission direction of the input signal. All of the above variations are within the scope of protection of the present invention.

[0077] According to one embodiment of the present invention, as shown in Figure 14, the single-photon detection device 200 according to the present invention further includes a low-pass filter unit 250.

[0078] The low-pass filter unit 250 is positioned after a plurality of interference units 100 along the transmission direction of the input signal, and is configured to perform low-pass filtering on the signal that has been filtered by the plurality of interference units 100. Figure 14 shows that the single-photon detector 200 includes a two-stage interference unit 100, and the low-pass filter unit 250 is positioned after the two-stage interference unit 100 along the transmission direction of the input signal. As will be readily apparent to those skilled in the art, the single-photon detector 200 may include more or fewer interference units 100.

[0079] As shown in the above embodiment, by arranging the four interference units 100 to operate at the fundamental frequency of the gate signal, one interference unit 100 to operate at the second harmonic frequency of the gate signal, and one interference unit 100 to operate at the third harmonic frequency of the gate signal, most of the signal of the gate interference signal can be filtered. A low-pass filter unit 250 is placed after the four-stage interference unit 100, and the operating frequency of the low-pass filter unit 250 can be selected to be slightly lower than the fourth harmonic frequency of the gate signal in order to further filter out the fourth harmonic frequency component in the gate interference signal.

[0080] According to one embodiment of the present invention, in a single-photon detection device 200, the number and parameters of the signal amplification unit 240 and the low-pass filter unit 250 can both be arranged according to actual needs.

[0081] According to one embodiment of the present invention, the present invention further provides a chip in which one or more single-photon detection devices according to the above embodiment are integrated on the chip.

[0082] According to one embodiment of the present invention, as shown in Figure 15, the present invention further provides a method 10 for performing single-photon detection using a single-photon detection device according to one or more of the above embodiments, comprising steps S101 to S108.

[0083] In step S101, a DC bias voltage is supplied to the single-photon inductor by a DC voltage source, bringing the single-photon inductor into a critical breakdown state.

[0084] In step S102, a gate signal generator provides a gate signal to the single-photon inductor.

[0085] In step S103, the single-photon inductor receives the optical signal and converts it into an electrical signal.

[0086] In step S104, the signal distribution module divides the input signal into a first signal and a second signal, and the input signal includes the electrical signal and an interference signal due to the capacitive response of the gate signal.

[0087] In step S105, the first signal is received and transmitted via the first signal path.

[0088] In step S106, the second signal is received via the second signal path, and the signal of the preset frequency components is filtered and transmitted.

[0089] In step S107, the phase of the transmission signal is shifted by 180° using the phase shift module.

[0090] In step S108, the coupling module receives the output signals from the first signal path and the second signal path, combines them, and outputs the combined signal.

[0091] According to one embodiment of the present invention, in a method 10 for performing single-photon detection, the difference in transmission distance between the first signal path and the second signal path is smaller than a first preset value.

[0092] According to one embodiment of the present invention, in a method 10 for single-photon detection, the second signal path includes a narrowband filter module, the passband of the narrowband filter module includes the preset frequency components, the passband of the narrowband filter module is 10 MHz or less, and the method 10 is The process further includes filtering the second signal using the narrowband filter module.

[0093] According to one embodiment of the present invention, in a method 10 for performing single-photon detection, the first signal path includes a power attenuation module, and the method 10 is The power attenuation module further includes adjusting the power of the first signal to make the power difference between the output signals of the first signal path and the second signal path less than a second preset value.

[0094] According to one embodiment of the present invention, in a method 10 for single-photon detection, the signal distribution module and the coupling module each include a 3-port radio frequency matching element having a first port, a second port, and a third port, wherein the 3-port radio frequency matching element of the signal distribution module is arranged such that the first port is coupled to a single-photon inductor, the second port is coupled to the first signal path, and the third port is coupled to the second signal path, and the 3-port radio frequency matching element of the coupling module is arranged such that the second port is coupled to the second signal path and the third port is coupled to the first signal path, and the method 10 is, The input signal is received by the first port of the three-port radio frequency matching element of the signal distribution module, The first signal is output by the second port of the three-port radio frequency matching element of the signal distribution module, The second signal is output by the third port of the three-port radio frequency matching element of the signal distribution module, The output signal of the second signal path is received by the second port of the three-port radio frequency matching element of the coupling module, The output signal of the first signal path is received by the third port of the three-port radio frequency matching element of the coupling module, The coupling module further includes outputting a signal obtained by combining the output signal of the first signal path and the output signal of the second signal path through the first port of the three-port radio frequency matching element of the coupling module.

[0095] According to one embodiment of the present invention, in a method 10 for performing single-photon detection, the single-photon detection apparatus further includes a plurality of interference units, the plurality of interference units are cascaded, the preset frequency component includes one of the frequency components of the gate signal, and the method 10 is The second signal path of each interference unit further includes filtering an interference signal corresponding to one of the frequency components of the gate signal.

[0096] According to one embodiment of the present invention, in a method 10 for performing single-photon detection, the single-photon detection apparatus further includes a plurality of signal amplification units, each of which is positioned in front of one of the interference units along the transmission direction of the input signal, and the method 10 is, The process further includes amplifying the input signal using the plurality of signal amplification units.

[0097] According to one embodiment of the present invention, in a method 10 for performing single-photon detection, the single-photon detection apparatus further includes a low-pass filter unit, which is installed after a plurality of interference units along the transmission direction of the input signal, and the method 10 is, The further step is to perform low-pass filtering on the output signal filtered by the plurality of interference units using the low-pass filter unit.

[0098] The specific limitations of the single-photon detection method 10 described above are the same as the specific limitations of the single-photon detection device including the interference unit 100, and the above description of the single-photon detection device including the interference unit 100 can be found by referring to the above description, so they are omitted here.

[0099] The following experimental verification will confirm the single-photon detection device including the interference unit 100 according to the present invention and the method 10 for performing single-photon detection.

[0100] Experiment 1: An avalanche photodiode was used as a single-photon inductor, with a 1.25 GHz square wave signal as the gate signal, and a total of four interference units were installed. Here, the operating frequency of the two-stage interference unit was 1.25 GHz, the operating frequency of the one-stage interference unit was 2.5 GHz, and the operating frequency of the one-stage interference unit was 3.75 GHz. A low-pass filter unit was installed after the four-stage interference unit, with an operating frequency of 4.5 GHz. A resistor network was used for the attenuation module, a capacitive network for the phase shift module, a surface acoustic wave (SAW) filter for the narrowband filter module, and directional couplers for the signal distribution module and coupling module.

[0101] Experiment 2: An avalanche photodiode was used as a single-photon inductor, with a 1.25 GHz sinusoidal gate signal, and a two-stage interference unit was installed. Both stages of the interference unit operated at 1.25 GHz. A low-pass filter unit was installed after the two-stage interference unit, with an operating frequency of 2.1 GHz. A surface acoustic wave (SAW) filter was used for the narrowband filter module, a coaxial resistive network attenuator was used for the attenuation module, and a radio frequency transmission line of appropriate length was used for the phase shift module.

[0102] As the results of the two experiments showed, the gate interference signal was filtered out to a large extent, allowing for the effective extraction of the electrical signal after photoelectric conversion, resulting in a clear optimization effect on afterpulse effect, temporal resolution, and photon counting rate across the entire frequency range.

[0103] Figure 16A shows the configuration diagram of the apparatus used in Experiment 2 of the above experiment. The gate signal is a 1.25 GHz sine wave signal, UNIC1 is the first stage interference unit with an operating frequency of 1.25 GHz, and UNIC2 is the second stage interference unit with an operating frequency of 1.25 GHz. AMP1 and AMP2 are signal amplifiers installed in front of the interference units UNIC1 and UNIC2, respectively, along the signal transmission direction. LF1 is a low-pass filter installed after the interference unit UNIC2 along the signal transmission direction with an operating frequency of 2.1 GHz. Another signal amplifier AMP3 is installed in front of the low-pass filter LF1 along the signal transmission direction, and a high-speed discriminator DISC1 is installed after the low-pass filter LF1 to discriminate and output the output signal.

[0104] Figure 16B shows the time distribution histogram of detection events for the single-photon detector in Experiment 2 of the above experiment. The detection efficiency in the figure is 29%, the afterpulse is 1.3%, the dark count is 3 kcps, and the temperature is 263 K. The steep gate peaks for each count in the figure indicate that the detector has good temporal resolution.

[0105] Furthermore, the present invention provides a non-instantaneous computer-readable storage medium in which computer-readable instructions are stored, and when the instructions are executed by a processor, the processor is made to execute the method 10 described in one or more embodiments.

[0106] This invention provides a single-photon detection device including an interference unit, an electrical chip, and a method for performing single-photon detection. The gate interference signal is filtered by an ultra-narrowband bandpass filter to obtain the fundamental or harmonic signal frequency components, and then interfered with by a coupling module (including the electrical signal after photoelectric conversion and the gate interference signal). Since the interference phenomenon occurs only within the passband and transition band of the ultra-narrowband bandpass filter from the perspective of the entire frequency domain, the impact on the main transmission signal is small. Multi-stage filtering effectively removes a large amount of gate interference signals and stably provides wider and continuous frequency domain passage, enabling the processing of avalanche narrow pulse signals. The signal-to-noise ratio, pulse waveform, and jitter effects of the avalanche narrow pulse signal are small, and there is a clear optimization effect on the detection efficiency, after-pulse effect, and time resolution of the single-photon detector.

Claims

1. A single-photon detection device including an interference unit, wherein the interference unit is A signal distribution module is arranged to split the input signal into a first signal and a second signal, A first signal path is coupled to the signal distribution module and is arranged to receive and transmit the first signal, A second signal path is coupled to the signal distribution module and is arranged to receive the second signal, filter the preset frequency component signal from the second signal, and transmit it; A phase shift module installed in the first signal path or the second signal path and arranged to shift the phase of the transmitted signal by 180°, The system includes a coupling module that is coupled to the first signal path and the second signal path, and is arranged to receive, combine, and output the output signals of the first signal path and the second signal path, The single-photon detection device is A single-photon inductor is arranged to receive an optical signal, convert it into an electrical signal, and output it, A DC voltage source is coupled to the single-photon inductor and provided with a DC bias voltage to the single-photon inductor, causing the single-photon inductor to enter a critical breakdown state. The system further includes a gate signal generator coupled to the single-photon inductor and arranged to provide a gate signal to the single-photon inductor, The input signal includes an interference signal due to the capacitance response of the electrical signal and the gate signal, the gate signal includes a periodic signal, and the preset frequency component includes one of the frequency components of the gate signal. The single-photon detection device is Including multiple interference units, A single-photon detection device characterized in that a plurality of the interference units are cascaded, and the second signal path of each interference unit filters an interference signal corresponding to one of the frequency components of the gate signal.

2. The difference in transmission distance between the first signal path and the second signal path is less than the first preset value, and / or The second signal path includes a narrowband filter module, The single-photon detection apparatus according to claim 1, characterized in that the passband of the narrowband filter module has preset frequency components.

3. The passband of the aforementioned narrowband filter module is 10 MHz or less, and / or, The single-photon detection apparatus according to claim 2, characterized in that the narrowband filter module includes one or more of a surface acoustic wave filter, a bulk acoustic wave filter, and a dielectric filter.

4. The first signal path includes a power attenuation module, The power attenuation module is configured to adjust the power of the first signal so that the power difference between the output signals of the first signal path and the second signal path is less than a second preset value, and / or The single-photon detection apparatus according to claim 1 or 2, characterized in that the power attenuation module includes one or more of the following: an analog voltage-controlled attenuator, a digitally controlled step attenuator, and a resistance network attenuator.

5. The phase shift module is installed on the second signal path and / or The single-photon detection apparatus according to claim 1 or 2, characterized in that the phase shift module includes one or more of the following: a radio frequency transmission line, an analog voltage-controlled phase shifter, a digitally controlled step phase shifter, a capacitive network single phase shifter, an inductance network phase shifter, and a capacitive-inductance hybrid network phase shifter.

6. The signal distribution module and the coupling module each include a three-port radio frequency matching element having a first port, a second port, and a third port, and the three-port radio frequency matching element of the signal distribution module is arranged as follows: The first port is coupled to a single-photon inductor and is arranged to receive the input signal. The second port is coupled to the first signal path and is arranged to output the first signal. The third port is coupled to the second signal path and is arranged to output the second signal. The three-port radio frequency matching elements of the coupling module are arranged as follows: The second port is coupled to the second signal path and is arranged to receive the output signal of the second signal path. The third port is coupled to the first signal path and is arranged to receive the output signal of the first signal path. The single-photon detection device according to claim 1 or 2, characterized in that the first port outputs a signal obtained by combining the output signal of the first signal path and the output signal of the second signal path.

7. The system further includes a plurality of signal amplification units, each of which is positioned in front of one of the interference units along the transmission direction of the input signal and is configured to amplify the input signal, and / or The single-photon detection apparatus according to claim 1, further comprising a low-pass filter unit installed after a plurality of interference units along the transmission direction of the input signal, and arranged to perform low-pass filtering on the output signal filtered by the plurality of interference units.

8. A chip characterized by integrating a single-photon detection device according to any one of claims 1 to 3.

9. A method for performing single-photon detection using a single-photon detection apparatus according to any one of claims 1 to 3, The DC voltage source provides a DC bias voltage to the single-photon inductor, causing the single-photon inductor to enter a critical breakdown state. The gate signal generator provides a gate signal to the single-photon inductor, The single-photon inductor receives an optical signal and converts it into an electrical signal, The signal distribution module divides the input signal, which includes the electrical signal and the interference signal due to the capacitive response of the gate signal, into a first signal and a second signal. The first signal is received and transmitted via the first signal path, The second signal is received via the second signal path, and the preset frequency components of the signal are filtered from the second signal and transmitted. The phase shift module shifts the phase of the transmitted signal by 180°, A method characterized by including receiving the output signals of the first signal path and the second signal path using the coupling module, coupling them, and outputting them.

10. The method according to 9, characterized in that the difference in transmission distance between the first signal path and the second signal path is smaller than the first preset value.

11. The second signal path includes a narrowband filter module, the passband of the narrowband filter module has the preset frequency components, and the passband of the narrowband filter module is 10 MHz or less, and the method is The further includes filtering the second signal with the narrowband filter module, and / or, The first signal path includes a power attenuation module, and the method is The method according to 9, further comprising adjusting the power of the first signal with the power attenuation module to make the power difference between the output signals of the first signal path and the second signal path less than a second preset value.

12. The signal distribution module and the coupling module each include a three-port radio frequency matching element having a first port, a second port, and a third port, wherein the three-port radio frequency matching element of the signal distribution module is arranged such that the first port is coupled to a single-photon inductor, the second port is coupled to the first signal path, and the third port is coupled to the second signal path, and the three-port radio frequency matching element of the coupling module is arranged such that the second port is coupled to the second signal path and the third port is coupled to the first signal path, and the method is as follows: The input signal is received by the first port of the three-port radio frequency matching element of the signal distribution module, The first signal is output by the second port of the three-port radio frequency matching element of the signal distribution module, The second signal is output by the third port of the three-port radio frequency matching element of the signal distribution module, The output signal of the second signal path is received by the second port of the three-port radio frequency matching element of the coupling module, The output signal of the first signal path is received by the third port of the three-port radio frequency matching element of the coupling module, The first port of the three-port radio frequency matching element of the coupling module outputs a signal obtained by combining the output signal of the first signal path and the output signal of the second signal path. The method according to 9, further comprising filtering an interference signal corresponding to one of the frequency components of the gate signal by the second signal path of each interference unit.

13. The single-photon detection apparatus further includes a plurality of signal amplification units, each signal amplification unit being positioned before one of the interference units along the transmission direction of the input signal, and the method is, The process further includes amplifying the input signal using the plurality of signal amplification units, and / or, The single-photon detection device further includes a low-pass filter unit installed after a plurality of interference units along the transmission direction of the input signal, and the method is The method according to 12, further comprising performing low-pass filtering on the output signal filtered by the plurality of interference units using the low-pass filter unit.

14. A non-instantaneous computer-readable storage medium that stores computer-readable instructions, and when an instruction is executed by a processor, causes the processor to perform the method according to claim 9.

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