Single photon detection device and 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 technical field of weak light detection, and in particular to a single-photon detection device including an interference unit and a single-photon detection method using the single-photon detection device. [Background technology]

[0002] Due to the demand for weak light sensing and detection in fields such as quantum key distribution, optical fiber sensing, optical fiber communication, laser radar, high energy physics, semiconductor device characterization and bioimaging, single-photon detection devices based on semiconductor avalanche photodiodes (APDs) have been widely used, among which APDs used in the optical fiber communication wavelength bands (1310 nm and 1550 nm) are mainly based on indium gallium arsenide (InGaAs) material.

[0003] In order to suppress the afterpulse noise of single-photon detectors based on gallium indium arsenide APDs and increase the photon count rate of the single-photon detectors, a gate drive scheme is adopted for the avalanche photodiode to reduce the avalanche charge and the post-avalanche recovery time. The gate drive scheme 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 mask the photon-induced avalanche signal. Therefore, the capacitive response of the gate signal must be effectively eliminated.

[0004] In the prior art, there are active noise cancellation, band rejection filtering, low pass filtering and self-differentiation technology methods. Among them, active noise cancellation technology can effectively eliminate the fundamental frequency and harmonic frequency of the capacitance response of the gate signal at the output end of APD, and can process narrow avalanche pulse signals by passing a wider and more continuous frequency range, but when the temperature and bias voltage of APD change, the capacitance response of the gate signal at the output end of APD also changes, and at this time, active noise cancellation technology needs to be re-adjusted to eliminate the capacitance response signal of the gate signal at the output end of APD, which has limited practicality.

[0005] The band-stop filter technology uses multiple radio frequency band-stop filters to suppress the fundamental frequency and harmonic frequency of the capacitance response of the gate signal at the APD output end, the general stop bandwidth of the band-stop filter is on the order of 100-300MHz, and has a certain transition band, this method can process the narrow avalanche pulse signal with a wider frequency domain passband, but there is a large frequency domain discontinuity near the fundamental frequency and harmonic frequency points of the gate signal, which reduces the signal-to-noise ratio of the narrow avalanche pulse signal, and the waveform of the pulse will have a certain broadening and distortion, resulting in large jitter.

[0006] The low-pass filter method has a smaller frequency domain passband for processing the narrow avalanche pulse signal, which generally does not exceed 90% of the gate signal frequency. The smaller frequency domain processing bandwidth reduces the signal-to-noise ratio of the narrow avalanche pulse signal, causing broadening and distortion in the pulse waveform, and increasing jitter.

[0007] The self-differential technology requires two differential signal channels to transmit and process wideband signals, which places high requirements on the wideband performance of the device. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE DISCLOSURE In view of at least one shortcoming of the prior art, the present invention provides a single photon detection apparatus that includes an interference unit. [Means for solving the problem]

[0009] The interference unit comprises: a signal distribution module arranged to split an input signal into a first signal and a second signal; a first signal path coupled to the signal distribution module and configured to receive and transmit the first signal; a second signal path coupled to the signal distribution module and configured to receive the second signal, and to filter and transmit a signal of a preset frequency component from the second signal; a phase shift module disposed in the first signal path or the second signal path and configured to shift a phase of a transmission signal by 180°; a combining module coupled to the first signal path and the second signal path and configured to receive, combine and output signals of the first signal path and the second signal path.

[0010] According to one aspect of the present invention, a difference in transmission distance between the first signal path and the second signal path is smaller than a 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 narrowband filter module has preset frequency components.

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

[0013] According to one aspect of the 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 configured to adjust a power of the first signal such that a difference in power of 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 invention, the power attenuation module includes one or more of an analog voltage controlled attenuator, a digitally controlled step attenuator, and a resistive network attenuator.

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

[0017] According to one aspect of the present invention, the phase shift module includes one or more of 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-inductive hybrid network phase shifter.

[0018] According to one aspect of the present invention, 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: a first port coupled to the single-photon inductive element and configured to receive the input signal; a second port coupled to the first signal path and configured to output the first signal; a third port coupled to the second signal path and configured to output the second signal; The three-port radio frequency matching element of the coupling module is arranged as follows: a second port coupled to the second signal path and configured to receive an output signal of the second signal path; a third port coupled to the first signal path and configured to receive an output signal of the first signal path; A 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 invention, the three-port radio frequency matching element includes a directional coupler, the second port and the third port of the directional coupler having a preset signal isolation.

[0020] According to one aspect of the present invention, the single photon detection device comprises: A single-photon inductive element arranged to receive an optical signal, convert it into an electrical signal, and output it; a DC voltage source coupled to the single-photon inductive element and configured to provide a DC bias voltage to the single-photon inductive element, thereby driving the single-photon inductive element into a critical breakdown state; a gating signal generator coupled to the single-photon guiding element and configured to provide a gating signal to the single-photon guiding element; The input signal includes an interference signal due to the capacitive response of the electrical signal and the gating signal.

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

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

[0023] According to one aspect of the present invention, the single photon detection device further includes a plurality of signal amplification units, Each of the signal amplification units is disposed in front of one of the interference units along the transmission direction of the input signal, and is configured to amplify and process the input signal.

[0024] According to one aspect of the present invention, the single photon detection device comprises: The signal processing device further includes a low-pass filter unit disposed after a plurality of the interference units along a transmission direction of the input signal, and configured to low-pass filter an output signal filtered by the plurality of the interference units.

[0025] The present invention further provides a chip on which the above-mentioned single photon detection device is integrated.

[0026] The present invention also provides a method for single-photon detection using the single-photon detection device as described above, comprising: providing a DC bias voltage to the single-photon inductive element by a DC voltage source to bring the single-photon inductive element into a critical breakdown state; providing a gating signal to the single-photon directing element by a gating signal generator; receiving an optical signal by the single-photon inductive element and converting it into an electrical signal; Dividing an input signal including the electrical signal and an interference signal due to a capacitance response of the gate signal into a first signal and a second signal by the signal distribution module; receiving and transmitting the first signal over the first signal path; receiving the second signal through the second signal path, filtering a signal of a preset frequency component from the second signal, and transmitting the filtered signal; Shifting the phase of the transmission signal by 180° using the phase shift module; receiving, combining and outputting the output signals of the first signal path and the second signal path by the combining module.

[0027] According to one aspect of the present invention, a difference in transmission distance between the first signal path and the second signal path is smaller than a 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 component, and the passband width of the narrowband filter module is 10 MHz. zThe method comprises: The method further includes filtering the second signal with the narrowband filter module.

[0029] According to one aspect of the invention, the first signal path includes a power attenuation module, and the method further comprises: The method further includes adjusting a power of the first signal by the power attenuation module so that a difference in power of the output signals of the first signal path and the second signal path is 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 three-port radio frequency matching element having a first port, a second port, and a third port, the three-port radio frequency matching element of the signal distribution module is arranged such that the first port couples to a single-photon directing element, the second port couples to the first signal path, and the third port couples to the second signal path, the three-port radio frequency matching element of the coupling module is arranged such that the second port couples to the second signal path, and the third port couples to the first signal path, and the method includes: receiving the input signal at a first port of a three-port radio frequency matching element of the signal distribution module; outputting the first signal through a second port of a three-port radio frequency matching element of the signal distribution module; outputting the second signal through a third port of a three-port radio frequency matching element of the signal distribution module; receiving an output signal of the second signal path with a second port of a three-port radio frequency matching element of the combination module; receiving the output signal of the first signal path by a third port of a three-port radio frequency matching element of the coupling module; The method further includes outputting a combined signal of the first signal path and the second signal path through a first port of a three-port radio frequency matching element of the combination module.

[0031] According to one aspect of the present invention, the single photon detection apparatus includes a plurality of the interference units, the plurality of interference units being cascaded, and the preset frequency component includes one of the frequency components of the gate signal, and the method includes: The method further includes filtering an interference signal corresponding to one of the frequency components of the gating signal by the second signal path of each of the interference units.

[0032] According to one aspect of the present invention, the single photon detection device further includes a plurality of signal amplification units disposed in front of one of the interference units along a transmission direction of the input signal, and the method includes: The method further includes amplifying the input signal by 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 disposed after a plurality of the interference units along a transmission direction of the input signal, and the method includes: The method further includes low-pass filtering the output signals filtered by the plurality of interference units by the low-pass filter unit.

[0034] The present invention also provides a non-transitory computer readable storage medium having stored thereon computer readable instructions which, when executed by a processor, cause the processor to perform the method. Effect of the Invention

[0035] The present invention provides a single-photon detection device, an electrical chip and a method for single-photon detection, which includes an interference unit, and is filtered by an ultra-narrow bandpass filter to obtain the fundamental or harmonic signal frequency components of the gate interference signal, which is then interfered with by a coupling module by the main transmission signal (including the electrical signal after photoelectric conversion and the gate interference signal), and the interference phenomenon only occurs within the passband and transition band of the ultra-narrow bandpass filter in the entire frequency domain, so that the impact on the main transmission signal is small. Through multi-stage filtering, a large amount of gate interference signals can be effectively eliminated, and a wider and more continuous frequency domain passband can be stably provided to process the narrow avalanche pulse signal, and the signal-to-noise ratio, pulse waveform and jitter of the narrow avalanche pulse signal are less affected, and there is an obvious optimization effect on the detection efficiency, afterpulse effect and time resolution of the single-photon detector. [Brief description of the drawings]

[0036] In order to more clearly describe the invention according to the embodiments of the present application, the drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without exceeding the scope of protection claimed by the present application. [Figure 1] FIG. 1 shows a detection device including an avalanche photodiode and its voltammetry curve. [Diagram 2] FIG. 4 is a diagram showing a gate voltage signal waveform applied to an avalanche photodiode. [Diagram 3] FIG. 1 is a diagram showing an output signal waveform of a single-photon detection device in the prior art. [Figure 4] FIG. 2 illustrates an interferometer unit of a single photon detection apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 2 illustrates an interferometer unit of a single photon detection apparatus according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing a frequency response curve of an ultra-narrow bandpass filter in a single-photon detection device according to an embodiment of the present invention. [Figure 7] FIG. 2 illustrates an interferometer unit of a single photon detection apparatus according to an embodiment of the present invention. [Figure 8] FIG. 2 illustrates an interferometer unit of a single photon detection apparatus according to an embodiment of the present invention. [Figure 9] FIG. 1 illustrates a single photon detection device including an interferometric unit according to one embodiment of the present invention. [Figure 10A] FIG. 2 shows a frequency response curve of an interference unit of a single photon detection device according to one embodiment of the present invention. [Figure 10B] FIG. 2 shows a frequency response curve of an interference unit of a single photon detection device according to one embodiment of the present invention. [Figure 11] FIG. 1 illustrates a single photon detection device including an interferometric unit according to one embodiment of the present invention. [Figure 12] 1 is a diagram showing an output signal waveform of a single-photon detection device including an interference unit according to an embodiment of the present invention. [Figure 13] FIG. 1 illustrates a single photon detection device including an interferometric unit according to one embodiment of the present invention. [Figure 14] FIG. 1 illustrates a single photon detection device including an interferometric unit according to one embodiment of the present invention. [Figure 15] FIG. 2 illustrates a method for single photon detection according to an embodiment of the present invention. [Figure 16A] FIG. 1 is a diagram showing a device configuration of a single-photon detection device according to an embodiment of the present invention. [Figure 16B] FIG. 2 shows a time distribution histogram of detection events of a single photon detection device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] The invention according to the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without performing creative labors belong to the scope of protection of the present application.

[0038] The above describes the embodiments of the present application in detail, and the present application uses specific examples to describe the principles and embodiments of the present application. The above description of the embodiments is only used to help understand the method and gist of the present application. At the same time, those skilled in the art will recognize that any modifications or variations made based on the concept of the present application and the specific embodiments and application scope of the present application are within the scope of protection of the present application. As described above, the contents of this specification should not be construed as limitations on the present application.

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

[0040] Avalanche photodiodes have an afterpulse effect. That is, within a certain period after the avalanche occurs, the avalanche photodiode randomly generates a secondary avalanche even if there is no photon incidence. 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, that is, the higher the APD reverse bias voltage, the more prominent the afterpulses. In order to suppress the 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 usually introduce a long dead time. That is, after successfully detecting one single-photon avalanche signal, photon counting is not performed for a long time afterwards, and the detection count rate of the single-photon detection device decreases. In order to increase the photon count rate and detection efficiency of the single photon detection device, a method of gate driving is usually used for the avalanche photodiode, as shown in FIG. 1, a DC bias is applied to the avalanche photodiode to bring it into a critical breakdown state, and a gate signal that changes periodically is applied to the avalanche photodiode after the DC bias is applied. As shown in FIG. 2, alternatively, the gate signal applied to the avalanche photodiode includes one or more periodic signals, for example, a sine wave signal, a square wave signal, and a triangular wave signal (FIG. 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, and within the remaining time of the gate signal, the reverse bias voltage is lower than the breakdown voltage, so that the avalanche current is quenched, thereby reducing the avalanche charge and the recovery time after the avalanche. By applying a gate voltage signal, the afterpulse of the avalanche photodiode can be effectively suppressed, and the photon count rate and detection efficiency of the single-photon detection device can be improved.

[0041] However, the parasitic capacitance of the avalanche photodiode and its connected circuit, and the capacitive response due to gate signal injection, hide the avalanche signal induced by the photons. As shown in Figure 3, the output signal of the avalanche photodiode contains many interference signals due to the capacitive response of the gate signal, making it difficult to read the electrical signal generated by the optical signal input conversion. Therefore, the interference signals introduced by the capacitive response of the gate signal must be effectively removed.

[0042] The present invention provides a single-photon detection device including an interference unit, and uses an ultra-narrowband interference circuit to eliminate the fundamental frequency component and harmonic frequency component of the interference signal caused by the capacitance response of the gate signal at the output end of the avalanche photodiode (APD). The passband width of the ultra-narrowband interference circuit generally does not exceed 10MHz, the transition band is generally less than 20MHz, and it is not affected by the operating state of the APD device itself. It can stably provide a wider and continuous frequency domain passband to process the narrow avalanche pulse signal, and has a small impact on the signal-to-noise ratio, pulse waveform and jitter of the avalanche narrow pulse signal, and has obvious optimization effects on the detection efficiency, afterpulse effect and time 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, and as shown in FIG. 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 combining 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 at the avalanche photodiode input, including an electrical signal generated by the avalanche photodiode in response to incident photons, and also including an interference signal due to a capacitive response of the gate signal, where the frequency of the interference signal coincides with the gate signal. The signal distribution module 110 splits the input signal into a first signal and a second signal, which are transmitted along a first signal path 120 and a 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 having approximately equal power, and the first signal and the second signal output from the signal distribution module 110 both include an electrical signal generated by the avalanche photodiode in response to the incident photons and an interference signal due to the capacitive response of the gate signal, and the first signal is transmitted along the first signal path 120.

[0046] The second signal path 130 is coupled to the signal distribution module 110 and configured to receive the second signal, filter and transmit the signal of the preset frequency component. 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 narrow-band filter module, and the signal of the preset frequency component in the input signal is filtered and transmitted by the narrow-band filter module, and the signal of the preset frequency component is one of the frequency components of the interference signal (hereinafter simply referred to as "gate interference signal") due to the capacity 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 for example, if the gate signal is a square wave signal, the gate interference signal has multiple frequency components (Fourier expansion of the square wave signal includes 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 configured to shift the phase of the transmission signal by 180°. FIG. 4 shows an embodiment in which the phase shift module 140 is installed in the second signal path 130, and the phase shift module 140 may also be installed in the first signal path 120. All of these embodiments are within the scope of protection of the present invention. In the embodiment shown in FIG. 4, the phase shift module 140 shifts the phase of the transmission signal of the second signal path 130, i.e., the signal of the preset frequency component, by 180°, and the phase-shifted signal continues to be transmitted along the second signal path 130.

[0048] The combining 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 of the first signal path 120 and the second signal path 130. The first signal path 120 receives and transmits a first signal, the first signal including an electrical signal generated by the avalanche photodiode in response to the incident photon and an interference signal due to the capacitive response of the gate signal, so that the transmission signal of the first signal path 120 includes the electrical signal generated by the avalanche photodiode in response to the incident photon and all frequency components of the gate interference signal. The second signal path 130 receives a second signal, filters and transmits a signal of a preset frequency component, the preset frequency component being one of the frequency components of the interference signal due to the capacitive response of the gate signal, so that the transmission 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°, and the phase shift module 140 is installed in the second signal path 130, so that the signal output by the second signal path 130 is one of the frequency components of the gated interference signal, and is a frequency signal after a phase shift of 180°. The output signal of the first signal path 120 and the output signal of the second signal path 130 are combined and offset with the signal of the preset frequency component with a phase difference of 180°, and the combining module 150 outputs a full frequency domain signal with the preset frequency component offset, that is, the combining module 150 outputs the electrical signal generated by the avalanche photodiode in response to the incident photon, and outputs the remaining gated interference signal after filtering the signal of the preset frequency component. Alternatively, if the gated signal is a sine wave signal and the gated interference signal contains only one frequency component, the gated interference signal can be filtered out by one filtering of the interference unit 100.

[0049] According to an embodiment of the present invention, in the interference unit 100 of the single photon detection device, the difference in the 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 divides the input signal into a first signal and a second signal, the first signal transmits along the first signal path 120, and the second signal transmits 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 changes of the first signal and the second signal depend on the module control with the time of signal transmission 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, i.e., the time required for the first signal to transmit along the first signal path 120 and the time required for the second signal to transmit along the second signal path 130 are the same. Alternatively, the narrowband filter module filters the signal of the preset frequency component from the second signal, and the phase shift module 140 shifts the signal of the preset frequency component by 180°, so that both the output signals of the first signal path 120 and the second signal path 130 contain the signal of the preset frequency component, and the phase difference between the first signal path output and the second signal path output of the signal of the preset frequency component is exactly 180°, and the signal of the preset frequency component can be all cancelled out. The difference in the 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 is, for example, when the signal transmission distances of the first signal path 120 and the second signal path 130 are completely equal, the cancellation effect of the output signals is higher.

[0050] According to an embodiment of the present invention, as shown in FIG. 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 width of the narrowband filter module 131 is less than or equal to 10 MHz, 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] The single-photon detection device including the interference unit 100 according to the above embodiments of the present invention uses an ultra-narrow bandpass filter to filter the gate interference signal to obtain the fundamental or harmonic signal frequency components, which are then interfered with by the coupling module by the main transmission signal (including the electrical signal after photoelectric conversion and the gate interference signal), and the interference phenomenon only occurs within the passband and transition band of the ultra-narrow bandpass filter in the entire frequency domain, so that the influence on the main transmission signal is small. Figure 6 shows the frequency response curve of the ultra-narrow bandpass filter.

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

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

[0056] The narrowband filter module 131 is installed in the second signal path 130, which causes the power loss of the transmission signal of the second signal path 130; the power attenuation module 121 is installed in the first signal path 120 to counter the power loss caused by the narrowband filter module 131 when performing narrowband filtering. The first signal is transmitted through the first signal path 120 and adjusted by the power attenuation module 121 to attenuate a certain power, and the second signal is transmitted through the second signal path 130 and the signal of the preset frequency component is filtered by the narrowband filter module 131, and the filtered signal is also attenuated by a certain power. By adjusting the working 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 a 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 higher the effect of filtering the interference signal of the preset frequency component. For example, if the power of the output signals of the first signal path 120 and the second signal path 130 is equal, the signal powers of the preset frequency components are equal and opposite in phase, and can be effectively cancelled out.

[0057] According to an embodiment of the present invention, the power attenuation module 121 of the interference unit 100 includes one or more of 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 the resistance parameter). The operating frequency band of the power attenuation module 121 is wide, and it is installed in the first signal path 120 to effectively attenuate the signal in the frequency domain of the first signal (including the electrical signal generated by the avalanche photodiode in response to the incident photon and the interference signal due to the capacitive response of the gate signal).

[0058] According to one embodiment of the present invention, in the interferometric unit 100 of the single photon detection apparatus, a 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 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-inductive 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 line, modulates the phase by selecting capacitance / inductance parameters, or modulates the attenuation value by 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 line whose phase shift amount depends on the frequency. Therefore, the phase shift module 140 is installed at the output end of the narrowband filter module 131 of the second signal path 130, and the operating band of the phase shift module 140 only needs to cover the operating band of the narrowband filter module 131.

[0061] According to an embodiment of the present invention, as shown in FIG. 8 , the signal distribution module 110 and the combining module 150 each include a three-port radio frequency matching element having a first port, a second port, and a third port (the three-port radio frequency matching element 111 and the three-port radio frequency matching element 151 are shown in FIG. 8 ); The three-port radio frequency matching element 111 of the signal distribution module 110 is arranged as follows: a first port coupled to the single-photon inductive element and configured to receive the input signal; a third port coupled to the first signal path 120 and configured to output the first signal; a second port coupled to a second signal path 130 and configured to output the second signal; The three-port radio frequency matching element 151 of the coupling module 150 is arranged as follows: the third port is coupled to the second signal path 130 and is arranged to receive the output signal of the second signal path 130; the second port is coupled to the first signal path 120 and is arranged to receive the output signal of the first signal path 120; The output signal of the first signal path 120 and the output signal of the second signal path 130 are combined in a three-port radio frequency matching element 151 to cancel the signal interference of the preset frequency component, and the first port of the three-port radio frequency matching element 151 outputs the combined signal.

[0062] The three-port radio frequency matching elements of the signal distribution module 110 and the combining module 150 use symmetrical usage methods to eliminate the difference between the two signal paths caused by the imbalance between the ports. For example, the second port of the three-port radio frequency matching element 111 of the signal distribution module 110 is arranged to couple to the first signal path 120 and output the first signal, and the third port is arranged to couple to the second signal path 130 and output the second signal, and since there is a difference between the second port and the third port of the three-port radio frequency matching element 111, there is also a difference in power between the first signal and the second signal output by the signal distribution module 110. In the combining module 150, the coupling method of the three-port radio frequency matching element 151 and the coupling method of the three-port radio frequency matching element 111 are compatible. That is, the second port of the three-port radio frequency matching element 151 is coupled to the second signal path 130 and is arranged 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, and since the second port and the third port of the three-port radio frequency matching element 151 have the same difference, the signal transmitted by the first signal path 120 and the signal transmitted by the second signal path 130 can obtain power compensation before being coupled. The power difference between the signal transmitted by the first signal path 120 and the signal transmitted by the second signal path 130 is smaller than the preset value, and further, after passing through the interference unit 100, the interference signal of the preset frequency component can be eliminated in a large proportion.

[0063] According to an embodiment of the present invention, in the interference unit 100, the three-port radio frequency matching element includes a directional coupler, and the second and third ports of the directional coupler have a preset signal isolation. The second port of the directional coupler of the signal distribution module 110 is arranged to couple to the first signal path 120 and output the first signal, the third port is arranged to couple to the second signal path 130 and output the second signal, the second port of the directional coupler of the combination module 150 is arranged to couple to the second signal path 130 and 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, which reduces the reflection of the signal transmitted on the first signal path 120 or the second signal path 130 to the second signal path 130 or the first signal path 120.

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

[0065] The single-photon inductive element 210 is arranged to receive an optical signal, convert it into an electrical signal, and output it. Alternatively, the single-photon inductive element 210 includes an avalanche photodiode, which operates under the action of a reverse bias voltage, and when there is no photon incidence, the reverse current is extremely weak, which is called dark current, and when there is photon incidence, the reverse current increases rapidly, which is called photocurrent. The greater the light intensity, the greater the reverse current, that is, 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 inductive element 210 and is arranged to provide a DC bias voltage to the single-photon inductive element 210. The DC voltage source 220 applies a DC bias voltage to the single-photon inductive element 210, causing it to enter a critical breakdown state.

[0067] The gate signal generator 230 is coupled to the single-photon inductive element 210 and is arranged to provide a gate signal to the single-photon inductive element 210. Upon application of a DC bias voltage, the gate signal generator 230 applies a periodically changing gate signal to the single-photon inductive element 210. Alternatively, the gate signal applied by the gate signal generator 230 to the single-photon inductive element 210 includes one or more periodic signals, such as a sine wave signal, a square wave signal, a triangular wave signal, etc. Within a half period of the gate signal, the single-photon inductive element 210 is in an avalanche breakdown state, and can generate an avalanche upon receiving a single-photon level optical signal, and output an avalanche current. Within the other half period of the gate signal, the single-photon inductive element 210 cannot respond to the incident optical signal, so that the avalanche charge and the recovery time after the avalanche are reduced.

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

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

[0070] Typical frequency response curves of the interference unit 100 of the single-photon detection device according to the above embodiments of the present invention are shown in Figures 10A and 10B, where Figure 10B illustrates the effect of adjusting the coordinate axis amplification (Zoom In) of Figure 10A, which shows that the interference phenomenon occurs within the passband and transition band of the ultra-narrow bandpass filter, and has little impact on the output signal in the entire frequency domain.

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

[0072] A number of interference units 100 are cascaded, with the second signal path 130 of each interference unit 100 filtering a signal corresponding to one of the frequency components of the gate signal.

[0073] The present invention provides a multi-stage interference unit 100, which can filter multiple frequency components in the gate interference signal one by one.

[0074] Regardless of the periodic signal waveform such as sine wave, square wave, triangular wave, etc., the gate signal is a linear combination of its fundamental frequency component and harmonic frequency component. By arranging the operating frequency and quantity of the interference units 100, for example, two interference units 100 operate at the fundamental frequency of the gate signal, one interference unit 100 operates at the second harmonic frequency of the gate signal, and one interference unit 100 operates at the third harmonic frequency of the gate signal, it is possible to filter most of the signal of the gate interference signal.

[0075] 12 shows a signal waveform output by the single-photon detection device 200 including the 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 FIG. 3, the single-photon induction element 210 can easily read the electrical signal generated in response to the photon incidence.

[0076] According to one embodiment of the present invention, as shown in FIG. 13, the single photon detection device 200 of the present invention further includes a plurality of signal amplification units 240, Each signal amplification unit 240 is disposed in front of one of the interference units 100 along the transmission direction of the input signal, and is arranged to amplify and process the input signal. The signal input to the interference unit 100 is pre-processed for subsequent narrow-band filtering. FIG. 13 shows that the single photon detection device 200 includes two-stage interference units 100, and one amplification unit 240 is disposed in front of each stage of the interference unit 100 along the transmission direction of the input signal. As can be easily understood by those skilled in the art, the single photon detection device 200 can further include more or less interference units 100, and further correspond to more or less amplification units 240, and the single photon detection device 200 may include one stage interference unit 100 and an amplification unit 240 disposed in front of the one stage interference unit 100 along the transmission direction of the input signal. All 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 FIG. 14, the single photon detection device 200 of the present invention further includes a low-pass filter unit 250.

[0078] The low-pass filter unit 250 is disposed after the plurality of interference units 100 along the transmission direction of the input signal, and is arranged to perform low-pass filtering on the signal filtered and output by the plurality of interference units 100. Fig. 14 shows that the single-photon detection device 200 includes a two-stage interference unit 100, and the low-pass filter unit 250 is disposed after the two-stage interference unit 100 along the transmission direction of the input signal. As will be easily understood by those skilled in the art, the single-photon detection device 200 may include more or less interference units 100.

[0079] As shown in the above embodiment, two interference units 100 are arranged to operate at the fundamental frequency of the gate signal, one interference unit 100 operates at the second harmonic frequency of the gate signal, and one interference unit 100 operates at the third harmonic frequency of the gate signal, so that most of the signal of the gate interference signal can be filtered. A low-pass filter unit 250 is installed after the above 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, so as to further filter the fourth harmonic frequency components in the gate interference signal.

[0080] According to an embodiment of the present invention, in the single photon detection device 200, the quantity and parameters of the signal amplification unit 240 and the low-pass filter unit 250 can all be configured according to actual needs.

[0081] According to one embodiment of the present invention, the present invention further provides a chip, in which the single photon detection device according to one or more embodiments described above is integrated.

[0082] According to one embodiment of the present invention, as shown in FIG. 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 embodiments described above, including steps S101 to S108.

[0083] In step S101, a DC bias voltage is provided to the single-photon induction element by a DC voltage source, so as to bring the single-photon induction element into a critical breakdown state.

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

[0085] In step S103, the optical signal is received by the single-photon guided element and converted into an electrical signal.

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

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

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

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

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

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

[0092] According to one embodiment of the present invention, in a method 10 for performing single photon detection, the second signal path includes a narrowband filter module, a passband of the narrowband filter module includes the preset frequency component, and a passband width of the narrowband filter module is less than or equal to 10 MHz, the method 10 comprising: The method further includes filtering the second signal with 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, the method 10 comprising: The method further includes adjusting a power of the first signal by the power attenuation module so that a difference in power of the output signals of the first signal path and the second signal path is less than a second preset value.

[0094] According to one embodiment of the present invention, in a method 10 for performing single photon detection, 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, the three-port radio frequency matching element of the signal distribution module is arranged such that the first port couples to a single photon directing element, the second port couples to the first signal path, and the third port couples to the second signal path, the three-port radio frequency matching element of the coupling module is arranged such that the second port couples to the second signal path, and the third port couples to the first signal path, and the method 10 includes: receiving the input signal at a first port of a three-port radio frequency matching element of the signal distribution module; outputting the first signal through a second port of a three-port radio frequency matching element of the signal distribution module; outputting the second signal through a third port of a three-port radio frequency matching element of the signal distribution module; receiving an output signal of the second signal path with a second port of a three-port radio frequency matching element of the combination module; receiving the output signal of the first signal path by a third port of a three-port radio frequency matching element of the coupling module; The method further includes outputting a combined signal of the first signal path and the second signal path through a first port of a three-port radio frequency matching element of the combination 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 the interference units, the plurality of interference units being cascaded, and the preset frequency component includes one of the frequency components of the gating signal, the method 10 comprising: The method further includes filtering an interference signal corresponding to one of the frequency components of the gating signal by the second signal path of each of the interference units.

[0096] According to one embodiment of the present invention, in a method 10 for performing single photon detection, the single photon detection device further includes a plurality of signal amplification units, each of the signal amplification units being disposed in front of one of the interference units along a transmission direction of the input signal, and the method 10 includes: The method further includes amplifying the input signal by 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 device further includes a low-pass filter unit, which is disposed after a plurality of the interference units along a transmission direction of the input signal, and the method 10 includes: The method further includes performing low-pass filtering on the output signals filtered by the plurality of interference units using the low-pass filter unit.

[0098] The specific limitations of the above single-photon detection method 10 are similar to the specific limitations of the single-photon detection device including the above interference unit 100, and reference can be made to the above description of the single-photon detection device including the interference unit 100, so they will be omitted here.

[0099] In the following, an experimental verification will be given to verify a single-photon detection apparatus including an interferometric unit 100 and a method 10 for performing single-photon detection according to the present invention.

[0100] Experiment 1: The avalanche photodiode is used as the single photon induction element, the gate signal is a square wave signal of 1.25 GHz, and a total of four-stage interference units are installed. Here, the operating frequency of the two-stage interference unit is 1.25 GHz, the operating frequency of the one-stage interference unit is 2.5 GHz, and the operating frequency of the one-stage interference unit is 3.75 GHz. A low-pass filter unit is installed after the four-stage interference unit, and the operating frequency is 4.5 GHz. The attenuation module uses a resistive network, the phase shift module uses a capacitive network, the narrowband filter module uses a surface acoustic wave filter (SAW), and the signal distribution module and coupling module use a directional coupler.

[0101] Experiment 2: The avalanche photodiode is used as the single photon induction element, the gate signal is a 1.25GHz sine wave signal, and a two-stage interference unit is set up. The operating frequencies of the two-stage interference units are both 1.25GHz. A low-pass filter unit is set up after the two-stage interference unit, and the configuration operating frequency is 2.1GHz. The narrowband filter module uses a surface acoustic wave filter (SAW), the attenuation module uses a coaxial resistor network attenuator, and the phase shift module uses a radio frequency transmission line of appropriate length.

[0102] As the results of two experiments show, the gate interference signal has been filtered out in a large amount, so that the electrical signal after photoelectric conversion can be effectively extracted, and there is obvious optimization effect on the afterpulse effect, time resolution and photon count rate within the entire frequency range.

[0103] FIG. 16A shows the configuration diagram of the device used in experiment 2 in the above experiment. The gate signal is a 1.25GHz sine wave signal, UNIC1 is the first stage interference unit, the operating frequency is 1.25GHz, and UNIC2 is the second stage interference unit, the operating frequency is 1.25GHz. AMP1, AMP2 are signal amplifiers installed in front of the interference units UNIC1, UNIC2 along the signal transmission direction, respectively. LF1 is a low-pass filter installed in the signal transmission direction after the interference unit UNIC2, the operating frequency is 2.1GHz. Another stage of 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 a time distribution histogram of detection events of the single photon detection device of Experiment 2 in the above experiment. In the figure, the detection efficiency is 29%, the after pulsing is 1.3%, the dark count is 3 kcps, and the temperature is 263 K. It can be seen that the peaks of each count gate in the figure are steep, and the device has good time resolution.

[0105] The present invention also provides a non-transitory computer-readable storage medium having computer-readable instructions stored thereon which, when executed by a processor, cause the processor to perform the method 10 described in one or more of the embodiments.

[0106] The present invention provides a single-photon detection device, an electrical chip and a method for single-photon detection, which includes an interference unit, and is filtered by an ultra-narrow bandpass filter to obtain the fundamental or harmonic signal frequency components of the gate interference signal, and then interferes with the main transmission signal (including the electrical signal after photoelectric conversion and the gate interference signal) by a combination module, and the interference phenomenon only occurs within the pass band and transition band of the ultra-narrow bandpass filter in the entire frequency domain, so that the impact on the main transmission signal is small. Through multi-stage filtering, a large amount of gate interference signals can be effectively eliminated, and a wider and more continuous frequency domain pass can be stably provided to process the avalanche narrow pulse signal, and the signal-to-noise ratio, pulse waveform and jitter of the avalanche narrow pulse signal are less affected, and there is an obvious optimization effect on the detection efficiency, afterpulse effect and time resolution of the single-photon detector.

Claims

1. 1. A single photon detection device including an interference unit, the interference unit comprising: a signal distribution module arranged to split an input signal into a first signal and a second signal; a first signal path coupled to the signal distribution module and configured to receive and transmit the first signal; a second signal path coupled to the signal distribution module and configured to receive the second signal, and to filter and transmit a signal of a preset frequency component from the second signal; a phase shift module disposed in the first signal path or the second signal path and configured to shift a phase of a transmission signal by 180°; a combining module coupled to the first signal path and the second signal path and configured to receive, combine and output signals of the first signal path and the second signal path.

2. 2. The single-photon detection device according to claim 1, wherein a difference in transmission distance between the first signal path and the second signal path is smaller than a first preset value.

3. the second signal path includes a narrowband filter module; 3. The single photon detection device according to claim 1, wherein the passband of the narrowband filter module has preset frequency components.

4. 4. The single-photon detection device according to claim 3, wherein the passband width of the narrow-band filter module is 10 MHz or less.

5. 4. The single photon detection device of claim 3, wherein the narrowband filter module includes one or more of a surface acoustic wave filter, a bulk acoustic wave filter, and a dielectric filter.

6. the first signal path includes a power attenuation module; 3. The single photon detection device of claim 1, wherein the power attenuation module is configured to adjust the power of the first signal so that a difference in power of the output signals of the first signal path and the second signal path is smaller than a second preset value.

7. 7. The single photon detection apparatus of claim 6, wherein the power attenuation module includes one or more of an analog voltage controlled attenuator, a digitally controlled step attenuator, and a resistive network attenuator.

8. 3. The single-photon detection device according to claim 1, wherein the phase-shift module is disposed on the second signal path.

9. 9. The single photon detection device of claim 8, wherein the phase shift module includes one or more of 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.

10. 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: a first port coupled to the single-photon inductive element and configured to receive the input signal; a second port coupled to the first signal path and configured to output the first signal; a third port coupled to the second signal path and configured to output the second signal; The three-port radio frequency matching element of the coupling module is arranged as follows: a second port coupled to the second signal path and configured to receive an output signal of the second signal path; a third port coupled to the first signal path and configured to receive an output signal of the first signal path; 3. The single-photon detection device according to claim 1, wherein a first port outputs a signal obtained by combining an output signal of the first signal path and an output signal of the second signal path.

11. 11. The single photon detection device of claim 10, wherein the three-port radio frequency matching element comprises a directional coupler, the second port and the third port of the directional coupler having a preset signal isolation.

12. A single-photon inductive element arranged to receive an optical signal, convert it into an electrical signal, and output it; a DC voltage source coupled to the single-photon inductive element and configured to provide a DC bias voltage to the single-photon inductive element to drive the single-photon inductive element into a critical breakdown state; a gating signal generator coupled to the single-photon guiding element and arranged to provide a gating signal to the single-photon guiding element; 3. The single-photon detection device according to claim 1, wherein the input signal includes an interference signal due to a capacitive response of the electrical signal and the gate signal.

13. 13. The single photon detection apparatus of claim 12, wherein the gating signal comprises a periodic signal, and the preset frequency component comprises one of the frequency components of the gating signal.

14. A plurality of said interference units; 14. The single photon detection device of claim 13, wherein a plurality of the interference units are cascaded, and the second signal path of each of the interference units filters an interference signal corresponding to one of the frequency components of the gate signal.

15. 15. The single photon detection device of claim 14, further comprising a plurality of signal amplification units, each of which is disposed in front of one of the interference units along a transmission direction of the input signal and configured to amplify the input signal.

16. 16. The single photon detection device of claim 14 or 15, further comprising a low-pass filter unit installed after a plurality of the interference units along the transmission direction of the input signal and arranged to low-pass filter the output signal filtered by the plurality of the interference units.

17. A chip on which the single photon detection device according to any one of claims 1 to 16 is integrated.

18. A method for single photon detection using the single photon detection device according to any one of claims 1 to 16, comprising the steps of: providing a DC bias voltage to the single-photon inductive element by a DC voltage source to bring the single-photon inductive element into a critical breakdown state; providing a gating signal to the single-photon directing element by a gating signal generator; receiving an optical signal by the single-photon inductive element and converting it into an electrical signal; Dividing an input signal including the electrical signal and an interference signal due to a capacitance response of the gate signal into a first signal and a second signal by the signal distribution module; receiving and transmitting the first signal over the first signal path; receiving the second signal through the second signal path, filtering a signal of a preset frequency component from the second signal, and transmitting the filtered signal; Shifting the phase of the transmission signal by 180° using the phase shift module; receiving, combining and outputting the output signals of the first signal path and the second signal path by the combining module.

19. 20. The method of claim 18, wherein a difference in transmission distance between the first signal path and the second signal path is less than a first preset value.

20. the second signal path includes a narrowband filter module, a passband of the narrowband filter module has the preset frequency component, and a passband width of the narrowband filter module is less than or equal to 10 MHz, the method further comprising:

20. The method of claim 18 or 19, further comprising filtering the second signal with the narrowband filter module.

21. the first signal path includes a power attenuation module, the method comprising:

20. The method of claim 18 or 19, further comprising adjusting the power of the first signal by the power attenuation module so that a difference in power of the output signals of the first signal path and the second signal path is less than a second preset value.

22. 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, the three-port radio frequency matching element of the signal distribution module being arranged such that a first port couples to a single-photon directing element, a second port couples to the first signal path, and a third port couples to the second signal path, the three-port radio frequency matching element of the coupling module being arranged such that a second port couples to the second signal path, and a third port couples to the first signal path, the method comprising: receiving the input signal at a first port of a three-port radio frequency matching element of the signal distribution module; outputting the first signal through a second port of a three-port radio frequency matching element of the signal distribution module; outputting the second signal through a third port of a three-port radio frequency matching element of the signal distribution module; receiving an output signal of the second signal path with a second port of a three-port radio frequency matching element of the coupling module; receiving an output signal of the first signal path by a third port of a three-port radio frequency matching element of the coupling module; 20. The method of claim 18 or 19, further comprising: outputting a signal that is a combination of the output signal of the first signal path and the output signal of the second signal path through a first port of a three-port radio frequency matching element of the combination module.

23. the single photon detection apparatus includes a plurality of the interference units, the plurality of interference units being cascaded, the preset frequency component includes one of the frequency components of the gating signal, and the method further comprises:

20. The method of claim 18 or 19, further comprising filtering an interference signal corresponding to one of the frequency components of the gating signal by the second signal path of each interference unit.

24. The single photon detection apparatus further includes a plurality of signal amplification units, each of which is disposed in front of one of the interference units along a transmission direction of the input signal, and the method includes:

24. The method of claim 23, further comprising amplifying the input signal with the plurality of signal amplification units.

25. The single photon detection device further includes a low-pass filter unit disposed after a plurality of the interference units along a transmission direction of the input signal, and the method includes:

24. The method of claim 23, further comprising: performing low-pass filtering on the output signals filtered by the plurality of interference units by the low-pass filter unit.

26. A non-transitory computer readable storage medium storing computer readable instructions which, when executed by a processor, cause the processor to perform the method of any one of claims 18 to 25.

Images