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CN-121702538-B - Avalanche signal identification device and method for single photon detector and quantum communication system

CN121702538BCN 121702538 BCN121702538 BCN 121702538BCN-121702538-B

Abstract

The application provides an avalanche signal identification device and method for a single photon detector and a quantum communication system, and relates to the technical field of single photon detection and quantum communication. The avalanche signal identification device comprises a coupler, a first signal processing branch circuit, a second signal processing branch circuit, a bandpass filter and an amplifier, wherein the coupler is used for dividing a mixed signal output by a single photon detector into a first path of signal and a second path of signal, the first signal processing branch circuit comprises a post-processing circuit and is used for processing the first path of signal to obtain a target signal for retaining the avalanche signal, the second signal processing branch circuit comprises the bandpass filter and is used for screening a gating signal from the second path of signal, the amplifier is used for amplifying the gating signal to obtain an identification signal which is adaptive to the target signal, and the identifier is used for comparing the identification signal with the target signal to realize identification of the avalanche signal. The application uses the gate control signal after the coupler is shunted as the identification reference, the identification signal synchronously follows the change, the manual recalibration of the threshold value is not needed, the dilemma of the traditional fixed threshold value method is solved, and the adaptability is strong.

Inventors

  • FAN YUANBIN
  • SHI TINGTING
  • YAN ZHENGYU
  • YUAN ZHILIANG

Assignees

  • 北京量子信息科学研究院

Dates

Publication Date
20260512
Application Date
20260213

Claims (8)

  1. 1. An avalanche signal discrimination apparatus for a single photon detector, comprising: the input end of the coupler is connected with the output end of the single photon detector, and the coupler is used for dividing a mixed signal output by the single photon detector into a first path of signal and a second path of signal, wherein the mixed signal comprises an avalanche signal and a gating signal; a first signal processing branch comprising: The input end of the post-processing circuit is connected with the first output end of the coupler and is used for processing the first path of signals to obtain a target signal for retaining the avalanche signal; A second signal processing branch comprising: the input end of the band-pass filter is connected with the second output end of the coupler and is used for screening the gating signal from the second path of signal; The amplifier is connected with the band-pass filter and used for amplifying the gating signal to obtain an identification signal which is adapted to the target signal; A delay calibration component, coupled to the amplifier, for compensating the discrimination signal based on a timing offset of the discrimination signal from an avalanche signal in the target signal to align the discrimination signal with the avalanche signal on a time axis; And the first input end of the discriminator is connected with the output end of the first signal processing branch, and the second input end of the discriminator is connected with the output end of the second signal processing branch and is used for receiving the target signal and the discriminating signal so as to realize the discrimination of the avalanche signal by comparing the discriminating signal with the target signal.
  2. 2. The avalanche signal identification apparatus according to claim 1, wherein the delay calibration component comprises an adjustable delay line.
  3. 3. The avalanche signal identification arrangement according to claim 1, wherein the gating signal comprises a sinusoidal signal, a square wave signal and/or a triangular wave signal.
  4. 4. The avalanche signal identification apparatus according to claim 1, wherein, The power ratio of the first path to the second path of the coupler is N:1, wherein N is larger than 1.
  5. 5. The avalanche signal identification apparatus according to claim 4, wherein the amplification factor of the amplifier is N or more.
  6. 6. An avalanche signal discrimination method for a single photon detector, characterized by being performed by an avalanche signal discrimination apparatus according to any one of claims 1-5, comprising: dividing a mixed signal into a first path of signal and a second path of signal, wherein the mixed signal comprises an avalanche signal and a gating signal; Processing the first path of signals to obtain target signals retaining the avalanche signals; screening the gating signal from the second path of signal; amplifying the screened gating signals to obtain identification signals adapting to the target signals; compensating the discrimination signal based on a timing deviation of the discrimination signal from an avalanche signal in the target signal to align the discrimination signal with the avalanche signal on a time axis; and comparing the identification signal with the target signal to realize the self-adaptive identification of the avalanche signal.
  7. 7. The avalanche signal identification method according to claim 6, wherein said comparing said identification signal with said target signal to achieve an adaptive identification of avalanche signals comprises: determining that an avalanche signal is present in case the amplitude of the target signal exceeds the amplitude of the discrimination signal at the corresponding point in time; in case the amplitude of the target signal does not exceed the amplitude of the discrimination signal at the corresponding point in time, it is determined that no avalanche signal or only noise is present.
  8. 8. A quantum communication system, comprising: A single photon detector for outputting a mixed signal, wherein the mixed signal comprises an avalanche signal and a gating signal; the avalanche signal discrimination apparatus in accordance with any one of claims 1-5, coupled to the single photon detector, for processing the mixed signal to achieve adaptive discrimination of avalanche signals from noise.

Description

Avalanche signal identification device and method for single photon detector and quantum communication system Technical Field The application relates to the technical field of single photon detection and quantum communication, in particular to an avalanche signal identification device and method for a single photon detector and a quantum communication system. Background The single photon detection technology is a core support technology in the fields of quantum communication, quantum sensing, laser radar and the like, and has the core challenge of accurately distinguishing real single photon avalanche signals from noise events in complex background noise (including thermal noise, dark count, shot noise and the like). The avalanche signal identification with high sensitivity needs to meet the two core requirements of low misjudgment rate (effective noise suppression) and high detection efficiency (complete acquisition of real signals). The essential difference between the single photon signal and the noise is represented by two key dimensions of a time domain and an amplitude domain, namely, in the time domain, the pulse width and the rising/falling edge slope of a real photon signal are determined by a physical mechanism of a detector, so that the detector has stability, and the width of a noise pulse is in an irregular rule or in a narrow or wide and discrete distribution. In the amplitude domain, the peak amplitude of the real signal follows a specific distribution, directly related to photon energy, detector gain, while the amplitude of noise is typically lower and irregular. In the prior art, the identification schemes of avalanche signals and noise are mainly divided into a pure threshold method and a pure slope method: The essence of the pure threshold method is to set a fixed level threshold, determine a signal exceeding the threshold as an avalanche signal, and determine a signal below the threshold as noise. The scheme has inherent defects that on one hand, weak avalanche signals and strong noise cannot be distinguished, on the other hand, due to fixed threshold values, the suitability is extremely poor, the baseline noise and the signal amplitude of the detector drift along with the environmental temperature change, the aging of the detector and other factors (for example, the increase of the refrigerating temperature of the detector can lead to the increase of the dark counting amplitude), the fixed threshold values cannot follow the changes, and the dilemma that the threshold values are too high to cause weak signal detection omission or the threshold values are too low to cause noise false detection is easy to occur, so that the detection efficiency and the noise suppression effect are difficult to balance. The pure slope method uses the rising edge/falling edge slope difference (the signal slope is large and stable, the noise slope is small and discrete) of the real signal and the noise to judge, but the scheme cannot distinguish the high slope interference pulse from the low slope signal pulse. When the detector ages, the signal slope is reduced due to temperature drift, or the noise slope is increased due to external interference enhancement, the slope distribution of the detector and the noise slope may overlap, the discrimination boundary is fuzzy, and if the detector is not recalibrated in time, the problem of 'early threshold adaptation, later detection omission/false detection' can occur. Therefore, an avalanche signal identification technology capable of adapting to signal and environmental changes and combining detection efficiency and noise suppression effect is needed to solve the shortcomings of the prior art. Disclosure of Invention In order to overcome the defects of poor adaptability, fuzzy discrimination boundary, easy omission detection/false detection and the like of a pure threshold method and a pure slope method in the prior art, the application provides an avalanche signal discrimination device and method for a single photon detector and a quantum communication system, and the avalanche signal is discriminated in a self-adaptive and high-precision manner. According to a first aspect of the application, at least one embodiment of the application provides an avalanche signal discrimination device for a single photon detector, comprising a coupler, an input end of which is connected with an output end of the single photon detector and is used for dividing a mixed signal output by the single photon detector into a first path signal and a second path signal, wherein the mixed signal comprises an avalanche signal and a gate signal, a first signal processing branch, which comprises a post-processing circuit, an input end of which is connected with a first output end of the coupler and is used for processing the first path signal to obtain a target signal for retaining the avalanche signal, a second signal processing branch, which comprises a bandpass filter, an input end of which