CN-121702537-B - Signal detection discrimination device and method for single photon detector and quantum communication system

CN121702537BCN 121702537 BCN121702537 BCN 121702537BCN-121702537-B

Abstract

The application provides a signal detection identification device and method for a single photon detector and a quantum communication system, and relates to the technical field of single photon detection. The signal detection and discrimination device comprises a post-processing component, an automatic level control circuit and a discriminator, wherein the post-processing component is used for receiving and carrying out post-processing on an original signal output by a single photon detector to generate a signal to be discriminated, the automatic level control circuit is used for receiving the original signal output by the single photon detector and generating a threshold value signal according to the level characteristic of the original signal, and the discriminator is used for receiving the signal to be discriminated and the threshold value signal, carrying out discrimination comparison and outputting a discrimination result. The application generates a dynamically adjustable non-fixed waveform threshold signal through an automatic level control circuit, utilizes the self-adaptive calibration of two parameters of amplitude and concavity, sets the lowest threshold at the peak position of the signal to capture weak signals, sets the high threshold at the two sides of the signal to inhibit noise, thoroughly breaks through the dilemma of the traditional fixed threshold method, and combines high detection efficiency and low misjudgment rate.

Inventors

FAN YUANBIN
SHI TINGTING
YAN ZHENGYU
ZHOU LAI
YUAN ZHILIANG

Assignees

北京量子信息科学研究院

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (8)

1. A signal detection discrimination apparatus for a single photon detector, comprising: The post-processing component is used for receiving and post-processing an original signal output by the single photon detector to generate a signal to be identified, wherein the original signal comprises a single photon signal and noise; The automatic level control circuit is used for receiving an original signal output by the single photon detector, setting a lowest threshold value at a signal peak value position to capture a weak signal through 'amplitude-concavity' double-parameter self-adaptive calibration according to the level characteristic of the original signal, setting high threshold values at two sides of the signal to inhibit noise, and generating a dynamically adjustable non-fixed waveform threshold value signal; Delay calibration means, connected to the post-processing means and the automatic level control circuit, for compensating the threshold signal according to a timing deviation of the threshold signal and the signal to be discriminated so as to align signal pulses of the threshold signal and the signal to be discriminated on a time axis; and the discriminator is respectively connected with the post-processing component and the delay calibration component and is used for receiving the signal to be discriminated and the threshold signal subjected to time sequence compensation, carrying out discrimination comparison and outputting discrimination results.
2. The signal detection discrimination apparatus of claim 1, wherein the delay calibration component includes an adjustable delay line.
3. The signal detection discrimination apparatus of claim 1, wherein the discriminator is configured to: Outputting a high level under the condition that the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding moment, and determining that a single photon signal exists; and outputting a low level under the condition that the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding moment, and determining that no single photon signal and/or noise exists.
4. The signal detection and discrimination apparatus of claim 1, wherein said threshold signal includes a sine wave, a square wave and/or a triangular wave.
5. A signal detection discrimination method for a single photon detector, characterized in that the signal detection discrimination method is performed by the signal detection discrimination apparatus according to any one of claims 1 to 4, the signal detection discrimination method comprising: Receiving an original signal output by the single photon detector, wherein the original signal comprises a single photon signal and noise; Post-processing is carried out on the original signal to generate a signal to be identified; Generating a dynamically adjustable non-fixed waveform threshold signal according to the level characteristics of the original signal; Compensating the threshold signal according to the time sequence deviation of the threshold signal and the signal to be identified so as to align the signal pulses of the threshold signal and the signal to be identified in a time axis; and comparing the signal to be identified with the threshold signal subjected to time sequence compensation, and outputting an identification result.
6. The signal detection discrimination method of claim 5, wherein said discriminating the signal to be discriminated from the threshold signal subjected to timing compensation, outputting a discrimination result, includes: Outputting a high level under the condition that the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding moment, and determining that a single photon signal exists; and outputting a low level under the condition that the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding moment, and determining that no single photon signal and/or noise exists.
7. The method of signal detection discrimination according to claim 5, wherein said threshold signal includes a sine wave, a square wave and/or a triangular wave.
8. A quantum communication system, comprising: The single photon detector is used for detecting photon signals in the quantum communication process and outputting original signals, wherein the original signals comprise single photon signals and noise; The signal detection discrimination apparatus of any one of claims 1-4, coupled to said single photon detector, for receiving said original signal and outputting a discrimination result to effect discrimination of said original signal.

Description

Signal detection discrimination device and method for single photon detector and quantum communication system Technical Field The application relates to the technical field of single photon detection, in particular to a signal detection 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 computing, weak light detection and the like, and has the core challenge of accurately distinguishing real single photon signals from noise events in complex background noise (including thermal noise, dark count and shot noise). The high-sensitivity single photon signal identification needs to meet two key requirements, namely low misjudgment rate, namely effective suppression of various noise interferences, and high detection efficiency, namely capturing of real single photon signals as much as possible. The essential difference between the single photon signal and the noise is mainly represented by two dimensions of a time domain and an amplitude domain, namely, in the time domain, the pulse width and the rising/falling edge slope of the real photon signal are determined by the physical mechanism of the detector, so that the pulse width of the noise pulse is clear and regular, and the width or the narrow or wide of the noise pulse is free from fixed law and can circulate. In the amplitude domain, the peak amplitude of the real single photon signal follows a specific distribution, which is directly related to photon energy, detector gain, while the amplitude of the noise is typically lower. In the prior art, the discrimination schemes of single photon signals and noise are mainly divided into a pure threshold method and a pure slope method: The core of the pure thresholding method is to set a fixed level threshold (e.g. "signal amplitude >3σ baseline noise"), determine a signal exceeding the threshold as a single photon signal, and determine a signal below the threshold as noise. However, this method has inherent drawbacks of not distinguishing weak single photon signals from strong noise on the one hand, and of extremely poor suitability due to fixed threshold on the other hand. The baseline noise and the signal amplitude of the detector can drift along with the change of environmental conditions (for example, the increase of the refrigerating temperature of the detector can lead to the increase of the dark count amplitude), a fixed threshold cannot follow the changes, the problems of weak signal missed detection caused by overhigh threshold or noise false detection caused by overlow threshold are easily caused, the dilemma of threshold tuning is formed, more noise pulses are introduced when the threshold is lowered to improve the weak signal detection efficiency, and the low-amplitude real single photon signals are filtered when the threshold is raised to inhibit noise. The pure slope method uses the difference between the true signal and the noise on the rising/falling slope (signal slope is large and stable, noise slope is small and discrete) to discriminate. However, the method has the defects that high-slope interference pulses cannot be distinguished from low-slope real signal pulses, and when the signal slope is reduced due to aging and temperature drift of a detector or the noise slope is increased due to external interference enhancement, slope distribution of the two signals is overlapped, so that discrimination boundaries are fuzzy, and if a threshold is not recalibrated in time, the problem of early threshold adaptation and later detection omission/false detection can occur. Therefore, a single photon detection and discrimination scheme is needed that can break through the limitations of the prior art, combine weak signal detection efficiency with noise suppression capability, and have strong adaptability to environmental changes and signal drift. Disclosure of Invention Aiming at the technical problems of poor adaptability, high false detection rate of missed detection, incapacity of balancing weak signal detection and noise suppression and the like in the pure threshold method and the pure slope method in the existing single photon detection identification technology, the application provides a signal detection identification device and method for a single photon detector and a quantum communication system, and the single photon signal identification with high sensitivity, low false judgment rate and strong environmental adaptability is realized through the technical means of dynamic threshold generation, accurate time sequence alignment and the like. According to a first aspect of the present application, at least one embodiment of the present application provides a signal detection and discrimination apparatus for a single photon detector, including a post-processing unit configured to receive an original signal output from the single p