Signal detection discrimination device, method and quantum communication system for single photon detectors
By employing dynamic threshold generation and timing alignment techniques, the contradiction between weak signal detection and noise suppression in single-photon detection is resolved, achieving high sensitivity and low false positive rate single-photon signal identification. This approach is applicable to quantum communication systems and enhances the robustness and adaptability of the identification scheme.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING ACAD OF QUANTUM INFORMATION SCI
- Filing Date
- 2026-02-12
- Publication Date
- 2026-05-12
AI Technical Summary
Among existing single-photon detection technologies, the pure threshold method and the pure slope method have poor adaptability, high false negative and false positive rates, cannot balance weak signal detection efficiency and noise suppression, and have poor adaptability to environmental changes.
By employing dynamic threshold generation and precise timing alignment techniques, a non-fixed waveform threshold signal is generated through an automatic level control circuit. Adaptive calibration using amplitude and slope dual parameters, combined with a delay calibration component to compensate for timing deviations, achieves the setting of the lowest threshold at the signal peak position and the high threshold on both sides of the signal, ensuring accurate identification of signal and noise.
It achieves high sensitivity and low false positive rate single-photon signal identification, can adapt to environmental changes, improves the robustness and accuracy of the identification scheme, solves the "dilemma" in traditional methods, and is suitable for quantum communication systems with high sensitivity and stability requirements.
Smart Images
Figure CN121702537B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of single-photon detection technology, and more specifically, to a signal detection and identification device, method, and quantum communication system for single-photon detectors. Background Technology
[0002] Single-photon detection technology is a core supporting technology in fields such as quantum communication, quantum computing, and weak light detection. Its core challenge lies in accurately distinguishing real single-photon signals from noise events amidst complex background noise (including thermal noise, dark counting, and shot noise). High-sensitivity single-photon signal identification must simultaneously meet two key requirements: first, a low false positive rate, i.e., effectively suppressing various types of noise interference; and second, high detection efficiency, i.e., capturing as many real single-photon signals as possible.
[0003] The fundamental difference between single-photon signals and noise lies primarily in two dimensions: the time domain and the amplitude domain. In the time domain, the pulse width and rise / fall slope of a real photon signal are determined by the physical mechanism of the detector and exhibit clear regularity; while the width of a noise pulse can be narrow or wide, with no fixed pattern. In the amplitude domain, the peak amplitude of a real single-photon signal follows a specific distribution, which is directly related to the photon energy and detector gain, while the amplitude of noise is typically lower.
[0004] In existing technologies, the discrimination schemes between single-photon signals and noise are mainly divided into two categories: pure thresholding methods and pure slope methods.
[0005] The core of the pure thresholding method is to set a fixed level threshold (e.g., "signal amplitude > 3σ baseline noise"), classifying signals exceeding this threshold as single-photon signals and those below as noise. However, this method has inherent drawbacks: on the one hand, it cannot distinguish between weak single-photon signals and strong noise; on the other hand, due to the fixed threshold, its adaptability is extremely poor. The detector's baseline noise and signal amplitude will drift with changes in environmental conditions (e.g., an increase in detector cooling temperature will lead to an increase in dark count amplitude). A fixed threshold cannot keep up with these changes, easily leading to problems such as "threshold too high causing missed detection of weak signals" or "threshold too low causing false detection of noise," creating a "dilemma" in threshold tuning—lowering the threshold to improve weak signal detection efficiency introduces more noise pulses; raising the threshold to suppress noise filters out low-amplitude true single-photon signals.
[0006] The pure slope method uses the difference in rising / falling edge slopes between the real signal and noise (signal slope is large and stable, noise slope is small and discrete) for identification. However, this method also has shortcomings: it cannot distinguish between high-slope interference pulses and low-slope real signal pulses; when the detector ages, temperature drift causes the signal slope to decrease, or the noise slope increases due to enhanced external interference, the slope distributions of the two may overlap, leading to blurred identification boundaries. If the threshold is not recalibrated in time, the problem of "early threshold adaptation, later missed / false detections" will occur.
[0007] Therefore, there is an urgent need for a single-photon detection and identification scheme that can overcome the limitations of existing technologies, balance weak signal detection efficiency and noise suppression capabilities, and be highly adaptable to environmental changes and signal drift. Summary of the Invention
[0008] To address the technical problems of existing single-photon detection and identification technologies, such as poor adaptability, high false positive and false negative rates, and inability to balance weak signal detection and noise suppression, the present application provides a signal detection and identification device, method, and quantum communication system for single-photon detectors. Through dynamic threshold generation, precise timing alignment, and other technical means, it achieves high sensitivity, low false positive rate, and strong environmental adaptability in single-photon signal identification.
[0009] According to a first aspect of this application, at least one embodiment of this application provides a signal detection and discrimination device for a single-photon detector, comprising: a post-processing unit for receiving and post-processing a raw signal output from the single-photon detector to generate a signal to be discriminated, wherein the raw signal includes a single-photon signal and noise; an automatic level control circuit for receiving the raw signal output from the single-photon detector and generating a threshold signal based on the level characteristics of the raw signal; and a discriminator connected to the post-processing unit and the automatic level control circuit respectively, for receiving the signal to be discriminated and the threshold signal, performing discrimination comparison, and outputting a discrimination result.
[0010] For example, in some embodiments of this application, a delay calibration component is further included, which is connected to the post-processing component and the automatic level control circuit respectively, for compensating the threshold signal according to the timing deviation between the threshold signal and the signal to be identified, so that the threshold signal and the signal pulse of the signal to be identified are aligned on the time axis.
[0011] For example, in some embodiments of this application, the delay calibration component includes an adjustable delay line.
[0012] For example, in some embodiments of this application, the discriminator is configured to: output a high level to determine the presence of a single-photon signal when the amplitude of the signal to be discriminated exceeds the amplitude of the threshold signal at the corresponding time; and output a low level to determine the absence of a single-photon signal and / or the presence of noise when the amplitude of the signal to be discriminated is lower than the amplitude of the threshold signal at the corresponding time.
[0013] For example, in some embodiments of this application, the threshold signal includes: a sine wave, a square wave, and / or a triangular wave.
[0014] According to a second aspect of this application, at least one embodiment of this application provides a signal detection and identification method for a single-photon detector, the signal detection and identification method being performed by a signal detection and identification device as described in any one of the first aspects, the signal detection and identification method comprising: receiving a raw signal output by the single-photon detector, wherein the raw signal includes a single-photon signal and noise; post-processing the raw signal to generate a signal to be identified; generating a threshold signal based on the level characteristics of the raw signal; comparing the signal to be identified with the threshold signal, and outputting an identification result.
[0015] For example, in some embodiments of this application, the method further includes: compensating the threshold signal based on the timing deviation between the threshold signal and the signal to be identified, so that the threshold signal and the signal pulse of the signal to be identified are aligned on the time axis.
[0016] For example, in some embodiments of this application, the step of comparing the signal to be identified with the threshold signal and outputting the identification result includes: when the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding time, outputting a high level to determine that a single photon signal exists; when the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding time, outputting a low level to determine that there is no single photon signal and / or that noise exists.
[0017] For example, in some embodiments of this application, the threshold signal includes: a sine wave, a square wave, and / or a triangular wave.
[0018] According to a third aspect of this application, at least one embodiment of this application provides a quantum communication system, comprising: a single-photon detector for detecting photon signals during quantum communication and outputting a raw signal, wherein the raw signal includes a single-photon signal and noise; and a signal detection and identification device as described in any one aspect of the first application, connected to the single-photon detector, for receiving the raw signal and outputting an identification result, thereby achieving identification of the raw signal.
[0019] Through the above exemplary embodiments, the signal detection and identification device, method, and quantum communication system for single-photon detectors provided in this application have at least one of the following beneficial effects:
[0020] To resolve the contradiction between weak signal detection and noise suppression: By generating a dynamically adjustable non-fixed waveform threshold signal through an automatic level control circuit, and using "amplitude-concavity" dual-parameter adaptive calibration, the lowest threshold is set at the signal peak position to capture weak signals, and a higher threshold is set on both sides of the signal to suppress noise. This completely breaks through the "dilemma" of the traditional fixed threshold method, and balances high detection efficiency with low false positive rate.
[0021] Strong adaptability to environmental and signal changes: The automatic level control circuit detects the level characteristics of the original signal in real time and dynamically adjusts the threshold voltage. It can adapt to the detector baseline noise drift and signal amplitude changes (such as temperature drift and signal characteristic changes caused by detector aging). This avoids the problem of "early adaptation and later missed / false detection" caused by fixed thresholds in traditional methods, and improves the robustness of the identification scheme.
[0022] Precise timing alignment avoids identification failure: By compensating for the timing deviation between the threshold signal and the signal to be identified through a delay calibration component, the signal pulses of the threshold signal and the signal to be identified within the gating window are precisely aligned on the time axis. This solves the identification failure problem caused by signal-threshold timing misalignment in gating mode and further improves identification accuracy.
[0023] With a wide range of applications, this invention supports the development of quantum communication: The device and method of this application can be directly applied to various single-photon detectors, and are especially suitable for quantum communication systems with extremely high requirements for discrimination sensitivity and stability. Through accurate single-photon signal discrimination, it provides reliable guarantee for signal transmission and decoding in quantum communication, and helps to promote the practical application of quantum communication technology.
[0024] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description
[0025] The above and other objects, features, and advantages of this application will become more apparent from the detailed description of exemplary embodiments with reference to the accompanying drawings. The drawings described below are merely some embodiments of this application and are not intended to limit the scope of this application.
[0026] Figure 1 This is a structural block diagram of the signal detection and identification device according to an embodiment of this application;
[0027] Figure 2 A flowchart illustrating an exemplary signal detection and identification method is provided.
[0028] Figure 3A comparison diagram is shown between an exemplary prior art scheme using a fixed threshold and a scheme using dynamically generated threshold signals as described in this application. Detailed Implementation
[0029] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.
[0030] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.
[0031] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.
[0032] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.
[0033] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of exemplary embodiments, and the modules or processes in the drawings are not necessarily essential for implementing this application, and therefore cannot be used to limit the scope of protection of this application.
[0034] Figure 1 This is a structural block diagram of the signal detection and identification device according to an embodiment of this application.
[0035] like Figure 1As shown, the signal detection and discrimination device for a single-photon detector includes: a post-processing unit 1, an automatic level control circuit 2, a delay calibration unit 3, and a discriminator 4.
[0036] The post-processing unit 1 is used to receive the raw signal output by the single-photon detector and perform post-processing to generate the signal to be identified.
[0037] The raw signal consists of single-photon signals and noise. Noise includes thermal noise, dark counts, shot noise, etc. Post-processing may include conventional signal conditioning operations such as signal filtering and amplification, with the aim of improving the signal-to-noise ratio of the raw signal and providing a clearer signal basis for subsequent identification.
[0038] Automatic Level Control (ALC) circuit 2 is connected to the single-photon detector to receive the raw signal and dynamically adjust the threshold voltage according to the level characteristics of the raw signal to generate a threshold signal with a non-fixed waveform.
[0039] Level characteristics include the amplitude distribution and peak characteristics of the signal and noise. The threshold signal is generated through adaptive calibration using a dual-parameter "amplitude-concavity" method. A minimum threshold is set at the signal peak to capture weak signals, while higher thresholds are set at the signal's edges to suppress noise, precisely balancing the needs of weak signal detection and noise suppression. Threshold signals include sine waves, square waves, and / or triangular waves.
[0040] The delay calibration component 3 is connected to the post-processing component 1 and the automatic level control circuit 2 respectively. It is used to detect the timing deviation between the threshold signal and the signal to be identified, and to perform delay compensation on the threshold signal so that the signal pulses of the threshold signal and the signal to be identified are accurately aligned on the time axis, avoiding identification failure caused by timing misalignment.
[0041] The delay calibration component includes an adjustable delay line, which allows for precise compensation of timing deviations by adjusting the delay parameters of the delay line.
[0042] The discriminator 4 is connected to the post-processing unit 1 and the delay calibration unit 3, respectively. It is used to receive the signal to be discriminated and the time-compensated threshold signal, perform real-time discrimination and comparison, and output the discrimination result. The discriminator 4 is specifically configured as follows: when the amplitude of the signal to be discriminated exceeds the amplitude of the threshold signal at the corresponding time, it outputs a high level to determine that a single-photon signal exists; when the amplitude of the signal to be discriminated is lower than the amplitude of the threshold signal at the corresponding time, it outputs a low level to determine that there is no single-photon signal and / or only noise exists.
[0043] This application also provides a signal detection and identification method for single-photon detectors.
[0044] like Figure 2As shown, the signal detection and identification method for a single-photon detector is performed by the signal detection and identification device as described above, and the signal detection and identification method includes:
[0045] S1. Signal Reception Steps: The post-processing unit and automatic level control circuit receive the raw signal output by the single-photon detector.
[0046] The original signal consists of single-photon signals and noise. The noise includes thermal noise, dark counting, shot noise, etc.
[0047] S2. Signal post-processing steps: The post-processing unit performs post-processing on the original signal (such as filtering, amplification, etc.) to generate the signal to be identified and improve the signal-to-noise ratio.
[0048] S3. Threshold signal generation steps: The automatic level control circuit receives the original signal and dynamically adjusts the threshold voltage according to the level characteristics of the original signal to generate a threshold signal with a non-fixed waveform.
[0049] Level characteristics include the amplitude distribution and peak characteristics of the signal and noise. The threshold signal is generated through adaptive calibration using a two-parameter "amplitude-concavity" method. The threshold signal includes sine waves, square waves, and / or triangular waves.
[0050] S4. Timing calibration step: The delay calibration component detects the timing deviation between the threshold signal and the signal to be identified, and performs delay compensation on the threshold signal so that the signal pulses of the threshold signal and the signal to be identified are accurately aligned on the time axis.
[0051] S5. Identification and Comparison Steps: The discriminator performs real-time identification and comparison between the signal to be identified and the threshold signal (after time-compensated) and outputs the identification result.
[0052] Specifically, the discriminator outputs a high level when the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding time, indicating the presence of a single-photon signal; and outputs a low level when the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding time, indicating the absence of a single-photon signal and / or the presence of noise.
[0053] Figure 3 A comparison diagram is shown between the existing technology using a fixed threshold scheme and the scheme of dynamically generating threshold signals proposed in this application, as follows: Figure 3 As shown: the left side shows the method using a fixed threshold. It can be seen that the traditional fixed threshold has a high false negative rate for weak signals with amplitudes close to noise. The right side shows the signal detection and identification method of this application. Taking the threshold signal as a concave sine wave as an example, the threshold is lowest in the central region of the threshold signal (corresponding to the signal peak position), allowing weak signals to pass through easily. At the same time, the high thresholds on both sides can effectively suppress random noise, successfully solving the contradiction between "weak signal detection" and "noise suppression".
[0054] This application also provides a quantum communication system.
[0055] The quantum communication system includes a single-photon detector and the signal detection and identification device described above.
[0056] The single-photon detector is used to detect photon signals during quantum communication and outputs the raw signal. The raw signal includes the single-photon signal and noise. The noise includes thermal noise, dark counting, shot noise, etc.
[0057] The signal detection and identification device is connected to the signal output terminal of the single-photon detector. It is used to receive the original signal, execute the above-mentioned signal detection and identification method, and output the identification result. This provides accurate single-photon signal identification support for signal transmission and decoding in quantum communication systems, thereby improving the reliability and security of quantum communication.
[0058] Through the above exemplary embodiments, the signal detection and identification device, method, and quantum communication system for single-photon detectors provided in this application have the following beneficial effects: By generating dynamically adjustable non-fixed waveform threshold signals such as concave sine waves through an automatic level control circuit, and utilizing "amplitude-concavity" dual-parameter adaptive calibration, a minimum threshold is set at the signal peak position to capture weak signals, while high thresholds are set on both sides of the signal to suppress noise. This completely overcomes the "dilemma" of the traditional fixed threshold method, balancing high detection efficiency and low false positive rate, and successfully resolving the contradiction between weak signal detection and noise suppression. Simultaneously, the automatic level control circuit can detect the level characteristics of the original signal in real time and dynamically adjust the threshold voltage, adapting to changes in signal characteristics caused by detector baseline noise drift, temperature drift, and detector aging, avoiding the problems of traditional methods. The method addresses the "early adaptation, late-stage false detection / false detection" problem caused by a fixed threshold, significantly improving the robustness and adaptability of the identification scheme to environmental and signal changes. Furthermore, by compensating for the timing deviation between the threshold signal and the signal to be identified using a delay calibration component, it ensures precise alignment of the threshold signal and the signal pulse of the signal to be identified within the gating window on the time axis. This effectively solves the identification failure problem caused by signal-threshold timing misalignment in gating mode, further improving identification accuracy. Moreover, the device and method of this application can be directly applied to various single-photon detectors, especially suitable for quantum communication systems with extremely high requirements for identification sensitivity and stability. Accurate single-photon signal identification provides reliable assurance for signal transmission and decoding in quantum communication, strongly supporting the practical advancement of quantum communication technology and possessing a wide range of application scenarios.
[0059] It should be clearly understood that this application describes how specific examples are formed and used, but this application is not limited to any details of these examples. Rather, based on the teachings of the disclosure of this application, these principles can be applied to many other embodiments.
[0060] Furthermore, it should be noted that the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.
[0061] Exemplary embodiments of this application have been specifically shown and described above. It should be understood that this application is not limited to the detailed structures, arrangements, or implementation methods described herein; rather, this application is intended to cover various modifications and equivalent arrangements that fall within the objectives and scope of the appended claims.
Claims
1. A signal detection and discrimination device for a single-photon detector, characterized in that, include: The post-processing unit is used to receive the raw signal output by the single-photon detector and perform post-processing to generate a signal to be identified, wherein the raw signal includes a single-photon signal and noise; An automatic level control circuit is used to receive the raw signal output by the single-photon detector and, based on the level characteristics of the raw signal, to perform adaptive calibration using a dual parameter of "amplitude-concavity" to set a minimum threshold at the signal peak position to capture weak signals and set high thresholds on both sides of the signal to suppress noise, thereby generating a dynamically adjustable non-fixed waveform threshold signal. The delay calibration component is connected to the post-processing component and the automatic level control circuit, respectively, and is used to compensate the threshold signal according to the timing deviation between the threshold signal and the signal to be identified, so that the signal pulses of the threshold signal and the signal to be identified are aligned on the time axis. The discriminator, connected to the post-processing unit and the delay calibration unit respectively, is used to receive the signal to be discriminated and the threshold signal after time-compensated processing, perform discrimination comparison, and output the discrimination result.
2. The signal detection and identification device as described in claim 1, characterized in that, The delay calibration component includes an adjustable delay line.
3. The signal detection and identification device as described in claim 1, characterized in that, The discriminator is configured as follows: If the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding time, a high level is output to determine the presence of a single-photon signal. If the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding time, a low level is output to determine that there is no single-photon signal and / or noise exists.
4. The signal detection and identification device as described in claim 1, characterized in that, The threshold signal includes: sine wave, square wave and / or triangle wave.
5. A signal detection and identification method for a single-photon detector, characterized in that, The signal detection and identification method is performed by the signal detection and identification device as described in any one of claims 1-4, and the signal detection and identification method includes: Receive the raw signal output by the single-photon detector, wherein the raw signal includes a single-photon signal and noise; The original signal is post-processed to generate the signal to be identified; Based on the level characteristics of the original signal, a dynamically adjustable non-fixed waveform threshold signal is generated; Based on the timing deviation between the threshold signal and the signal to be identified, the threshold signal is compensated so that the signal pulses of the threshold signal and the signal to be identified are aligned on the time axis. The signal to be identified is compared with the threshold signal after time-compensation, and the identification result is output.
6. The signal detection and identification method as described in claim 5, characterized in that, The step of comparing the signal to be identified with the time-compensated threshold signal and outputting the identification result includes: If the amplitude of the signal to be identified exceeds the amplitude of the threshold signal at the corresponding time, a high level is output to determine the presence of a single-photon signal. If the amplitude of the signal to be identified is lower than the amplitude of the threshold signal at the corresponding time, a low level is output to determine that there is no single-photon signal and / or noise exists.
7. The signal detection and identification method as described in claim 5, characterized in that, The threshold signal includes: sine wave, square wave and / or triangle wave.
8. A quantum communication system, characterized in that, include: A single-photon detector is used to detect photon signals during quantum communication and outputs a raw signal, wherein the raw signal includes a single-photon signal and noise; The signal detection and identification device according to any one of claims 1-4 is connected to the single-photon detector and is used to receive the original signal and output the identification result, so as to realize the identification of the original signal.