Method for calibrating a measuring position, calibration system and storage medium

Abstract

The present application relates to the technical field of quantum precision measurement, and a kind of measurement position calibration method, calibration system and storage medium;The present application issues position query command after reaching preset working time t1 in measurement work, obtains current photon number C2 and compares with initial photon number C1, and the ratio of C2 / C1 is used as real-time criterion of position drift.Compared with the scheme in the prior art, the experiment needs to be suspended passively after finding that the photon count is significantly reduced, and the NV imaging scanning positioning is re-performed, the present application can actively monitor the position state during measurement, and find drift in time, avoid a large amount of invalid data acquisition caused by delayed discovery.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement technology, specifically to a measurement position calibration method, calibration system, and storage medium for a single NV color center measurement system. Background Technology

[0002] Solid-state spin quantum sensing technology is an important branch of the rapidly developing field of quantum precision measurement in recent years. Among them, quantum detection technology based on diamond nitrogen-vacancy (NV) color centers has shown broad application prospects in fields such as magnetic field detection, electric field detection, and temperature sensing due to its advantages such as being able to operate at room temperature and pressure and having high sensitivity.

[0003] In quantum detection devices based on NV centers, an excitation beam typically irradiates a diamond containing NV centers, causing the NV centers to produce photofluorescence. The fluorescence signal is then collected by a photodetector or a single-photon counter, thereby enabling the detection of the physical quantity to be measured. The diamond is usually supported on a displacement stage, and the relative position of the diamond and the excitation beam is adjusted by the displacement stage to ensure that the excitation spot accurately covers the target NV center, thereby achieving maximum fluorescence collection efficiency.

[0004] Depending on the distribution density of NV centers in the diamond and the detection scheme, the impact of stage drift on the measurement results varies significantly. For diamonds with uniformly distributed NV centers, when the excitation spot area is much smaller than the diamond area (for example, a diamond size of 400µm × 400µm and an excitation spot diameter of approximately 25µm), even if the stage drifts slightly, the spot still covers the area with uniformly distributed NV centers, and the change in fluorescence intensity is not significant. Furthermore, such schemes typically use high-power excitation light and photodetectors for fluorescence reception, so the slight drift of the stage has a negligible impact on the measurement results. Similarly, for diamonds with a small area but uniformly distributed NV centers, if a high-power excitation light is used in conjunction with a photodetector, the impact of stage drift is also relatively small.

[0005] However, the situation is quite different for diamond detection schemes containing a single NV center. Diamonds with a single NV center typically employ low-power excitation light to reduce power consumption and minimize photobleaching of the NV center, while a single-photon counter is used to acquire fluorescence signals for single-photon-level sensitive detection. In this scenario, the excitation spot covers only a very small area containing the single NV center. Any tiny drift of the displacement stage can cause the spot center to shift, or even cause the NV center to move out of the spot's coverage area, leading to a significant decrease in photon count. In actual measurements, especially in ODMR (Optically Probemed Magnetic Resonance) experiments, each measurement point requires numerous cyclic acquisitions (e.g., millions of cycles per point in pulsed ODMR experiments), and the experiments are lengthy. During these long-term experiments, the cumulative drift of the displacement stage causes a gradual decrease in photon count. If position calibration is not performed in time, this will result in a reduced signal-to-noise ratio, decreased data accuracy, and increased errors in the fitting results.

[0006] Therefore, there is a need in the field for a method that can monitor position drift in real time during measurement and automatically perform position calibration when necessary to ensure the accuracy of data acquisition in single NV color center diamond testing equipment. Summary of the Invention

[0007] To address the problem of decreased photon count and reduced data quality caused by the relative position drift between the light spot and the NV center in existing single NV center diamond testing equipment during long-term measurements, this invention provides a measurement position calibration method, system, and storage medium that can monitor the position drift status in real time during the measurement process and automatically trigger position calibration when necessary to ensure the accuracy of data acquisition.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A measurement position calibration method is used in a solid-state spin quantum detection device. The solid-state spin quantum detection device includes at least a diamond containing a single NV center, a displacement stage and a displacement stage controller supporting the diamond, an excitation beam for exciting the single NV center to generate photofluorescence, a microwave field for outputting a force that compels the single NV center to spin-flip, and a single-photon counter for collecting the photofluorescence. The excitation beam irradiates the diamond in the form of spatial light transmission. The method includes the following steps: S1. Initial position acquisition: The relative position of the diamond and the excitation beam is adjusted by displacement. When the number of photons recorded by the single photon counter in real time is within the preset optimal range, the adjustment is stopped, and the current position information and the number of photons C1 are recorded. S2, Work and Position Query: Perform measurement work at the initial position. When the measurement work reaches the preset working time t1, issue a position query command and stop the measurement work. The displacement stage controller provides the current position information and photon count C2. S3. Position Judgment and Calibration: Determine the change in photon count. If C2 / C1 ≥ the set ratio value, no position calibration is required. If C2 / C1 < the set ratio value, control the displacement stage to adjust the position of the diamond until the real-time photon count is stable within the preset optimal range, thus completing the diamond measurement position calibration process. The set ratio value is in the range of 85% ≤ the set ratio value ≤ 100%.

[0009] Preferably, the preset optimal range is the peak region of the photon number variation curve with position, and its lower boundary is not less than 95% of the maximum value of the peak region.

[0010] Preferably, in S1 and S3, the X-axis, Y-axis and Z-axis of the displacement stage need to be adjusted respectively.

[0011] Preferably, the range of the set ratio value is 90% ≤ the set ratio value ≤ 100%.

[0012] Preferably, in S3, if the real-time photon count still cannot be made within the preset optimal range after the set adjustment time t2, it is determined that the single NV color center is outside the travel range of the displacement stage, and the diamond needs to be moved again until the single NV color center is within the travel range of the displacement stage.

[0013] Preferably, in S3, the displacement stage is controlled to adjust the position of the diamond using a step-by-step search strategy. That is, starting from the current position, the displacement is set in a certain direction. If the real-time photon count increases, the displacement continues in that direction. If the real-time photon count decreases, the displacement returns to the previous position and moves in the opposite direction until the real-time photon count is stable within the preset optimal range.

[0014] Preferably, in S3, the photon count is first coarsely adjusted manually to reach a certain range, and then finely adjusted automatically to the preset optimal range by the displacement stage controller.

[0015] Preferably, the displacement stage has a displacement resolution of no more than 10 nm, a stroke of 50-200 μm, and both manual and automatic adjustment functions.

[0016] The present invention also provides a measurement position calibration system for a solid-state spin quantum detection device. The system includes an initial position acquisition module, a working and position query module, and a position judgment and calibration module. Each module implements the corresponding functions of S1, S2, and S3 in the above method.

[0017] The present invention also provides a storage medium storing a computer program, which, when executed by data processing hardware, enables the operation of the above-described measurement position calibration method after the initial parameter setting is completed.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention issues a position query command after a preset working time t1 has elapsed during measurement. The current photon count C2 is obtained and compared with the initial photon count C1. The ratio of C2 to C1 is used as the real-time criterion for position drift. Compared to existing technologies that require passively pausing the experiment and restarting NV imaging scanning after a significant drop in photon count, this invention actively monitors the position status during measurement, promptly detecting drift and avoiding the collection of a large amount of invalid data due to delayed detection.

[0019] This invention sets a proportional threshold (85% ≤ set proportional value ≤ 100%). When C2 / C1 is not lower than the threshold, it is considered that the position has not shifted significantly, and measurement can continue. Position calibration is triggered only when C2 / C1 is lower than the threshold. This threshold can be flexibly set according to the accuracy requirements of different experimental scenarios—for high-precision measurement scenarios, a higher threshold (such as above 90%) can be set to capture minute drifts in time; for scenarios with larger tolerances, a lower threshold can be set to reduce unnecessary calibration interruptions, thereby achieving a balance between measurement efficiency and data quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of a solid-state spin quantum detection device; Figure 2 This is a flowchart of the method in Example 1; Figure 3 This is a schematic diagram of diamonds arrayed on a substrate in Example 1; Figure 4 The image shows the spectral image of the diamond array distributed in Example 1. Figure 5 A graph showing the change in the number of photons as a function of position, recorded by a single-photon counter; Figure 6 This refers to the measurement position calibration system in Example 2; Figure 7 This is a schematic diagram of the storage medium in Example 3. Detailed Implementation

[0022] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, one or more embodiments are now described with reference to the accompanying drawings, wherein similar reference numerals are used throughout the text to refer to similar components. In the following description, numerous specific details are set forth for purposes of explanation in order to provide a more thorough understanding of one or more embodiments. However, it will be apparent that one or more embodiments may be practiced in various circumstances without these specific details, and the various embodiments may be combined with and referenced to each other without contradiction.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. 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 comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Example 1

[0025] This invention provides a measurement position calibration method for solid-state spin quantum detection devices. (See attached diagram) Figure 1 As shown, the solid-state spin quantum detection device includes at least a diamond 1 containing a single NV center, a displacement stage 2 and a displacement stage controller 3 supporting the diamond, an excitation beam 4 for exciting the single NV center to generate photoluminescence 5, a microwave field 6 for outputting a microwave field 6 to force the single NV center to spin flip, and a single photon counter 7 for collecting the photoluminescence. The excitation beam 4 irradiates the diamond 1 in the form of spatial light transmission.

[0026] Regarding the statement in the text that "the excitation beam 4 irradiates the diamond 1 in the form of spatial light transmission", it specifically means that the excitation beam eventually enters the diamond in a spatial light mode by transmitting a distance. In the existing fiber optic transmission mode, the diamond is usually bonded to the end of the fiber, and the relative position of the light spot and the NV color center is relatively stable. The calibration method mentioned in this application is more suitable for scenarios where the diamond 1 and the excitation beam do not have a strong positioning connection.

[0027] Specifically, the system architecture of the solid-state spin quantum detection device is as follows: The laser 9 outputs an excitation beam, which, after being switched on and off by the acousto-optic modulator 10, is shaped sequentially by optical elements such as the adjustable aperture 11 and collimating lens group 12. The beam is then transmitted spatially to the dichroic mirror 8 and reflected into the objective lens 16. The objective lens 16 focuses the excitation beam 4 onto the surface of the diamond 1 containing a single NV color center, which is supported on the displacement stage 2, exciting the single NV color center to generate photofluorescence 5. The photofluorescence 5 is collected by the objective lens 16 and passes through the dichroic mirror 8. It is then filtered by the filter 13 to remove stray light and spatially filtered by the pinhole 14 before being received by the single-photon counter 7 for photon counting. The microwave module outputs a microwave signal to the antenna 15 and radiates it to the diamond 1, forming a microwave field 6 that forces the single NV color center to spin-flip. The displacement stage controller 3 is communicatively connected to the displacement stage 2, enabling it to control the displacement stage in the X, Y, and Z axes and to query and provide feedback on its current position.

[0028] In the aforementioned detection equipment, the spot of the excitation beam 4 shining on the diamond 1 is usually adjusted to cover only the very small area where a single NV color center is located. Therefore, any slight drift of the displacement stage may cause the center of the spot to shift, or further cause the NV color center to move out of the spot coverage area, thereby causing a significant decrease in photon count and resulting in measurement inaccuracy.

[0029] In this embodiment, the diamond 1 used, viewed from above, occupies an area no larger than a circle with a diameter of 2 μm. In other words, an excitation spot with a diameter of 2 μm is sufficient to cover the diamond 1. Regarding the number of diamonds 1, they can exist individually or be distributed in multiple, spaced-out configurations, as shown in the attached figure. Figure 3 As shown, it includes a substrate 110 (preferably a diamond substrate), on which a number of diamonds 1 are arrayed and spaced apart, and the distance between adjacent diamonds 1 is about 5 μm. In actual detection, one of the diamonds 1 can be selected as the sensing core of the solid-state spin quantum detection device.

[0030] The following details each step of the measurement position calibration method of the present invention; see appendix. Figure 2 The method includes steps S1-S3.

[0031] S1. Initial position acquisition: The relative position of the diamond and the excitation beam is adjusted by displacement. When the number of photons recorded in real time by the single photon counter is within the preset optimal range, the adjustment is stopped, and the current position information and the number of photons C1 are recorded.

[0032] Specifically, taking an array-distributed diamond as an example, the initial position acquisition process includes the following sub-steps: First, NV imaging is used to image the color center distribution of all or part of the diamond 1 on the surface of the substrate 110, obtaining spectral images of multiple single NV color centers, as shown in the attached figure. Figure 4 As shown; based on the spectral image, the diamond with the best fluorescence brightness is selected as the sensing core for this experiment, and the diamond is moved to the area directly below the laser spot; then, within this area, the relative position of diamond 1 and excitation beam 4 is adjusted using displacement stage 2 (i.e., adjusting the X, Y, and Z axes), while a single-photon counter records the photon count in real time. When the photon count reaches the preset optimal range, the adjustment is stopped, and the coordinate position of displacement stage 2 at this time is recorded as the initial position information, and the current photon count C1 is recorded. C1 is the reference photon count value when the single NV color center is fully covered by the excitation spot at the initial position.

[0033] The preset optimal range is the peak region of the photon count versus position curve, with its lower boundary not lower than 95% of the maximum value of the peak region. Specifically, when the displacement stage is finely adjusted near a certain position, the photon count recorded by the single-photon counter will exhibit peak characteristics as the position changes, as shown in the attached figure. Figure 5 As shown in the figure, the area within the red box represents the peak region of the photon count. The preset optimal range is the region within this peak curve where the photon count is not lower than 95% of the maximum value. If the photon count falls within this range, the alignment between the light spot and the NV color center is considered to meet the measurement requirements. Preferably, the preset optimal range can be set to a region where the photon count is not lower than 97% or 99% of the maximum value to further improve alignment accuracy.

[0034] In step S1, adjustments need to be made to the X, Y, and Z axes of the displacement stage. This is because the excitation beam, after being focused by the objective lens, forms a diffraction-limited spot on the diamond surface. This spot has a specific intensity distribution in three-dimensional space—the intensity is highest at the center of the spot in the XY plane, decreasing as it deviates from the center. Similarly, the spot has a depth of focus along the Z-axis. When the diamond deviates from the focal plane along the Z-axis, even if the XY position remains unchanged, the excitation efficiency decreases, leading to a decrease in photon count. Therefore, adjusting only the X and Y axes cannot guarantee that the NV color center is in the optimal excitation state; the Z-axis must also be adjusted simultaneously to ensure that the NV color center is within the high-intensity region of the spot in three-dimensional space.

[0035] S2, Work and Position Query: Perform measurement work at the initial position. When the measurement work reaches the preset working time t1, issue a position query command and stop the measurement work. The displacement stage controller provides the current position information and photon count C2.

[0036] Specifically, after obtaining the initial position in S1, the device enters the formal measurement phase. This measurement includes, but is not limited to, continuous wave ODMR experiments, pulsed ODMR experiments, and other quantum sensing measurements based on NV color centers. During the measurement process, the displacement stage may drift due to environmental factors (such as vibration, airflow, temperature fluctuations, etc.), causing a shift in the relative position of the light spot and the NV color center.

[0037] The preset working time t1 is determined based on the type and parameters of the measurement work. For example, for continuous wave ODMR experiments, the acquisition time for each frequency point is relatively short, and t1 can be set as the cumulative time after completing the scanning of several frequency points; for pulse ODMR experiments, the number of cycles for each point can reach millions, and the single-point acquisition time is long, so t1 can be set as the time after the single-point acquisition is completed or after the acquisition of several points is completed. The specific value of t1 should ensure that the position query is triggered before the displacement stage drift significantly affects the data quality. Preferably, the value of t1 ranges from 10 seconds to 2 minutes, and can be calibrated according to experimental conditions and platform stability.

[0038] When the measurement operation reaches the preset working time t1, the system issues a position query command and pauses the current measurement operation (specifically, pausing the current measurement operation means pausing the recording of current measurement data, but maintaining the normal operation of the excitation beam and microwave field, or only maintaining the excitation beam). The displacement stage controller responds to the position query command, feeding back the current position information (including X, Y, and Z axis coordinates), while the single-photon counter records the current photon count C2. C2 reflects the actual photon count level caused by displacement stage drift after the measurement operation of time t1.

[0039] S3. Position Judgment and Calibration: The system judges the change in photon count. If C2 / C1 ≥ a set ratio value, no position calibration is required. If C2 / C1 < a set ratio value, the displacement stage is controlled to adjust the position of the diamond until the real-time photon count stabilizes within the preset optimal range, completing the diamond measurement position calibration process. The set ratio value ranges from 85% ≤ 100%.

[0040] The ratio C2 / C1 serves as a quantitative criterion for the degree of position drift. When C2 / C1 ≥ the set ratio, it indicates that the decrease in photon count after time t1 is within an acceptable range, the displacement stage has not drifted significantly, and measurement work can continue without calibration. When C2 / C1 < the set ratio, it indicates that the decrease in photon count has exceeded the tolerance threshold, the displacement stage drift has affected the measurement quality, and position calibration is required.

[0041] The set ratio value can be flexibly set according to the accuracy requirements of different experimental scenarios, and the value range is 85% to 100%. For example, for pulse ODMR experiments with high accuracy requirements, the set ratio value can be set to 90% or 95% to more sensitively capture position drift; for fast scanning scenarios with larger tolerances, the set ratio value can be set to 85% to reduce unnecessary calibration interruptions. Preferably, the value range of the set ratio value is 90% ≤ set ratio value ≤ 100%.

[0042] When position calibration is required, the displacement stage is controlled to adjust the position of the diamond. For example, the position calibration employs a step-by-step search strategy: starting from the current position, the diamond is displaced in a certain direction (e.g., the positive X-axis) by a set step size, and the photon count of the real-time single-photon counter is read. If the real-time photon count increases compared to the previous position, the diamond continues to be displaced in that direction by the same step size; if the real-time photon count decreases, the diamond returns to the previous position and is displaced in the opposite direction (e.g., the negative X-axis) by a set step size, observing the change in photon count. This strategy is used sequentially in the X-axis, Y-axis, and Z-axis directions until the real-time photon count stabilizes within a preset optimal range, completing the position calibration.

[0043] The set step size can be determined based on the resolution of the displacement stage and the spot size. For example, the set step size can be set to 10nm to 500nm, preferably 50nm to 200nm. During the search process, a variable step size strategy can be adopted—initially using a larger step size to quickly approach the peak region, and then reducing the step size for precise positioning when the photon count approaches the preset optimal range, thereby improving search efficiency.

[0044] During position calibration, the measurement work is paused. Once a position that meets the preset optimal range is found, the calibrated position information is recorded, and the measurement work resumes. For example, the data processing of the first measurement point and the position calibration process can be performed in parallel to reduce the impact of calibration pauses on the overall experimental progress.

[0045] In S3, if the real-time photon count still cannot be brought within the preset optimal range after the set adjustment time t2, it is determined that the single NV color center is outside the travel range of the displacement stage, and the diamond needs to be moved again until the single NV color center is within the travel range of the displacement stage. Specifically, when the cumulative drift of the displacement stage exceeds its travel range, the step-by-step search strategy will be unable to find a position that meets the preset optimal range within the travel range. By setting an adjustment time t2 (exemplarily, t2 is 2 to 5 minutes), after the search timeout, it is determined that the NV color center has shifted out of the travel range of the displacement stage, and the system issues a prompt, requiring the operator to manually move the diamond or re-perform NV imaging scanning and positioning to bring the NV color center back into the travel range of the displacement stage.

[0046] In S3, the position calibration process can employ a combination of manual coarse adjustment and automatic fine adjustment. Specifically, when C2 / C1 is significantly lower than a set ratio (for example, C2 / C1 is below 50%), it indicates a large drift of the displacement stage. Manual coarse adjustment of the displacement stage can be used first to restore the photon count to a certain intermediate range. Then, the displacement stage controller automatically executes a step-by-step search strategy for fine adjustment until the photon count stabilizes within the preset optimal range. Manual coarse adjustment is suitable for large-scale displacement correction, while automatic fine adjustment is suitable for small-scale, high-precision positioning. Combining the two improves calibration efficiency.

[0047] In some solutions, the displacement stage has a displacement resolution of no more than 10 nm, a travel distance of 50-200 μm, and both manual and automatic adjustment functions. For example, the displacement stage is a piezoelectric ceramic triaxial displacement stage with an X-axis and Y-axis travel of 100 μm, a Z-axis travel of 80 μm, a displacement resolution of 3 nm, and both manual knob coarse adjustment and voltage-controlled automatic fine adjustment functions. Manual adjustment achieves large-range displacement through mechanical knobs on the displacement stage, while automatic adjustment achieves nanometer-level precise displacement by applying a control voltage through the displacement stage controller. Example 2

[0048] This invention also provides a measurement position calibration system for solid-state spin quantum detection devices. The measurement position calibration system includes an initial position acquisition module, a working and position query module, and a position determination and calibration module. (See attached diagram) Figure 6 As shown, the three modules are connected in sequence and work together to complete the position calibration process. The functions and internal structure of each module are described in detail below.

[0049] I. Initial Position Acquisition Module The initial position acquisition module has the following functions: adjusting the relative position of the diamond 1 and the excitation beam 4 by displacement; stopping the adjustment when the number of photons recorded in real time by the single photon counter 7 is within the preset optimal range; and recording the current position information and the number of photons C1.

[0050] Specifically, the initial position acquisition module includes a color center positioning submodule, a displacement control submodule, a photon count monitoring submodule, and a position recording submodule.

[0051] The color center positioning submodule is used to identify the positional distribution of individual NV color centers on the surface of diamond 1. Taking an array-distributed diamond as an example, the color center positioning submodule controls the excitation beam 4 to perform NV imaging scanning on all or part of the diamond 1 on the surface of the substrate 110, obtaining spectral images of multiple individual NV color centers (as shown in the attached diagram). Figure 4As shown, based on the spectral image, the diamond 1 with the best fluorescence brightness is selected as the sensing core for this experiment, and the displacement stage 2 is controlled to move the diamond 1 to the area directly below the laser spot. For example, the color center positioning submodule can be implemented by a host computer running an NV imaging scanning program. The host computer controls the displacement stage controller 3 to drive the displacement stage 2 to perform point-by-point scanning, while simultaneously collecting fluorescence data from the single-photon counter 7 to generate a color center distribution image.

[0052] The displacement control submodule is communicatively connected to the displacement stage controller 3 and is used to send displacement commands to the displacement stage controller 3 to control the displacement stage 2 to adjust its displacement in the X, Y, and Z axes. The displacement control submodule supports both single-axis independent adjustment and multi-axis linkage adjustment modes. During the initial position acquisition stage, the multi-axis linkage mode is preferably used to simultaneously adjust the position of the diamond 1 in three-dimensional space, improving alignment efficiency. For example, the displacement control submodule can be implemented by a displacement control unit on a host computer. The displacement control unit sends displacement commands to the displacement stage controller 3 via an RS-232 or USB communication interface. The displacement stage controller 3 is, for example, a piezoelectric ceramic controller capable of outputting three independent control voltage channels to drive the piezoelectric ceramic actuators of the X, Y, and Z axes of the displacement stage 2 respectively.

[0053] The photon count monitoring submodule is communicatively connected to the single-photon counter 7, and is used to read the photon count value of the single-photon counter 7 in real time during displacement adjustment, and compare the real-time photon count with a preset optimal range. The preset optimal range is the peak region of the photon count versus position curve (as shown in the attached figure). Figure 5 As shown in the figure, the area within the red box represents the peak region of the photon count, and its lower boundary is no less than 95% of the maximum value of the peak region. When the real-time photon count falls into the preset optimal range, the photon count monitoring submodule sends a stop adjustment signal to the displacement control submodule. For example, the photon count monitoring submodule can be implemented by a field-programmable gate array (FPGA). The FPGA receives the photon pulse signal output by the single-photon counter 7 in real time through a TTL pulse interface and counts it. Simultaneously, it compares the count value with a pre-stored preset optimal range threshold and outputs the comparison result. The single-photon counter 7 is exemplarily an avalanche photodiode single-photon counting module, capable of detecting a single photon and outputting a standard TTL pulse.

[0054] The position recording submodule is used to record the current position information (including X-axis, Y-axis, and Z-axis coordinates) and the current photon count C1 fed back by the displacement stage controller 3 after the photon count monitoring submodule determines that the photon count has entered the preset optimal range. C1 serves as the reference value for subsequent position drift judgment and is stored in the system storage unit. The position recording submodule also synchronizes the initial position information to the working and position query module as the starting position for the measurement work. Exemplarily, the position recording submodule can be implemented by the data storage unit of the host computer, which is exemplarily a non-volatile memory (such as a solid-state drive or flash memory) used to persistently save the position coordinates and the photon count reference value C1.

[0055] The workflow of the initial position acquisition module is as follows: the color center positioning submodule performs NV imaging scanning, identifies and selects the single NV color center target area with the best fluorescence brightness; the displacement control submodule controls the displacement stage 2 to perform XYZ three-axis displacement adjustment within the target area; the photon count monitoring submodule reads the photon count of the single photon counter 7 in real time and compares it with the preset optimal range; when the photon count enters the preset optimal range, the displacement control submodule stops the displacement adjustment, and the position recording submodule records the current position information and the photon count C1.

[0056] II. Job and Location Query Module The functions of the working and position query module include: performing measurement work at the initial position; issuing a position query command and stopping the measurement work when the measurement work reaches the preset working time t1; and the displacement stage controller 3 providing the current position information and photon count C2.

[0057] Specifically, the work and location query module includes a measurement control submodule, a timing submodule, a location query submodule, and a data recording submodule.

[0058] The measurement control submodule is used to control the solid-state spin quantum detection device to perform measurement work in its initial position. The measurement work includes, but is not limited to, continuous-wave ODMR experiments, pulsed ODMR experiments, and other quantum sensing measurements based on NV centers. The measurement control submodule is communicatively connected to devices such as the microwave module and laser 9, and controls the output of the microwave field 6, the switching of the excitation beam 4, and the data acquisition timing according to preset experimental parameters. During the measurement work, the single-photon counter 7 continuously collects photofluorescence signals 5 for experimental data analysis. Exemplarily, the measurement control submodule can be implemented by an FPGA timing controller. The FPGA timing controller controls the driver of the acousto-optic modulator 10 through a digital I / O interface to achieve precise switching of the excitation beam 4, controls the output frequency and power of the microwave module through a microwave signal source control interface, and synchronously collects fluorescence data from the single-photon counter 7 through a counter interface. The microwave module exemplarily includes a microwave signal source and a power amplifier. The microwave signal is amplified by the power amplifier and radiated to the diamond 1 through the antenna 15.

[0059] The timing submodule is used to time the duration of the measurement work and compare the accumulated time with the preset working time t1. The preset working time t1 is determined according to the type and parameters of the measurement work. For example, for continuous wave ODMR experiments, the acquisition time of each frequency point is short, and t1 can be set as the accumulated time after completing the scanning of several frequency points; for pulse ODMR experiments, the number of cycles at each point can reach millions, and the single-point acquisition time is long, so t1 can be set as the time after the single-point acquisition is completed or after the acquisition of several points is completed. The specific value of t1 should ensure that the position query is triggered before the drift of the displacement stage 2 significantly affects the data quality. Preferably, the value of t1 is in the range of 10 seconds to 2 minutes, and can be calibrated according to the experimental conditions and platform stability. When the timing submodule determines that the accumulated time has reached t1, it sends a pause signal to the measurement control submodule and a trigger signal to the position query submodule. For example, the timing submodule can be implemented by an internal hardware timer of the FPGA. The hardware timer performs precise timing based on the system clock of the FPGA, and the timing accuracy is 8ns for example.

[0060] Upon receiving the trigger signal from the timing submodule, the position query submodule sends a position query command to the stage controller 3. The stage controller 3 responds to the position query command, providing feedback on the current position information (including real-time coordinates of the X, Y, and Z axes). Simultaneously, the position query submodule reads the current photon count C2 from the single-photon counter 7. C2 reflects the actual photon count level caused by the drift of the stage 2 after a measurement period of time t1. For example, the position query submodule can be implemented by the communication interface unit of a host computer, sending position query commands to the stage controller 3 and receiving position feedback data via an RS-232 or USB interface; simultaneously, it reads the photon count value C2 for the current period from the single-photon counter 7 via the FPGA.

[0061] The data recording submodule records the current position information, current photon count C2, and corresponding measurement timestamp fed back by the displacement stage controller 3, and transmits the data to the position judgment and calibration module. The data recording submodule also saves current experimental progress information (such as the current scanning frequency point, number of acquisitions completed, etc.) during measurement pauses, so that measurement can resume from the pause point after calibration. For example, the data recording submodule can be implemented by the host computer's memory cache and storage unit—experimental progress information is temporarily stored in the memory cache to ensure fast read / write, while key data such as position information and photon count C2 are synchronously written to non-volatile memory to prevent loss in case of power failure.

[0062] The workflow of the operation and position query module is as follows: the measurement control submodule starts the measurement operation at the initial position; the timing submodule keeps track of the measurement duration; when the accumulated time reaches t1, the measurement control submodule pauses the measurement operation, the position query submodule sends a position query command to the displacement stage controller 3 and reads the current photon count C2; the data recording submodule records the current position information, C2 and experimental progress, and transmits the data to the position judgment and calibration module.

[0063] III. Position Determination and Calibration Module The position determination and calibration module has the following functions: determining the change in photon count; if C2 / C1 ≥ a set ratio value, no position calibration is required; if C2 / C1 < a set ratio value, controlling the displacement stage 2 to adjust the position of diamond 1 until the real-time photon count is stable within the preset optimal range, thus completing the measurement position calibration process of diamond 1. The set ratio value is in the range of 85% ≤ 100%.

[0064] Specifically, the position determination and calibration module includes a ratio calculation submodule, a judgment submodule, a calibration execution submodule, and an exception handling submodule.

[0065] The ratio calculation submodule receives the photon count C2 transmitted by the working and position query module, reads the photon count C1 recorded by the initial position acquisition module from the system storage unit, and calculates the ratio of C2 / C1. The C2 / C1 ratio serves as a quantitative criterion for the degree of position drift—a ratio of 1 indicates no change in the photon count and no drift in displacement stage 2; a smaller ratio indicates a more severe decrease in the photon count and a greater drift in displacement stage 2. For example, the ratio calculation submodule can be implemented by the computing unit of a host computer. The computing unit reads C1 and C2 from the memory, obtains the C2 / C1 ratio through division, and outputs the result to the judgment submodule.

[0066] The judgment submodule compares the C2 / C1 ratio with a preset ratio value and outputs the judgment result. The preset ratio value ranges from 85% to 100% and can be configured according to the accuracy requirements of the experimental scenario. For example, for pulse ODMR experiments with high accuracy requirements, the preset ratio value can be configured to 90% or 95%; for fast scanning scenarios with larger tolerances, the preset ratio value can be configured to 85%. Preferably, the preset ratio value ranges from 90% to 100%. When C2 / C1 ≥ the preset ratio value, the judgment submodule outputs a "no calibration required" signal, and the system resumes measurement work; when C2 / C1 < the preset ratio value, the judgment submodule outputs a "calibration required" signal, triggering the calibration execution submodule. For example, the judgment submodule can be implemented by a digital comparator in an FPGA, which compares the C2 / C1 ratio with a pre-stored preset ratio value and outputs a comparison result flag; it can also be implemented by software comparison logic in a host computer, where the comparison judgment between the ratio and the threshold is completed through program code.

[0067] The calibration execution submodule is used to control the displacement stage 2 to perform position calibration when the determination submodule outputs a "calibration required" signal. The calibration execution submodule is communicatively connected to the displacement stage controller 3 and adjusts the position of the diamond 1 by sending displacement commands to the displacement stage controller 3. The calibration execution submodule is also communicatively connected to the single-photon counter 7, which reads the photon count in real time during the calibration process and compares the real-time photon count with the preset optimal range.

[0068] For example, the calibration execution submodule employs a step-by-step search strategy to perform position calibration: starting from the current position, it moves a set step size along a certain direction (such as the positive X-axis) and reads the photon count of the real-time single-photon counter 7. If the real-time photon count increases compared to the previous position, it continues to move a set step size along that direction; if the real-time photon count decreases, it returns to the previous position and moves a set step size along the opposite direction. This strategy is followed sequentially in the X-axis, Y-axis, and Z-axis directions until the real-time photon count stabilizes within a preset optimal range. The set step size is exemplarily 10nm to 500nm, preferably 50nm to 200nm. During the search process, the calibration execution submodule can employ a variable step size strategy—initially using a larger step size to quickly approach the peak region, and then reducing the step size for precise positioning when the photon count approaches the preset optimal range. For example, the calibration execution submodule can be implemented by the search control program of the host computer and the displacement stage controller 3 in concert. The search control program of the host computer calculates the next displacement direction and step size according to the photon number change trend, generates a displacement command and sends it to the displacement stage controller 3. The displacement stage controller 3 outputs the corresponding control voltage to drive the piezoelectric ceramic actuator of the displacement stage 2 to complete the displacement.

[0069] The calibration execution submodule also supports a calibration mode combining manual coarse adjustment and automatic fine adjustment. When C2 / C1 is significantly lower than the set ratio value (for example, C2 / C1 is lower than 50%), it indicates that the displacement stage 2 has a large drift. The calibration execution submodule can issue a manual coarse adjustment prompt, allowing the operator to manually adjust the displacement stage 2 by rotating the knobs to correct a large range of displacements, restoring the photon count to a certain intermediate range. Subsequently, the calibration execution submodule automatically executes a step-by-step search strategy for fine adjustment until the photon count stabilizes within the preset optimal range. For example, the manual coarse adjustment prompt can be presented on the host computer's display screen in the form of text or a graphical interface, or a prompt signal can be issued by an audible and visual alarm.

[0070] When the calibration execution submodule determines that the real-time photon count has stabilized within the preset optimal range, it records the calibrated position information and sends a recovery signal to the work and position query module, allowing the measurement work to resume from the pause point. For example, the data processing and position calibration process for the first measurement point can be performed in parallel to reduce the impact of calibration pauses on the overall experimental progress.

[0071] The anomaly handling submodule is used to handle abnormal situations during the calibration process. Specifically, the anomaly handling submodule monitors the calibration time of the calibration execution submodule. When the calibration time exceeds the set adjustment time t2 (exemplarily, t2 is 2 to 5 minutes) and the real-time photon count still has not entered the preset optimal range, the anomaly handling submodule determines that the single NV color center is outside the travel range of the displacement stage 2. At this time, the anomaly handling submodule issues an alarm signal, prompting the operator to move the diamond 1 back to the point where the single NV color center is within the travel range of the displacement stage 2. For example, the operator can manually move the diamond 1 or re-perform NV imaging scanning and positioning to make the NV color center fall back into the travel range of the displacement stage 2, and then re-acquire the initial position through the initial position acquisition module. For example, the anomaly handling submodule can be implemented by a monitoring timer and an alarm unit of the host computer—the monitoring timer starts timing at the beginning of calibration, and when the timing value exceeds t2, it triggers the alarm unit, which displays an alarm message on the host computer screen and / or drives an audible and visual alarm to issue an alarm signal.

[0072] The workflow of the position determination and calibration module is as follows: the ratio calculation submodule calculates the C2 / C1 ratio; the judgment submodule compares the ratio with a set ratio value; if the ratio is greater than or equal to the set ratio value, no calibration is required, and the measurement work is resumed; if the ratio is less than the set ratio value, the calibration execution submodule controls the displacement stage 2 to perform stepwise search calibration, and the anomaly handling submodule monitors the calibration time synchronously; when the real-time photon count enters the preset optimal range, the calibration is completed, the position after calibration is recorded, and the measurement work is resumed; when the calibration timeout occurs, the anomaly handling submodule issues an alarm prompt.

[0073] IV. System Implementation The initial position acquisition module, working and position query module, and position judgment and calibration module can be implemented by data processing hardware through the execution of computer programs. For example, the data processing hardware includes an FPGA and a host computer, where the FPGA is responsible for high-time-precision hardware control (such as issuing displacement commands to the displacement stage 2, reading data from the single-photon counter 7, and controlling the switching of the microwave module and laser 9), and the host computer is responsible for data processing, judgment logic, human-computer interaction, and experimental parameter configuration. The host computer can be, for example, an industrial control computer or a personal computer. Data transmission between the modules is achieved through an internal bus or communication interface.

[0074] The system may further include a storage unit for storing parameters such as photon count C1, C2, position information, preset optimal interval parameters, set ratio values, preset working time t1, set adjustment time t2, as well as NV imaging scan data, experimental progress information, etc. The storage unit may be, exemplarily, a non-volatile memory (such as a solid-state drive, flash memory, or EEPROM), which can be integrated into data processing hardware or used as a standalone storage device. Example 3

[0075] This invention also provides a storage medium, as shown in the attached figure. Figure 7 As shown, the storage medium 100 stores a computer program 101. When the computer program 101 is executed by the data processing hardware, it can perform the operation of the measurement position calibration method as described in Embodiment 1 above after the initial parameter setting is completed.

[0076] In the example scheme, when the computer program 101 stored in the storage medium 100 is executed by the data processing hardware, it performs the following operations: S1. Initial Position Acquisition: The relative position of the diamond and the excitation beam is adjusted by displacement. Adjustment stops when the number of photons recorded in real time by the single-photon counter is within a preset optimal range, and the current position information and photon count C1 are recorded. The preset optimal range is the peak region of the photon count versus position curve, with its lower boundary not lower than 95% of the maximum value of the peak region. During adjustment, the X, Y, and Z axes of the displacement stage need to be adjusted respectively to ensure that the NV color center is within the high-intensity region of the light spot in three-dimensional space.

[0077] S2. Operation and Position Query: Measurement is performed at the initial position. When the measurement reaches the preset working time t1, a position query command is issued and the measurement stops. The displacement stage controller provides the current position information and photon count C2. The value of t1 ranges from 10 seconds to 2 minutes and can be calibrated according to the experimental type and platform stability.

[0078] S3. Position Judgment and Calibration: The system judges the change in photon count. If C2 / C1 ≥ a set ratio value, no position calibration is required. If C2 / C1 < a set ratio value, the displacement stage is controlled to adjust the position of the diamond until the real-time photon count stabilizes within the preset optimal range, completing the diamond measurement position calibration process. The set ratio value ranges from 85% ≤ 100%, preferably 90% ≤ 100%.

[0079] In S3, position calibration employs a step-by-step search strategy: starting from the current position, a set step size is used to move along a certain direction. If the real-time photon count increases, the movement continues along that direction; if the real-time photon count decreases, the position returns to the previous position and moves in the opposite direction until the real-time photon count stabilizes within the preset optimal range. The set step size is 10nm to 500nm, preferably 50nm to 200nm.

[0080] In S3, if the set adjustment time t2 is exceeded (for example, t2 is 2 to 5 minutes) and the real-time photon count still cannot be within the preset optimal range, it is determined that the single NV color center is outside the travel range of the displacement stage, and the diamond needs to be moved again until the single NV color center is within the travel range of the displacement stage.

[0081] The data processing hardware includes, but is not limited to, FPGA, DSP, ARM processor, or host computer CPU. For example, in this embodiment, the data processing hardware is an FPGA, and the computer program is stored in the storage medium as firmware, which is read and executed by the FPGA. The initial parameter settings include parameters such as a preset optimal range threshold, a set ratio value, a preset working time t1, a set adjustment time t2, and a set step size. Before the experiment begins, the operator completes the parameter configuration through the host computer software and writes it into the FPGA.

[0082] The storage medium includes, but is not limited to, any one of ROM, PROM, EPROM, EEPROM, Flash memory, magnetic surface memory, optical disc, or cloud server. For example, in this embodiment, the storage medium is an EEPROM, integrated with the FPGA on the same circuit board. The computer program is automatically loaded into the FPGA and runs when the device is powered on, requiring no additional manual intervention, thereby automating the execution of the measurement position calibration method.

[0083] It should be noted that the computer program stored in the storage medium described in this embodiment performs operations that correspond one-to-one with each step of the measurement position calibration method described in Embodiment 1 above. For relevant details, please refer to the description in Embodiment 1, which will not be repeated here.

[0084] The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0085] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0086] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0087] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A measurement position calibration method for a solid-state spin quantum detection device, the solid-state spin quantum detection device comprising at least a diamond containing a single NV center, a displacement stage and a displacement stage controller supporting the diamond, an excitation beam for exciting the single NV center to generate photofluorescence, a microwave field for outputting a microwave field to force the single NV center to spin-flip, and a single-photon counter for collecting the photofluorescence, wherein the excitation beam irradiates the diamond in the form of spatial light transmission, characterized in that, The method includes the following steps: S1. Initial position acquisition: The relative position of the diamond and the excitation beam is adjusted by displacement. When the number of photons recorded by the single photon counter in real time is within the preset optimal range, the adjustment is stopped, and the current position information and the number of photons C1 are recorded. S2, Work and Position Query: Perform measurement work at the initial position. When the measurement work reaches the preset working time t1, issue a position query command and stop the measurement work. The displacement stage controller provides the current position information and photon count C2. S3. Position Judgment and Calibration: Determine the change in photon count. If C2 / C1 ≥ the set ratio value, no position calibration is required. If C2 / C1 < the set ratio value, control the displacement stage to adjust the position of the diamond until the real-time photon count is stable within the preset optimal range, thus completing the diamond measurement position calibration process. The set ratio value is in the range of 85% ≤ the set ratio value ≤ 100%.

2. The measurement position calibration method as described in claim 1, characterized in that: The preset optimal range is the peak region of the photon number variation curve with position, and its lower boundary is not less than 95% of the maximum value of the peak region.

3. The measurement position calibration method as described in claim 1, characterized in that: In S1 and S3, the X-axis, Y-axis and Z-axis of the displacement stage need to be adjusted respectively.

4. The measurement position calibration method as described in claim 1, characterized in that: The range of the set ratio value is 90% ≤ the set ratio value ≤ 100%.

5. The measurement position calibration method as described in claim 1, characterized in that: In S3, if the set adjustment time t2 is exceeded and the real-time photon count still cannot be within the preset optimal range, it is determined that the single NV color center is outside the travel range of the displacement stage, and the diamond needs to be moved again until the single NV color center is within the travel range of the displacement stage.

6. The measurement position calibration method as described in claim 1, characterized in that: In S3, the displacement stage is used to adjust the position of the diamond using a step-by-step search strategy. That is, starting from the current position, the displacement is set in a certain direction. If the real-time photon count increases, the displacement continues in that direction. If the real-time photon count decreases, the displacement returns to the previous position and moves in the opposite direction until the real-time photon count is stable within the preset optimal range.

7. The measurement position calibration method as described in claim 1, characterized in that: In S3, the photon count is first coarsely adjusted manually to reach a certain range, and then finely adjusted automatically to the preset optimal range by the displacement stage controller.

8. The measurement position calibration method as described in claim 7, characterized in that: The displacement stage has a displacement resolution of no more than 10 nm, a stroke of 50-200 μm, and is equipped with both manual and automatic adjustment functions.

9. A measurement position calibration system for a solid-state spin quantum detection device, the solid-state spin quantum detection device comprising at least a diamond containing a single NV center, a displacement stage and a displacement stage controller supporting the diamond, an excitation beam for exciting the single NV center to generate photofluorescence, a microwave field for outputting a microwave field to force the single NV center to spin-flip, and a single-photon counter for collecting the photofluorescence, wherein the excitation beam irradiates the diamond in the form of spatial light transmission, characterized in that... The system includes: The initial position acquisition module has the following functions: adjusting the relative position of the diamond and the excitation beam by displacement; stopping the adjustment when the number of photons recorded in real time by the single photon counter is within the preset optimal range; and recording the current position information and the number of photons C1. The working and position query module has the following functions: performing measurement work at the initial position; issuing a position query command and stopping the measurement work when the measurement work reaches the preset working time t1; and the displacement stage controller providing the current position information and photon count C2. The position determination and calibration module has the following functions: determining the change in photon count; if C2 / C1 ≥ a set ratio value, no position calibration is required; if C2 / C1 < a set ratio value, controlling the displacement stage to adjust the position of the diamond until the real-time photon count is stable within the preset optimal range, thus completing the diamond measurement position calibration process. The set ratio value is in the range of 85% ≤ 100%.

10. A storage medium, characterized in that, The storage medium stores a computer program, which, when executed by the data processing hardware, can perform the measurement position calibration method as described in any one of claims 1-6 after the initial parameter settings are completed.

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