Quantum magnetometer, magnetic field measurement method and storage medium

Abstract

The invention relates to the technical field of quantum precision measurement, and provides a quantum magnetometer which comprises a solid-state spinning color center probe, a microwave module, a laser module, a photoelectric detection module, a lock-in amplification module, a PID module and a data processing module. According to the scheme, an ODMR sweep frequency spectrum line does not need to be drawn when the magnetic field is measured every time, tracking of the changing magnetic resonance frequency can be rapidly achieved through comparison of the target data and the demodulation result, the time for obtaining the new magnetic resonance frequency is greatly shortened, and the magnetic measurement efficiency of the quantum magnetometer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum precision measurement, and particularly relates to a quantum magnetometer based on solid-state spin color centers, a method for measuring vector or non-vector magnetic fields, and a storage medium. Background Art

[0002] In recent years, the research on solid-state spin color center systems in the field of quantum precision has developed rapidly. Especially for the detection of magnetic fields, a detection method mainly based on optically detected magnetic resonance (ODMR) has been developed. By studying the linear relationship between the magnetic resonance frequency and the external magnetic field, the sensing measurement and quantification of the external magnetic field can be realized. However, some current research is still more theoretical, and many application problems still need to be solved in the process of productizing related technologies.

[0003] In the solution of the present application, discussions are mainly focused on related problems of obtaining the magnetic resonance frequency. In the prior art, the methods for extracting the resonance frequency mainly include manual point selection and curve fitting. However, both of these methods need to obtain the ODMR sweep spectrum line through the frequency sweep method when measuring different magnetic fields to obtain the resonance frequency, and the resonance frequency acquisition time is relatively long. In addition, the method of manual point selection has problems such as low accuracy and inability to be productized, and the method of curve fitting has problems such as a complex fitting and derivation process and limited measurement bandwidth.

[0004] Based on this, the present invention designs a quantum magnetometer based on solid-state spin color centers, a method for measuring vector or non-vector magnetic fields, and a storage medium. Summary of the Invention

[0005] The present invention proposes a quantum magnetometer based on solid-state spin color centers, a method for measuring vector or non-vector magnetic fields, and a storage medium to solve the problems existing in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A quantum magnetometer, comprising: A solid-state spin color center probe for sensing a magnetic field and generating feedback fluorescence; A microwave module for outputting a microwave signal acting on the solid-state spin color center probe; A laser module for outputting a laser signal acting on the solid-state spin color center probe; An optoelectronic detection module for receiving the feedback fluorescence and generating a voltage signal; A lock-in amplifier module for signal processing and modulation and demodulation; A PID module for feedback adjustment of the microwave signal to switch its frequency to the microwave resonance frequency characterizing the current magnetic field; A data processing module for data processing, plotting, and analysis.

[0007] Preferably, the lock-in amplification module is a two-phase digital demodulator.

[0008] Preferably, it further includes a phase self-adjustment module, which is used to automatically adjust the initial phase of the lock-in amplification module according to a set target.

[0009] Preferably, it further includes a magnetic field generation module, which is used to generate a bias magnetic field acting on the solid-state spin color center probe.

[0010] Preferably, it further includes an azimuth adjustment module, which is used to automatically or manually adjust the spatial position of the magnetic field generation module.

[0011] Preferably, it further includes a feature point self-acquisition module, which is used to automatically identify the magnetic resonance feature points on the ODMR spectrum line and obtain the microwave resonance frequency corresponding to the magnetic resonance feature points.

[0012] Preferably, the microwave module includes a combiner, which is used to combine multiple microwave signals into one and output them to the solid-state spin color center probe.

[0013] Preferably, the photoelectric detection module includes a single-channel voltage signal output unit and a signal splitting unit. The single-channel voltage signal output unit is used to receive the feedback signal and output a total voltage signal. The signal splitting unit is used to split the total voltage signal into multiple sub-voltage signals for output, and the number of sub-voltage signals is the same as the number of microwave signals. The lock-in amplification module processes and demodulates each sub-voltage signal.

[0014] Preferably, the solid-state spin color center probe is an ensemble diamond NV color center probe or an ensemble diamond germanium vacancy color center probe or an ensemble diamond silicon vacancy color center.

[0015] Preferably, the microwave module includes eight independently arranged microwave signal generating units.

[0016] Preferably, the solid-state spin color center probe is a diamond NV single color center probe or a silicon carbide color center probe or a diamond germanium vacancy single color center probe or a diamond silicon vacancy single color center probe or a hexagonal boron nitride color center probe.

[0017] Preferably, the microwave module includes two independently arranged microwave signal generating units.

[0018] A magnetic field measurement method, applied to the aforementioned quantum magnetometer, includes an initial parameter acquisition step and an official measurement step, where: The initial parameter acquisition step includes: S1. Control the microwave module to output a swept-frequency microwave signal; S2. Start the quantum magnetometer based on the swept microwave signal for measurement, and draw a target ODMR spectrum line; S3. Obtain the microwave resonance frequency at the magnetic resonance characteristic point on the target ODMR spectrum line; S4. Select several microwave resonance frequencies and record them as the initial microwave frequencies; The formal measurement steps include: S5. Control the microwave module to output a point-frequency microwave signal at the initial microwave frequency; S6. Set the lock-in amplifier module to output a frequency-modulated signal to modulate the point-frequency microwave signal; S7. Start the quantum magnetometer based on the point-frequency microwave signal, measure the magnetic field to be measured, and obtain the demodulation result; S8. The PID module adjusts the microwave signal according to the demodulation result and the target value so that its frequency switches to the microwave resonance frequency characterizing the magnetic field to be measured; S9. Analyze and calculate the microwave resonance frequency characterizing the magnetic field to be measured, and output the characterization result of the magnetic field to be measured.

[0019] Preferably, when the solid-state spin color center probe is a four-axis solid-state spin color center probe, it includes the following two detection modes: Mode 1: The initial parameter acquisition step further includes: S11. Set a bias magnetic field so that the target ODMR spectrum line has eight magnetic resonance characteristic points, that is, has eight microwave resonance frequencies; S12. Select n of the microwave resonance frequencies as the initial microwave frequencies, where n ≤ 8; The formal measurement steps further include: S13. Keep the output of the bias magnetic field unchanged; S14. Control the microwave module to output n point-frequency microwave signals at the selected initial microwave frequencies; S15. Apply n different magnitudes of frequency-modulated signals to modulate the n point-frequency microwave signals one by one; S16. Through the adjustment of the PID module, obtain n groups of microwave resonance frequencies characterizing the magnetic field to be measured; S17. Analyze and calculate, and output the magnetic field information; Mode 2, the initial parameter acquisition step further includes: S21. Set a bias magnetic field so that the target ODMR spectrum line has four magnetic resonance characteristic points, that is, has four microwave resonance frequencies; S22. Select the maximum value or the minimum value or both of the four microwave resonance frequencies as the initial microwave frequencies; The formal measurement steps further include: S23. Keep the output of the bias magnetic field unchanged; S24. Control the microwave module to output corresponding numbers of frequency-point microwave signals according to the initial microwave frequency; S25. Apply a frequency modulation signal to modulate the frequency-point microwave signals one by one; S26. Through PID module adjustment, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S27. Analyze and calculate, and output magnetic field information.

[0020] Preferably, in the above Mode 1, when n = 8 or n = 4 and all microwave resonance frequencies are on the same side of the center frequency of the swept-frequency microwave signal, the magnetic field information includes magnetic field vector information.

[0021] Preferably, when the solid-state spin color center probe is a single-axial solid-state spin color center probe, it includes the following two detection modes: Mode 1: The initial parameter acquisition step further includes: S31. Set a bias magnetic field and draw a target ODMR spectrum line based on the bias magnetic field; S32. Select one or all of the microwave resonance frequencies as the initial microwave frequency; The formal measurement step further includes: S33. Keep the output of the bias magnetic field unchanged; S34. Control the microwave module to output corresponding numbers of frequency-point microwave signals according to the initial microwave frequency; S35. Apply a frequency modulation signal to modulate each frequency-point microwave signal one by one; S36. Through PID module adjustment, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S37. Analyze and calculate, and output magnetic field information;

[0022] Mode 2: The initial parameter acquisition step further includes: S41. Without applying a bias magnetic field, draw a target ODMR spectrum line based on the characteristics of the solid-state spin color center itself; S42. Select one or all of the microwave resonance frequencies as the initial microwave frequency; The formal measurement step further includes: S43. Control the microwave module to output corresponding numbers of frequency-point microwave signals according to the initial microwave frequency; S44. Apply a frequency modulation signal to modulate the frequency-point microwave signals one by one; S45. Through PID module adjustment, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S46. Analyze and calculate, and output magnetic field information.

[0023] Preferably, in the formal measurement step, the voltage signal is demodulated by a two-phase digital demodulation method; Through phase adjustment, one of the two demodulated component values is made to be a near-zero value, and the other component value is used as the input value of the PID module to compare with the target value, and the frequency adjustment parameter of the microwave signal is output.

[0024] A storage medium stores a computer program thereon, and when the computer program is executed by a processor, the steps of the magnetic field measurement method as described above are implemented.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: In this solution, it is not necessary to draw an ODMR sweep spectrum line every time the magnetic field is measured. It can quickly track the changing magnetic resonance frequency by comparing the target data with the demodulation result, greatly shortening the acquisition time of the new magnetic resonance frequency and improving the magnetic field measurement efficiency of the quantum magnetometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0027] Figure 1 It is a system schematic diagram of the quantum magnetometer in Embodiment 1; Figure 2 It is an ODMR spectrum line (diamond NV color center probe) drawn with the demodulation value R as the ordinate; Figure 3 It is an ODMR spectrum line (diamond NV color center probe) drawn with the demodulated Y-term component value as the ordinate; Figure 4 It is an ODMR spectrum line (diamond NV color center probe) without modulation processing; Figure 5 It is a schematic diagram of four axial directions of an ensemble diamond NV color center; Figure 6 It is a system schematic diagram of a quantum magnetometer based on an ensemble diamond NV color center probe; Figure 7 It is a system schematic diagram of a quantum magnetometer based on a single diamond NV color center probe; Figure 8 It is a flowchart of a method for measuring a magnetic field using a quantum magnetometer. EMBODIMENTS

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Introduction to the prior art: The key to the principle of optically detected magnetic resonance (ODMR) is to use the sensitivity and high resolution of optics to detect magnetic resonance signals. In a common optically detected magnetic resonance experiment, first, a sample needs to be placed in an external magnetic field so that the nuclear or electron magnetic moments in the sample can interact with the external magnetic field. Then, by irradiating the sample with microwaves of a specific frequency, the nuclei or electrons in the sample undergo energy level transitions. These energy level transitions cause the sample to absorb or emit electromagnetic radiation of a specific frequency, forming a magnetic resonance signal, and then the magnetic resonance signal is detected by optical technology.

[0030] The so-called ODMR spectrum generally refers to the detection curve drawn by the optically detected magnetic resonance measurement method through the frequency sweep method (this curve is divided into two types: modulated and unmodulated. The point on the curve where the magnetic resonance frequency is located is also called the magnetic resonance characteristic point. On the modulated ODMR spectrum, the magnetic resonance characteristic point is the zero crossing point, and on the unmodulated ODMR spectrum, the magnetic resonance characteristic point is the peak value point of the resonance peak). Since it uses a frequency-swept microwave for operation, the spectrum drawing time is long, which is not conducive to quickly extracting characteristic values for magnetic field calculation.

[0031] Currently, quantum precision measurement systems based on solid-state spin color centers (such as diamond NV color centers, silicon carbide color centers, diamond germanium vacancy color centers, hexagonal boron nitride color centers, or diamond silicon vacancy color centers, etc.) often use the principle of optically detected magnetic resonance for magnetic field sensing detection.

[0032] Solid-state spin color centers include multi-axial color centers and single-axial color centers. Among them, some single-axial color centers (such as diamond NV single color centers, silicon carbide color centers, diamond germanium vacancy single color centers, diamond silicon vacancy single color centers, or hexagonal boron nitride color centers) often have higher-precision detection capabilities and are favored by scientific researchers. Some multi-axial color centers (such as four-axial color centers, such as ensemble diamond NV color centers, ensemble diamond germanium vacancy color centers, or ensemble diamond silicon vacancy color centers) can perform vector magnetic field calculations and have strong product application scenarios. Regarding single-axial color centers, due to their single axis, there is only a pair of magnetic resonance characteristic points on the ODMR sweep spectrum. For four-axial color centers, due to their four axes, by adjusting the angular relationship between the magnetic field and the axis, the number of magnetic resonance characteristic points on their ODMR sweep spectrum can be 2, 4, 6, or 8.

[0033] Collection of embodiments of quantum magnetometers Embodiment 1

[0034] See the appendix Figure 1 , this embodiment discloses a quantum magnetometer, which includes a solid-state spin color center probe, a microwave module, a laser module, a photoelectric detection module, a lock-in amplifier module, a PID module, and a data processing module, where: The solid-state spin color center probe is used to sense the magnetic field to be measured and generate feedback fluorescence; the mode of measuring the magnetic field by the solid-state spin color center belongs to the prior art. It is known that the magnitude of the magnetic field to be measured can be analyzed and calculated through the feedback fluorescence. In a specific example, the solid-state spin color center probe 3 should include a solid-state spin color center and a nearby microwave antenna, and the microwave signal is transmitted through the microwave antenna and acts on the solid-state spin color center; The microwave module is used to output a microwave signal acting on the solid-state spin color center probe; in a specific example, the microwave module includes a microwave source, a microwave amplifier, and a microwave circulator. The microwave source is the emission source of the microwave signal, the microwave amplifier can amplify the microwave power, and the microwave circulator can prevent the reverse transmission of the microwave signal.

[0035] The laser module is used to output a laser signal acting on the solid-state spin color center probe; in a specific example, the laser module should include a laser and some optical elements. The excitation laser wavelength output by the laser should be able to effectively excite the selected solid-state spin color center probe (for example, if the solid-state spin color center is a diamond NV color center, the excitation laser should be around 532 nm). Preferably, the optical elements include but are not limited to some optical fibers, optical couplers, dichroic lenses, filter films, etc., which are specifically determined according to the system structure design.

[0036] The photoelectric detection module is used to receive the feedback fluorescence and generate a voltage signal; in this example, in a specific example, the photoelectric detection module should include a photodetector (such as an avalanche diode). The feedback fluorescence should be purified before contacting the photodetector to eliminate the stray light transmitted along with the feedback fluorescence (for example, using an optical filter lens, etc.); in addition, the feedback fluorescence generated at the solid-state spin color center probe can be transmitted to the photodetector through an optical fiber or in the form of spatial light.

[0037] The lock-in amplifier module is used for signal processing and modulation and demodulation; in this example, the lock-in amplifier module should at least implement the modulation of the microwave signal and the demodulation of the voltage signal. Further, it is also necessary to condition and perform analog-to-digital conversion on the voltage signal before demodulation. In a specific solution, an existing lock-in amplifier can be selected for the lock-in amplifier module.

[0038] The PID module is used to perform feedback regulation on the microwave signal to switch its frequency to the microwave resonance frequency characterizing the current magnetic field. Regarding the PID module, it has an input value and a target value. By comparing the two, a feedback regulation parameter can be output to change the input value until it is equal to or close to the target value. In this example, the demodulation result output by the lock-in amplifier module serves as the input value of the PID module. To facilitate understanding of the role and principle of the PID module in this embodiment, a quantum magnetometer based on a diamond NV color center probe is taken as an example for explanation here. It implements the CW-ODMR method by sweeping the microwave frequency. The measured output fluorescence signal is converted into a voltage signal by the photoelectric detection module and then input to the lock-in amplifier module. After being demodulated by the bidirectional digital demodulation method, the demodulation result (demodulation value R, demodulation X-term component value, demodulation Y-term component value, and phase value) is obtained. When constructing the ODMR spectrum line with the demodulation result and the microwave frequency as the vertical and horizontal coordinates respectively, a spectrum line similar to Figure 2 or Figure 3 as shown will be obtained. Analyzing the spectrum line, it can be seen that the magnetic resonance characteristic points are all zero-crossing points. Therefore, when switching the magnetic field, only by making the vertical coordinate zero can the microwave resonance frequency under the current magnetic field (i.e., the horizontal coordinate at the zero-crossing point) be traced. Based on this principle, we set the target value of the PID module to 0, and the rapid locking of the microwave resonance frequency can be achieved. This method of obtaining the microwave resonance frequency does not require drawing the ODMR spectrum line by sweeping a large range of frequencies, greatly improving the acquisition speed of the microwave resonance frequency, that is, improving the magnetic measurement efficiency.

[0039] The data processing module is used for data processing, plotting, and analysis, and outputs the characterization result of the magnetic field to be measured. In a specific example, the data processing module is included in the upper computer and at least internally stores a program method for calculating the magnetic field based on the microwave resonance frequency, a functional module for realizing the drawing of the ODMR spectrum line, etc.

[0040] In some preferred designs, the lock-in amplifier module is a dual-phase digital demodulator. The demodulation result obtained by demodulating through the dual-phase demodulation sub-unit includes the demodulation value R, the demodulation X-term component value, the demodulation Y-term component value, and the phase value. In a further design, it also includes a phase self-adjustment module. The phase self-adjustment module is used to automatically adjust the initial phase of the lock-in amplifier module according to the set target. Specifically, when using a dual-phase digital lock-in amplifier for modulation and demodulation and hoping that the drawn ODMR spectrum line is as shown in the appendix Figure 3When shown as such, initial phase adjustment is required to obtain more accurate measurement requirements. Conventionally, it is carried out by manually continuously adjusting the initial phase and observing whether one of the component values meets the set target. This process has low automation, so an automated design is carried out in the software program. In a specific example, the set target can be: to make the demodulated X-term component value or the demodulated Y-term component value equal to zero or near zero (i.e., a near-zero value). According to this set target, the software program can continuously correct the initial phase and complete the closed loop by judging whether the set target is achieved. The programming of this program is relatively simple and will not be elaborated here.

[0041] In some other preferred designs, the quantum magnetometer further includes a magnetic field generating module for generating a bias magnetic field acting on the solid-state spin color center probe. The main reason for setting this module is that when the solid-state spin color center is a four-axis color center (such as an ensemble diamond NV color center), by applying a bias magnetic field, the number of magnetic resonance characteristic points on the ODMR spectrum can be regulated, so as to realize the tracking of multiple magnetic resonance frequencies and achieve richer data detection and processing functions (such as vector magnetic field detection, improving detection stability, etc.). Specifically, the magnetic field generating module can be a permanent magnet or an energized coil; As a preferred design matching the magnetic field generating module, the quantum magnetometer is also equipped with an azimuth adjustment module. The azimuth adjustment module is used to adjust the spatial position of the magnetic field generating module. By changing the relative angle between the bias magnetic field and the solid-state spin color center probe, an ODMR spectrum line with different numbers of magnetic resonance characteristic points can be formed. As a usage method, the position adjustment device can be manually adjusted to realize the angle transformation of the bias magnetic field; of course, further, the position adjustment device is an automated device, and the control processing module includes a position adjustment unit. The position adjustment unit can control the position adjustment device according to the set instruction to realize the automatic adjustment of the bias magnetic field. In an exemplary scheme, the principle of the automatic adjustment software program is: control the position adjustment device to continuously start, switch the application angle of the bias magnetic field, and simultaneously automatically identify the number of magnetic resonance characteristic points on the ODMR. When the number is equal to the number of the set instruction, the angle self-adjustment process is completed. The programming of this program is relatively simple and will not be elaborated here.

[0042] In some preferred designs, the quantum magnetometer further includes a characteristic point self-acquisition module. The characteristic point self-acquisition module is used to automatically identify the magnetic resonance characteristic points on the ODMR spectrum line and obtain the microwave resonance frequency corresponding to the magnetic resonance characteristic points. In the existing technology, generally, the magnetic resonance characteristic points on the ODMR spectrum line are obtained by manual clicking. The defects of this method have been proposed in the background technology. Therefore, this preferred design proposes the function of automatically identifying characteristic points. In an exemplary scheme, when the drawn ODMR sweep spectrum line is as shown in the appendix Figure 2 or in the appendix Figure 3When shown as such, the magnetic resonance feature point is the zero crossing point. At this time, the recognition target of the feature point acquisition module is the zero crossing point; when the drawn ODMR sweep spectrum line is as shown in the appendix Figure 4 When shown as such, the magnetic resonance feature point is the point where the peak is located. Therefore, at this time, the recognition target of the feature point acquisition module is the coordinate value of the peak point.

[0043] In some preferred designs, the microwave module further includes a combiner, which is used to combine multiple microwave signals into one path and output them to the solid-state spin color center probe. The purpose is to let the multiple microwave signals be mixed and then form a microwave field through a microwave antenna to act on the solid-state spin color center probe. This can reduce the number of microwave antennas used and also reduce the microwave transmission lines, optimizing the structural design.

[0044] In some preferred designs, the photoelectric detection module includes a single-channel voltage signal output unit and a signal splitting unit. The single-channel voltage signal output unit is used to receive the feedback signal and output a total voltage signal. The signal splitting unit is used to split the total voltage signal into multiple split voltage signals for output, and the number of split voltage signals is the same as the number of microwave signals. The lock-in amplifier module processes and demodulates each split voltage signal. In a specific example, when there are multiple microwave signals, it is necessary to obtain the same number of voltage signals and demodulate them. The conventional technology is to independently collect the feedback fluorescence through multiple photodetectors to obtain a single-channel voltage signal output. However, the above design only requires one photodetector to collect the feedback fluorescence and output a single-channel voltage signal, and then a signal splitting unit splits this voltage signal into the required number of split voltage signals. This design can simplify the structural design and facilitate the miniaturization design of the probe structure. Among them, the signal splitting unit is a conventional existing product, and it can be directly selected and purchased, so it will not be elaborated here.

[0045] Generally speaking, the various solutions described in Embodiment 1 can be used as a basic design to describe the structure and function of the quantum magnetometer. However, the characteristics of the solid-state spin color center are diverse, and the multi-axial and single-axial color centers have different characteristics. For these distinguishing features, some specific designs should be made. Based on this consideration, Embodiment 2 and Embodiment 3 are proposed. Embodiment 2

[0046] On the premise of Embodiment 1, this embodiment requires that the solid-state spin color center probe 5 is an ensemble diamond NV color center probe or an ensemble diamond germanium vacancy color center probe or an ensemble diamond silicon vacancy color center.

[0047] It can be clearly seen that the solid-state spin color centers in the above probes all have four-axial color centers (as shown in the appendix Figure 5As shown in the figure, it is an axial diagram of the NV color center of the ensemble diamond), so when measuring the magnetic field, the component detection data of the magnetic field in the four axes can be obtained, and the angle of each axis is determined. Based on this, the direction and size of the magnetic field can be inferred through the component detection data and the angle relationship (this part of the technology is already existing technology and will not be repeated here).

[0048] In some preferred designs, the microwave module includes eight working microwave output units, which means that eight independent and different microwave signals can be output. When working, each microwave signal is independently modulated, feedback-adjusted, and the like. This method is easier to implement (correspondingly, when only one working microwave output unit is used for work, a control method needs to be designed to output eight different microwave signals, and the process is more complicated). In this design, each working microwave output unit contains at least one microwave source. Furthermore, the working microwave output unit includes a microwave source, a microwave amplifier, and a microwave circulator.

[0049] Furthermore, the microwave output module includes a combiner, which is used to combine eight working microwaves into one and output it to the space where the solid-state spin color center probe is located. In an exemplary scheme, when there are eight independent and different microwave signals, six two-in-one combiners can be added, through which the eight working microwaves can be combined into one and output to one microwave antenna.

[0050] Furthermore, the photoelectric detection module includes a voltage signal output unit and a one-to-eight signal splitting module, the voltage signal output unit is used to receive a feedback signal and output a total voltage signal, the one-to-eight signal splitting module is used to split the total voltage signal into eight divided voltage signal outputs (equal division is sufficient, there are related products on the market, and it is a known technology), and the modulation and demodulation unit processes and demodulates each of the divided voltage signals.

[0051] To facilitate understanding of the above scheme design, this example introduces a system structure of a quantum magnetometer based on an ensemble diamond NV color center probe, as shown in the attached figure. Figure 6As shown, it includes a 532nm laser 1, eight microwave output devices 2, an ensemble diamond NV color center probe 3, a photodiode 4, eight lock-in amplifiers 5 and a host computer 6. Among them, the host computer 6 contains a PID module and a data acquisition card. The microwave signals output by the eight microwave output devices 2 are modulated (the modulation signal is provided by the lock-in amplifier 5, preferably a frequency modulation signal), and then merged into a working microwave through six two-in-one combiners 21 and enter the ensemble diamond NV color center probe 3. The 532nm laser 1 outputs 532nm laser, and is transmitted through an optical fiber and enters the ensemble diamond NV color center probe 3 through a dichroic mirror 41. Under the excitation of the working microwave and the 532nm laser, the ensemble diamond NV color center probe 3 transmits back the feedback fluorescence. The feedback fluorescence is reflected by the dichroic mirror 41 and filtered by a filter 42 and then collected by the photodiode 4. The photodiode 4 receives the fluorescence signal and outputs a voltage signal. The voltage signal is divided into eight sub-voltage signals through an eight-way signal splitting module 43. The eight sub-voltage signals are received and demodulated by the eight lock-in amplifiers 5 one by one. The host computer 6 is used to realize various control requirements and data processing functions of the whole machine (covering various functions mentioned in the foregoing method embodiments).

[0052] Appendix Figure 6 is a schematic diagram, which should not limit other system solutions of this embodiment (for example, a solution using a microwave module with less than eight working microwave output units to output microwave signals, or a solution without using a combiner to combine multiple microwave signals, and each microwave signal acts on a solid-state spin color center through a microwave antenna alone, etc. For another example, a solution using eight voltage signal output units to each receive a feedback signal, that is, without using a signal splitting module, etc.).

[0053] Although using a four-axis color center can perform vector magnetic field measurement, scalar magnetic field measurement can also be performed. The above solution only preferably introduces the vector magnetic field measurement solution and does not limit the solution using a four-axis color center for scalar magnetic field measurement. Embodiment 3

[0054] On the premise of Embodiment 1, this embodiment requires that the solid-state spin color center probe is a diamond NV single color center probe, or a silicon carbide color center probe, or a diamond germanium vacancy single color center probe, or a diamond silicon vacancy single color center probe, or a hexagonal boron nitride color center probe.

[0055] It can be understood that since the aforementioned solid-state spin color center probe has a single color center axis and a strong ability to sense the external magnetic field, in the prior art, it is also disclosed that the aforementioned color center also calculates the magnetic field magnitude through the magnetic resonance frequency, so it can be used as the solid-state spin color center probe in this embodiment.

[0056] In some preferred designs, the microwave module includes a working microwave output unit. Preferably, the working microwave output unit includes a microwave source, a microwave amplifier, and a microwave circulator.

[0057] For the convenience of understanding the foregoing design, by way of example, this example introduces the system composition of a quantum magnetometer based on a diamond single NV color center probe. As shown in the appendix Figure 7 shown, regarding this system structure, it basically coincides with the devices in the system shown in the appendix Figure 6 shown. The difference is that there are only two microwave output devices 2, two lock-in amplifiers 5, and a two-in-one multiplexer 21, and their working principles are also the same. To avoid text redundancy, it will not be elaborated here.

[0058] One of the advantages of this solution is that it simplifies the structural design of the quantum magnetometer and reduces the equipment cost.

[0059] Example 1 can only be used for the measurement of scalar magnetic fields, but not for the measurement of vector magnetic fields.

[0060] Set of embodiments of the magnetic field measurement method Example 4

[0061] See the appendix Figure 8 , this embodiment discloses a magnetic field measurement method, which can be applied to any of the foregoing quantum magnetometers, and includes an initial parameter acquisition step and an official measurement step, where: The initial parameter acquisition step includes: S1. Control the microwave module to output a swept-frequency microwave signal; In specific operations, the parameters of the swept-frequency microwave are set through the microwave initial adjustment unit. These parameters include the center frequency, scanning range, step frequency, and interval time. In this step, a modulation signal can also be applied to process this swept-frequency microwave. Taking the quantum magnetometer based on the diamond NV color center probe as an example, the exemplary configuration scheme is as follows: set the swept-frequency center frequency to 2.87 GHz, the scanning range to 400 MHz, the step frequency to 1 MHz, and the interval time to 1 ms (of course, a frequency modulation signal of 10 KHz can also be applied to modulate the swept-frequency microwave).

[0062] S2. Start the quantum magnetometer to perform measurements based on the swept-frequency microwave signal, and draw a target ODMR spectrum line; In this step, under the dual action of the swept-frequency microwave signal and the laser signal, the solid-state self-selected color center probe outputs feedback fluorescence. By processing and mapping based on this detection signal, a target ODMR spectrum line can be obtained. Regarding the line type of the target ODMR spectrum line, there are generally two types. One is that the magnetic resonance characteristic point is the zero crossing point (the swept-frequency microwave is modulated), and the other is that the magnetic resonance characteristic point is the peak point (the swept-frequency microwave is not modulated). In this step, the PID module does not start to function.

[0063] S3. Obtain the microwave resonance frequency at the magnetic resonance feature point on the target ODMR spectrum line; Regarding the means of obtaining the microwave resonance frequency, manual clicking can be used. Of course, a software program can also be set up to automatically obtain the microwave resonance frequency, such as curve fitting.

[0064] S4. Select several microwave resonance frequencies and record them as the initial microwave frequencies; Regarding the significance of the initial parameter acquisition step, it is based on the ODMR spectrum line under frequency modulation. Through analysis, it can be seen that the microwave resonance frequency of any magnetic field belongs to the abscissa of the zero-crossing point on the ODMR spectrum line under frequency modulation. Therefore, if we set the locking condition based on the zero-crossing point, we can quickly lock the microwave resonance frequency of the next magnetic field. Of course, the prerequisite is that we have a starting microwave resonance frequency that matches the current solid-state spin color center probe. This is the actual purpose of this step.

[0065] The formal measurement steps include: S5. Control the microwave module to output a point-frequency microwave signal at the initial microwave frequency; During formal measurement, there is no need to use a swept-frequency microwave anymore. Instead, directly work with a point-frequency microwave signal and a laser signal.

[0066] S6. Set the lock-in amplifier module to output a frequency-modulated signal to modulate the point-frequency microwave signal; Exemplarily, a frequency-locking signal can be output by the lock-in amplifier to modulate the point-frequency microwave signal.

[0067] S7. Based on the point-frequency microwave signal, start the quantum magnetometer, measure the magnetic field to be measured, and obtain the demodulation result; Exemplarily, the quantum magnetometer can be started by the CW-ODMR method. The acquired feedback fluorescence is converted into a voltage signal by the photoelectric detection module. The voltage signal is processed through conditioning and analog-to-digital conversion, and then demodulated by the lock-in amplifier to obtain the demodulation result.

[0068] S8. The PID module performs feedback adjustment on the microwave signal according to the demodulation result and the target value, so that its frequency switches to the microwave resonance frequency representing the magnetic field to be measured; Exemplarily, the demodulated R value can be used as the input value of the PID module. Set the target value to 0, and change the microwave signal by adjusting the feedback parameters to finally lock the microwave operating frequency.

[0069] S9. Analyze and calculate the microwave resonance frequency representing the magnetic field to be measured, and output the magnetic field to be measured characterization result.

[0070] The method of using the microwave resonance frequency for magnetic field measurement is already in the prior art and will not be introduced here.

[0071] In addition, we know that the selection of solid-state self-selected color centers has diversity and different functionalities. Based on this, for solid-state self-selected color center probes of different types and functions, this solution also proposes some supporting solutions. For specific details, please refer to Embodiment 5 and Embodiment 6. Embodiment 5

[0072] Based on Embodiment 4, this example introduces some usage methods when the solid-state spin color center probe is a four-axial solid-state spin color center probe. The mentioned four-axial solid-state spin color center probe is mainly an ensemble diamond NV color center probe, an ensemble diamond germanium vacancy color center probe, or an ensemble diamond silicon vacancy color center.

[0073] For a four-axial solid-state spin color center probe, it can be used for vector magnetic field detection or only scalar magnetic field measurement. The following specifically introduces two magnetic field detection modes.

[0074] Mode 1

[0075] The initial parameter acquisition step further includes: S11. Set a bias magnetic field so that the target ODMR spectral line has eight magnetic resonance characteristic points, that is, has eight microwave resonance frequencies. During implementation, manually or automatically adjust the angle of the bias magnetic field, and at the same time observe the number of magnetic resonance characteristic points on the ODMR spectral line on the display device until eight magnetic resonance characteristic points appear. When this situation occurs, the angle of the bias magnetic field must be fixed and maintained. During formal measurement, the output of the same bias magnetic field must also be ensured.

[0076] S12. Select n microwave resonance frequencies as the initial microwave frequencies, where n ≤ 8. Note that microwave resonance frequencies always appear in pairs (two microwave resonance frequencies symmetric about the center frequency of the swept microwave signal are a pair). When selecting microwave resonance frequencies, it is recommended to select an even number. The selection process can be obtained manually or automatically recognized by the program.

[0077] The formal measurement step further includes: S13. Maintain the output of the bias magnetic field unchanged. During actual measurement, the magnetic field sensed by the solid-state spin color center probe is the bias magnetic field and the magnetic field to be measured.

[0078] S14. Control the microwave module to output n point-frequency microwave signals according to the selected initial microwave frequencies. As an explanation, in an exemplary solution, as shown in the appendix Figure 6 Eight point-frequency microwave signals are synchronously output by 8 microwave sources, and then the eight point-frequency microwave signals are combined into one by a combiner and radiated to the solid-state spin color center through a microwave antenna.

[0079] S15. Apply n different magnitudes of frequency-modulated signals to modulate with the n point-frequency microwave signals one by one; The feedback fluorescence output by the solid-state spin color center probe is generated by the simultaneous action of multiple point-frequency microwave signals. Applying frequency-modulated signals of different magnitudes is to facilitate distinguishing the demodulation results corresponding to each path of point-frequency microwave signals after phase-locked demodulation.

[0080] As an explanation, in an exemplary solution, as shown in the appendix Figure 6 As shown, use eight phase-locked amplification modules to each output a frequency-modulated signal to modulate eight microwave signals.

[0081] S16. After adjustment by the PID module, obtain n groups of microwave resonance frequencies characterizing the magnetic field to be measured; In an exemplary solution, eight PID modules are designed to each lock a group of microwave resonance frequencies.

[0082] S17. Analyze and calculate, and output magnetic field information.

[0083] In the above-mentioned Mode 1, in a preferred design, make n = 8 or n = 4 and all microwave resonance frequencies are on the same side of the center frequency of the swept-frequency microwave signal. At this time, detection data of magnetic field components in four axial directions can be obtained. Based on this, magnetic field vector information can be obtained.

[0084] In other cases, it can only be used for the measurement of scalar magnetic fields.

[0085] Specifically, a space coordinate system is constructed in the quantum magnetometer to assist in describing vector magnetic field information.

[0086] The function of the above-mentioned Mode 1 is to realize vector detection of the magnetic field. A magnetometer with vector detection function has a wider range of applications, but its system composition is relatively complex and the cost is relatively high.

[0087] Mode 2

[0088] The initial parameter acquisition step further includes: S21. Set a bias magnetic field to make the target ODMR spectral line have four magnetic resonance characteristic points, that is, have four microwave resonance frequencies; During implementation, manually or automatically adjust the angle of the bias magnetic field, and at the same time observe the number of magnetic resonance characteristic points on the ODMR spectral line on the display device until four magnetic resonance characteristic points appear; when this situation occurs, the angle of the bias magnetic field must also be fixed and maintained. During formal measurement, the output of the same bias magnetic field must also be ensured.

[0089] S22. Select the maximum value or the minimum value or both (the maximum value and the minimum value) of the four microwave resonance frequencies as the initial microwave frequency; Specifically, for the ODMR spectrum to have four magnetic resonance characteristic points, it is required that the bias magnetic field forms only two angles of different magnitudes with the axes of the four color centers, that is, it is only required that the bias magnetic field is parallel to the axis of one of the color centers (this part belongs to the knowledge known in the art), in order to Figure 4 take an example, the two resonance peaks on the leftmost and rightmost represent the magnetic field components on the color center axis parallel to the bias magnetic field, and the two resonance peaks in the middle represent the superposition of the magnetic field components of the other three color center axes. During actual measurement, the two resonance peaks in the middle will also show splitting, which will cause the PID to be unable to achieve frequency locking. Based on this consideration, only the maximum value or the minimum value or both of the four microwave resonance frequencies are selected for tracking here.

[0090] In addition, the selection process of the microwave resonance frequency can be obtained manually or automatically recognized by the program.

[0091] The formal measurement steps further include: S23. Maintain and output the bias magnetic field unchanged; S24. Control the microwave module to output a corresponding number of dot-frequency microwave signals at the initial microwave frequency; As an explanation, in an exemplary solution, two dot-frequency microwave signals are synchronously output by two microwave sources, and then the two dot-frequency microwave signals are combined into one by a combiner and radiated by a microwave antenna to act on the solid-state spin color center.

[0092] S25. Apply a frequency modulation signal to modulate the dot-frequency microwave signals one by one; As an explanation, in an exemplary solution, two lock-in amplifier modules are used to output frequency modulation signals to modulate the microwave sources.

[0093] S26. Through the adjustment of the PID module, obtain the microwave resonance frequency characterizing the magnetic field to be measured; In an exemplary solution, two PID modules are designed to lock a group of microwave resonance frequencies respectively.

[0094] S27. Analyze and calculate, and output the magnetic field information.

[0095] The function of the above-mentioned mode two is to realize scalar magnetic field measurement, which can be applied to some specific scenarios of magnetic field directions. Its application range and function are relatively single, but its overall machine composition is simpler and the cost is lower.

[0096] Both the above-mentioned mode one and mode two need to apply a bias magnetic field. Therefore, components for providing a bias magnetic field, such as energized coils or permanent magnets, can be configured in the quantum magnetometer. Of course, the component for providing the bias magnetic field can also be used as a configured part and not installed in the quantum magnetometer body. Example Six

[0097] Based on Example 4, this example introduces some usage methods when the solid-state spin color center probe is a uniaxial solid-state spin color center probe. The mentioned uniaxial solid-state spin color center probe is mainly a diamond NV single-color center probe, or a silicon carbide color center probe, or a diamond germanium vacancy single-color center probe, or a diamond silicon vacancy single-color center probe, or a hexagonal boron nitride color center probe.

[0098] For a uniaxial solid-state spin color center probe, only scalar magnetic field measurement can be performed, and vector magnetic field detection cannot be performed. Based on the aforementioned detection method using a bias magnetic field, Working Mode 1 in this example is proposed.

[0099] Working Mode 1

[0100] The initial parameter acquisition step further includes: S31. Set a bias magnetic field and draw a target ODMR spectrum line based on the bias magnetic field; Adjust the magnitude or direction of the bias magnetic field until a relatively clear and usable ODMR spectrum line appears. Due to the uniaxial characteristics, this ODMR spectrum line has only two magnetic resonance characteristic points.

[0101] S32. Select one or all of the microwave resonance frequencies as the initial microwave frequency; Either one or both of the two symmetric microwave resonance frequencies can be selected, and it can be obtained manually or automatically recognized by the program.

[0102] The formal measurement step further includes: S33. Maintain the output of the bias magnetic field unchanged; S34. Control the microwave module to output corresponding dot-frequency microwave signals according to this initial microwave frequency; As an explanation, in an exemplary solution, as shown in the appendix Figure 7 Two microwave sources can be used to output two-way dot-frequency microwave signals.

[0103] S35. Apply a frequency modulation signal to modulate each dot-frequency microwave signal one by one; As an explanation, in an exemplary solution, as shown in the appendix Figure 7 Two lock-in amplifier modules can be used to output two kinds of frequency modulation signals.

[0104] S36. After adjustment by the PID module, obtain the microwave resonance frequency representing the magnetic field to be measured; In an exemplary solution, two PID modules are designed to lock a group of microwave resonance frequencies respectively.

[0105] S37. Analyze and calculate, and output the magnetic field information.

[0106] This magnetic field information is scalar magnetic field information.

[0107] In the above mode, a bias magnetic field generating module is used, which can be a permanent magnet or a powered coil. The bias magnetic field generating module can be integrated with the quantum magnetometer or can be an independent supporting component.

[0108] In addition, experiments have shown that a single-axial solid-state spin color center probe will also produce a zero-magnetic field resonance peak due to internal stress in a zero-magnetic field environment, which is manifested in the appearance of two magnetic resonance characteristic points on the ODMR spectrum. For a single-axial solid-state spin color center probe, its ODMR spectrum itself will only produce two magnetic resonance characteristic points. Therefore, it can be considered to directly use the microwave resonance frequency under zero magnetic field as the initial microwave frequency for tracking, and thus working mode 2 is proposed.

[0109] Working mode 2

[0110] The initial parameter acquisition step further comprises: S41, without applying a bias magnetic field, drawing a target ODMR spectrum line based on the inherent characteristics of the solid-state spin color center; Under the action of internal stress, solid-state spin color centers can produce ODMR spectral lines with two magnetic resonance characteristic points without the need for an external magnetic field.

[0111] S42, selecting one or all of the microwave resonance frequencies as the initial microwave frequency; One or two microwave resonance frequencies can be selected arbitrarily. The selection process can be obtained manually or automatically by program recognition.

[0112] The formal measurement steps also include: S43, controlling the microwave module to output a corresponding number of point-frequency microwave signals according to the initial microwave frequency; S44, applying a frequency modulation signal to modulate the point frequency microwave signal in a one-to-one correspondence; S45, obtaining a microwave resonance frequency representing the magnetic field to be measured through adjustment by a PID module; S46. Analyze and calculate, and output magnetic field information.

[0113] The above-mentioned working mode 2 is different from the aforementioned magnetic field measurement method. Its biggest advantage is that it eliminates the use of the bias magnetic field and simplifies the structure or use composition of the quantum magnetometer. Embodiment 7

[0114] In the aforementioned magnetic field measurement schemes, it is mentioned that the demodulation results are compared with the target data to obtain the frequency adjustment parameters. Among them, regarding the demodulation results, different demodulation methods have different expressions of demodulation results. For example, in single-phase demodulation, the demodulation result only includes the demodulation value R value (non-negative); in dual-phase demodulation, the demodulation result includes the demodulation value R value (non-negative), the demodulation X-term component value, the demodulation Y-term component value and the phase value.

[0115] For better understanding, taking a quantum magnetometer using a diamond NV - color - center probe as an example, the ODMR spectrum constructed using the demodulation value R and the microwave frequency is as shown in the appendix Figure 2 As shown, if the demodulation value R is used as the input value of the PID module for comparison with the target value to analyze the spectrum, when the magnetic field is switched, the new magnetic resonance characteristic point is the zero - crossing point on the graph (the zero - crossing point is the target locked by the PID, so the target value is generally set to 0). The magnetic resonance characteristic point of the previous magnetic field is point A (or point B). To move the magnetic resonance characteristic point from point A (or point B) to the zero - crossing point, a frequency adjustment parameter needs to be provided. For example, if the magnetic resonance characteristic point is at point A, a positive frequency adjustment parameter needs to be set to increase the frequency of the microwave signal; if the magnetic resonance characteristic point is at point B, a negative frequency adjustment parameter needs to be set to decrease the frequency of the microwave signal. Therefore, when outputting the frequency adjustment parameter, it is also necessary to judge the direction of feedback adjustment. The conventional solution is: randomly apply a positive (or negative) frequency adjustment parameter, and then judge whether the demodulation result after adjustment is closer to the zero point. If so, continue to apply the positive (or negative) frequency adjustment parameter until the frequency locking process is completed; if not, apply a negative (or positive) frequency adjustment parameter for frequency adjustment. This frequency adjustment method, due to the need to judge the adjustment direction, results in a long frequency adjustment time and there is a bandwidth limitation (taking the appendix Figure 2 as an example, the above - mentioned adjustment steps can only be implemented in the part between the peak points of the two waves).

[0116] Since the direction needs to be considered during the feedback adjustment of the aforementioned microwave signal, it will additionally increase the speed of frequency locking and affect the magnetic field measurement speed of the whole machine.

[0117] To improve the feedback adjustment efficiency of the PID module, the following preferred scheme design is proposed in this embodiment: In the formal measurement step, the voltage signal is demodulated by the two - phase digital demodulation method; Through phase adjustment, one of the two demodulated component values is made close to zero, and the other component value is used as the input value of the PID module for comparison with the target value, and the frequency adjustment parameter of the microwave signal is output.

[0118] In an exemplary scheme, a two - phase digital lock - in amplifier is used to work. It demodulates the voltage signal by the two - phase digital demodulation method, and the output demodulation result includes the demodulation value R, the demodulated X - term component value, the demodulated Y - term component value, and the phase value. Phase adjustment is performed on this two - phase digital lock - in amplifier (referring to the phase of the frequency - modulated signal or the reference signal) to make the demodulated X - term component value (or the demodulated Y - term component value) zero, use the demodulated Y - term component value (or the demodulated X - term component value) as the input value of the PID module, set the target value, compare the input value and the target value to output the frequency adjustment parameter, and adjust the microwave signal output by the microwave source.

[0119] For ease of understanding, taking a quantum magnetometer using a diamond NV color center probe as an example, the demodulated X-term component value is made zero, the demodulated Y-term component value is used as the input value of the PID module, and the target value is set to 0. In this scenario, an ODMR spectrum is constructed with the demodulated Y-term component value and the microwave frequency, as shown in the appendix Figure 3 As shown, when the magnetic field changes, the new magnetic resonance feature point is the zero-crossing point on the graph (the zero-crossing point is the target locked by the PID. When the demodulation result is equal to 0, it means it is a magnetic resonance feature point. Therefore, the target value is generally set to 0). The magnetic resonance feature point of the previous magnetic field is point A (or point B). To move the magnetic resonance feature point from point A (or point B) to the zero-crossing point, a frequency adjustment parameter needs to be provided. Analyzing the spectrum shown in the appendix Figure 3 As shown, it will be found that the demodulated Y-term component value has positive and negative values before and after the zero-crossing point. Therefore, when the demodulated Y-term component value is greater than 0, the microwave signal frequency can be decreased, and vice versa, the microwave signal frequency can be increased. This feedback adjustment method is faster, effectively shortening the adjustment time of the PID module, improving the magnetic field measurement speed of the entire quantum magnetometer, and having a wider measurement bandwidth.

[0120] In the foregoing solution, it is mentioned that by adjusting the initial phase, one of the two demodulated component values is made close to zero. Regarding the near-zero value, its best value is selected as 0, but it can also fluctuate slightly above and below 0 (the fluctuation range can be limited to less than 10% of the amplitude of the component value); conventionally, the initial phase is manually adjusted, and it is observed in real time whether the selected component value on the phase lock is zero. Of course, automatic phase adjustment can also be achieved by designing a software program.

[0121] Embodiment of the storage medium

[0122] Corresponding to the above magnetic field measurement method, this embodiment also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the various magnetic field measurement methods described above are implemented.

[0123] The various embodiments in the specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0124] Those skilled in the art may further realize that the units and algorithm steps of each example described in connection with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed 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 for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0125] The steps of the methods or algorithms described in connection with the embodiments disclosed herein can be directly implemented by hardware, software modules executed by a processor, or a combination of the two. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0126] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0127] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, so that those skilled in the technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A quantum magnetometer, characterized in that, Including: A solid-state spin color center probe for sensing a magnetic field and generating feedback fluorescence; A microwave module for outputting a microwave signal acting on the solid-state spin color center probe; A laser module for outputting a laser signal acting on the solid-state spin color center probe; A photoelectric detection module for receiving the feedback fluorescence and generating a voltage signal; A lock-in amplifier module for signal processing and modulation and demodulation; A PID module for performing feedback adjustment on the microwave signal so that its frequency is switched to the microwave resonance frequency characterizing the current magnetic field; A data processing module for data processing, plotting, and analysis.

2. The quantum magnetometer according to claim 1, wherein, The lock-in amplifier module is a dual-phase digital demodulator.

3. The quantum magnetometer according to claim 2, characterized in that, It further includes a phase self-adjustment module for automatically adjusting the initial phase of the lock-in amplifier module according to a set target.

4. The quantum magnetometer according to claim 1, wherein It further includes a magnetic field generation module for generating a bias magnetic field acting at the solid-state spin color center probe.

5. The quantum magnetometer according to claim 4, characterized in that, It further includes an azimuth adjustment module for automatically or manually adjusting the spatial position of the magnetic field generation module.

6. The quantum magnetometer according to claim 1, wherein, It further includes a feature point self-acquisition module for automatically identifying the magnetic resonance feature points on the ODMR spectrum line and acquiring the microwave resonance frequency corresponding to the magnetic resonance feature points.

7. The quantum magnetometer according to claim 1, characterized in that, The microwave module includes a combiner for combining multiple microwave signals into one and outputting them to the solid-state spin color center probe.

8. The quantum magnetometer according to claim 1, characterized in that, The photoelectric detection module includes a single-channel voltage signal output unit and a signal splitting unit. The single-channel voltage signal output unit is used for receiving the feedback signal and outputting a total voltage signal. The signal splitting unit is used for splitting the total voltage signal into multiple sub-voltage signals for output, and the number of sub-voltage signals is the same as the number of microwave signals. The lock-in amplifier module processes and demodulates each sub-voltage signal.

9. The quantum magnetometer according to any one of claims 1-8, characterized in that, The solid-state spin color center probe is an ensemble diamond NV color center probe or an ensemble diamond germanium vacancy color center probe or an ensemble diamond silicon vacancy color center.

10. The quantum magnetometer according to claim 9, characterized in that, The microwave module includes eight independently arranged microwave signal generation units.

11. The quantum magnetometer according to any one of claims 1-8, characterized in that, The solid-state spin color center probe is a diamond NV single color center probe or a silicon carbide color center probe or a diamond germanium vacancy single color center probe or a diamond silicon vacancy single color center probe or a hexagonal boron nitride color center probe.

12. The quantum magnetometer according to claim 11, characterized in that, The microwave module includes two independently arranged microwave signal generation units.

13. A magnetic field measurement method, applied to the quantum magnetometer according to any one of claims 1-8, characterized in that, It includes an initial parameter acquisition step and a formal measurement step, where: The initial parameter acquisition step includes: S1. Controlling the microwave module to output a frequency-swept microwave signal; S2. Based on the frequency-swept microwave signal, starting the quantum magnetometer to perform measurement and plotting a target ODMR spectrum line; S3. Acquiring the microwave resonance frequency at the magnetic resonance feature points on the target ODMR spectrum line; S4. Selecting several microwave resonance frequencies and recording them as the initial microwave frequencies; The formal measurement step includes: S5. Controlling the microwave module to output a point-frequency microwave signal at the initial microwave frequency; S6. Setting the lock-in amplifier module to output a frequency-modulated signal to modulate the point-frequency microwave signal; S7. Based on the point-frequency microwave signal, starting the quantum magnetometer to measure the magnetic field to be measured and obtaining the demodulation result; S8. The PID module performs feedback regulation on the microwave signal according to the demodulation result and the target value to switch its frequency to the microwave resonance frequency characterizing the magnetic field to be measured; S9. Analyze and calculate the microwave resonance frequency characterizing the magnetic field to be measured, and output the characterization result of the magnetic field to be measured.

14. The magnetic field measurement method according to claim 13, characterized in that, When the solid-state spin color center probe is a four-axis solid-state spin color center probe, it includes the following two detection modes: Mode 1: The initial parameter acquisition step further includes: S11. Set a bias magnetic field to make the target ODMR spectrum have eight magnetic resonance characteristic points, that is, have eight microwave resonance frequencies; S12. Select n of the microwave resonance frequencies as the initial microwave frequencies, where n ≤ 8; The formal measurement step further includes: S13. Keep the output of the bias magnetic field unchanged; S14. Control the microwave module to output n point-frequency microwave signals at the selected initial microwave frequencies; S15. Apply n different magnitudes of frequency modulation signals to modulate the n point-frequency microwave signals one by one; S16. Through the regulation of the PID module, obtain n groups of microwave resonance frequencies characterizing the magnetic field to be measured; S17. Analyze and calculate, and output the magnetic field information; Mode 2, the initial parameter acquisition step further includes: S21. Set a bias magnetic field to make the target ODMR spectrum have six magnetic resonance characteristic points, that is, have six microwave resonance frequencies; S22. Select the maximum value or the minimum value or both of the six microwave resonance frequencies as the initial microwave frequency; The formal measurement step further includes: S23. Keep the output of the bias magnetic field unchanged; S24. Control the microwave module to output the corresponding number of point-frequency microwave signals at this initial microwave frequency; S25. Apply a frequency modulation signal to modulate the point-frequency microwave signals one by one; S26. Through the regulation of the PID module, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S27. Analyze and calculate, and output the magnetic field information.

15. The magnetic field measurement method according to claim 14, wherein, In the above Mode 1, when n = 8 or n = 4 and all microwave resonance frequencies are on the same side of the center frequency of the swept-frequency microwave signal, the magnetic field information includes magnetic field vector information.

16. The magnetic field measurement method according to claim 13, characterized in that, When the solid-state spin color center probe is a single-axis solid-state spin color center probe, it includes the following two detection modes: Mode 1: The initial parameter acquisition step further includes: S31. Set a bias magnetic field and draw a target ODMR spectrum based on the bias magnetic field; S32. Select one or all of the microwave resonance frequencies as the initial microwave frequencies; The formal measurement step further includes: S33. Keep the output of the bias magnetic field unchanged; S34. Control the microwave module to output the corresponding number of point-frequency microwave signals at this initial microwave frequency; S35. Apply a frequency modulation signal to modulate each point-frequency microwave signal one by one; S36. Through the regulation of the PID module, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S37. Analyze and calculate, and output the magnetic field information; Mode 2: The initial parameter acquisition step further includes: S41. Do not apply a bias magnetic field and draw a target ODMR spectrum based on the characteristics of the solid-state spin color center itself; S42. Select one or all of the microwave resonance frequencies as the initial microwave frequencies; The formal measurement step further includes: S43. Control the microwave module to output corresponding numbers of dot-frequency microwave signals according to the initial microwave frequency; S44. Apply a frequency modulation signal to modulate the dot-frequency microwave signals one by one; S45. Through the adjustment of the PID module, obtain the microwave resonance frequency characterizing the magnetic field to be measured; S46. Analyze and calculate, and output magnetic field information.

17. The magnetic field measurement method according to any one of claims 13-16, characterized in that In the formal measurement step, demodulate the voltage signal by the two-phase digital demodulation method; Through phase adjustment, make one of the two demodulated component values be a near-zero value, and use the other component value as the input value of the PID module to compare with the target value, and output the frequency adjustment parameter of the microwave signal.

18. A storage medium, characterized in that, The computer program is stored on the storage medium, and when the computer program is executed by the processor, the steps of the magnetic field measurement method according to any one of claims 13-17 are implemented.

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