Magnetic flux acquirer, diamond color center micro-nano-scale magnetic field measuring device and diamond color center micro-nano-scale magnetic field measuring method

Abstract

The invention provides a magnetic flux acquirer and a diamond color center micro-nano scale magnetic field measuring device and method.The magnetic flux acquirer comprises a first magnetic guide probe and a second magnetic guide probe, and the first magnetic guide probe and the second magnetic guide probe are the same in shape and symmetrically installed on the two sides of a diamond; the first magnetic guide probe and the second magnetic guide probe clamp the diamond and are used for guiding magnetic induction lines to the diamond, and the first magnetic guide probe and the second magnetic guide probe are both made of high-permeability materials; the diamond color center magnetic field measuring device based on the magnetic flux acquirer can measure the magnetic property of a micro-nano scale sample; according to the diamond color center-based micro-nano scale magnetic field measuring device, the sensitivity of micro-nano scale magnetic field sensing can be improved by applying a magnetic field modulation detection method. According to the technical scheme, the technical problem that in the prior art, the requirement for sensitivity improvement of micro-nano-scale magnetic field precision measurement is difficult to meet is solved.

Description

Technical Field

[0001] The present invention relates to the field of quantum precision measurement and micro-nano scale magnetic field measurement technology, and in particular to a magnetic flux acquirer, a diamond color center micro-nano scale magnetic field measurement device and method. Background Art

[0002] Precision measurement of magnetic fields at the micro-nano scale is of great significance in research fields such as material magnetism and micro-nano devices. The current solution for precision magnetic field measurement with the highest spatial resolution is diamond scanning probe technology that combines magnetic field measurement technology based on nitrogen-vacancy (NV) color centers with atomic force microscopy (AFM) technology. This can achieve nanoscale magnetic field detection based on nanodiamond probes. However, nanodiamond probes often have only a single NV color center, and the coherence time is shortened due to proximity to the diamond surface, resulting in a magnetic field detection sensitivity of only nT / Hz. 1 / 2 -μT / Hz 1 / 2 Magnitude.

[0003] On the other hand, in order to improve the sensitivity of magnetic field measurement, a spin ensemble is usually used, such as an alkali metal atomic vapor spin ensemble. The magnetic field measurement sensitivity based on alkali metal atomic vapor is better than 1fT / Hz. 1 / 2 , but requires a higher chamber temperature (400-500K) and a larger chamber volume (mm 3 -cm 3 ), the size is difficult to meet the needs of precise measurement of magnetic fields at the micro-nano scale.

[0004] Magnetic flux convergence and flux guidance technologies based on high magnetic permeability materials are used to improve the sensitivity or spatial resolution of magnetic sensors. For atomic magnetometers based on alkali metal atomic vapor, the intrinsic magnetic noise of high magnetic permeability materials is higher than their maximum measurement sensitivity, and due to the limitations of their mm-scale gas chambers and heating devices, high spatial resolution magnetic field measurements using flux guidance will degrade the sensitivity of atomic magnetometers to pT / Hz. 1 / 2 -nT / Hz 1 / 2 At the same time, the introduction of high magnetic permeability materials will destroy the low magnetic environment, which may cause the atomic magnetometer to fail to work properly. From the above, it can be seen that the current technology has a bottleneck in improving the sensitivity of micro-nanoscale sensing. Summary of the invention

[0005] The present invention provides a magnetic flux acquirer, a diamond color center micro-nanoscale magnetic field measurement device and a method, which can solve the technical problem that the demand for precise measurement of micro-nanoscale magnetic fields is difficult to meet in the prior art.

[0006] According to one aspect of the present invention, a magnetic flux acquirer is provided, which includes a first magnetic guide probe and a second magnetic guide probe. The first magnetic guide probe and the second magnetic guide probe have the same shape and are symmetrically installed on both sides of the diamond. The first magnetic guide probe and the second magnetic guide probe clamp the diamond to guide the magnetic induction line to the diamond. The first magnetic guide probe and the second magnetic guide probe are both made of high magnetic permeability material.

[0007] Furthermore, the first magnetic guidance probe includes a first probe segment, a second probe segment, a third probe segment and a fourth probe segment connected in sequence, and the angle between any two adjacent probe segments is an obtuse angle; the second magnetic guidance probe includes a fifth probe segment, a sixth probe segment, a seventh probe segment and an eighth probe segment, and the angle between any two adjacent probe segments is an obtuse angle; the diamond is arranged between the first probe segment and the fifth probe segment, and the sample to be tested is arranged between the fourth probe segment and the eighth probe segment.

[0008] Furthermore, the diamond is a cube, the heights of the first probe segment and the fifth probe segment are equal to the edge length of the diamond, and the thicknesses of the first magnetic guidance probe and the second magnetic guidance probe are equal to the edge length of the diamond.

[0009] According to another aspect of the present invention, a diamond color center micro-nanoscale magnetic field measuring device based on a magnetic flux acquirer is provided, characterized in that the diamond color center micro-nanoscale magnetic field measuring device comprises a sample vibration measuring platform assembly and a diamond color center magnetic field measuring assembly, the sample vibration measuring platform assembly comprises a sample probe, a sample probe base, a resonant reed, a piezoelectric ceramic and a base, the end of the sample probe is used to install the sample particles to be measured, the sample probe is mounted on the sample probe base, the sample probe base is mounted on the resonant reed, the resonant reed is mounted on the piezoelectric ceramic, the piezoelectric ceramic is mounted on the base, the piezoelectric ceramic is used to drive the resonant reed to vibrate, and the resonant reed drives the sample to be measured to move up and down in the gap of the magnetic flux acquirer by driving the sample probe; the diamond color center magnetic field measuring assembly comprises diamond, a magnetic flux acquirer, a fluorescence collecting lens, a rod mirror waveguide, a filter, a first photodetector, a microwave coil and microwave waveguide parts, a spectroscope, a laser, a neutral attenuation plate, a second photodetector A detector, a phase-locked amplifier and a processing unit, the flux acquirer is the flux acquirer of any one of claims 1 to 3, the diamond is bonded to the incident end of the fluorescence collecting lens, the fluorescence collecting lens is bonded to one end of the rod mirror waveguide, the other end of the rod mirror waveguide is connected to the filter, the filter is closely attached to the first photodetector, the incident end of the fluorescence collecting lens is sleeved with a microwave coil and a microwave waveguide part, the fluorescence collecting lens is used to collect the fluorescence signal emitted by the diamond, the microwave coil and the microwave waveguide part are used to apply a microwave pulse sequence to the diamond, the direction of the microwave magnetic field generated by the microwave coil and the microwave waveguide part is perpendicular to the axial direction of the diamond NV color center, the laser is divided into two beams of laser light after passing through a spectroscope, one beam is emitted to the diamond, and the other reflected laser beam is incident on the second photodetector after passing through a neutral attenuation plate, the phase-locked amplifier is used to perform differential detection on the signal generated by the first photodetector and the signal generated by the second photodetector, and the processing unit is used to obtain the magnetic field to be measured according to the differential detection signal.

[0010] Furthermore, the diamond color center micro-nanoscale magnetic field measurement device also includes a magnetic shielding barrel, a first coil and a second coil. The sample vibration measurement table assembly and the diamond color center magnetic field measurement assembly are arranged in the magnetic shielding barrel. The diamond color center magnetic field measurement assembly is arranged between the first coil and the second coil. The first coil and the second coil are used to apply an additional bias magnetic field at the diamond to adjust the electron spin magnetic resonance frequency of the NV color center.

[0011] Furthermore, the microwave coil and microwave waveguide parts include a microwave coil and a microwave waveguide, the microwave coil is used to radiate microwave signals to the diamond, and the microwave waveguide is used to access the microwave signals.

[0012] Furthermore, the diamond is cut in a set direction, and the set direction is parallel to the top of the flux acquirer, ensuring that the direction of the magnetic field at the gap of the flux acquirer is parallel to the NV color center axis.

[0013] According to another aspect of the present invention, a method for detecting a diamond color center by micro-nanoscale magnetic field modulation is provided. The method for detecting a diamond color center by micro-nanoscale magnetic field modulation uses the diamond color center micro-nanoscale magnetic field measuring device as described above to perform magnetic field modulation detection. The method for detecting a diamond color center by micro-nanoscale magnetic field modulation comprises: step 1, after installing the sample to be tested, starting the vibration modulation of the sample to be tested to generate an AC signal of the magnetic field; step 2, performing optical magnetic resonance spectrum measurement on the diamond NV color center ensemble; step 3, obtaining the resonance frequency f of the electron spin of the NV color center in the set direction of the diamond from the optical magnetic resonance spectrum. ± If the resonance frequency cannot be distinguished, adjust the bias magnetic field at the position of the diamond and re-measure the optical magnetic resonance spectrum until the resonance frequency can be distinguished; Step 4, with f ± The Rabi oscillation of the NV color center is measured at the microwave frequency to obtain the width of the π / 2, π, and 3π / 2 pulses at a given microwave power; Step 5: After the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined and the phase parameters can be adjusted. Meet the optimal sensitivity condition and record the value; Step 6, reduce the vibration amplitude of the sample, resulting in a decrease in the amplitude of the AC magnetic field signal captured by the flux collector, but an increase in the DC magnetic field signal. At this time, starting from step 2, the resonance frequency is re-determined by optical magnetic resonance spectroscopy measurement until the phase parameter is completed in step 5 Measurement of; Step 7, phase parameters The changes satisfy Where B is the maximum amplitude of the AC magnetic field introduced by the sample vibration modulation, γ is the electron gyromagnetic ratio, G is the measurement coefficient related to the microwave sequence used, and according to the phase parameter Realize micro-nanoscale magnetic field measurement of diamond color center.

[0014] Furthermore, in step one, the piezoelectric ceramic drives the resonant reed to vibrate, and controls the sample probe to drive the sample to be tested to enter and exit the detection end gap of the magnetic flux acquirer, causing the magnetic induction intensity entering the magnetic flux acquirer to be converted from a DC signal to an AC signal, and the frequency of change of the magnetic induction intensity obtained by the magnetic flux acquirer is the same as the vibration frequency.

[0015] Furthermore, in step two, the laser emits laser to continuously irradiate the diamond to initialize the electron spin of the NV color center, and a continuous microwave pulse sequence is applied to the diamond through the microwave coil and microwave waveguide parts; the fluorescence signal generated by the NV color center is collected by the fluorescence collection lens, and the fluorescence signal is transmitted to the filter through the rod mirror waveguide, and finally incident on the first photodetector; the laser beam reflected by the spectroscope is incident on the second photodetector after passing through the neutral attenuation plate, and the laser light intensity incident on the second photodetector is the same as the fluorescence intensity incident on the first photodetector, so that balanced detection of the two photodetectors is achieved; the signal generated by the first photodetector and the signal generated by the second photodetector are differentially detected by the phase-locked amplifier, and the change curve of the fluorescence signal corresponding to the microwave frequency is obtained, which is the optical magnetic resonance spectrum.

[0016] Furthermore, in step 5, after the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined. After driving the sample to be tested, the fluorescence signal change can be obtained by adjusting the range of [0,2π] The size of the sine response curve can be obtained, and the corresponding response curve with the maximum slope is selected. At this time, the diamond has the highest sensitivity to the AC magnetic field. value.

[0017] Furthermore, the reference frequency of the phase-locked amplifier is N / f, where f is the driving frequency of the piezoelectric ceramic, N is an integer related to the length of the laser and microwave composition sequence, and the vibration frequency of the resonant reed is determined by the transverse relaxation time T2 of the NV color center spin ensemble in the diamond.

[0018] By applying the technical solution of the present invention, a magnetic flux acquirer is provided. The magnetic flux acquirer guides the magnetic field generated by micro-nano scale materials or devices to the vicinity of the diamond containing the NV color center ensemble by setting a first magnetic guide probe and a second magnetic guide probe. The first magnetic guide probe and the second magnetic guide probe are symmetrically installed on both sides of the diamond, thereby amplifying the magnetic field intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1a to Figure 1c A schematic diagram showing the structure and installation method of a magnetic flux acquirer provided in a specific embodiment of the present invention is shown;

[0021] Figure 2a and Figure 2b A schematic diagram of finite element simulation results of magnetic guidance performance of a typical embodiment of a magnetic flux acquirer provided according to a specific embodiment of the present invention is shown;

[0022] Figure 3a and Figure 3b A schematic diagram of a sample vibration measurement table assembly of a diamond color center micro-nanoscale magnetic field measurement device based on a magnetic flux acquirer according to a specific embodiment of the present invention is shown;

[0023] Figure 4a and Figure 4b The front view and the side view of the diamond color center magnetic field measurement component of the diamond color center micro-nanoscale magnetic field measurement device based on the magnetic flux acquirer provided according to the specific embodiment of the present invention are shown;

[0024] Figure 5 A schematic structural diagram of a diamond color center micro-nanoscale magnetic field measuring device based on a magnetic flux acquirer provided in a specific embodiment of the present invention is shown;

[0025] Figure 6a A schematic diagram of a laser-microwave pulse sequence based on a spin echo sequence provided according to a specific embodiment of the present invention is shown;

[0026] Figure 6b A schematic diagram of a laser-microwave pulse sequence based on a CPMG2 sequence provided according to a specific embodiment of the present invention is shown;

[0027] Figure 7 A flow chart of a modulation detection method provided according to a specific embodiment of the present invention is shown.

[0028] The above drawings include the following reference numerals:

[0029] 1. The first magnetic guide probe; 2. The second magnetic guide probe; 3. Diamond; 4. The back plate of the magnetic flux acquirer; 5. The sample probe; 6. The sample to be tested; 7. The sample probe base; 8. The resonant reed; 9. The piezoelectric ceramic; 10. The base; 11. The fluorescence collecting lens; 12. The rod mirror waveguide; 13. The filter; 14. The first photodetector; 15. The microwave coil and the microwave waveguide parts; 151. The microwave coil; 152. The microwave waveguide; 16. The spectroscope; 17. The neutral attenuation plate; 18. The second photodetector; 19. The first coil; 20. The second coil; 21. The magnetic shielding barrel. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0033] like Figure 1a to Figure 1c As shown, according to a specific embodiment of the present invention, a magnetic flux acquirer is provided, which includes a first magnetic guide probe and a second magnetic guide probe. The first magnetic guide probe and the second magnetic guide probe have the same shape and are symmetrically installed on both sides of the diamond. The first magnetic guide probe and the second magnetic guide probe clamp the diamond to guide the magnetic induction lines to the diamond. The first magnetic guide probe and the second magnetic guide probe are both made of high magnetic permeability materials.

[0034] By applying this configuration, a magnetic flux acquirer is provided. The magnetic flux acquirer guides the magnetic field generated by micro-nano scale materials or devices to the vicinity of the diamond containing the NV color center ensemble by setting a first magnetic guide probe and a second magnetic guide probe. The first magnetic guide probe and the second magnetic guide probe are symmetrically installed on both sides of the diamond, thereby amplifying the magnetic field intensity.

[0035] Furthermore, in the present invention, in order to better maintain the magnetic induction lines in the magnetic guidance probe, the first magnetic guidance probe 1 includes a first probe segment 1a, a second probe segment 1b, a third probe segment 1c and a fourth probe segment 1d connected in sequence, and the angle between any two adjacent probe segments is an obtuse angle; the second magnetic guidance probe 2 includes a fifth probe segment 2a, a sixth probe segment 2b, a seventh probe segment 2c and an eighth probe segment 2d, and the angle between any two adjacent probe segments is an obtuse angle; the diamond is arranged between the first probe segment 1a and the fifth probe segment 2a, and the sample to be tested is arranged between the fourth probe segment 1d and the eighth probe segment 2d.

[0036] Furthermore, in the present invention, the diamond is a cube. To increase the field strength at the diamond, the height of the first probe segment and the fifth probe segment is equal to the edge length of the diamond. The thickness of the first magnetic guide probe and the second magnetic guide probe is equal to the edge length of the diamond.

[0037] According to another aspect of the present invention, a diamond color center micro-nanoscale magnetic field measuring device based on a magnetic flux acquirer is provided, the diamond color center micro-nanoscale magnetic field measuring device comprises a sample vibration measuring platform assembly and a diamond color center magnetic field measuring assembly, the sample vibration measuring platform assembly comprises a sample probe, a sample probe base, a resonant reed, a piezoelectric ceramic and a base, the end of the sample probe is used to install the sample particles to be measured, the sample probe is mounted on the sample probe base, the sample probe base is mounted on the resonant reed, the resonant reed is mounted on the piezoelectric ceramic, the piezoelectric ceramic is mounted on the base, the piezoelectric ceramic is used to drive the resonant reed to vibrate, the resonant reed drives the sample to be measured to move up and down in the gap of the magnetic flux acquirer by driving the sample probe; the diamond color center magnetic field measuring assembly comprises diamond, a magnetic flux acquirer, a fluorescence collecting lens, a rod mirror waveguide, a filter, a first photodetector, a microwave coil and microwave waveguide parts, a spectroscope, a laser, a neutral attenuation plate, a second photodetector A device, a phase-locked amplifier and a processing unit, the magnetic flux acquirer is the magnetic flux acquirer of any one of claims 1 to 3, the diamond is bonded to the incident end of the fluorescence collecting lens, the fluorescence collecting lens is bonded to one end of the rod mirror waveguide, the other end of the rod mirror waveguide is connected to the filter, the filter is closely attached to the first photodetector, the incident end of the fluorescence collecting lens is sleeved with a microwave coil and a microwave waveguide part, the fluorescence collecting lens is used to collect the fluorescence signal emitted by the diamond, the microwave coil and the microwave waveguide part are used to apply a microwave pulse sequence to the diamond, the direction of the microwave magnetic field generated by the microwave coil and the microwave waveguide part is perpendicular to the axial direction of the diamond NV color center, the laser is divided into two laser beams after passing through a spectroscope, one beam is emitted to the diamond, and the other reflected laser beam is incident to the second photodetector after passing through a neutral attenuation plate, the phase-locked amplifier is used to perform differential detection on the signal generated by the first photodetector and the signal generated by the second photodetector, and the processing unit is used to obtain the magnetic field to be measured according to the differential detection signal.

[0038] By using this configuration, a nanoscale magnetic field measurement device for diamond color centers based on a magnetic flux collector is provided. The magnetic field measurement sensitivity of the device based on the NV color center ensemble in diamond is better than 1pT / Hz. 1 / 2, it can be measured at room temperature or low temperature, and the size of the diamond itself can be <1mm, which can achieve magnetic field measurement that takes into account both spatial resolution and sensitivity; through the geometric structure design of high magnetic permeability materials, magnetic flux convergence is achieved, so that the sensitivity of magnetic field measurement is increased by hundreds to thousands of times, and it does not affect the normal operation of the diamond color center magnetometer; and the combination of magnetic flux acquisition and guidance technology based on high magnetic permeability materials and high-sensitivity magnetic field detection technology based on diamond color center ensemble can meet the needs of improving the sensitivity of micro-nanoscale magnetic field measurement; the magnetic field generated by micro-nanoscale materials or devices is guided to the vicinity of diamond containing NV color center ensemble by a magnetic flux acquirer, and the magnetic field signal to be measured is converted from DC to AC by mechanical modulation, and the advantage of high sensitivity of NV color center AC magnetic field measurement is used to achieve precise measurement of micro-nanoscale magnetic signals.

[0039] Furthermore, in order to provide a bias magnetic field, the diamond color center micro-nanoscale magnetic field measurement device in the present invention also includes a magnetic shielding barrel, a first coil and a second coil. The sample vibration measurement table assembly and the diamond color center magnetic field measurement assembly are arranged in the magnetic shielding barrel. The diamond color center magnetic field measurement assembly is arranged between the first coil and the second coil. The first coil and the second coil are used to apply an additional bias magnetic field at the diamond to adjust the electron spin magnetic resonance frequency of the NV color center.

[0040] Furthermore, in the present invention, in order to apply a microwave pulse sequence to diamond, the microwave coil and microwave waveguide parts include a microwave coil and a microwave waveguide, the microwave coil is used to radiate microwave signals to diamond, and the microwave waveguide is used to access the microwave signals.

[0041] Further, in the present invention, diamond is a diamond cut in a set direction (i.e. Figure 4a The

[111] direction in the figure is set to be parallel to the top of the flux collector to ensure that the magnetic field direction at the gap of the flux collector is parallel to the NV color center axis.

[0042] According to another aspect of the present invention, a method for detecting a diamond color center by micro-nanoscale magnetic field modulation is provided. The method uses the diamond color center micro-nanoscale magnetic field measuring device as described above to perform magnetic field modulation detection. The method comprises: step 1, after the sample to be tested is installed, vibration modulation of the sample to be tested is started to generate an AC signal of the magnetic field; step 2, optical magnetic resonance spectrum measurement of the diamond NV color center ensemble is performed; step 3, the resonance frequency f of the electron spin of the NV color center in the set direction of the diamond is obtained from the optical magnetic resonance spectrum. ± If the resonance frequency cannot be distinguished, adjust the bias magnetic field at the position of the diamond and re-measure the optical magnetic resonance spectrum until the resonance frequency can be distinguished; Step 4, with f ±The Rabi oscillation of the NV color center is measured at the microwave frequency to obtain the width of the π / 2, π, and 3π / 2 pulses at a given microwave power; Step 5: After the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined and the phase parameters can be adjusted. Meet the optimal sensitivity condition and record the value; Step 6, reduce the vibration amplitude of the sample, resulting in a decrease in the amplitude of the AC magnetic field signal captured by the flux collector, but an increase in the DC magnetic field signal. At this time, starting from step 2, the resonance frequency is re-determined by optical magnetic resonance spectroscopy measurement until the phase parameter is completed in step 5 Measurement of; Step 7, phase parameters The changes satisfy Where B is the maximum amplitude of the AC magnetic field introduced by the sample vibration modulation, γ is the electron gyromagnetic ratio, G is the measurement coefficient related to the microwave sequence used, and according to the phase parameter Realize micro-nanoscale magnetic field measurement of diamond color center.

[0043] Using this configuration, a method for measuring the micro-nanoscale magnetic field of diamond color centers based on a flux collector is provided. The magnetic field measurement sensitivity of the NV color center ensemble in diamond is better than 1pT / Hz. 1 / 2 , it can be measured at room temperature or low temperature, and the size of the diamond itself can be <1mm, which can achieve magnetic field measurement that takes into account both spatial resolution and sensitivity; through the geometric structure design of high magnetic permeability materials, magnetic flux convergence is achieved, so that the sensitivity of magnetic field measurement is increased by hundreds to thousands of times, and it does not affect the normal operation of the diamond color center magnetometer; and the combination of magnetic flux acquisition and guidance technology based on high magnetic permeability materials and high-sensitivity magnetic field detection technology based on diamond color center ensemble can meet the needs of improving the sensitivity of micro-nanoscale magnetic field measurement; the magnetic field generated by micro-nanoscale materials or devices is guided to the vicinity of diamond containing NV color center ensemble by a magnetic flux acquirer, and the magnetic field signal to be measured is converted from DC to AC by mechanical modulation, and the advantage of high sensitivity of NV color center AC magnetic field measurement is used to achieve precise measurement of micro-nanoscale magnetic signals.

[0044] Furthermore, in the present invention, in step one, the piezoelectric ceramic drives the resonant reed to vibrate, and controls the sample probe to drive the sample to be tested to enter and exit the detection end gap of the magnetic flux acquirer, causing the magnetic induction intensity entering the magnetic flux acquirer to be converted from a DC signal to an AC signal, and the frequency of change of the magnetic induction intensity obtained by the magnetic flux acquirer is the same as the vibration frequency.

[0045] In order to obtain the photomagnetic resonance spectrum, in step 2, the laser emits laser to continuously irradiate the diamond to initialize the NV color center electron spin, and a continuous microwave pulse sequence is applied to the diamond through the microwave coil and microwave waveguide parts; the fluorescence signal generated by the NV color center is collected by the fluorescence collection lens, and the fluorescence signal is transmitted to the filter through the rod mirror waveguide, and finally incident on the first photodetector; the laser beam reflected by the spectroscope is incident on the second photodetector after passing through the neutral attenuation plate, and the laser light intensity incident on the second photodetector is the same as the fluorescence intensity incident on the first photodetector, so that balanced detection of the two photodetectors is achieved; the signal generated by the first photodetector and the signal generated by the second photodetector are differentially detected by the phase-locked amplifier to obtain the change curve of the fluorescence signal corresponding to the microwave frequency, which is the photomagnetic resonance spectrum.

[0046] Further, in the present invention, in step 5, after the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined, and after driving the sample to be tested, the fluorescence signal change can be obtained by adjusting the range of [0,2π] The size of the sine response curve can be obtained, and the corresponding response curve with the maximum slope is selected. At this time, the diamond has the highest sensitivity to the AC magnetic field. value.

[0047] In the present invention, the reference frequency of the phase-locked amplifier is N / f, where f is the driving frequency of the piezoelectric ceramic, N is an integer related to the length of the laser and microwave composition sequence, and the vibration frequency of the resonant reed is determined by the transverse relaxation time T2 of the NV color center spin ensemble in the diamond.

[0048] In order to further understand the present invention, the following Figures 1a to 7 The magnetic flux acquirer, diamond color center micro-nanoscale magnetic field measurement device and method provided by the present invention are described in detail.

[0049] like Figures 1a to 7 As shown, a first aspect of an embodiment of the present application provides a magnetic flux acquirer.

[0050] The magnetic flux acquirer is made of high magnetic permeability material, such as Permalloy material, high magnetic permeability manganese-zinc ferrite material, etc.

[0051] The magnetic flux acquirer comprises a first magnetic guide probe 1 and a second magnetic guide probe 2, which together with a diamond 3 containing an NV color center ensemble form a micro-nano magnetic probe. In one embodiment, the diamond containing the NV color center ensemble is a cube with an edge length of a, and the size of the magnetic guide probe at one end close to the diamond is also a to increase the field strength at the diamond. The first magnetic guide probe 1 and the second magnetic guide probe 2 are of the same shape and are symmetrically installed on both sides of the diamond, such as Figure 1aAs shown. In a typical embodiment, a=0.5mm, two magnetic guide probes clamp a diamond cube, and the distance between the center of the diamond and the bottom of the magnetic flux acquirer is h>>a. In the typical embodiment, h=25mm. In practical applications, the h parameter is adjusted according to the required detection distance. The thickness of the high magnetic permeability material of the magnetic flux acquirer is d=a, which ensures that the field strength distribution in the diamond area is as uniform as possible while reducing the cross-sectional area of ​​the high magnetic permeability material at the diamond end to increase the field strength. The probe spacing at the bottom of the magnetic flux acquirer is l. In the typical embodiment, l=0.5mm. In practical applications, magnetic flux acquirers with different spacings l can be replaced according to different detection requirements, and the range of l is from 1mm-1μm. The center line spacing on both sides of the two magnetic guide probes is w>>a. In the typical embodiment, w=10mm. In practical applications, w can be appropriately increased according to conditions to reduce the crossing of the magnetic induction lines between the two magnetic guide probes. The bending angles in the magnetic flux acquirer are all obtuse angles, which are 135° in the typical embodiment. In practical applications, they can be increased according to the situation. The larger the angle, the more conducive it is to keep the magnetic induction lines in the magnetic guide probe.

[0052] The installation method of the magnetic flux acquirer is as follows Figure 1c In a typical embodiment, the thickness of the magnetic flux acquirer is d=a=0.5 mm, and it is attached to the magnetic flux acquirer back plate 4 to facilitate positioning and enhance the structural strength of the assembly.

[0053] According to a typical embodiment, a two-dimensional finite element simulation is performed on the magnetic induction line, such as Figure 2a and Figure 2b As shown, the material of the magnetic flux acquirer in the simulation is Permalloy. Without the magnetic flux acquirer, the magnetic field size at the diamond is 0.005Gs. After the magnetic flux acquirer is applied, the magnetic induction line is guided to the vicinity of the diamond, and the magnetic field size generated is about 7.5Gs, and the magnetic field strength is amplified by 1500 times.

[0054] The second aspect of the embodiment of the present application provides a diamond color center micro-nanoscale magnetic field measurement device based on a magnetic flux acquirer. The magnetic field measurement device includes a sample vibration measurement platform component and a diamond color center magnetic field measurement component.

[0055] The sample vibration measurement platform assembly is as follows Figure 3a and Figure 3bAs shown, a sample probe 5 is inserted into the gap at the detection end of the magnetic flux acquirer, and the end of the sample probe 5 is glued with the sample particles to be tested. The sample probe 5 is mounted on the sample probe base 7, the sample probe base 7 is mounted on the resonance reed 8, the resonance reed 8 is mounted on the piezoelectric ceramic 9, and the piezoelectric ceramic 9 is mounted on the base 10. The above device is used for the installation of the sample to be tested on the magnetic flux acquirer and the driving of vibration modulation. The piezoelectric ceramic 9 drives the resonance reed 8 to vibrate, and the resonance reed 8 drives the sample to be tested to move up and down in the gap of the magnetic flux acquirer. The modulation detection method of the sample to be tested will be described in detail later.

[0056] The diamond color center magnetic field measurement component is as follows Figure 4a and Figure 4b The diamond 3 is bonded to the incident end of the fluorescence collecting lens 11 , the fluorescence collecting lens 11 is bonded to one end of the rod mirror waveguide 12 , the other end of the rod mirror waveguide 12 is connected to the filter 13 , and the filter 13 is closely attached to the first photodetector 14 .

[0057] The incident end of the fluorescence collecting lens 11 is covered with a microwave coil and a microwave waveguide component 15 .

[0058] The fluorescence collecting lens 11 is a compound parabolic lens, which is used to collect as many fluorescence signals as possible emitted by the diamond 3. The rod mirror waveguide 12 transmits the fluorescence signal to the filter 13 and then enters the first photodetector 14.

[0059] The filter 13 is a long pass filter with a starting wavelength of 650 nm. The effective surface of the first photodetector 14 should be larger than the cross section of the rod mirror waveguide 12 .

[0060] The microwave coil and microwave waveguide component 15 includes a microwave coil 151 and a microwave waveguide 152, which are connected by a solder jumper at the connection point. The microwave waveguide 152 is a microstrip line waveguide with a designed impedance matching of 50Ω. The microwave signal is connected by a coaxial cable to ensure the maximum microwave transmission efficiency to the microwave coil 151.

[0061] The diamond 3 is cut in the

[111] direction, and its

[111] axis is parallel to the top of the flux collector, ensuring that the magnetic field direction at the gap of the flux collector is parallel to the NV color center axis, and the microwave magnetic field direction generated by the microwave coil 151 is perpendicular to the NV color center axis. In addition, the laser is generated by Figure 4a The laser light is incident on the diamond 3 through the beam splitter 16 in the direction shown, and the wavelength of the laser light is 510nm-570nm, and is 532nm in the typical embodiment.

[0062] The transmittance-reflectivity ratio of the beam splitter 16 is T:R=95:5, and the laser beam reflected by the beam splitter 16 is incident on the second photodetector 18 after passing through the neutral attenuation plate 17. The intensity of the laser light incident on the second photodetector 18 is the same as the fluorescence intensity incident on the first photodetector 14, so that balanced detection of the two photodetectors is achieved and the influence of laser fluctuation is eliminated.

[0063] The diamond color center magnetic field measurement assembly and the sample vibration measurement platform assembly together constitute a diamond color center micro-nanoscale magnetic field measurement device, which is installed as follows: Figure 5 As shown, it is installed in a magnetic shielding barrel 21 to eliminate the interference of environmental magnetic noise. In addition, the magnetic field measuring device is respectively equipped with a first coil 19 and a second coil 20 to apply an additional bias magnetic field at the diamond to adjust the electron spin magnetic resonance frequency of the NV color center.

[0064] Based on the diamond color center micro-nanoscale magnetic field measurement device described in the embodiment of the present application, the third aspect of the embodiment of the present application provides a modulation detection method, which is applied to magnetic sensing testing of micro-nanoscale materials or structures.

[0065] In a typical embodiment, the modulation detection method is, on the one hand, the piezoelectric ceramic 9 drives the resonance reed 8 to vibrate, and controls the sample probe 5 to drive the sample to be tested 6 to enter and exit the detection end gap of the magnetic flux acquirer, so that the magnetic induction intensity entering the magnetic flux acquirer is converted from a DC signal to an AC signal, and the vibration frequency is about 20-100kHz, and the change frequency of the magnetic induction intensity obtained by the magnetic flux acquirer is the same as the vibration frequency. On the other hand, the diamond 3 is irradiated with a 532nm laser to initialize the NV color center electron spin, and a microwave pulse sequence is applied to the diamond 3 through a microwave coil and a microwave waveguide part 15 to measure the magnetic field, and then the laser irradiates the diamond 3 to generate a fluorescence signal for reading and reinitializing the NV color center spin. The applied microwave pulse frequency is the resonant frequency of the diamond NV color center spin. The fluorescence signal generated by the NV color center is collected by the fluorescence collection lens 11, and then the fluorescence signal is transmitted to the filter 13 through the rod mirror waveguide 12, and finally the first incident photodetector 14. The signal generated by the first photodetector 14 and the signal generated by the second photodetector 15 are differentially detected by a phase-locked amplifier, and the measured magnetic field is obtained based on the signal after differential detection. The reference frequency of the phase-locked amplifier is N / f, where f is the driving frequency of the piezoelectric ceramic 9, and is also the magnetic field modulation frequency caused by the vibration of the sample to be measured between the flux acquirers, and N is an integer related to the length of the sequence composed of lasers and microwaves.

[0066] The selection of the vibration frequency of the resonant spring is determined by the transverse relaxation time T2 of the NV color center spin ensemble in the diamond. Generally, the vibration frequency f>1 / T2. In a typical embodiment, f=2 / T2.

[0067] The microwave pulse sequence and the laser sequence together form a laser-microwave pulse sequence to complete the initialization, manipulation and reading of the NV color center spin ensemble. Figure 6a and Figure 6b As shown, the units in the brackets are laser-microwave pulse sequence units, and the pulse sequence is repeated continuously during the measurement process. In a typical embodiment, the laser-microwave pulse sequence includes two laser pulses of the same length, each of which is followed by a group of spin echo microwave pulse sequences, the first group of microwave pulses includes three pulses of π / 2-π-π / 2, and the second group of microwave pulses includes three pulses of π / 2-π-3π / 2. In the two groups of pulses, the interval from the end of the first pulse to the start of the third pulse is 2τ=1 / f, and the total length of the laser-microwave pulse is N / f, where N is an integer. The selection of N should satisfy the condition that the length of the laser pulse is sufficient to fully initialize the NV color center spin ensemble. The third pulse of the two groups of microwave pulses and The phase difference with other microwave pulses is (i.e. the third pulse of the first group of microwave pulses The phase difference between the first pulse of the first group of microwave pulses π / 2 is The third pulse of the first set of microwave pulses The phase difference between the second pulse π of the first group of microwave pulses is The third pulse of the second set of microwave pulses The phase difference between the first pulse of the second group of microwave pulses π / 2 is The third pulse of the second set of microwave pulses The phase difference between the second pulse π of the second group of microwave pulses is ). In the specific implementation process, after the sample to be tested is driven, the fluorescence signal change can be obtained by adjusting the range of [0,2π] The size of the sine response curve can be obtained, and the corresponding response curve with the maximum slope is selected. value, at this time, the diamond has the highest measurement sensitivity to the AC magnetic field. Gradually reduce the driving intensity of the sample to be measured, and it can be observed that the AC magnetic field signal decreases until the drive stops and the AC magnetic field amplitude becomes 0.

[0068] In other embodiments, the microwave pulse sequence may be a variety of dynamic spin decoupling sequences, such as CPMG sequence, XY8 sequence, etc., and it is only necessary to adjust the last pulse phase of each group of microwave pulse sequences to The measurement is performed in the same manner as in the embodiment using a spin echo microwave pulse sequence. Figure 6bA laser-microwave pulse sequence using the CPMG2 sequence is demonstrated, in which the π pulse phase is 90° different from the initial phase.

[0069] The full flow diagram of the modulation detection method of a typical embodiment is as follows: Figure 7 shown.

[0070] (1) Place the sample vibration measurement table assembly and the diamond color center magnetic field measurement assembly in a magnetic shielding barrel, and apply an additional bias magnetic field to the diamond through the first coil and the second coil. After the sample to be tested is installed, start the vibration modulation of the sample to be tested to generate an AC signal of the magnetic field.

[0071] (2) The optical magnetic resonance spectrum of the diamond NV color center ensemble is measured. The specific method is to continuously irradiate the diamond with a laser and apply a continuous microwave signal at the same time. The microwave frequency is swept and the fluorescence signal is received by a photodetector. The curve of the fluorescence signal corresponding to the microwave frequency is obtained, which is the optical magnetic resonance spectrum.

[0072] (3) The resonance frequency f of the electron spin of the diamond

[111] NV color center is obtained by optical magnetic resonance spectroscopy. ± If the resonance frequency cannot be distinguished, adjust the bias magnetic field at the location of the diamond and re-measure the optical magnetic resonance spectrum until the resonance frequency can be distinguished.

[0073] (4) With f ± The Rabi oscillation of the NV color center is measured at a microwave frequency to obtain the widths of π / 2, π, and 3π / 2 pulses under a given microwave power. The specific method is that after the laser pulse initializes the NV color center electron spin ensemble, a microwave pulse with a width of τ is applied, and then a laser pulse is applied to detect the fluorescence signal. By changing the length of τ, the Rabi oscillation curve is obtained, and the pulse widths corresponding to different pulses can be obtained according to the first oscillation period.

[0074] (5) After the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined by adjusting the pulse width in the range of [0,2π] The size of the sine response curve can be obtained, and the corresponding response curve with the maximum slope is selected. At this time, the diamond has the highest sensitivity to the AC magnetic field. value.

[0075] (6) Reduce the vibration amplitude of the sample, resulting in a decrease in the amplitude of the AC magnetic field signal captured by the flux collector, but an increase in the DC magnetic field signal. At this time, starting from (2), the resonance frequency is re-determined by optical magnetic resonance spectroscopy measurement until the phase parameter is completed at (5). measurement.

[0076] (7) Phase parameters The changes satisfy Where B is the maximum amplitude of the AC magnetic field introduced by the sample vibration modulation, γ is the electron gyromagnetic ratio, G is the measurement coefficient related to the microwave sequence used, and according to the phase parameter Realize micro-nanoscale magnetic field measurement of diamond color center.

[0077] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0078] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A magnetic flux acquirer, characterized in that: The magnetic flux acquirer includes a first magnetic guide probe and a second magnetic guide probe. The first magnetic guide probe and the second magnetic guide probe have the same shape and are symmetrically installed on both sides of the diamond. The first magnetic guide probe and the second magnetic guide probe clamp the diamond to guide the magnetic induction line to the diamond. The first magnetic guide probe and the second magnetic guide probe are both made of high magnetic permeability materials.

2. The magnetic flux acquirer according to claim 1, characterized in that: The first magnetic guidance probe includes a first probe segment, a second probe segment, a third probe segment and a fourth probe segment connected in sequence, and the angle between any two adjacent probe segments is an obtuse angle; the second magnetic guidance probe includes a fifth probe segment, a sixth probe segment, a seventh probe segment and an eighth probe segment, and the angle between any two adjacent probe segments is an obtuse angle; the diamond is arranged between the first probe segment and the fifth probe segment, and the sample to be tested is arranged between the fourth probe segment and the eighth probe segment.

3. The magnetic flux acquirer according to claim 1, characterized in that: The diamond is a cube, the heights of the first probe segment and the fifth probe segment are equal to the edge length of the diamond, and the thicknesses of the first magnetic guidance probe and the second magnetic guidance probe are equal to the edge length of the diamond.

4. A diamond color center micro-nanoscale magnetic field measurement device based on a magnetic flux acquirer, characterized in that: The diamond color center micro-nanoscale magnetic field measurement device comprises a sample vibration measurement platform component and a diamond color center magnetic field measurement component. The sample vibration measurement platform assembly includes a sample probe, a sample probe base, a resonant reed, a piezoelectric ceramic and a base, wherein the end of the sample probe is used to mount the sample particles to be measured, the sample probe is mounted on the sample probe base, the sample probe base is mounted on the resonant reed, the resonant reed is mounted on the piezoelectric ceramic, the piezoelectric ceramic is mounted on the base, the piezoelectric ceramic is used to drive the resonant reed to vibrate, and the resonant reed drives the sample to be measured to move up and down in the gap of the magnetic flux acquirer by driving the sample probe; The diamond color center magnetic field measurement component includes diamond, the flux acquirer, a fluorescence collection lens, a rod mirror waveguide, a filter, a first photodetector, a microwave coil and microwave waveguide parts, a spectroscope, a laser, a neutral attenuation plate, a second photodetector, a phase-locked amplifier and a processing unit. The flux acquirer is the flux acquirer described in any one of claims 1 to 3, the diamond is bonded to the incident end of the fluorescence collection lens, the fluorescence collection lens is bonded to one end of the rod mirror waveguide, the other end of the rod mirror waveguide is connected to the filter, the filter is tightly attached to the first photodetector, and the incident end of the fluorescence collection lens is covered with the microwave coil and microwave waveguide. The components are used to collect the fluorescence collecting lens and the fluorescence signal emitted by the diamond. The microwave coil and the microwave waveguide components are used to apply a microwave pulse sequence to the diamond. The direction of the microwave magnetic field generated by the microwave coil and the microwave waveguide components is perpendicular to the axis of the diamond NV color center. The laser is divided into two laser beams after passing through the spectroscope, one beam is emitted to the diamond, and the other reflected laser beam is incident on the second photodetector after passing through the neutral attenuation plate. The phase-locked amplifier is used to perform differential detection on the signal generated by the first photodetector and the signal generated by the second photodetector. The processing unit is used to obtain the magnetic field to be measured according to the differential detection signal.

5. The diamond color center micro-nanoscale magnetic field measurement device based on magnetic flux acquirer according to claim 4 is characterized in that: The diamond color center micro-nanoscale magnetic field measurement device also includes a magnetic shielding barrel, a first coil and a second coil. The sample vibration measurement table assembly and the diamond color center magnetic field measurement assembly are arranged in the magnetic shielding barrel. The diamond color center magnetic field measurement assembly is arranged between the first coil and the second coil. The first coil and the second coil are used to apply an additional bias magnetic field at the diamond to adjust the electron spin magnetic resonance frequency of the NV color center.

6. The diamond color center micro-nanoscale magnetic field measurement device based on magnetic flux acquirer according to claim 5, characterized in that: The microwave coil and microwave waveguide parts include a microwave coil and a microwave waveguide, the microwave coil is used to radiate microwave signals to the diamond, and the microwave waveguide is used to access microwave signals.

7. The diamond color center micro-nanoscale magnetic field measurement device based on magnetic flux acquirer according to claim 6, characterized in that: The diamond is cut in a set direction, and the set direction is parallel to the top of the flux acquirer, ensuring that the magnetic field direction at the gap of the flux acquirer is parallel to the NV color center axis.

8. A method for detecting diamond color center micro-nanoscale magnetic field modulation, characterized in that: The magnetic field modulation detection method uses the diamond color center micro-nanoscale magnetic field measurement device according to any one of claims 4 to 7 to perform magnetic field modulation detection, and the magnetic field modulation detection method includes: Step 1: After the sample to be tested is installed, vibration modulation of the sample to be tested is started to generate an AC signal of the magnetic field; Step 2: Perform optical magnetic resonance spectroscopy measurement on the diamond NV color center ensemble; Step 3: Obtain the resonance frequency f of the electron spin of the NV color center in the set direction of the diamond from the optical magnetic resonance spectrum ± If the resonance frequency cannot be distinguished, adjust the bias magnetic field at the position of the diamond and re-measure the optical magnetic resonance spectrum until the resonance frequency can be distinguished. Step 4: f ± The Rabi oscillation of the NV color center is measured at the microwave frequency to obtain the widths of π / 2, π, and 3π / 2 pulses at a given microwave power; Step 5: After the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined, the phase parameter φ can be adjusted to meet the optimal sensitivity condition and the φ value at this time can be recorded; Step 6: Reduce the vibration amplitude of the sample, so that the amplitude of the AC magnetic field signal captured by the magnetic flux collector decreases, but the DC magnetic field signal increases. At this time, start from step 2 and re-determine the resonance frequency through optical magnetic resonance spectrum measurement until the measurement of the phase parameter φ is completed in step 5; Step seven, the change of phase parameter φ satisfies φ=GγB, where B is the maximum amplitude of the AC magnetic field introduced by the vibration modulation of the sample, γ is the electron gyromagnetic ratio, and G is a measurement coefficient related to the microwave sequence used. The micro-nanoscale magnetic field measurement of the diamond color center is achieved based on the phase parameter φ.

9. The diamond color center micro-nanoscale magnetic field modulation detection method according to claim 8, characterized in that: In step one, the piezoelectric ceramic drives the resonant reed to vibrate, and controls the sample probe to drive the sample to be tested to enter and exit the detection end gap of the magnetic flux acquirer, causing the magnetic induction intensity entering the magnetic flux acquirer to be converted from a DC signal to an AC signal. The frequency of change of the magnetic induction intensity obtained by the magnetic flux acquirer is the same as the vibration frequency.

10. The diamond color center micro-nanoscale magnetic field modulation detection method according to claim 8, characterized in that: In the step 2, the laser emits laser to continuously irradiate the diamond to initialize the NV center electron spin, and a continuous microwave pulse sequence is applied to the diamond through the microwave coil and microwave waveguide parts; the fluorescence signal generated by the NV center is collected by the fluorescence collection lens, and then transmitted to the filter through the rod mirror waveguide, and finally incident on the first photodetector; the laser beam reflected by the beam splitter is incident on the second photodetector after passing through the neutral attenuation plate, and the laser light intensity incident on the second photodetector is the same as the fluorescence intensity incident on the first photodetector, so that balanced detection of the two photodetectors is achieved; The signal generated by the first photodetector and the signal generated by the second photodetector are differentially detected by a phase-locked amplifier to obtain a curve of the change of the fluorescence signal corresponding to the microwave frequency, which is the photomagnetic resonance spectrum.

11. The method for measuring the micro-nanoscale magnetic field of a diamond color center according to claim 10, characterized in that: In step five, after the microwave pulse width is determined, the laser-microwave pulse sequence to be run can be determined. After driving the sample to be tested, the fluorescence signal change can be obtained. By adjusting the size of φ in the range of [0,2π], a sinusoidal response curve can be obtained. The φ value at the point where the slope of the corresponding response curve is the largest is selected. At this time, the diamond has the highest measurement sensitivity to the AC magnetic field, and the φ value at this time is recorded.

12. The method for measuring the micro-nanoscale magnetic field of a diamond color center according to claim 11, characterized in that: The reference frequency of the phase-locked amplifier is N / f, where f is the driving frequency of the piezoelectric ceramic, and N is an integer related to the length of the laser and microwave composition sequence. The selection of the vibration frequency of the resonant reed is determined by the transverse relaxation time T2 of the NV color center spin ensemble in the diamond.

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