A magnetic detection device and method based on NV color centers under ultra-high pressure

Abstract

The present invention discloses a magnetic detection device and method based on NV color centers under ultrahigh pressure, which belongs to the field of extreme physical property characterization. A [111]-face diamond with a diameter of 100μm and containing NV color centers is used as the upper and lower anvils of the DAC device, wherein the 100μm table enables the pressure inside the pressure chamber to reach an ultrahigh pressure environment of more than 100 GPa, and the pressure conditions are higher; and compared with ordinary diamond color centers, the color centers in the [111] direction have higher signal quality under ultrahigh pressure; an antenna is made of aluminum foil and placed between the upper and lower anvils, so that it deforms into a microstrip patch antenna close to the anvil surface under ultrahigh pressure environment. Compared with other types of antennas, it has the highest quality of microwave signal transmission and the lowest loss, and can measure optical detection magnetic resonance (ODMR) spectrum under ultrahigh pressure conditions of 100 GPa and above. The present invention can perform relatively accurate quantitative testing of the magnetic properties of materials under ultrahigh pressure in a highly integrated manner.

Description

Technical Field

[0001] The present invention belongs to the field of extreme physical property characterization, and specifically relates to a magnetic detection device and method based on NV color centers under ultra-high pressure. Background Art

[0002] Extreme conditions refer to extreme physical conditions such as ultra-high pressure (>100 GPa), extremely low temperature (<30 mK), and ultra-strong magnetic fields (>15 T). The ultra-high pressure environment can change the atomic distance to a considerable extent and increase the probability of overlap of electron orbits between molecules in real space, thereby regulating the interaction between material molecules, unit cell configuration, and band structure, etc. It is an extremely important exogenous physical condition in condensed matter physics research.

[0003] In recent years, ultrahigh-pressure technology has become a crucial tool for superconducting physics research. For example, diamond nitrogen-vacancy (NV) color centers have been used to precisely detect localized magnetic fields. In 1965, Dyer et al. discovered the existence of NV color centers in diamond and the presence of quantized energy levels that exhibit the Zeeman effect. In 1997, Wrachtrup et al. achieved optically detected magnetic resonance (ODMR) of NV color centers at room temperature.

[0004] However, due to the limitations of ultrahigh-voltage technology, current magnetic measurement techniques struggle to effectively couple NV color center systems with their optical modules. The fidelity of microwave module transmission signals and the NV color center's reception of microwave signals are also low. Conventional coil antennas are prone to deformation, affecting the distribution of the radiation band. Existing magnetic measurement devices are even more difficult to detect local magnetic fields under ultrahigh voltage conditions. Summary of the Invention

[0005] In response to the problem that current magnetic measurement devices are not suitable for local magnetic field detection under ultra-high pressure conditions, the present invention provides a magnetic detection device and method based on NV color centers under ultra-high pressure. By combining diamond anvil cell technology with NV color center technology, accurate measurement of ODMR spectra under ultra-high pressure is achieved, providing an effective method for measuring the local magnetic properties of materials.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A magnetic detection device based on NV color centers under ultra-high pressure, comprising a confocal optical path module, a PC module, a microwave emission module and an ultra-high pressure test module, wherein:

[0008] The confocal optical path module is used to generate pump light, transmit the pump light to the ultra-high voltage test module to initialize the NV color center in the ultra-high voltage test module and generate radiation transition, and at the same time receive the fluorescence signal generated by the ultra-high voltage test module;

[0009] The PC module is directly electrically connected to the confocal optical path module and the microwave transmission module, respectively, and is used to collect the photoelectric signals in the confocal optical path module and control the microwave sequence in the microwave transmission module;

[0010] The microwave transmission module is used to control the level signal and generate a pulse sequence to match the timing of the confocal optical module. It inputs the high-frequency microwave signal into the ultra-high voltage test module to put the NV color center into a coherent state and adjust the decoherence time of the color center system.

[0011] The ultrahigh-pressure test module is used to generate an ultrahigh-pressure environment higher than 100 GPa. It receives the pump light transmitted from the confocal optical path module through the optical window, receives the high-frequency microwave signal transmitted from the microwave transmission module through the antenna, and transmits the fluorescence signal to the confocal optical path module.

[0012] Furthermore, the confocal optical path module includes:

[0013] Laser for generating 532nm pump light;

[0014] Attenuation plate, used to adjust the light intensity of the laser input when it is emitted;

[0015] The half-wave plate is used to adjust the polarization of the laser emitted by the attenuation plate, so that the phase difference between the o-light and the e-light is converted to n times;

[0016] A polarization beam splitter is used to separate the o-light and e-light of the laser beam emitted from the half-wave plate, and deflect the e-light 90° into the first and second silver-coated mirrors;

[0017] The first and second silver-coated reflectors are placed facing each other at an angle of 45 degrees, and are used to adjust the propagation direction of the laser beam emitted from the polarization beam splitter so as to enter the long-wavelength dichroic mirror;

[0018] A long-wavelength dichroic mirror is used to reflect the laser beam into the objective lens so that it acts on the ultra-high voltage test module, while allowing the fluorescence generated by the radiation transition process in the ultra-high voltage test module to pass through and enter the single-photon counter;

[0019] A single photon counter is used to collect and count the photons of fluorescence passing through the long-wavelength dichroic mirror;

[0020] The data acquisition card is used to collect and store the photon counts from the single photon counter and transmit them to the PC module for processing.

[0021] Furthermore, the PC module includes a server host-level PC processing terminal and a control program.

[0022] Furthermore, the microwave transmission module includes:

[0023] A TTL pulse generator, connected to the single photon counter and modulated by the PC module, is used to emit a pulse train so that the pulse train matches the number of detected photons in timing;

[0024] A microwave source, used for emitting microwaves;

[0025] The microwave switch is used to receive the level signal from the TTL pulse generator and the microwave signal from the microwave source, and control whether the input microwave signal is output according to the TTL level signal;

[0026] An amplifier, used to amplify the input microwave signal strength and output it;

[0027] The circulator is used to provide a circular path for the microwave signal output by the amplifier and adjust the signal phase difference.

[0028] Furthermore, the ultra-high voltage test module includes:

[0029] The upper and lower diamonds of the diamond anvil are composed of two diamonds with opposite surfaces, which are used to create ultra-high pressure conditions in the sample chamber;

[0030] Metal gasket, placed between the upper and lower diamonds of the diamond anvil, used to fix the test sample;

[0031] A microstrip patch antenna is placed between the diamond and metal spacers on the diamond anvil to transmit microwave signals to act on the NV color centers on the table.

[0032] Cubic boron nitride, used to isolate the microstrip patch antenna from the metal spacer;

[0033] The sample cavity is located between the microstrip patch antenna and the diamond under the diamond anvil, and is used to accommodate the pressure transmission medium and the sample to be tested;

[0034] The magnetron module is placed below the diamond under the diamond anvil and is used to adjust the magnetic field size and direction required for color center testing.

[0035] On the other hand, the present invention provides a magnetic detection method based on NV color centers under ultrahigh pressure, which is applied to the aforementioned magnetic detection device and includes the following steps:

[0036] Step 1: Set up the confocal optical path module, configure the PC module, and microwave transmission module and initialize them;

[0037] Step 2: Setting up the ultrahigh pressure test module, including adjusting the upper and lower diamonds of the diamond anvil to make them centered and parallel, setting the gasket, arranging the sample cavity, filling the pressure transmission medium, setting up the microwave antenna, and loading the sample;

[0038] Step 3: pressurizing the sample in the sample cavity and placing it in a Raman spectrometer to collect a diamond first-order Raman standard pressure spectrum to determine the internal pressure of the sample cavity;

[0039] Step 4: Place the upper and lower diamonds of the diamond anvil cell in the ultrahigh voltage test module and initialize them. Use the test program of the PC module to control the microwave emission module to generate microwave signals, generate ODMR spectra in the PC module, and obtain the magnetic information of the sample by processing and analyzing the spectroscopic signals.

[0040] Step 5: Adjust the magnetic control module to change the magnetic field strength in the sample chamber, repeat step 3 to obtain the sample's response information to the external magnetic field, and repeat step 4 to obtain the magnetic susceptibility response curve of the sample under a certain pressure;

[0041] Step 6: Pressurize the sample in the sample chamber again, and repeat steps 3-5 to obtain the magnetic response curves of the sample under different pressure conditions;

[0042] Step 7: After the test is completed, the diamond anvil press is removed to release the pressure, and steps 3-5 are repeated to obtain the magnetic response curve of the sample under reduced pressure until the pressure inside the sample chamber drops to atmospheric pressure, and the experiment is terminated.

[0043] The beneficial effects of the present invention are:

[0044] The present invention uses 100 μm table diamond as anvil and cBN as insulating medium. The extremely high hardness of both makes it possible to achieve ultra-high pressure test environment. The pressure chamber is packed with a pressure calibration material (ruby). Ruby can be used as a calibration material at low pressure, and the diamond vibration peak is directly used for calibration at high pressure. The real-time hydrostatic pressure in the pressure chamber is calculated in real time through the displacement of the ruby ​​Raman vibration peak and the first-order Raman shift of the diamond, thereby achieving ultra-high pressure test conditions of 100 GPa and above inside the pressure chamber.

[0045] The present invention fabricates NV color centers on a diamond tabletop, aligning their eigenaxis with the normal of the grown diamond test tabletop. Platinum foil is also used as the transmitting antenna. Under ultrahigh voltage, the platinum foil undergoes significant lateral deformation, forming a microstrip patch antenna that is tightly connected to the test platform, ensuring the intensity and quality of the microwave signal. This combined effect stabilizes the resonant signal generated by Zeeman splitting, achieving a total contrast ratio of 7%, meeting testing requirements.

[0046] The present invention integrates the magnetron module directly below the anvil and applies an external magnetic field in the form of a proportionally changing magnetic field arrangement. It has a small volume and can perform relatively accurate quantitative testing of the magnetization intensity of materials under ultra-high pressure in a highly integrated manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a structural module diagram of a magnetic detection device based on NV color centers under ultra-high pressure in the present invention;

[0048] Figure 2 This is a schematic diagram of the connection of components of a magnetic detection device based on NV color centers under ultra-high pressure in the present invention;

[0049] Figure 3 This is the side view of the ultra-high voltage test module;

[0050] Figure 4 This is a top view of the ultra-high voltage test module;

[0051] Figure 5 This is the first-order Raman spectrum of

[111] diamond at a pressure of 140.6 GPa;

[0052] Figure 6 This is the ODMR spectrum of the NV color center on the

[111] surface diamond at a pressure of 140.6 GPa.

[0053] Among them: 1. Confocal optical path module; 2. PC module; 3. Microwave emission module; 4. Ultra-high voltage test module; 101. Laser; 102. Attenuator; 103. Half-wave plate; 104. Polarization beam splitter; 105. First silver-coated reflector; 106. Second silver-coated reflector; 107. Long-wave pass dichroic mirror; 108. Objective lens; 109. Single-photon counter; 110. Data acquisition card; 301. TTL pulse generator; 302. Microwave source; 303. Microwave switch; 304. Amplifier; 305. Circulator; 41. Diamond on diamond anvil; 42. Diamond under diamond anvil; 43. Metal gasket; 44. Microstrip patch antenna; 45. Cubic boron nitride; 46. Sample cavity; 47. Magnetron module. DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to the accompanying drawings and examples.

[0055] The structure of the magnetic detection device based on NV color center under ultra-high pressure of the present invention is as follows: Figure 1 As shown, it includes four modules: confocal optical path module 1, PC module 2, microwave emission module 3, and ultra-high voltage test module 4.

[0056] Among them, the confocal optical path module 1 is used to generate and control pump light, transmit the pump light to the ultra-high voltage test module 4, so that the NV color center is fully initialized and generates radiation transition, and at the same time receives the fluorescence signal generated by the ultra-high voltage test module 4; the PC module 2 is directly connected to the confocal optical path module 1 and the microwave transmission module 3 respectively, and is used to collect the photoelectric signal in the confocal optical path module 1 and control the microwave sequence in the microwave transmission module 3; the microwave transmission module 3 is used to control the level signal, generate a pulse sequence and input the high-frequency microwave signal into the ultra-high voltage test module 4, so that the NV color center is in a coherent state and adjust the decoherence time of the color center system; the ultra-high voltage test module 4 mainly includes a diamond anvil and a accommodating cavity for placing the sample. The diamond anvil generates an ultra-high pressure environment (>100GPa), receives the pump light transmitted from the confocal optical path module 1 through the anvil hole, receives the microwave signal transmitted from the microwave transmission module 3 through the antenna and transmits the fluorescence signal to the confocal optical path module 1.

[0057] like Figure 2 As shown in the figure, a specific schematic diagram of component connection is given.

[0058] The confocal optical path module 1 includes:

[0059] Laser 101: After stabilization, it is used as a pump light source to generate 532nm laser light to initialize the diamond NV color center ensemble, so that most of the NV color centers enter the coherent state and are in the M s =0 energy level.

[0060] Attenuation plate 102: adjusts the light intensity of the laser input by laser 101 when it is emitted, thereby obtaining an ODMR spectrum with higher contrast.

[0061] Half-wave plate 103 adjusts the laser polarization so that the phase difference between the o-light and the e-light in the laser emitted by the attenuation plate 102 is converted to n times, so as to facilitate the separation of the two columns of light in the polarization beam splitter 104.

[0062] Polarization beam splitter (PBS) 104: separates the o-light and e-light of the laser beam emitted from the half-wave plate 103, and deflects the e-light by 90 degrees to enter the subsequent test optical path.

[0063] The first and second silver-plated reflective mirrors 105 and 106 are placed facing each other at an angle of 45 degrees to adjust the propagation direction of the laser beam and make the spatial distribution of components more reasonable.

[0064] Long-wave pass dichroic mirror 107 reflects the laser beam into the lens of objective lens 108 so that it acts on the ultra-high voltage test module 4 , while allowing the fluorescence generated by the radiation transition process in the diamond NV color center to pass through and enter the single photon counter 109 .

[0065] Objective lens 108 : serves as the light alignment unit and optical path unit of the microscope, provides a light field of view and focuses the laser beam into the ultra-high voltage test module 4 .

[0066] Single photon counter (SPCM) 109 collects and counts the photons of the fluorescence that passes through the long-wavelength dichroic mirror 107 .

[0067] Data acquisition card 110: collects and stores the photon counts from the single photon counter 109 and transmits them to the PC module 2 for further processing via a data transmission protocol.

[0068] PC Module 2: This includes a server-level PC processing terminal and control program. It collects and processes the photon count information transmitted by the data acquisition card 110 and matches it with the microwave pulse signal to obtain the ODMR spectrum. It also controls the microwave source and TTL pulse generator 301 through a preset program, outputting a specific test sequence.

[0069] The microwave transmission module 3 includes:

[0070] TTL pulse generator 301: connected to the single photon counter 109, modulated by the PC module 2, and emits a pulse sequence set by the program according to the TTL level rules, so that the microwave pulse matches the number of photons detected under the corresponding conditions in terms of timing;

[0071] Microwave source 302: used to transmit microwaves in the 0-6 GHz band. Generally, 2-4 GHz is selected for testing under high-pressure conditions. Under ultra-high pressure conditions, the diamond color center energy level spacing changes, and the ODMR spectrum shifts toward high frequencies. Therefore, the test band needs to be selected based on the actual zero-field center peak position.

[0072] Microwave switch 303: receives the level signal from the TTL pulse generator 301 and the microwave signal from the microwave source 302, and controls whether to output the input microwave signal according to the TTL level signal;

[0073] Amplifier 304: amplifies the input microwave signal strength and outputs it;

[0074] Circulator 305: provides a circular path for the microwaves output by amplifier 304, adjusts the phase difference of the input signal, and prevents the microwave signal reflected by the wall from damaging the amplifier 304.

[0075] Also refer to Figure 3-Figure 4 ,in Figure 3 This is the side view of the ultra-high voltage test module. Figure 4 Specifically, the ultra-high voltage test module 4 includes:

[0076] The upper and lower diamonds 41 and 42 of the diamond anvil are composed of two diamonds with opposing table surfaces. The upper diamond 41 of the diamond anvil uses a

[111] -faced diamond with shallow NV color centers prepared on its surface. The table diameter is 100 μm. When the upper and lower diamonds 41 and 42 of the diamond anvil are subjected to force F, due to the small table surface, ultrahigh pressure conditions can be created in the sample chamber 46.

[0077] Metal gasket 43: Made of a Ni, Cr, or Al alloy, it is used to restrain the pressure-transmitting medium, preventing it from overflowing under high pressure. It also provides a high-pressure environment for the central sample chamber 46 and secures the test sample. It also protects the upper and lower diamonds 41 and 42 of the diamond anvil, preventing damage to the diamond and sample under high pressure.

[0078] Microstrip patch antenna 44: Made from 5 μm platinum foil, its actual thickness is even smaller under UHV conditions. Positioned close to diamond 41 on the diamond anvil, it transmits microwave signals to target the NV centers within the table. This ensures the quality and intensity of the microwave signal even after the antenna deforms under UHV conditions.

[0079] Cubic boron nitride (cBN) 45 : serves as an insulating medium to isolate the microstrip patch antenna 44 from the metal spacer 43 .

[0080] Sample chamber 46: contains the pressure medium and the samples to be tested. As a pressure transmission medium, it has good ductility and can not diffuse outside the diamond table under ultra-high pressure, thereby ensuring stable pressure loading, and The test sample is encapsulated with a pressure calibration material (ruby) that can be used as a calibration material at low pressures. The test sample is located below the microstrip patch antenna 44, which improves microwave signal reception while preventing the strong ferromagnetism of some samples from interfering with the magnetic resonance signal of the NV color center. It is also located above the magnetron module 47, facilitating magnetic susceptibility testing after magnetization.

[0081] It should be noted that cubic boron nitride 45 and silicon dioxide They all have extremely high hardness, which makes it possible to reach and stably maintain an ultra-high pressure environment of 100 GPa or even 140 GPa inside the sample chamber 46.

[0082] The magnetic control module 47 is composed of an array of identical small cylindrical magnets. By placing cylindrical magnets of different numbers and array forms below the diamond 42 under the diamond anvil, the magnetic field size and direction required for the color center test can be adjusted.

[0083] Example

[0084] Before conducting ultra-high voltage magnetic measurement, Figure 1The four structural modules are set up and adjusted. For the confocal optical path module 1, the specific connection method of the whole device is as follows Figure 2 As shown in the figure, the thicker black line segment represents the optical signal transmission process in the device, and the thinner black line segment represents the microwave signal or electrical signal transmission process.

[0085] First follow Figure 1-Figure 2 The confocal optical path module 1 is initialized and calibrated according to the optical path component connection sequence shown in FIG. The 532 nm laser light generated by the steady-state laser 101 is polarized by the attenuator 102 and half-wave plate 103 placed at the front end of the laser window. The o-light is filtered out by the polarization beam splitter 104 to obtain the e-light. The e-light is reflected twice by the first and second silver-coated mirrors 105 and 106 and then enters the long-wavelength pass dichroic mirror 107 placed in the microscope's quasi-axis. After passing through the objective lens 108, it enters the color center portion of the ultra-high voltage test module 4. Photons in the 600-800 nm band generated by radiative transitions within the color center pass through the objective lens 108 and the dichroic mirror 107 and enter the single-photon counter 109 at the other end of the long-wavelength pass dichroic mirror 107. The single-photon counter 109 transmits the electrical signals to the TTL pulse generator 301 and the data acquisition card 110 to implement the counting function. The data acquisition card 110 transmits the counted data to the program in the PC module 2 for processing.

[0086] PC module 2 uses a server-level computer. After connecting the computer to the data acquisition card 110, TTL pulse generator 301 and microwave source 302 via USB protocol, the front-end software processing environment for the experiment is configured. A program is written to control the output pulse waveform of the antenna in the input ultra-high voltage test module 4 and the reading sequence of the single photon counter 109, and the time sequence is adjusted to synchronize the two. Through frequency sweep measurement, the magnetic resonance signal of the NV color center is finally read out on PC module 2 to perform magnetic field decoupling and calculation operations.

[0087] The core components of microwave transmission module 3 are a TTL pulse generator 301 and a microwave source 302. These are connected to a microwave switch 303 via a coaxial cable. A high-frequency microwave sequence controlled by a PC enters microwave switch 303 and is output under the control of a TTL signaling protocol. Depending on the sequence, the microwave signal is input into amplifier 304 and circulator 305. The circulator 305 interface is directly connected to the microstrip patch antenna 44 fixed above the sample in the ultra-high voltage test module 4, allowing the signal to propagate to the color center to meet the transition conditions.

[0088] The main components of the ultra-high pressure test module 4 are the upper and lower diamond anvils 41 and 42. The specific operation method of setting up the device is as follows: take a pair of test tables with a diameter of 100 μm

[111] face diamond containing NV color center is used as the upper and lower diamonds 41 and 42 of the diamond anvil, which are fixed on the anvil and placed opposite to each other. Then, a suitable metal gasket 43 is selected to perform pre-pressing and punching operation on it, and the hole diameter is slightly smaller than the test table. Then, cubic boron nitride 45 is pressed into the metal gasket 43 as an insulating layer, and then a hole is punched in the middle of the metal gasket 43 as a sample cavity 46 with a diameter of about half of the test table. SiO2 is filled in the sample cavity 46 as a pressure transmission medium, and the sample is loaded and wrapped therein. Finally, the microstrip patch antenna 44 is fixed on the metal gasket 43 on the lower side of the diamond 41 on the diamond anvil to ensure that the microstrip patch antenna 44 and the metal gasket 43 are separated by cubic boron nitride 45. Then, the magnetic control module 47 is adjusted by adjusting the arrangement of the columnar magnet array to test the magnetic response properties of the sample under different external magnetic field environments.

[0089] After the experimental device is installed, the sample in the sample cavity 46 is pressurized and then placed in a Raman spectrometer to collect the diamond first-order Raman standard pressure spectrum to determine the internal pressure of the sample cavity 46, such as Figure 5 As shown, 1603.7cm -1 This is the vibration peak formed after diamond produces Raman shift under high pressure, corresponding to a pressure environment of 140.6 GPa. Place the installed upper and lower diamonds 41 and 42 of the diamond anvil in the ultrahigh pressure test module 4, turn on the laser 101, and after a period of relaxation, turn on the light source of the microscopic test platform. Perform the light alignment and calibration operations through the objective lens 108. After calibration, turn on the data acquisition card 110, TTL pulse generator 301, and microwave source 302. After the reading stabilizes, open the test software of PC module 2, set the test parameters, measure, and draw a real-time double-peak ODMR spectrum. According to the formula: A rough estimate of the magnetic field size is Figure 6 As shown, where h is Planck's constant; is the absolute value of the frequency interval between the two peaks in the image, which is 433.2 MHz in the figure; Take 2 as the Landau factor; Take 4π×10 for the Bohr magnetic moment -7 . The calculated projection size of the magnetic field generated by the sample at 140.6 GPa in the NV axis direction is 7.73 mT. Adjust the attenuation plate 102 and the microwave frequency parameters, collect data after multiple measurements, use origin software to draw the spectrum, use peak fitting to obtain the peak position parameters, substitute them into the linear regression equation for fitting, and then obtain the magnetic field distribution data under the corresponding pressure. Repeat the above operation to the highest pressure required for the test, and you can get the response curve of the test sample to the external magnetic field under pressure loading. Thereafter, perform a slow pressure reduction operation. After each pressure reduction, it needs to be placed on the Raman spectrometer for peak position calibration and then placed in this system for testing, so as to obtain the response curve of the test sample to the external magnetic field under pressure unloading.

[0090] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic detection device based on NV color centers under ultra-high pressure, characterized in that: It includes confocal optical path module, PC module, microwave emission module and ultra-high voltage test module, among which, The confocal optical path module is used to generate pump light, transmit the pump light to the ultra-high voltage test module to initialize the NV color center in the ultra-high voltage test module and generate radiation transition, and at the same time receive the fluorescence signal generated by the ultra-high voltage test module; The PC module is directly electrically connected to the confocal optical path module and the microwave transmission module, respectively, and is used to collect the photoelectric signals in the confocal optical path module and control the microwave sequence in the microwave transmission module; The microwave transmission module is used to control the level signal and generate a pulse sequence to match the timing of the confocal optical module. It inputs the high-frequency microwave signal into the ultra-high voltage test module to put the NV color center into a coherent state and adjust the decoherence time of the color center system. The ultrahigh-pressure test module is used to generate an ultrahigh-pressure environment exceeding 100 GPa. It receives pump light transmitted from the confocal optical path module through the anvil hole, receives high-frequency microwave signals transmitted from the microwave transmission module through the antenna, and transmits fluorescence signals to the confocal optical path module. Specifically, it includes: The upper and lower diamonds of the diamond anvil are composed of two diamonds with opposite surfaces, which are used to create ultra-high pressure conditions in the sample chamber; Metal gasket, placed between the upper and lower diamonds of the diamond anvil, used to fix the test sample; A microstrip patch antenna, placed between the diamond and metal spacers on the diamond anvil, transmits microwave signals to act on the NV color centers on the table. Platinum foil is used as the transmitting antenna. Under ultrahigh voltage, the platinum foil will produce lateral deformation, forming a microstrip patch antenna. Cubic boron nitride, used to isolate the microstrip patch antenna from the metal spacer; The sample cavity is located between the microstrip patch antenna and the diamond under the diamond anvil, and is used to accommodate the pressure transmission medium and the sample to be tested. Among them, SiO2 is used as the pressure transmission medium, and ruby ​​is encapsulated in the SiO2. The ruby ​​is used as a pressure calibration material under low pressure, and the diamond vibration peak is directly used for calibration under high pressure. The magnetron module is placed below the diamond under the diamond anvil and is used to adjust the magnetic field size and direction required for color center testing.

2. The ultra-high pressure NV color center-based magnetic detection device according to claim 1, characterized in that: The confocal optical path module includes: Laser for generating 532nm pump light; Attenuation plate, used to adjust the light intensity of the laser input when it is emitted; The half-wave plate is used to adjust the polarization of the laser emitted by the attenuation plate, so that the phase difference between the o-light and the e-light is converted to n times; A polarization beam splitter is used to separate the o-light and e-light of the laser beam emitted from the half-wave plate, and deflect the e-light 90° into the first and second silver-coated mirrors; The first and second silver-coated reflectors are placed facing each other at an angle of 45 degrees, and are used to adjust the propagation direction of the laser beam emitted from the polarization beam splitter so as to enter the long-wavelength dichroic mirror; A long-wavelength dichroic mirror is used to reflect the laser beam into the objective lens so that it acts on the ultra-high voltage test module, while allowing the fluorescence generated by the radiation transition process in the ultra-high voltage test module to pass through and enter the single-photon counter; A single photon counter is used to collect and count the photons of fluorescence passing through the long-wavelength dichroic mirror; The data acquisition card is used to collect and store the photon counts from the single photon counter and transmit them to the PC module for processing.

3. The ultra-high pressure NV color center-based magnetic detection device according to claim 2, characterized in that: The PC module includes a server host-level PC processing terminal and a control program.

4. The ultra-high pressure NV color center-based magnetic detection device according to claim 3, characterized in that: The microwave transmission module includes: A TTL pulse generator, connected to the single photon counter and modulated by the PC module, is used to emit a pulse train so that the pulse train matches the number of detected photons in timing; A microwave source, used for emitting microwaves; The microwave switch is used to receive the level signal from the TTL pulse generator and the microwave signal from the microwave source, and control whether the input microwave signal is output according to the TTL level signal; An amplifier, used to amplify the input microwave signal strength and output it; The circulator is used to provide a circular path for the microwave signal output by the amplifier and adjust the signal phase difference.

5. A magnetic detection method based on NV color centers under ultrahigh pressure, applied to a magnetic detection device based on NV color centers under ultrahigh pressure according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: Set up the confocal optical path module, configure the PC module, and microwave transmission module and initialize them; Step 2: Setting up the ultrahigh pressure test module, including adjusting the upper and lower diamonds of the diamond anvil to make them centered and parallel, setting the gasket, arranging the sample cavity, filling the pressure transmission medium, setting up the microwave antenna, and loading the sample; Step 3: pressurizing the sample in the sample cavity and placing it in a Raman spectrometer to collect a diamond first-order Raman standard pressure spectrum to determine the internal pressure of the sample cavity; Step 4: Place the upper and lower diamonds of the diamond anvil cell in the ultrahigh voltage test module and initialize them. Use the test program of the PC module to control the microwave emission module to generate microwave signals, generate ODMR spectra in the PC module, and obtain the magnetic information of the sample by processing and analyzing the spectroscopic signals. Step 5: Adjust the magnetic control module to change the magnetic field strength in the sample chamber, repeat step 3 to obtain the sample's response information to the external magnetic field, and repeat step 4 to obtain the magnetic susceptibility response curve of the sample under a certain pressure; Step 6: Pressurize the sample in the sample chamber again, and repeat steps 3-5 to obtain the magnetic response curves of the sample under different pressure conditions; Step 7: After the test is completed, the diamond anvil press is removed to release the pressure, and steps 3-5 are repeated to obtain the magnetic response curve of the sample under reduced pressure until the pressure inside the sample chamber drops to atmospheric pressure, and the experiment is terminated.

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