Vector microwave detection device

Abstract

A vector microwave detection device comprises a detection mechanism which is provided with a microwave plate for transmitting to-be-measured microwaves and an NV color center probe, and the detection mechanism is configured to enable the NV color center probe to move along a preset path in a microwave field of the to-be-measured vector microwaves; the microscope lens is mounted above the detection mechanism, is suitable for focusing the laser onto the NV color center probe so as to enable the NV color center to emit fluorescence under the action of the laser, and is suitable for collecting the fluorescence emitted by the NV color center under the action of the laser; the counting mechanism is suitable for counting the fluorescence collected by the microscope lens; and the calculation mechanism is suitable for obtaining the polarization direction of the vector microwave field to be measured according to the projection relationship between the first and second Labir oscillation frequencies of the NV color center probe in each strong effective field and the vector microwave to be measured in the direction of each strong effective field.

Description

Technical Field

[0001] The utility model relates to the field of microwave detection, in particular to a vector microwave detection device. Background Art

[0002] Due to the characteristics of NV color center in diamond, it has long been considered as a good sensor, especially sensitive to external magnetic field. 3v A point defect in a symmetrical diamond consisting of a substitutional nitrogen atom and a lattice vacancy. This NV color center can be produced as a byproduct of the synthesis process in chemical vapor deposition (CVD) diamond, or by electron irradiation or ion implantation followed by annealing of commercial diamond or nanodiamond. NV color centers exist in two charge states, and currently only the NV with a unit negative charge is known. - Can be laser polarized and spin coherently manipulated.

[0003] When using the NV color center to detect the external physical field, in the traditional method of measuring the external physical field, it is first necessary to polarize the NV color center with a 532 nm laser so that the initial spin state of the NV color center is in the ground state |0>. Secondly, it is necessary to apply a bias magnetic field along the NV axis to modulate the resonant frequency of the NV color center to resonate with the frequency of the vector microwave to be measured. Then, by measuring the Rabi oscillation driven by the microwave, the resonant Rabi frequency is extracted to detect the vector microwave to be measured. In the above measurement method, the measurement result is related to the polarization direction of the vector microwave to be measured, and the Rabi frequency is proportional to the projection of the vector microwave to be measured on the plane perpendicular to the NV axis. The polarized vector microwave to be measured can be decomposed into a left-handed component B + and the right-hand component B - , where the left-hand and right-hand components B + and B - Resonating with |0>→|+1> and |0>→|-1>, respectively, requires very precise adjustment of the static magnetic field biased along the NV axis to reverse the polarization along the NV axis. To extract the polarization direction of the actual vector microwave to be measured, a total of five unknown quantities must be determined, including three amplitude quantities and two phase quantities. Therefore, traditional methods require at least three NV color centers, or NV ensembles, to provide polarization information of the microwave to be measured. This significantly reduces measurement efficiency and requires changing the magnetic field direction, increasing costs.

[0004] Although using the NV ensemble for measurement can improve the signal-to-noise ratio, the NV color centers with different orientations in the NV ensemble are located in different positions in the diamond. Therefore, the actual measurement results are the average microwave fields within a certain spatial range at the limit of optical resolution (equivalent to the laser wavelength of 532nm). The spatial resolution is limited by the theoretical optical limit. Utility Model Content

[0005] In view of the above technical problems, the present invention provides a vector microwave detection device to achieve accurate detection of vector microwaves.

[0006] As one aspect of the present invention, the vector microwave detection device comprises:

[0007] A detection mechanism, wherein a microwave plate for transmitting the microwave to be measured and an NV color center probe are provided on the detection mechanism, and the detection mechanism is configured to enable the NV color center probe to move along a preset path in the microwave field of the vector microwave to be measured;

[0008] a microscope lens, mounted above the detection mechanism, adapted to focus the laser onto the NV color center probe so that the NV color center probe emits fluorescence under the action of the laser, and adapted to collect the fluorescence emitted by the NV color center probe under the action of the laser;

[0009] a counting mechanism adapted to count the fluorescence collected by the microscope lens; wherein, at each position of the preset path, the NV color center probe is capable of generating Rabi oscillations under the action of the microwave field to be measured, and the intensity of the fluorescence recorded by the counting mechanism is adapted to determine the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under each strong effective field;

[0010] The calculation mechanism is adapted to obtain the polarization direction of the vector microwave field to be measured according to the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction.

[0011] According to an embodiment of the present invention, the detection mechanism includes:

[0012] A piezoelectric platform, wherein a microwave plate is mounted on the piezoelectric platform;

[0013] A translation stage, mounted on the piezoelectric platform, wherein the translation stage is configured to be movable in different directions;

[0014] The sample stage is suitable for carrying the NV color center probe. The sample stage is connected to the translation stage. The sample stage moves under the drive of the translation stage so that the NV color center probe is located at different positions in the microwave field of the vector microwave to be measured.

[0015] According to an embodiment of the present invention, the vector microwave detection device further includes:

[0016] Laser, suitable for emitting laser light;

[0017] The acousto-optic modulator is suitable for modulating the laser light emitted by the laser to control the on and off of the laser.

[0018] According to an embodiment of the present invention, the vector microwave detection device further includes:

[0019] A total reflection prism is suitable for transmitting laser light emitted by a laser to an acousto-optic modulator, and for transmitting laser light output by the acousto-optic modulator.

[0020] According to an embodiment of the present invention, the vector microwave detection device further includes:

[0021] The dichroic mirror is adapted to reflect the laser light from the acousto-optic modulator to the microscope lens; and is adapted to transmit the fluorescence collected by the microscope lens so as to transmit the fluorescence to the counting mechanism.

[0022] According to an embodiment of the present invention, the vector microwave detection device further includes:

[0023] A first filter is disposed between the dichroic mirror and the counting mechanism and is adapted to filter the fluorescence from the dichroic mirror;

[0024] The second filter is adapted to filter the laser light emitted by the laser device and transmit the filtered laser light to the total reflection prism.

[0025] According to an embodiment of the present invention, the laser light emitted by the laser passes through the acousto-optic modulator twice, so that the acousto-optic modulator performs secondary modulation on the laser light;

[0026] The vector microwave detection device also includes:

[0027] a reflecting mirror adapted to reflect the laser light from the laser that passes through the AOM for the first time, so that the laser light passes through the AOM again;

[0028] The third filter is disposed between the AOM and the reflector, and is adapted to filter the laser light coming from the laser and passing through the AOM for the first time, and is adapted to filter the laser light reflected by the reflector.

[0029] According to the vector microwave detection device provided by the utility model, an NV color center probe is used to detect the vector microwaves. A detection mechanism is used to move the NV color center probe along a preset path in the microwave field of the vector microwave to be measured. A counting mechanism is used to count the fluorescence of the NV color center probe as it moves along the preset path, thereby obtaining the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in each strong effective field. A calculation mechanism is used to obtain the polarization direction of the vector microwave field to be measured based on the first and second Rabi oscillation frequencies of the NV color center probe in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction, thereby achieving detection of the vector microwaves. The vector microwave detection device of the utility model does not require the use of a separate bias magnetic field. Therefore, the vector microwave detection device of the utility model embodiment has the advantages of simple experimental configuration, low cost, and high measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The flowchart of the vector microwave detection method provided according to the embodiment of the present utility model is shown.

[0031] Figure 2 A main view of the NV color center along the NV axis when there is no strong effective field provided by an embodiment of the present invention is shown.

[0032] Figure 3 A main view of the NV color center along the NV axis in the presence of a strong effective field provided by an embodiment of the present invention is shown.

[0033] Figure 4 A decomposition schematic diagram of a polarized vector microwave field to be measured provided according to an embodiment of the present utility model is shown.

[0034] Figure 5 It shows the direction of B1 when establishing a coordinate system along a characteristic direction according to an embodiment of the present invention.

[0035] Figure 6 The optical detection magnetic resonance spectrum of the NV color center provided according to an embodiment of the present invention is shown.

[0036] Figure 7 It shows that when the polarization direction of microwaves is measured according to an embodiment of the present invention, the polarization direction of microwaves may have an angular deviation due to different frequencies.

[0037] Figure 8 A schematic diagram of two coordinate systems provided according to an embodiment of the present utility model is shown.

[0038] Figure 9 A schematic diagram of a vector microwave detection device provided according to an embodiment of the present utility model is shown.

[0039] Figure 10 A three-dimensional diagram of a detection mechanism provided according to an embodiment of the present utility model is shown.

[0040] Figure 11 A schematic diagram showing the relative relationship between the NV color center probe and the microwave antenna provided according to an embodiment of the present utility model is shown.

[0041] Figure 12 A schematic structural diagram of an NV color center probe with two strong effective fields provided according to an embodiment of the present invention is shown.

[0042] Figure 13 Shown Figure 10 Front view along the NV axis.

[0043] Figure 14 A cross-sectional view of a diamond sample and a long straight microwave antenna for transmitting vector microwaves to be measured provided according to an embodiment of the present utility model is shown.

[0044] Figure 15 The polarization directions of the vector microwaves to be measured at different positions according to the embodiment of the present utility model are shown.

[0045] Figure 16 The energy level structure of the NV color center under zero field and strong effective field provided by the embodiment of the present invention is shown.

[0046] Description of Reference Numerals

[0047] 1 Detection mechanism

[0048] 11 Piezoelectric platform

[0049] 12-position translation stage

[0050] 13 sample stage

[0051] 2 microscope lenses

[0052] 3 counting mechanism

[0053] 4Third filter

[0054] 5 NV color center probe

[0055] 6 microwave plates

[0056] 7 lasers

[0057] 8Acousto-optic modulator

[0058] 9 Total reflection prism

[0059] 10 dichroic mirror

[0060] 11First filter

[0061] 12 Second filter

[0062] 13 reflectors

[0063] 14 diamond samples

[0064] 15 microwave antenna DETAILED DESCRIPTION

[0065] Figure 1 The flowchart of the vector microwave detection method provided according to the embodiment of the present utility model is shown.

[0066] like Figure 1 As shown, the vector microwave detection method includes operations S1 to S3.

[0067] In operation S1, the NV color center probe in the microwave field of the vector microwave to be measured is moved along a preset path; wherein the NV color center probe is an NV color center in a strong effective field or in two mirror-symmetrical strong effective fields; wherein the strong effective field refers to a transverse effective field that causes the resonance peak splitting of the optical detection magnetic resonance spectrum (ODMR spectrum) to be greater than 20 MHz.

[0068] In operation S2, for each position of the preset path, measuring a first Rabi oscillation frequency and a second Rabi oscillation frequency of the NV color center probe under each strong effective field;

[0069] In operation S3 , the polarization direction of the vector microwave field to be measured is obtained according to the relationship between the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction.

[0070] According to the embodiment of the present invention, the NV color center is an NV monochromatic center, that is, the present invention utilizes a single NV color center as an NV color center probe, that is, the high spatial resolution of the single NV color center probe is used to achieve the measurement of vector microwaves. Through theoretical calculations, it is known that the energy eigenstate of the NV color center is a superposition state of |±1>. Because the NV color center probe has one or two strong effective fields, this strong effective field can achieve energy level degeneration of the NV color center and at any position of the vector microwave to be measured, each strong effective field corresponds to a first Rabi oscillation and a second Rabi oscillation. The polarization direction of the vector microwave field to be measured can be obtained based on the relationship between the first Rabi oscillation frequency, the second Rabi oscillation frequency, and the projection of the vector microwave to be measured in each strong effective field direction.

[0071] According to the embodiments of the present invention, the traditional vector microwave measurement method requires the use of a magnetic field to degenerate the energy levels of the NV color center. Since the energy levels of the NV color center are non-degenerate under a strong effective field, the vector microwave detection method provided by the embodiments of the present invention utilizes the strong effective field of the NV color center probe. The utility model does not require the use of a bias magnetic field. Therefore, the method of the embodiments of the present invention has the advantages of simple experimental configuration, low cost, and high measurement efficiency.

[0072] According to an embodiment of the present invention, the strong effective field in the NV color center probe is generated due to the presence of a charged defect next to the NV color center. The charge will generate an electric field, and at the same time, lattice distortion will be generated around the charged defect. The strong effective field includes both electric field force and distortion effects.

[0073] According to embodiments of the present invention, the method for measuring a vector microwave field to be measured can also determine the magnitude of the vector microwave field to be measured. Because the Rabi oscillation frequency is proportional to the magnitude of the projection of the vector microwave field along the direction of the strong effective field, the magnitude of the microwave field can be inferred from the known angle of the strong effective field.

[0074] Figure 2 A main view of the NV color center along the NV axis when there is no strong effective field provided by an embodiment of the present invention is shown.

[0075] Figure 3 A main view of the NV color center along the NV axis in the presence of a strong effective field provided by an embodiment of the present invention is shown.

[0076] like Figure 2 As shown in the figure, the dots represent carbon atoms. When there is no strong effective field, the three adjacent carbon atoms in the NV color center are arranged in a regular triangle in the plane perpendicular to the NV axis. Figure 3 As shown, the dots represent carbon atoms. In the case of only one strong effective field, there is a characteristic direction, which can be compared to the direction of the height of the triangle, that is, the direction of the strong effective field. This characteristic direction is Figure 3 The dotted line direction in , therefore, the characteristic direction of the strong effective field can be used as a reference direction to measure the vector microwave field to be measured.

[0077] Figure 4 A decomposition schematic diagram of a polarized vector microwave field to be measured provided according to an embodiment of the present utility model is shown.

[0078] like Figure 4 The polarized vector microwave field to be measured can be decomposed into two components, left-handed and right-handed, B. + and B -When there is no strong effective field, since there is no characteristic direction in the plane perpendicular to the NV color center, the effect of rotating the vector microwave direction to be measured around the NV axis by any angle is equivalent.

[0079] Figure 5 It shows the direction of B1 when establishing a coordinate system along a characteristic direction according to an embodiment of the present invention.

[0080] like Figure 5 As shown, since the direction of the strong effective field, that is, the characteristic direction, is perpendicular to the axial direction of the NV center, a first coordinate system is established with the axial direction of the NV center as the Z axis and the two directions perpendicular to the Z axis as the x axis and y axis respectively. The direction of the component B1 of the polarized vector microwave field to be measured can be uniquely determined in the first coordinate system.

[0081] According to an embodiment of the present invention, the NV color center probe includes a first strong effective field and a second strong effective field. The method for determining the NV color center probe includes: operations S11 to S13.

[0082] In operation S11 , ODMR spectra of a plurality of NV monochromatic centers in a diamond sample are acquired.

[0083] In operation S12 , an NV color center corresponding to an ODMR spectrum having two resonance peaks under zero magnetic field is selected as a target NV color center.

[0084] Figure 6 The optical detection magnetic resonance spectrum of the NV color center provided according to an embodiment of the present invention is shown.

[0085] like Figure 6 As shown, the horizontal axis is the microwave frequency, and the vertical axis is the intensity of the optical detection magnetic resonance spectrum (ODMR spectrum). Figure 6 The ODMR spectrum in has two resonance peaks near the positions of 2820 MHz and 2860 MHz.

[0086] In operation S13, the Rabi oscillation of each target NV color center is measured. When the Rabi oscillation frequency of the initial NV color center has two frequency components, the target NV color center is determined to be an NV color center probe. We call this NV color center probe a "mirror two-state strong effective field NV color center."

[0087] According to an embodiment of the present invention, a method for determining a first strong effective field direction and a second strong effective field of an NV color center probe includes the following steps.

[0088] First, the NV color center probe is moved along a preset path in a preset microwave field. Secondly, for each position along the preset path, the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the first strong effective field, as well as the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the second strong effective field, are measured respectively. Finally, the direction of the first strong effective field and the direction of the second strong effective field are determined based on the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the first strong effective field, the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the second strong effective field, and the projection of the preset microwave field in the direction of the first strong effective field and the direction of the second strong effective field.

[0089] Figure 7 The figure shows that when measuring the polarization direction of microwaves according to an embodiment of the present invention, the polarization direction of microwaves may have an angular deviation due to different frequencies.

[0090] like Figure 7 As shown, in the coordinate system S1, when the polarization direction of microwaves is measured using polarization directions B1 and B2 of different frequencies, the polarization directions of different frequencies may have angular deviations, resulting in inaccurate measurement results.

[0091] According to an embodiment of the present invention, when the NV color center probe includes a first strong effective field and a second strong effective field, the polarization direction of the vector microwave to be measured can be measured by establishing two sets of coordinate systems.

[0092] Figure 8 A schematic diagram of two coordinate systems provided according to an embodiment of the present utility model is shown.

[0093] like Figure 8 As shown, the NV color center probe with two strong effective fields establishes two coordinate systems through two states, namely the coordinate system oxyz and the coordinate system ox ， y ， z ， , the z-axis of the coordinate system oxyz and the coordinate system ox ， y ， z ， z in ， The axis direction is the same as the NV axis direction of the NV color center probe, the x axis of the coordinate system oxyz and the coordinate system ox ， y ， z ， x in ， The axes are in the same direction as the first strong effective field and the second strong effective field, for example, the x-axis of the coordinate system oxyz is in the same direction as the first strong effective field, and the coordinate system ox ， y ， z ， x in ，The axis is in the same direction as the second strongest effective field. ， y ， z ， y in ， The axis is perpendicular to the direction of the first strong effective field and the second strong effective field. For example, the y axis of the coordinate system oxyz is perpendicular to the direction of the first strong effective field, and the coordinate system ox ， y ， z ， y in ， The axis is perpendicular to the direction of the second strongest effective field. The above two coordinate systems can decompose the polarization direction of microwaves of a single frequency in the two coordinate systems respectively, and can accurately measure the polarization direction of microwaves of a specific frequency.

[0094] Figure 9 A schematic diagram of a vector microwave detection device provided according to an embodiment of the present utility model is shown.

[0095] Figure 10 A three-dimensional diagram of a detection mechanism provided according to an embodiment of the present utility model is shown.

[0096] like Figure 9-10 As described above, the vector microwave detection device includes: a detection mechanism 1, a microscope lens 2, a counting mechanism 3 and a calculation mechanism (not shown in the figure).

[0097] The detection mechanism 1 is equipped with a microwave plate 6 for transmitting the microwave to be measured and an NV color center probe 5. The detection mechanism 1 is configured to position the NV color center probe 5 at different positions within the microwave field of the microwave to be measured. A microscopic lens 2 is mounted above the detection mechanism 1 and is adapted to focus a laser onto the NV color center probe, causing the NV color center probe 5 to emit fluorescence under the action of the laser, and to collect the fluorescence emitted by the NV color center probe 5 under the action of the laser. A counting mechanism 3 is adapted to count the fluorescence collected by the microscopic lens 2. Within the microwave field of the vector microwave to be measured, the NV color center probe 5 can undergo Rabi oscillation under the action of the microwave field. The fluorescence intensity recorded by the counting mechanism 3 (e.g., an APD) is used to determine the first and second Rabi oscillation frequencies of the NV color center probe in the first strong effective field, as well as the first and second Rabi oscillation frequencies in the second strong effective field. A calculation mechanism is adapted to derive the polarization direction of the vector microwave field to be measured based on the relationship between the first and second Rabi oscillation frequencies in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction.

[0098] According to the vector microwave detection device provided by the embodiment of the present invention, an NV color center probe is used to detect the vector microwave. A detection mechanism 1 is used to move the NV color center probe along a preset path in the microwave field of the vector microwave to be measured, and a counting mechanism 5 is used to count the fluorescence of the NV color center probe 5 as it moves along the preset path, thereby obtaining the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe 5 in each strong effective field. A calculation mechanism is used to obtain the polarization direction of the vector microwave field to be measured based on the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction, thereby achieving the detection of the vector microwave. The vector microwave detection device of the present invention does not require the use of a bias magnetic field. Therefore, the vector microwave detection device of the embodiment of the present invention has the advantages of simple experimental configuration, low cost, and high measurement efficiency.

[0099] According to an embodiment of the present invention, a microwave antenna 15 is provided on the microwave board 6 to provide vector microwaves to be measured.

[0100] Figure 11 A schematic diagram of the relative position relationship between the NV color center probe and the microwave antenna provided according to an embodiment of the present utility model is shown.

[0101] like Figure 11 As shown, the NV color center probe is always in the microwave field of the vector microwave to be measured.

[0102] Figure 12 A schematic structural diagram of an NV color center probe with two strong effective fields provided according to an embodiment of the present invention is shown.

[0103] Figure 13 Shown Figure 12 Front view along the NV axis.

[0104] like Figure 12-13 The figure shows the structure of the NV color center probe with two strong effective fields, where the orange spheres are N atoms, the purple spheres are vacancies, the black spheres are C atoms, the blue arrows represent the NV axis of the NV color center probe, the orange arrows represent the x-axis direction of the NV color center probe coordinate system, and the red and green arrows represent the directions of the first strong effective field and the second strong effective field, respectively. Figure 11 It can be seen that the first strong effective field and the second strong effective field are mirror-symmetric with respect to the vertical symmetry plane of the NV color center probe, so the optical detection magnetic resonance spectrum of the NV color center probe is degenerate.

[0105] Continue to refer Figure 10 ,like Figure 10 As shown, the detection mechanism 1 includes: a piezoelectric platform 11 , a displacement stage 12 , and a sample stage 13 .

[0106] A microwave plate 6 is mounted on the piezoelectric platform 11. A translation stage 13 is mounted on the piezoelectric platform 1 and is configured to move in various directions. The sample stage 13 is adapted to support the NV color center probe 5. The sample stage 13 is connected to the translation stage 12 and is driven by the translation stage 12 to move the sample stage 13 to position the NV color center probe 5 at different locations within the microwave field of the vector microwave to be measured.

[0107] According to an embodiment of the present invention, the vector microwave detection device further includes a laser 7 and an acousto-optic modulator 8. The laser 7 is adapted to emit laser light. The acousto-optic modulator 8 is adapted to modulate the laser light emitted by the laser 8 to control the on and off of the laser light.

[0108] According to an embodiment of the present invention, the vector microwave detection device further includes a total reflection prism 9, which is adapted to transmit the laser light emitted by the laser 7 to the acousto-optic modulator 8, and is adapted to transmit the laser light output by the acousto-optic modulator 8.

[0109] According to an embodiment of the present invention, the vector microwave detection device further includes a dichroic mirror 10 adapted to reflect the laser light from the acousto-optic modulator 8 to the microscope head 2 , and adapted to transmit the fluorescence collected by the microscope 2 so that the fluorescence is transmitted to the counting mechanism 3 .

[0110] According to an embodiment of the present invention, the vector microwave detection device further includes a first filter 11 and a second filter 12. The first filter 11 is disposed between the dichroic mirror 10 and the counting mechanism 4 and is adapted to filter the fluorescence emitted from the dichroic mirror 10. The second filter 12 is adapted to filter the laser light emitted by the laser 7 and transmit the filtered laser light to the total reflection prism.

[0111] According to an embodiment of the present invention, the laser light emitted by the laser 7 passes through the acousto-optic modulator twice, so that the acousto-optic modulator 8 performs secondary modulation on the laser light.

[0112] According to an embodiment of the present invention, the vector microwave detection device further includes a reflector 13 and a third filter 4. The reflector 13 is adapted to reflect the laser light emitted by the laser and after it passes through the AOM 8 for the first time, so that the laser light passes through the AOM 8 again. The third filter 4 is disposed between the AOM 8 and the reflector 13 and is adapted to filter the laser light that passes through the AOM 8 for the first time and to filter the laser light reflected by the reflector 13.

[0113] According to the embodiments of the present invention, for an NV color center probe with a strong effective field, it is necessary to assume that the direction and magnitude of the vector microwave to be measured remain unchanged at the two resonant frequencies. In order to measure the polarization direction of the microwave frequency we are interested in, a reference microwave field with a given magnitude and direction that remains unchanged is still required. Due to the symmetry of the diamond sample, there is an NV probe with two strong effective fields, where the first strong effective field and the second strong effective field are mirror-symmetric with respect to the symmetry plane of the NV color center probe (e.g., Figure 12 ), thus strictly satisfying the condition of constant resonant frequency. Utilizing this condition, we only need to measure the resonant frequency of the vector microwave to be measured. The microwave resonant frequency can be modulated by applying a bias electric field along the NV axis of the NV center probe.

[0114] The following embodiments illustrate the process of detecting vector microwaves using an NV color center probe 5 having two strong effective fields (two-state strong effective fields).

[0115] First, the preparation of NV color center probe 5 with a strong two-state effective field.

[0116] Diamond samples were grown using MP-CVD, and the surface of the diamond samples was specially polished. A 200 nm layer of PMMA was spin-coated, and a circular hole array with a diameter of about 10 nm was made on the PMMA using electron beam lithography. Ion implantation, circular hole array, the implantation dose is about 15×10 15 / cm. Then inject The diamond sample containing ions was annealed at 1050°C. Finally, the automated program we designed scanned the diamond sample and found the NV color center probe 5 with two strong effective fields (two-state strong-strong effective field).

[0117] Next, the NV color center probe 5 is calibrated.

[0118] According to an embodiment of the present invention, before using the NV color center probe 5 to detect the vector microwave field to be measured, it is necessary to determine the directions of the first strong effective field and the second strong effective field in the NV color center probe 5. The NV color center probe 5 is calibrated as follows using a long straight wire or a long straight microwave antenna with a known microwave field distribution as a calibration object.

[0119] The NV color center probe 5 is always placed in the microwave field (ie, the preset microwave field) of a long straight microwave antenna (eg, a copper wire).

[0120] The NV color center probe 5 is moved along a preset path in a preset microwave field, and the Rabi oscillation at each position of the preset path is measured. The Rabi oscillation at different positions is subjected to Fourier transform to obtain two frequency components f1 and f2, where f1 is the first Rabi frequency of the first strong effective field and f2 is the first Rabi frequency of the second strong effective field. The preset frequency is Ω + The polarization direction of the microwave field (~2820MHz) and the direction of the first strong effective field and the two angles θ1 and θ2 in the direction of the first strong effective field correspond to f1 and f2 respectively. The corresponding angles are obtained by changing the microwave frequency. Ω - The two Rabi frequencies g1 and g2 of the first strong effective field are (2860 MHz), g1 is the second Rabi frequency of the first strong effective field, and g2 is the second Rabi frequency of the second strong effective field. The NV axis direction and the component of the strong effective field perpendicular to the NV axis are finally determined by fitting f1, f2, g1 and g2 at different positions using the least squares method. Finally, based on the fluorescence images produced by multiple NV color centers in the sample, the directions of all strong effective fields are transformed into the corresponding geometric coordinates of the diamond, making it easier to use it as a NV color center probe.

[0121] Finally, the calibrated NV color center probe 5 is used to detect the vector microwave to be measured.

[0122] Figure 14 A cross-sectional view of a diamond sample and a microwave antenna for transmitting vector microwaves to be measured provided according to an embodiment of the present utility model is shown.

[0123] Figure 15 The polarization directions of the vector microwaves to be measured at different positions according to the embodiment of the present utility model are shown.

[0124] like Figure 14 As shown, the calibrated NV color center probe 5 can be sufficiently close to the micro-nano level microwave antenna 15 and measure the near-field distribution of the vector microwave to be measured. The microwave antenna 15 can be, for example, a long straight copper wire. The distance h between the center of the microwave antenna 15 and the diamond sample is about 30 microns. The polarization direction of the vector microwave to be measured at different positions is as follows Figure 14 shown.

[0125] Figure 16 The energy level structure of the NV color center under zero field, strong effective field, and magnetic field provided by the embodiment of the present invention is shown.

[0126] like Figure 16 As shown, the electron spin energy levels of the NV color center are degenerate under zero field. 14 The N nuclear spin causes a 2.2MHz hyperfine splitting of the energy levels. Under a strong effective field, the electron spin energy levels degenerate and due to the longitudinal strong effective field The effect of the magnetic field causes an overall translation, and the hyperfine splitting of the nuclear spin is suppressed, so the influence of the nuclear spin can be ignored. However, the hyperfine splitting of the nuclear spin cannot be ignored under a magnetic field.

[0127] The NV color center probe 5 is fixed on the piezoelectric platform 11, and the fluorescence image is scanned. The NV color center probe 5 and the piezoelectric platform 11 can be connected through the translation stage 12 to adjust the relative position of the NV color center probe 5 and the microwave antenna 15, and the Rabi oscillation of the NV color center probe 5 at different positions is measured. The principle of extracting the direction information of the microwave vector field is as follows: Figure 7 As shown in the figure, the two strong effective field directions of the NV color center probe 5 are along the x and x' directions of the two coordinate systems respectively, and the two frequency components of the Rabi oscillation are proportional to the projections of the microwave vector B2 in these two directions. Therefore, measuring the Rabi frequency can obtain the microwave vector in the oblique coordinate system. The coordinates on the NV center probe 5 are calibrated. Since the coordinates x' and x are completely known, the direction of the microwave vector can be inferred. Using LabVIEW, the data can be processed on-site to obtain the near-field distribution of the polarization vector of the microwave antenna 15.

[0128] The vector microwave detection device of this utility model calibrates the direction of the strong effective field of a two-state strong effective field NV color center and measures the Rabi frequency under the strong effective field to obtain the directional information of the microwave vector. This device uses a single NV color center to measure the microwave vector, with high spatial resolution, simple experimental configuration, low cost, and high measurement efficiency.

[0129] The above specific embodiments further illustrate the purpose, 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 vector microwave detection device, comprising: A detection mechanism, wherein a microwave plate for transmitting the microwave to be measured and an NV color center probe are provided on the detection mechanism, and the detection mechanism is configured to enable the NV color center probe to move along a preset path in the microwave field of the vector microwave to be measured; a microscope lens, mounted above the detection mechanism, adapted to focus the laser onto the NV color center probe so that the NV color center emits fluorescence under the action of the laser, and adapted to collect the fluorescence emitted by the NV color center under the action of the laser; a counting mechanism adapted to count the fluorescence collected by the microscope lens; wherein, at each position of the preset path, the NV color center probe is capable of generating Rabi oscillations under the action of the microwave field to be measured, and the intensity of the fluorescence recorded by the counting mechanism is adapted to determine the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under each strong effective field; The calculation mechanism is adapted to obtain the polarization direction of the vector microwave field to be measured according to the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in each strong effective field and the projection of the vector microwave to be measured in each strong effective field direction.

2. The vector microwave detection device according to claim 1, wherein the detection mechanism comprises: A piezoelectric platform, wherein a microwave plate is mounted on the piezoelectric platform; A translation stage, mounted on the piezoelectric platform, wherein the translation stage is configured to be movable in different directions; The sample stage is suitable for carrying the NV color center probe. The sample stage is connected to the translation stage. The sample stage moves under the drive of the translation stage so that the NV color center probe is located at different positions in the microwave field of the vector microwave to be measured.

3. The vector microwave detection device according to claim 1, further comprising: Laser, suitable for emitting laser light.

4. The vector microwave detection device according to claim 1, further comprising: The acousto-optic modulator is suitable for modulating the laser light emitted by the laser to control the on and off of the laser.

5. The vector microwave detection device according to claim 4, further comprising: A total reflection prism is suitable for transmitting laser light emitted by a laser to an acousto-optic modulator, and for transmitting laser light output by the acousto-optic modulator.

6. The vector microwave detection device according to claim 4, further comprising: A dichroic mirror, suitable for reflecting the laser light from the acousto-optic modulator to the microscope head; The invention is also suitable for transmitting the fluorescence collected by the microscope head so as to transmit the fluorescence to the counting mechanism.

7. The vector microwave detection device according to claim 6, further comprising: The first filter is arranged between the dichroic mirror and the counting mechanism and is suitable for filtering the fluorescence from the dichroic mirror.

8. The vector microwave detection device according to claim 1, further comprising: The second filter is adapted to filter the laser light emitted by the laser device and transmit the filtered laser light to the total reflection prism.

9. The vector microwave detection device according to claim 4, wherein: The laser light emitted by the laser passes through the acousto-optic modulator twice so that the acousto-optic modulator performs secondary modulation on the laser light.

10. The vector microwave detection device according to claim 9, further comprising: a reflecting mirror adapted to reflect the laser light from the laser that passes through the AOM for the first time, so that the laser light passes through the AOM again; The third filter is disposed between the AOM and the reflector, and is adapted to filter the laser light coming from the laser and passing through the AOM for the first time, and is adapted to filter the laser light reflected by the reflector.

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