Vector microwave detection method and vector microwave detection device

Abstract

The invention discloses a vector microwave detection method and a vector microwave detection device. The vector microwave detection method comprises the following steps: enabling an NV color center probe in a microwave field of vector microwaves to be detected to move along a preset path; wherein the NV color center probe is an NV color center in a strong effective field or two mirror symmetry strong effective fields; aiming at a plurality of positions on the preset path, measuring a first pulling ratio oscillation frequency and a second pulling ratio oscillation frequency of the NV color center in each strong effective field; and obtaining the projection of the vector microwave to be measured in the direction of each strong effective field according to the first Rabian oscillation frequency and the second Rabian oscillation frequency of the NV color center in each strong effective field, and then obtaining the polarization direction of the vector microwave field to be measured.

Description

Technical Field

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

[0002] Due to the characteristics of NV color centers in diamond, it has long been considered a good sensor, especially sensitive to external magnetic fields. 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 annealing commercial diamond or nanodiamond after electron irradiation or ion implantation. 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 NV color centers to detect external physical fields, in the traditional method of measuring external physical fields, 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. , and secondly, a bias magnetic field needs to be applied 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, and then the resonant Rabi frequency is extracted by measuring the Rabi oscillation driven by the microwave 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 a right-handed component B-, where the left-handed and right-handed components are and Respectively and , Resonance occurs, so it is necessary to adjust the static magnetic field biased along the NV axis very accurately to reverse it along the NV axis. In order to extract the polarization direction of the actual vector microwave to be measured, a total of 5 unknown quantities need to be determined, including three amplitude quantities and two phase quantities. Therefore, the traditional method requires at least three NV color centers, namely the NV ensemble, to give the polarization information of the microwave to be measured, which greatly reduces the measurement efficiency and requires changing the direction of the magnetic field, which increases the cost.

[0004] Although measurements using the NV ensemble can improve the signal-to-noise ratio, 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 wavelength of the laser, 532nm). The spatial resolution is limited by the theoretical optical limit. Summary of the invention

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

[0006] As one aspect of the present invention, a vector microwave detection method is provided, comprising:

[0007] 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;

[0008] For a plurality of positions on 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;

[0009] The polarization direction of the vector microwave field to be measured is obtained 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.

[0010] According to an embodiment of the present invention, the two mirror-symmetrical strong effective fields include a first strong effective field and a second strong effective field, and the method for determining the NV color center probe includes:

[0011] Obtain ODMR spectra of multiple NV color centers in a diamond sample;

[0012] The NV color center corresponding to the ODMR spectrum with two resonance peaks under zero magnetic field is selected as the target NV color center;

[0013] The Rabi oscillation of each target NV color center is measured, and when the Rabi oscillation frequency of the target NV color center has two frequency components, the target NV color center is determined to be the NV color center probe.

[0014] According to an embodiment of the present invention, a method for determining the first strong effective field direction and the second strong effective field of the NV color center probe comprises:

[0015] Moving the NV color center probe along a preset path in a preset microwave field;

[0016] For a plurality of positions on the preset path, respectively measuring a first Rabi oscillation frequency and a second Rabi oscillation frequency of the NV color center probe under the first strong effective field and a first Rabi oscillation frequency and a second Rabi oscillation frequency of the NV color center probe under the second strong effective field;

[0017] The direction of the first strong effective field and the direction of the second strong effective field are determined according to the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in the first strong effective field, the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in the second strong effective field, and the projection relationship between the preset microwave field and the direction of the first strong effective field and the direction of the second strong effective field.

[0018] As a second aspect of the present invention, a vector microwave detection device is also provided, comprising:

[0019] 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;

[0020] A microscope lens, installed 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;

[0021] A counting mechanism, adapted to count the fluorescence collected by the microscope lens; wherein, at multiple positions on the preset path, the NV color center probe can undergo Rabi oscillation 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;

[0022] 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.

[0023] According to an embodiment of the present invention, the detection mechanism comprises:

[0024] A piezoelectric platform, on which the microwave plate is mounted;

[0025] A translation stage, mounted on the piezoelectric platform, the translation stage being configured to be movable in different directions;

[0026] 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 of the microwave field of the vector microwave to be measured.

[0027] According to an embodiment of the present invention, the above-mentioned vector microwave detection device further includes:

[0028] A laser device, adapted to emit said laser light;

[0029] The acousto-optic modulator is suitable for modulating the laser light emitted by the laser to control the on and off of the laser light.

[0030] According to an embodiment of the present invention, the above-mentioned vector microwave detection device further includes:

[0031] A total reflection prism is used to transmit the laser light emitted by the laser to the AOM, and is used to transmit the laser light output by the AOM.

[0032] According to an embodiment of the present invention, the above-mentioned vector microwave detection device further includes:

[0033] The dichroic mirror is used to reflect the laser light from the AOM to the microscope head; and is used to transmit the fluorescence collected by the microscope head so that the fluorescence is transmitted to the counting mechanism.

[0034] According to an embodiment of the present invention, the above-mentioned vector microwave detection device further includes:

[0035] A first filter, disposed between the dichroic mirror and the counting mechanism, adapted to filter the fluorescence from the dichroic mirror;

[0036] 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.

[0037] 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;

[0038] The vector microwave detection device also includes:

[0039] A reflecting mirror, adapted to reflect the laser light from the laser and passing through the AOM for the first time, so that the laser light passes through the AOM again;

[0040] 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.

[0041] According to an embodiment of the present invention, a NV color center probe using a single NV color center is used, that is, the high spatial resolution of a single NV color center is used to achieve the measurement of vector microwaves. It can be known from theoretical calculations that the energy eigenstate of the NV color center is Superposition state. Since the NV color center probe has a strong effective field or switches between two strong effective fields, the effective field can realize the energy level degeneration of the NV color center at any position of the vector microwave to be measured. Each strong effective field corresponds to the first Rabi oscillation and the second Rabi oscillation. The polarization direction of the vector microwave field to be measured can be obtained according to the projection relationship between the first Rabi oscillation frequency, the second Rabi oscillation frequency and the vector microwave to be measured and the direction of each strong effective field.

[0042] According to an embodiment 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. However, since the energy levels of the NV color center are non-degenerate under an effective field, the vector microwave detection method provided in an embodiment of the present invention utilizes the effective field of the NV color center probe and does not require the use of a bias magnetic field. Therefore, this method has the advantages of simple experimental configuration, low cost, and high measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A flow chart of a vector microwave detection method provided according to an embodiment of the present invention is shown.

[0044] Figure 2 A front view of the NV color center along the NV axis direction when there is no strong effective field provided according to an embodiment of the present invention is shown.

[0045] Figure 3 A front view of the NV color center along the NV axis in the presence of a strong effective field according to an embodiment of the present invention is shown.

[0046] Figure 4 A decomposition schematic diagram of a polarized vector microwave field to be measured provided according to an embodiment of the present invention is shown.

[0047] 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.

[0048] Figure 6 The optical detection magnetic resonance spectrum of the NV color center provided according to an embodiment of the present invention is shown.

[0049] Figure 7 It shows that when the polarization direction of microwaves is measured according to an embodiment of the present invention, the angular deviation of the polarization direction of microwaves due to different frequencies.

[0050] Figure 8 A schematic diagram of two coordinate systems provided according to an embodiment of the present invention is shown.

[0051] Fig. 9 A schematic diagram of a vector microwave detection device provided according to an embodiment of the present invention is shown.

[0052] Fig.10 A structural diagram of a detection mechanism provided according to an embodiment of the present invention is shown.

[0053] Fig.11 A schematic diagram showing the relative position relationship between the NV color center probe and the microwave antenna provided according to an embodiment of the present invention is shown.

[0054] Fig.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.

[0055] Fig.13 Shows Fig.12 Front view along the NV axis.

[0056] Fig.14 A plan 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 invention is shown.

[0057] Fig.15 The polarization directions of the vector microwaves at different positions to be measured according to the embodiment of the present invention are shown.

[0058] Fig.16 The energy level structure of the NV color center under zero field and strong effective field provided by an embodiment of the present invention is shown.

[0059] Description of Reference Numerals

[0060] 1. Detection mechanism

[0061] 11 Piezoelectric platform

[0062] 12 stage

[0063] 13 Sample stage

[0064] 2 microscope lenses

[0065] 3 Counting mechanism

[0066] 4Third filter

[0067] 5 NV color center probe

[0068] 6 Microwave Plate

[0069] 7 Lasers

[0070] 8Acousto-optic modulator

[0071] 9Total reflection prism

[0072] 10Dichroic Mirror

[0073] 11First filter

[0074] 12 Second filter

[0075] 13. Reflector

[0076] 14 Diamond samples

[0077] 15 Microwave Antenna DETAILED DESCRIPTION

[0078] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0079] Figure 1 A flow chart of a vector microwave detection method provided according to an embodiment of the present invention is shown.

[0080] like Figure 1 As shown, the vector microwave detection method includes operations S1 to S3.

[0081] 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.

[0082] 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;

[0083] In operation S3 , the polarization direction of the vector microwave field to be measured is obtained 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.

[0084] The NV color center according to the embodiment of the present invention is a NV single color center, that is, the embodiment of the present invention uses a single NV color center as an NV color center probe, and the measurement of vector microwaves is achieved through the high spatial resolution of the NV color center probe. It can be known from theoretical calculations that the energy eigenstate of the NV color center is Superposition state. Since the NV color center probe has one or two effective fields, the effective field can realize the energy level degeneration of the NV color center. At any position of the vector microwave to be measured, each strong effective field will produce the first Rabi oscillation and the second Rabi oscillation. The polarization direction of the vector microwave field to be measured can be obtained according to 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.

[0085] According to an embodiment of the present invention, the traditional vector microwave measurement method needs to utilize 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 in the embodiment of the present invention utilizes the effective field of the NV color center probe and does not require the use of a bias magnetic field. Therefore, the method of the embodiment of the present invention has the advantages of simple experimental configuration, low cost, and high measurement efficiency.

[0086] 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 lattice distortion will occur around the charged defect. The strong effective field includes both electric field force and distortion.

[0087] According to an embodiment of the present invention, the method for measuring the vector microwave field to be measured provided by the embodiment of the present invention can also obtain the size of the vector microwave field to be measured. Since the size of the Rabi oscillation frequency is proportional to the size of the projection of the vector microwave field along the direction of the strong effective field, the size of the microwave field can be inferred from the premise that the strong effective field angle is known.

[0088] Figure 2 A front view of the NV color center along the NV axis direction when there is no strong effective field provided according to an embodiment of the present invention is shown.

[0089] Figure 3 A front view of the NV color center along the NV axis in the presence of a strong effective field according to an embodiment of the present invention is shown.

[0090] 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.

[0091] Figure 4 A decomposition schematic diagram of a polarized vector microwave field to be measured provided according to an embodiment of the present invention is shown.

[0092] like Figure 4 As shown in FIG. 1 , the polarized vector microwave field to be measured can be decomposed into two components, left-handed and right-handed, B when there is no strong effective field. + 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 direction of the vector microwave to be measured around the NV axis by any angle is equivalent.

[0093] 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.

[0094] like Figure 5 As shown, since the direction of the strong effective field, i.e. the characteristic direction, is perpendicular to the axial direction of the NV color center, a first coordinate system is established with the axial direction of the NV color center as the z-axis and the two directions perpendicular to the z-axis as the x-axis and the 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.

[0095] 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.

[0096] In operation S11 , ODMR spectra of a plurality of NV color centers in a diamond sample are acquired.

[0097] 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.

[0098] Figure 6 The optical detection magnetic resonance spectrum of the NV color center provided according to an embodiment of the present invention is shown.

[0099] 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. Figure 6 The ODMR spectrum in has two resonance peaks near the positions of 2820 MHz and 2860 MHz.

[0100] 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, which we call a "mirror two-state strong effective field NV color center".

[0101] 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.

[0102] First, the NV color center probe is moved along a preset path in a preset microwave field. Secondly, the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the first strong effective field and 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 for multiple positions on the preset path. Finally, the direction of the first strong effective field and the direction of the second strong effective field are determined according to 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 relationship between the preset microwave field and the direction of the first strong effective field and the direction of the second strong effective field.

[0103] Figure 7 It shows that when the polarization direction of microwaves is measured according to an embodiment of the present invention, the angular deviation of the polarization direction of microwaves due to different frequencies.

[0104] 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 measurement result is inaccurate because the polarization directions of different frequencies may have an angle deviation.

[0105] 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 measurement of the polarization direction of the vector microwave to be measured can be achieved by establishing two sets of coordinate systems.

[0106] Figure 8 A schematic diagram of two coordinate systems provided according to an embodiment of the present invention is shown.

[0107] like Figure 8 As shown in Figure 2, 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 ox ， y ， z ， x in ， The axes are in the same direction as the first strong effective field and the second strong effective field, respectively. 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 y-axis of the coordinate system oxyz and the y-axis of the coordinate system ox ， y ， z ， The 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 ， The 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.

[0108] Fig. 9 A schematic diagram of a vector microwave detection device provided according to an embodiment of the present invention is shown.

[0109] Fig.10 A stereoscopic view of a detection mechanism provided according to an embodiment of the present invention is shown.

[0110] like Figure 9-10 The vector microwave detection device comprises: a detection mechanism 1, a microscope lens 2, a counting mechanism 3 and a calculation mechanism (not shown in the figure).

[0111] The detection mechanism 1 is provided with a microwave plate 6 and an NV color center probe 5 for transmitting the microwave to be measured, and the detection mechanism 1 is configured to enable the NV color center probe 5 to be located at different positions of the microwave field of the microwave to be measured. The microscope lens 2 is installed above the detection mechanism 1, and is suitable for focusing the laser on the NV color center probe so that the NV color center probe 5 emits fluorescence under the action of the laser, and is suitable for collecting the fluorescence emitted by the NV color center probe 5 under the action of the laser. The counting mechanism 3 is suitable for counting the fluorescence collected by the microscope lens 2. Among them, in 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, and the fluorescence intensity recorded by the counting mechanism 3 (for example, APD) is suitable for determining the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under the first strong effective field and the first Rabi oscillation frequency and the second Rabi oscillation frequency under the second strong effective field. The calculation mechanism is suitable for obtaining the polarization direction of the vector microwave field to be measured according to the first Rabi oscillation frequency, the second Rabi oscillation frequency under each strong effective field and the projection relationship of the vector microwave to be measured in each strong effective field direction.

[0112] According to the detection device of vector microwaves provided by the embodiment of the present invention, the NV color center probe is used to detect the vector microwaves. The detection mechanism 1 is used to make the NV color center probe move along a preset path in the microwave field of the vector microwave to be measured, and the counting mechanism 5 is used to count the fluorescence of the NV color center probe 5 when it moves along the preset path, so as to obtain the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe 5 in each strong effective field, and the calculation mechanism is used 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, so as to realize the detection of the vector microwaves. The vector microwave detection device of the present invention does not need to use a bias magnetic field separately, so the vector microwave detection device of the embodiment of the present invention has the advantages of simple experimental configuration, low cost, high measurement efficiency, etc.

[0113] According to the embodiment of the present invention, a microwave antenna 15 is disposed on the microwave board 6 .

[0114] Fig.11 A schematic diagram showing the relative position relationship between the NV color center probe and the microwave antenna provided according to an embodiment of the present invention is shown.

[0115] like Fig.11 As shown, the NV color center probe is always in the microwave field of the vector microwave to be measured.

[0116] Fig.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.

[0117] Fig.13 Shows Fig.12 Front view along the NV axis.

[0118] like Figure 12-13 The figure shows the structure of an 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. Fig.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 resonance spectrum of the NV color center probe is degenerate.

[0119] Continue to refer Fig.10 ,like Fig.10 As shown, the detection mechanism 1 includes: a piezoelectric platform 11, a displacement stage 12, and a sample stage 13.

[0120] A microwave plate 6 is mounted on the piezoelectric platform 11. A translation stage 13 is mounted on the piezoelectric platform 1, and the translation stage 13 is configured to be movable in different directions. The sample stage 13 is suitable for carrying the NV color center probe 5, and the sample stage 13 is connected to the translation stage 12. The sample stage 13 moves under the drive of the translation stage 12, so that the NV color center probe 5 is at different positions of the microwave field of the vector microwave to be measured.

[0121] According to an embodiment of the present invention, the vector microwave detection device further comprises 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.

[0122] According to an embodiment of the present invention, the vector microwave detection device further includes a total reflection prism 9, which is suitable for transmitting the laser light emitted by the laser 7 to the acousto-optic modulator 8, and is suitable for transmitting the laser light output by the acousto-optic modulator 8.

[0123] According to an embodiment of the present invention, the vector microwave detection device further includes a dichroic mirror 10, which is adapted to reflect the laser from the acousto-optic modulator 8 to the microscope head 2, and is adapted to filter the fluorescence collected by the microscope 2 so that the fluorescence is transmitted to the counting mechanism 3.

[0124] 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 arranged between the dichroic mirror 10 and the counting mechanism 4 and is suitable for filtering the fluorescence from the dichroic mirror 10. The second filter 12 is suitable for filtering the laser light emitted by the laser 7 and transmitting the filtered laser light to the total reflection prism.

[0125] According to an embodiment of the present invention, the laser light emitted by the laser 7 passes through the AOM twice, so that the AOM 8 performs secondary modulation on the laser light.

[0126] 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 suitable for reflecting the laser light emitted by the laser and passing through the AOM 8 for the first time, so that the laser light passes through the AOM 8 again. The third filter 4 is arranged between the AOM 8 and the reflector 13, and is suitable for filtering the laser light passing through the AOM 8 for the first time and for filtering the laser light reflected by the reflector 13.

[0127] According to an embodiment 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 remain unchanged is still required. Since the diamond sample has symmetry, there is an NV probe with two strong effective fields, wherein 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. Fig.12 ), so the condition of constant resonance frequency is strictly satisfied. Using this condition, we only need to measure the resonance frequency of the vector microwave to be measured. The modulation of the microwave resonance frequency can be achieved by adding a bias electric field along the NV axis direction of the NV color center probe.

[0128] The following embodiments illustrate the process of detecting vector microwaves using the NV color center probe 5 having two strong effective fields (two-state strong effective fields).

[0129] First, the NV color center probe 5 with a two-state strong effective field was prepared.

[0130] Diamond samples were grown using MPCVD, 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, implantation dose is about 15×10 15 / cm. Then inject The diamond sample with ions was annealed at 1050°C. Finally, the diamond sample was scanned by the automatic program designed by us to find the NV color center probe 5 with two strong effective fields (double-state strong effective field).

[0131] Next, the NV color center probe 5 is calibrated.

[0132] 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 method of calibrating the NV color center probe 5 using a long straight wire or a long straight microwave antenna with a known microwave field distribution as a calibration object is as follows.

[0133] 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).

[0134] The NV color center probe 5 is moved along a preset path in a preset microwave field, and the Rabi oscillations at multiple positions on the preset path are measured. The Rabi oscillations at different positions are 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 two angles between the polarization direction of the microwave field (2820 MHz) and the direction of the first strong effective field and the direction of the second strong effective field and , corresponding to f1 and f2 respectively, changing the microwave frequency to obtain the corresponding - The two Rabi frequencies g1 and g2 of (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, according to the fluorescence images produced by multiple NV color centers in the sample, the directions of all strong effective fields are transformed to the corresponding geometric coordinates of diamond, making it convenient to use it as a NV color center probe.

[0135] Finally, the calibrated NV color center probe 5 is used to detect the vector microwave to be measured.

[0136] Fig.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 invention is shown.

[0137] Fig.15 The polarization directions of the vector microwaves at different positions to be measured according to the embodiment of the present invention are shown.

[0138] like Fig.14 As shown, the calibrated NV color center probe 5 can be sufficiently close to the micro-nano 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 directions of the vector microwave to be measured at different positions are shown in FIG. Fig.14 shown.

[0139] Fig.16 The energy level structures of NV color centers under zero field, strong effective field, and magnetic field provided by embodiments of the present invention are shown.

[0140] like Fig.16 As shown in Figure 2, the electron spin energy levels of the NV color center are degenerate under zero field, and the 14N nuclear spin causes a hyperfine splitting of 2.2 MHz. Under strong effective field, the electron spin energy levels are 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 under the magnetic field cannot be ignored.

[0141] 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 respectively along the x 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 gives the microwave vector in the oblique coordinate system. According to the calibration of NV color center probe 5, since the coordinate system The information of and x is completely known, so the direction of the microwave vector can be deduced in the end. The data can be processed on site using the Labview program, and the near-field distribution of the polarization vector of the microwave antenna 15 can be obtained in the end.

[0142] The embodiment of the present invention obtains the direction information of the microwave vector by calibrating the direction of the strong effective field of the two-state strong effective field NV color center and measuring the Rabi frequency under the strong effective field respectively. The method measures the microwave vector through a single NV color center, has high spatial resolution, and has the advantages of simple experimental configuration, low cost, and high measurement efficiency.

[0143] 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 description is only a specific embodiment of the present invention and is 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 method, comprising: 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; For each position of the preset path, measuring the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe under each strong effective field; The projection of the vector microwave to be measured in each strong effective field direction is obtained 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 then the polarization direction of the vector microwave to be measured is obtained.

2. The vector microwave detection method according to claim 1, wherein: The two mirror-symmetrical strong effective fields include a first strong effective field and a second strong effective field, and the method for determining the NV color center probe includes: Obtain ODMR spectra of multiple NV color centers in a diamond sample; The NV color center corresponding to the ODMR spectrum with two resonance peaks under zero magnetic field is selected as the target NV color center; The Rabi oscillation of each target NV color center at the resonance frequency is measured, and when the Rabi oscillation frequency of the target NV color center has two frequency components, the target NV color center is determined to be the NV color center probe.

3. The vector microwave detection method according to claim 2, wherein: The method for determining the first strong effective field direction and the second strong effective field direction of the NV color center probe comprises: Moving the NV color center probe along a preset path in a preset microwave field; For a plurality of positions on the preset path, respectively measuring a first Rabi oscillation frequency and a second Rabi oscillation frequency of the NV color center probe under the first strong effective field and a first Rabi oscillation frequency and a second Rabi oscillation frequency of the NV color center probe under the second strong effective field; The direction of the first strong effective field and the direction of the second strong effective field are determined according to the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in the first strong effective field, the first Rabi oscillation frequency and the second Rabi oscillation frequency of the NV color center probe in the second strong effective field, and the direction of the preset microwave field.

4. A vector microwave detection device, comprising: A detection mechanism, wherein a microwave plate for transmitting the vector 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, installed 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; A counting mechanism, adapted to count the fluorescence collected by the microscope lens; wherein, at multiple positions on the preset path, the NV color center probe can undergo Rabi oscillation 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.

5. The vector microwave detection device according to claim 4, wherein the detection mechanism comprises: A piezoelectric platform, on which the microwave plate is mounted; A translation stage, mounted on the piezoelectric platform, the translation stage being 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 of the microwave field of the vector microwave to be measured.

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

7. The vector microwave detection device according to claim 6, further comprising: A total reflection prism is used to transmit the laser light emitted by the laser to the AOM, and is used to transmit the laser light output by the AOM.

8. The vector microwave detection device according to claim 6, further comprising: a dichroic mirror adapted to reflect the laser light from the AOM to the microscope head; And it is suitable for transmitting the fluorescence collected by the microscope lens so that the fluorescence is transmitted to the counting mechanism.

9. The vector microwave detection device according to claim 5, further comprising: A first filter, disposed between the dichroic mirror and the counting mechanism, adapted to filter the fluorescence from the dichroic mirror; 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.

10. The vector microwave detection device according to claim 6, 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; The vector microwave detection device also includes: A reflecting mirror, adapted to reflect the laser light from the laser and passing 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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