A method for measuring a conductive emission current of a diamond NV color center

Abstract

The application discloses a kind of based on diamond NV color center's conduction emission current sub-measurement method, including accurately measuring the magnetic field distribution above standard radiation structure using NV color center quantum magnetic field measuring device, constructing high-frequency corrected current-magnetic field mapping model, obtain magnetic field reference value;Using NV color center quantum magnetic field measuring device carries out magnetic field measurement, obtains magnetic field measured data, constructs numerical reconstruction model based on equivalent magnetic dipole array;The numerical reconstruction model is used as independent verification benchmark, according to the magnetic field reference value, the magnetic field measured data, the standard analytical model theoretical value before and after correction constructs contrast verification system, based on the current-magnetic field mapping model, inverse calculation conduction emission current, output measurement result.

Description

Technical Field

[0001] This invention relates to the field of quantum measurement technology of conducted emission current, and in particular to a method for quantum measurement of conducted emission current based on diamond NV color centers. Background Technology

[0002] With the widespread application of high-speed integrated circuits and high-frequency electronic devices, the requirements for conducting emission current measurement in the electromagnetic compatibility field are constantly increasing. Currently, the industry mostly uses traditional electromagnetic sensing equipment combined with the analytical model of the IEC 61967-6 standard for testing. This type of solution can basically meet the usage requirements in the low-frequency band, but it has obvious technical shortcomings.

[0003] On the one hand, traditional measuring devices are prone to interfering with the electromagnetic field being measured, altering the original field distribution and leading to distorted measurement results. Furthermore, their spatial resolution is insufficient, making it difficult to locate microscopic electromagnetic interference sources on the device surface. On the other hand, existing standard analytical models do not consider effects such as electromagnetic coupling and field distortion at high frequencies, resulting in a sharp increase in calculation errors at frequencies of 1 GHz and above, and their measurement upper limit cannot meet the current testing needs of high-frequency equipment.

[0004] Diamond NV centers, with their advantages in quantum magnetic field detection, possess high sensitivity, low field disturbance, and excellent spatial resolution, making them a cutting-edge technology for precise magnetic field measurement. While NV centers are currently used in magnetic field detection, a current-magnetic field mapping model adapted to the 1–6 GHz high-frequency band has not yet been established for conducted emission current measurement. Furthermore, a complete measurement system integrating magnetic field measurement, numerical reconstruction, and cross-validation is lacking, thus hindering the full realization of their technological advantages.

[0005] In summary, existing measurement technologies suffer from poor high-frequency adaptability, insufficient accuracy, and low resolution, while the NV color center application system is still incomplete and cannot meet the actual needs of accurate detection of high-frequency conducted emission current. Therefore, it is urgent to propose a completely new measurement method. Summary of the Invention

[0006] The purpose of this invention is to provide a quantum measurement method for conduction emission current based on diamond NV color centers.

[0007] To achieve the above objectives, the present invention is implemented according to the following technical solution: This invention includes the following steps: The magnetic field distribution above a standard radiating structure was accurately measured using the NV color center quantum magnetic field measurement device. A high-frequency corrected current-magnetic field mapping model was constructed to obtain magnetic field reference values. The magnetic field was measured using the NV color center quantum magnetic field measurement device to obtain the measured magnetic field data, and a numerical reconstruction model based on the equivalent magnetic dipole array was constructed. Using the numerical reconstruction model as an independent verification benchmark, a comparative verification system is constructed based on the magnetic field reference value, the measured magnetic field data, and the theoretical values ​​of the standard analytical model before and after correction. Based on the current-magnetic field mapping model, the conducted emission current is calculated and the measurement results are output.

[0008] Furthermore, the optical path of the NV color center quantum magnetic field measurement device includes a 532nm solid-state laser cut into pulsed laser by an acousto-optic modulator, which is reflected by a dichroic mirror through a variable beam shaping optical path and enters the microscope objective lens, focusing to illuminate the NV color center diamond placed above the device under test; the fluorescence emitted by the NV color center under laser excitation is collected by the same objective lens, and after the residual laser is filtered out by a high-pass filter, it is split by a non-polarizing beam splitter: one path is focused to an avalanche photodiode for high-speed point measurement, and the other path is imaged to a CMOS camera for wide-field imaging.

[0009] Furthermore, the pulsed laser is coordinated and time-controlled by an eight-channel nanosecond-level pulse generator, and the acousto-optic modulator cuts the continuous laser into pulsed lasers with a pulse width of 500ns and a repetition frequency of 1MHz; the microwave is transmitted from the radio frequency source to the microstrip line via a power amplifier and a microwave switch, generating a uniform transverse microwave magnetic field at the diamond position to drive electron paramagnetic resonance transition.

[0010] Furthermore, the synchronous control timing of the eight-channel nanosecond-level pulse generator includes: channel 1 drives the acousto-optic modulator to generate pulsed laser at a frequency of 1MHz and a pulse width of 500ns; channel 2 triggers the microwave source to perform a step-by-step frequency sweep at a frequency of 12.5Hz and a pulse width of 100ns, with a step size of 350kHz; channel 3 delays channel 1 by 500ns and controls the microwave switch at a frequency of 1MHz and a pulse width of 500ns; channel 4 triggers the CMOS camera exposure at a frequency of 25Hz and a pulse width of 5000ns; the system performs pixel-level magnetic field mapping at a sampling rate of 25fps.

[0011] Furthermore, the method for constructing the high-frequency corrected current-magnetic field mapping model includes: For the standard radiating structure, a high-precision three-dimensional numerical model is constructed based on full-wave electromagnetic simulation. A standard current excitation is applied to the high-precision three-dimensional numerical model, and the surface current density distribution of the standard radiating structure is extracted. The standard radiating structure is a microstrip line structure with a length of 90 mm, a dielectric substrate with a relative permittivity of 2.2, a width of 45 mm, a thickness of 0.127 mm, a copper signal line width of 0.35 mm, a thickness of 0.0175 mm, a ground plane thickness of 1 mm, and a characteristic impedance of approximately 50 Ω. ; The surface current distribution is discretized into an equivalent magnetic dipole array to obtain an equivalent current source matrix. Based on the equivalent current source matrix, the magnetic field reference value of the target field point in space is calculated using the Biot-Savart law. The calculation results of the IEC 61967-6 standard analytical model are used as input and the magnetic field reference value is used as output. A frequency-related correction function is obtained by fitting using the least squares method. The corrected model is used as the final current-magnetic field mapping model. The correction function is applicable to the correction of the magnetic field value at the standard reference point above the microstrip line in the 1GHz to 6GHz frequency band.

[0012] Furthermore, the method for discretizing the surface current distribution into an equivalent magnetic dipole array includes: The surface of the standard radiating structure is divided into a regular grid. The surface current density in each grid cell is averaged by area weighting to obtain the grid average current density. For each grid cell, the complex circulating current value is calculated based on the line integral of its central closed loop to obtain the equivalent current source matrix, where the matrix elements characterize the equivalent magnetic dipole intensity at the geometric center of the corresponding grid cell.

[0013] Furthermore, the method for performing magnetic field measurements using the NV color center quantum magnetic field measuring device includes: A standard radiation structure was placed below the diamond probe of the NV center, and a static bias magnetic field parallel to the axis of the NV center was applied. The photodetector magnetic resonance spectrum of the NV center was measured by frequency sweep to determine the resonance peak frequency corresponding to the microwave frequency to be measured. Under current excitation conditions identical to the actual measurement conditions, the Rabi oscillation measurement method was used: at the microwave resonance frequency, the duration of the microwave pulse was changed, and the corresponding fluorescence intensity changes were recorded to obtain the Rabi oscillation curve, from which the Rabi oscillation angular frequency was extracted. Calculate microwave magnetic field strength ,in It is the electron gyromagnetic ratio.

[0014] The beneficial effects of this invention are: This invention is a quantum measurement method for conduction emission current based on diamond NV color centers. Compared with existing technologies, this invention has the following technical advantages: This invention utilizes the quantum energy levels of the NV color center to respond to microwave magnetic fields. Combined with the established high-frequency correction model, the upper limit of accurate measurement of conducted emission current can be raised to 6GHz and above, solving the problem of poor high-frequency adaptability of traditional methods. The diamond probe causes minimal disturbance to the measured electromagnetic field, and the measurement results more realistically reflect the original field distribution, improving the accuracy of the measurement. By adjusting the focusing spot size, the system can achieve extremely high spatial resolution. Combined with CMOS wide-field imaging, a two-dimensional magnetic field distribution map within a centimeter-level field of view can be obtained without mechanical scanning, providing a powerful tool for locating microscopic electromagnetic interference sources on the chip surface. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the steps of a quantum measurement method for conduction emission current based on diamond NV color centers according to the present invention. Figure 2 This is a fitting graph of the Rabi oscillation frequency curve in one of the embodiments of this specification. Detailed Implementation

[0016] The present invention will be further described below through specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0017] The present invention discloses a quantum measurement method for conduction emission current based on diamond NV color centers, comprising the following steps: like Figure 1 As shown, this embodiment includes the following steps: The magnetic field distribution above a standard radiating structure was accurately measured using the NV color center quantum magnetic field measurement device. A high-frequency corrected current-magnetic field mapping model was constructed to obtain magnetic field reference values. The magnetic field was measured using the NV color center quantum magnetic field measurement device to obtain the measured magnetic field data, and a numerical reconstruction model based on the equivalent magnetic dipole array was constructed. The numerical reconstruction model is used as an independent verification benchmark. A comparative verification system is constructed based on the magnetic field reference value, the measured magnetic field data, and the theoretical values ​​of the standard analytical model before and after correction. Based on the current-magnetic field mapping model, the conducted emission current is calculated and the measurement results are output. The principle of the comparative verification system is a three-way cross-comparison of the magnetic field reference value, the measured magnetic field data, and the theoretical values ​​of the standard analytical model before and after correction.

[0018] In this embodiment, the optical path of the NV color center quantum magnetic field measurement device includes a 532nm solid-state laser cut into pulsed laser by an acousto-optic modulator, which is reflected by a dichroic mirror through a variable beam shaping optical path and enters the microscope objective lens, focusing to illuminate the NV color center diamond placed above the device under test; the fluorescence emitted by the NV color center under laser excitation is collected by the same objective lens, and after the residual laser is filtered out by a high-pass filter, it is split by a non-polarizing beam splitter: one path is focused to an avalanche photodiode for high-speed point measurement, and the other path is imaged to a CMOS camera for wide-field imaging.

[0019] In this embodiment, the pulsed laser is coordinated and time-controlled by an eight-channel nanosecond-level pulse generator, and the acousto-optic modulator cuts the continuous laser into pulsed lasers with a pulse width of 500ns and a repetition frequency of 1MHz; the microwave is transmitted from the radio frequency source to the microstrip line via a power amplifier and a microwave switch, generating a uniform transverse microwave magnetic field at the diamond position to drive electron paramagnetic resonance transition.

[0020] In this embodiment, the synchronous control timing of the eight-channel nanosecond-level pulse generator includes: channel 1 drives the acousto-optic modulator to generate pulsed laser at a frequency of 1MHz and a pulse width of 500ns; channel 2 triggers the microwave source to perform a step-sweep frequency at a frequency of 12.5Hz and a pulse width of 100ns, with a step size of 350kHz; channel 3 delays channel 1 by 500ns and controls the microwave switch at a frequency of 1MHz and a pulse width of 500ns; channel 4 triggers the CMOS camera exposure at a frequency of 25Hz and a pulse width of 5000ns; the system performs pixel-level magnetic field mapping at a sampling rate of 25fps.

[0021] In this embodiment, the method for constructing a high-frequency corrected current-magnetic field mapping model includes: For the standard radiating structure, a high-precision three-dimensional numerical model is constructed based on full-wave electromagnetic simulation. A standard current excitation is applied to the high-precision three-dimensional numerical model, and the surface current density distribution of the standard radiating structure is extracted. The standard radiating structure is a microstrip line structure with a length of 90 mm, a dielectric substrate with a relative permittivity of 2.2, a width of 45 mm, a thickness of 0.127 mm, a copper signal line width of 0.35 mm, a thickness of 0.0175 mm, a ground plane thickness of 1 mm, and a characteristic impedance of approximately 50 Ω. ; The surface current distribution is discretized into an equivalent magnetic dipole array to obtain an equivalent current source matrix. Based on the equivalent current source matrix, the magnetic field reference value of the target field point in space is calculated using the Biot-Savart law. The calculation results of the IEC 61967-6 standard analytical model are used as input, and the magnetic field reference value is used as output. A frequency-related correction function is obtained by fitting using the least squares method. The corrected model is used as the final current-magnetic field mapping model. The correction function is applicable to the correction of magnetic field values ​​at the standard reference point above the microstrip line in the 1GHz to 6GHz frequency band. In the actual evaluation, based on the equivalent current source matrix, for the target field point r=(0,0,2mm) (the standard reference point directly above the center of the microstrip), all equivalent magnetic dipole elements are traversed, and the contribution of each element is calculated using the Biot-Savart law. The data is recorded: The first step of the code defines key parameters in the header: the height of the observation plane from the conductor strip (2mm), the plane size (150mm×150mm), and the grid spacing (1mm to maintain the same resolution as the current loop), and loads the equivalent circulating current file generated in the previous stage; The second step is to create an observation surface parallel to the xz plane at a height of y=2mm, with the center of the conductor as the origin; use linspace to generate a uniform grid, with a default of 151×151=22801 observation points, each point corresponding to the location of the field point to be calculated later; The third step is to initialize three complex matrices to store the Bx, By, and Bz components, and then iterate through each current loop, for the i-th current loop... circulation The magnetic field contribution generated by the magnetic dipole method across the entire observation grid is calculated by first determining the relative position vector r and the distance, and then calculating the unit vector r. The magnetic moment m has only a y component ( S=1mm 2 Substitute into the formula The three components are obtained; the fourth step is to calculate the total field amplitude. The output file contains coordinates, magnitudes, and the real and imaginary parts of each component, and is saved in NumPy binary format. When the microstrip line length is 90mm, the relative permittivity of the dielectric substrate is 2.2, the width is 45mm, and the thickness is 0.127mm; the copper signal line width is 0.35mm, the thickness is 0.0175mm, and the ground plane thickness is 1mm; the characteristic impedance within the frequency band is approximately 50Ω, and the feed power is 30dBm, the correction function is obtained by fitting the discrete data points of the magnetic field value 2mm above the microstrip line in the 1GHz-6GHz frequency band using the least squares method: ,in For frequency, The current magnitude is expressed in dB.

[0022] In this embodiment, the method for discretizing the surface current distribution into an equivalent magnetic dipole array includes: The surface of the standard radiating structure is divided into a regular grid. The surface current density in each grid cell is averaged by area weighting to obtain the grid average current density. For each grid cell, the complex circulating current value is calculated based on the line integral of its central closed loop to obtain the equivalent current source matrix, where the matrix elements characterize the equivalent magnetic dipole strength at the geometric center of the corresponding grid cell. In the actual evaluation, the original data came from electromagnetic simulation software, which recorded the current density at each point on the surface of the microstrip structure; Python code was used to convert the continuously distributed surface current into equivalent current loops on a regular grid, with each loop representing the total current effect within a 1mm×1mm cell; The first step involves reading the original file, filtering out blank and comment lines, and keeping only valid data lines that begin with a space or a number, while removing the header row. The second step involves creating a uniform grid with 1mm intervals in the x-direction (typically 0-5mm, microstrip width) and z-direction (typically 0-150mm, microstrip length). It is assumed that the microstrip extends along the z-direction, the x-direction is the width, and the y-direction is the thickness (typically close to 0). The third step maps the non-uniformly sampled or raw data points from the triangular grid to the regular grid. The code uses NumPy's digitize function to determine the position of each raw point in a 1mm grid cell, and uses add.at to accumulate the data: the current density of each point is multiplied by its representative area and then accumulated to the corresponding grid, while the area itself is also accumulated. For grids with data, the total current is divided by the total area to obtain the grid average current density Kz_grid and Ky_grid. The fourth step involves the equivalent current loop flowing in the xy plane (around the z-axis) for each 1mm × 1mm element, with its total current... The value is determined by the current passing through the unit; the specific calculation involves multiplying Kz (current density in the z-direction) by the width dx in the x-direction, adding Ky (current density in the y-direction) multiplied by the length dz in the z-direction, and then multiplying by 2. The "×2" factor is because the current loop contributes from both the top and bottom edges, or it can be understood as equating the surface current to the edge current of the line current loop; the unit conversion is 1 mm to 1 e. -3 The final result is a complex current in amperes (A). The fifth step is to extract the center coordinates of the grid cells with data, set the y-coordinate to 0 (microstrip surface), save the real and imaginary parts separately, and only output the cells with Area_sum>0.

[0023] In this embodiment, the method for performing magnetic field measurement using the NV color center quantum magnetic field measuring device includes: A standard radiation structure was placed below the diamond probe of the NV center, and a static bias magnetic field parallel to the axis of the NV center was applied. The photodetector magnetic resonance spectrum of the NV center was measured by frequency sweep to determine the resonance peak frequency corresponding to the microwave frequency to be measured. Under current excitation conditions identical to the actual measurement conditions, the Rabi oscillation measurement method was used: at the microwave resonance frequency, the duration of the microwave pulse was changed, and the corresponding fluorescence intensity changes were recorded to obtain the Rabi oscillation curve, from which the Rabi oscillation angular frequency was extracted. Calculate microwave magnetic field strength ,in It is the electron gyromagnetic ratio.

[0024] The above description is only a preferred 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 within the protection scope of the present invention.

Claims

1. A quantum measurement method for conduction emission current based on diamond NV color centers, characterized in that, Includes the following steps: The magnetic field distribution above a standard radiating structure was accurately measured using the NV color center quantum magnetic field measurement device. A high-frequency corrected current-magnetic field mapping model was constructed to obtain magnetic field reference values. The magnetic field was measured using the NV color center quantum magnetic field measurement device to obtain the measured magnetic field data, and a numerical reconstruction model based on the equivalent magnetic dipole array was constructed. Using the numerical reconstruction model as an independent verification benchmark, a comparative verification system is constructed based on the magnetic field reference value, the measured magnetic field data, and the theoretical values ​​of the standard analytical model before and after correction. Based on the current-magnetic field mapping model, the conducted emission current is calculated and the measurement results are output.

2. The quantum measurement method for conduction emission current based on diamond NV color centers according to claim 1, characterized in that, The optical path of the NV color center quantum magnetic field measurement device includes a 532nm solid-state laser cut into pulsed laser by an acousto-optic modulator, which is reflected by a dichroic mirror through a variable beam shaping optical path and enters the microscope objective lens to focus and irradiate the NV color center diamond placed above the device under test. The fluorescence emitted by the NV color center under laser excitation is collected by the same objective lens. After the residual laser is filtered out by a high-pass filter, the light is split by a non-polarizing beam splitter: one path is focused to an avalanche photodiode for high-speed point measurement, and the other path is imaged to a CMOS camera for wide-field imaging.

3. The quantum measurement method for conduction-emission current based on diamond NV color centers according to claim 2, characterized in that, The pulsed laser is coordinated and time-controlled by an eight-channel nanosecond-level pulse generator. The acousto-optic modulator cuts the continuous laser into pulsed lasers with a pulse width of 500 ns and a repetition frequency of 1 MHz. The microwave is transmitted from an RF source to a microstrip line via a power amplifier and a microwave switch, generating a uniform transverse microwave magnetic field at the diamond position to drive electron paramagnetic resonance transitions.

4. The quantum measurement method for conduction-emission current based on diamond NV color centers according to claim 3, characterized in that, The synchronous control timing of the eight-channel nanosecond-level pulse generator includes: channel 1 drives an acousto-optic modulator to generate pulsed laser at a frequency of 1MHz and a pulse width of 500ns; channel 2 triggers a microwave source to perform a step-sweep frequency at a frequency of 12.5Hz and a pulse width of 100ns, with a step size of 350kHz; channel 3 delays channel 1 by 500ns and controls a microwave switch at a frequency of 1MHz and a pulse width of 500ns; channel 4 triggers a CMOS camera to expose at a frequency of 25Hz and a pulse width of 5000ns; the system performs pixel-level magnetic field mapping at a sampling rate of 25fps.

5. The quantum measurement method for conduction emission current based on diamond NV color centers according to claim 1, characterized in that, The method for constructing a high-frequency corrected current-magnetic field mapping model includes: For the standard radiating structure, a high-precision three-dimensional numerical model is constructed based on full-wave electromagnetic simulation. A standard current excitation is applied to the high-precision three-dimensional numerical model, and the surface current density distribution of the standard radiating structure is extracted. The standard radiating structure is a microstrip line structure with a length of 90 mm, a dielectric substrate with a relative permittivity of 2.2, a width of 45 mm, a thickness of 0.127 mm, a copper signal line width of 0.35 mm, a thickness of 0.0175 mm, a ground plane thickness of 1 mm, and a characteristic impedance of approximately 50 Ω. ; The surface current distribution is discretized into an equivalent magnetic dipole array to obtain an equivalent current source matrix. Based on the equivalent current source matrix, the magnetic field reference value of the target field point in space is calculated using the Biot-Savart law. The calculation results of the IEC 61967-6 standard analytical model are used as input and the magnetic field reference value is used as output. A frequency-related correction function is obtained by fitting using the least squares method. The corrected model is used as the final current-magnetic field mapping model. The correction function is applicable to the correction of the magnetic field value at the standard reference point above the microstrip line in the 1GHz to 6GHz frequency band.

6. The quantum measurement method for conduction-emission current based on diamond NV color centers according to claim 5, characterized in that, A method for discretizing the surface current distribution into an equivalent magnetic dipole array includes: The surface of the standard radiating structure is divided into a regular grid. The surface current density in each grid cell is averaged by area weighting to obtain the grid average current density. For each grid cell, the complex circulating current value is calculated based on the line integral of its central closed loop to obtain the equivalent current source matrix, where the matrix elements characterize the equivalent magnetic dipole intensity at the geometric center of the corresponding grid cell.

7. The quantum measurement method for conduction emission current based on diamond NV color centers according to claim 1, characterized in that, The method for performing magnetic field measurements using the NV color center quantum magnetic field measuring device includes: A standard radiation structure was placed below the diamond probe of the NV center, and a static bias magnetic field parallel to the axis of the NV center was applied. The photodetector magnetic resonance spectrum of the NV center was measured by frequency sweep to determine the resonance peak frequency corresponding to the microwave frequency to be measured. Under current excitation conditions identical to the actual measurement conditions, the Rabi oscillation measurement method was used: at the microwave resonance frequency, the duration of the microwave pulse was changed, and the corresponding fluorescence intensity changes were recorded to obtain the Rabi oscillation curve, from which the Rabi oscillation angular frequency was extracted. Calculate microwave magnetic field strength ,in It is the electron gyromagnetic ratio.

Images