Current measurement device based on diamond nv color centers

Abstract

The application provides a current measurement device based on diamond NV color centers, which comprises a microwave source circuit unit configured to output a microwave signal; a diamond NV color center optical fiber probe group unit comprising a plurality of optical fibers, the top end of each optical fiber being provided with a diamond NV color center, and the top end of the plurality of optical fibers having different distances from a wire to be measured; the diamond NV color center optical fiber probe group unit is configured to receive the microwave signal and feed back the microwave signal to the microwave source circuit unit, so that the microwave source circuit unit outputs a microwave signal with a desired frequency according to the feedback to match the energy level resonance frequency of the diamond NV color center under different magnetic field strengths; and a current measurement unit configured to measure the current according to the energy level resonance frequency of the diamond NV color center. According to the embodiment of the application, the magnetic field generated by a larger current wire can be detected by using a lower frequency microwave signal through simultaneous detection of a plurality of diamond NV color centers spaced apart from the wire to be measured by a specific distance.

Description

Technical Field

[0001] This application relates to the field of current measurement, and more specifically, to a current measurement device based on diamond NV color centers. Background Technology

[0002] Current measurement based on diamond nitrogen-vacancy centers (NV centers) is a high-precision magnetic measurement method. It utilizes the sensitivity of NV centers to magnetic fields to establish a quantitative relationship between microwave radiation frequency and the current being measured using optically detected magnetic resonance (ODMR). Specifically, when a current passes through a conductor, the magnetic field generated acts on the NV center system. Due to the Zeeman effect, the ground-state spin levels of the NV centers undergo linear splitting. The splitting distance is strictly proportional to the magnetic field strength generated by the conductor current. By precisely controlling the emission frequency of the microwave source, selective transitions can be excited between the ground-state spin sublevels of the NV centers when the microwave energy and the splitting distance reach resonance. This quantum state transition process can be monitored in real time by an optical system through changes in fluorescence intensity, thus establishing a precise correspondence between microwave frequency, magnetic field strength, and current value.

[0003] Because current-carrying conductors generate magnetic fields, diamond NV centers can be used to estimate the current amplitude within the conductor. Diamond NV centers can non-contactly measure the amplitude of a current by sensing the magnetic field generated by the current in the conductor within the surrounding space. Therefore, to measure currents of varying intensities, the frequency of the microwave source needs to be adjusted accordingly to match the resonant frequency of the diamond NV centers under different magnetic field strengths. Thus, as the core component of a current detection system, the frequency stability and accuracy of the microwave source are crucial for measurement precision and form the basis for achieving high-precision current intensity measurement.

[0004] While current measurement technology based on diamond NV centers (nitrogen NV centers) offers numerous advantages, it still faces several challenges and bottlenecks in microwave source technology. The resonant frequencies between the electron spin states of diamond NV centers are specific, dictating that the operating frequency of the microwave source must fall within this resonant frequency range, typically between several GHz and tens of GHz. The output frequency range of the microwave source is influenced by the complexity of its design and manufacturing techniques. Extending the frequency range may require more complex circuit design and higher manufacturing costs. Simultaneously, the microwave source needs to provide highly stable frequencies to ensure accurate detection of optically detected magnetic resonance signals; furthermore, high-resolution frequency control is crucial for accurately measuring small magnetic field variations. The wider the output frequency range of the microwave source, the higher the requirements for frequency stability and resolution. Wide-range microwave sources require more complex frequency synthesis techniques to maintain frequency stability and resolution. High-performance microwave sources are often expensive, thus limiting the widespread adoption of diamond NV center-based current measurement technology in commercial and industrial applications.

[0005] Application content

[0006] This application aims to propose a current measurement device based on diamond NV centers to solve the high cost problem caused by the high performance requirements of microwave sources when using diamond NV centers for current measurement.

[0007] According to one aspect of this application, a current measuring device based on diamond NV color centers is proposed, comprising:

[0008] A microwave source circuit unit configured to output microwave signals;

[0009] The diamond NV color center fiber optic probe unit includes multiple optical fibers, each of which is equipped with a diamond NV color center fiber optic probe at its tip. The tips of the multiple optical fibers are at different distances from the conductor to be tested. The diamond NV color center fiber optic probe unit is configured to use the microwave signal to sense the magnetic field strength at the location of the diamond NV color center fiber optic probe and emit an optical signal.

[0010] The current measurement unit is configured to receive the optical signal and use the optical signal to calculate the current amplitude.

[0011] According to some embodiments, the current measuring device further includes:

[0012] The laser source is configured to output laser light to the diamond NV color center fiber optic probe unit to excite the diamond NV color center to undergo energy level transition and emit the optical signal.

[0013] According to some embodiments, the current measuring device further includes a dichroic mirror and a photodetector group, wherein the dichroic mirror is configured to sieve the optical signal transmitted from the diamond NV color center probe to the photodetector through an optical fiber, so that the optical signal can be detected by the photodetector group.

[0014] According to some embodiments, the optical signal includes fluorescence, and the photodetector array is configured to detect the fluorescence, obtain the fluorescence intensity, and convert the fluorescence intensity into a voltage signal.

[0015] According to some embodiments, the current measurement unit includes a fluorescence data processing module configured to receive the voltage signal and calculate the magnetic field strength using the voltage signal.

[0016] According to some embodiments, the fluorescence data processing module is further configured to identify the spectrum formed by the voltage signal to determine the energy level resonance frequency, and calculate the magnetic field strength based on the energy level resonance frequency, so as to calculate the current amplitude using the magnetic field strength.

[0017] According to some embodiments, the current measuring device further includes:

[0018] An optical fiber coupler is configured to couple the laser emitted by the laser so that the coupled laser is input into each optical fiber in the diamond NV color center optical fiber probe unit.

[0019] According to some embodiments, the current measuring unit is further configured to perform current measurement by the following formula:

[0020]

[0021] Where: B is the magnetic field strength in T, μ0 is the free permeability in 4π×10⁻⁷T·m / A, I is the current through the conductor under test in A, and r is the distance from the center of the conductor under test to the magnetic field measurement point in m.

[0022] According to some embodiments, the fluorescence data processing unit is further configured to use the energy level resonant frequency to regulate the microwave frequency of the microwave source circuit unit, so as to stabilize it at the energy level resonant frequency.

[0023] According to some embodiments, the diamond NV center fiber optic probe unit is further configured to generate an energy level transition and emit the optical signal when the microwave frequency of the microwave signal matches the energy level difference of the ground state of the diamond NV center.

[0024] According to embodiments of this application, by simultaneously detecting multiple diamond NV color centers spaced at specific intervals from the conductor under test, a lower frequency microwave signal can be used to detect the magnetic field generated by a conductor with a large current, effectively reducing the frequency output range of the microwave source, significantly reducing the manufacturing cost of the microwave source, and ensuring the frequency stability and resolution of the frequency source.

[0025] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The above and other objectives, features, and advantages of this application will become more apparent by referring to the accompanying drawings and describing exemplary embodiments in detail.

[0027] Figure 1 A block diagram of a current measuring device based on diamond NV color centers according to an example embodiment of this application is shown.

[0028] Figure 2A schematic diagram of a current measuring instrument for diamond NV color centers according to an example embodiment of this application is shown. Detailed Implementation

[0029] Exemplary embodiments of the present application will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same drawings in the figures show the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0030] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, apparatus, or operations may be employed. In these cases, well-known structures, methods, apparatuses, implementations, materials, or operations will not be shown or described in detail.

[0031] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0032] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0033] The specific embodiments according to this application will now be described in detail with reference to the accompanying drawings.

[0034] Figure 1 A block diagram of a current measurement device based on diamond NV centers according to an example embodiment of this application is shown, as follows: Figure 1 The current measuring device shown includes a microwave source circuit unit 101, a diamond NV color center fiber optic probe group unit 103, and a current measuring unit 105.

[0035] According to an embodiment of this application, microwave source circuit unit 101 is configured to output microwave signals.

[0036] The diamond NV color center fiber optic probe unit 103 includes multiple optical fibers, each with a diamond NV color center fiber optic probe at its tip. The tips of the multiple optical fibers are at different distances from the conductor to be tested. The diamond NV color center fiber optic probe unit 103 is configured to use microwave signals to sense the magnetic field strength at the location of the diamond NV color center fiber optic probe and emit light signals.

[0037] In a specific embodiment, the diamond NV center fiber optic probe unit 103 is configured to receive the microwave signal output by the microwave source circuit unit 101 and use the microwave signal to feed back to the microwave source circuit unit, so that the microwave source circuit unit outputs a microwave signal with a desired frequency according to the feedback, so as to match the energy level resonance frequency of the diamond NV center under different magnetic field strengths.

[0038] According to an embodiment of this application, the current measurement unit 105 is configured to receive an optical signal and use the optical signal to calculate the current amplitude.

[0039] According to an embodiment of this application, the current measurement further includes a laser source configured to output laser light to the diamond NV center fiber optic probe unit 103 to excite the diamond NV centers to undergo energy level transitions and emit optical signals. By applying continuous laser and microwave, the current measurement unit 105 can obtain a photodetector magnetic resonance spectrum, and then the current measurement unit 105 can calculate the magnetic field strength by analyzing the resonance peak spacing in the resonance spectrum, thereby calculating the current amplitude.

[0040] In some embodiments, the diamond NV center fiber optic probe unit 103 is further configured to generate an energy level transition and emit an optical signal by using the laser output from the laser source when the microwave frequency of the microwave signal matches the energy level difference of the ground state of the diamond NV center.

[0041] In a specific embodiment, when a 532nm laser is used to irradiate the diamond NV color center, the applied microwave frequency is matched with the energy level difference between the Ms=0 and Ms=1 states of the ground state of the NV color center, which excites the resonant transition between the energy levels of the diamond NV color center. The quantum state transition process can be monitored in real time by the current measurement unit 105 through the change of optical signal, forming a photodetector magnetic resonance spectrum. The resonance peak can be observed at the resonance frequency. By analyzing the resonance peak spacing in the resonance spectrum, the magnetic field strength can be calculated, and then the current amplitude can be obtained.

[0042] In some embodiments, the current measuring device further includes an optical fiber coupler configured to couple laser light emitted by a laser such that the coupled laser light is input into each fiber in the diamond NV color center optical fiber probe unit.

[0043] In other embodiments, the current measuring device further includes a dichroic mirror and a photodetector array, wherein the dichroic mirror is configured to sieve the optical signal transmitted from the diamond NV color center probe to the photodetector via optical fiber, so that the optical signal can be detected by the photodetector array.

[0044] In a specific embodiment, the optical signal includes fluorescence, and the photodetector group is configured to detect the fluorescence output by the dichroic mirror, obtain the fluorescence intensity, and convert the fluorescence intensity into a voltage signal.

[0045] According to an embodiment of this application, the current measurement unit 105 includes a fluorescence data processing module, wherein the fluorescence data processing module is configured to receive a voltage signal and calculate the magnetic field strength using the voltage signal.

[0046] In some embodiments, the fluorescence data processing module is further configured to identify the spectrum formed by the voltage signal to determine the energy level resonance frequency, and calculate the magnetic field strength based on the energy level resonance frequency to calculate the current amplitude using the magnetic field strength.

[0047] In a specific embodiment, the fluorescence data processing module calculates the magnetic field strength using formula (1).

[0048] ΔE=γB (1)

[0049] Where ΔE is the energy level resonance frequency, γ is the gyromagnetic ratio of the diamond NV color center, γ=2.8MHz / Gs, and B is the external magnetic field strength.

[0050] In other embodiments, after obtaining the magnetic field strength, the current measurement unit calculates the current measurement using formula (2).

[0051]

[0052] Where B is the magnetic field strength in tons (T), and μ0 is the free permeability, with a value of 4π × 10⁻⁶. -7 T·m / A, where I is the current passing through the conductor under test in A, and r is the distance from the center of the conductor under test to the magnetic field measurement point in m.

[0053] In some embodiments, the fluorescence data processing unit is further configured to regulate the microwave frequency of the microwave source circuit unit 101 using the energy level resonant frequency, so that it is stabilized at the energy level resonant frequency.

[0054] According to an embodiment of this application, the current measurement unit 105 also uses the voltage signal to generate a frequency control signal and sends it to the microwave source circuit unit 101, so that the microwave source circuit unit 101 adjusts the frequency of the output microwave signal to match the resonant frequency of the diamond NV color center under different magnetic field strengths.

[0055] according to Figure 1 The embodiment shown uses multiple diamond NV color centers spaced at specific intervals from the conductor under test for simultaneous detection. This allows the use of lower frequency microwave signals to detect the magnetic field generated by a large current conductor, effectively reducing the frequency output range of the microwave source, significantly reducing the manufacturing cost of the microwave source, and ensuring the frequency stability and resolution of the frequency source.

[0056] Figure 2 A schematic diagram of a current measuring instrument for diamond NV color centers according to an example embodiment of this application is shown, as follows: Figure 2 As shown, the laser outputs laser light, which is split into a group of beams of equal power by a laser beam splitter. These beams then pass through a dichroic mirror group and enter a set of fiber couplers. The laser light then travels along the optical fibers to the tips of the fibers and illuminates diamonds fixed to the tips of each fiber. These diamonds are bonded to the end faces of the fiber tips. The magnetic field strength generated around a current-carrying straight conductor is inversely proportional to the distance between the conductors. For example... Figure 2 As shown, the diamond NV center fiber optic probe group fixed at the top of each fiber contains several fibers with NV center diamonds bonded to them, and the length of the fibers in this group decreases sequentially by a preset length Ln.

[0057] When the laser is activated, the microwave source is simultaneously turned on. The microwave source outputs a modulated microwave signal, which is transmitted to each diamond NV color center via a microwave antenna array. Since changes in current intensity lead to changes in magnetic field intensity, this affects the resonant frequency of the NV color centers. To measure current intensities of different magnitudes, the frequency of the microwave source needs to be adjusted accordingly to match the resonant frequencies of the NV color centers under different magnetic field intensities.

[0058] When the microwave frequency of the microwave signal matches the energy level resonance frequency of the diamond NV center, the laser output from the laser excites the diamond NV center to undergo energy level transitions, emitting fluorescence. At this point, when the microwave frequency matches the resonance frequency between the ground state energy levels of the diamond NV center, the fluorescence weakens, and a resonance peak is observed in the resonance spectrum. The quantum state of the diamond NV center can be read by detecting changes in fluorescence intensity.

[0059] In a specific embodiment, when the diamond NV center is placed in an external magnetic field, the energy levels of the diamond NV center split due to the Zeeman effect. For example, the spin state mS = ±1 of the diamond NV center is degenerate under the action of an external magnetic field, and a transition from the mS = -1 or mS = +1 state to the mS = 0 state can be excited by a microwave signal. This stimulated transition between Zeeman magnetic energy levels is called magnetic resonance. Therefore, the magnetic field strength can be determined by the energy level splitting difference, that is, the energy level resonance frequency, as shown in formula (1).

[0060] When the laser is activated, the microwave source is simultaneously turned on. The microwave source outputs a modulated microwave signal, which is transmitted to each diamond NV color center via a microwave antenna array. Since changes in current intensity lead to changes in magnetic field intensity, this affects the resonant frequency of the NV color centers. To measure current intensities of different magnitudes, the frequency of the microwave source needs to be adjusted accordingly to match the resonant frequencies of the NV color centers under different magnetic field intensities.

[0061] The fluorescence is reflected back along the optical fiber, mixed with the original laser to form a hybrid laser, and then transmitted back to the dichroic mirror via an optical fiber coupler. The dichroic mirror filters the laser, ensuring that the reflected fluorescence can be detected by a set of photodetectors, and the detected fluorescence intensity data is transmitted to a fluorescence signal processor.

[0062] After the fluorescence intensity is detected by a photodetector, it is converted into a voltage signal, and a magnetic resonance spectrum is obtained. The splitting change of the fluorescence intensity peak in the magnetic resonance spectrum reflects the change of the energy level of the diamond NV color center with the external magnetic field. Therefore, by measuring the resonance frequency spacing between the two peaks in the ODMR spectrum, the strength of the external magnetic field can be calculated.

[0063] Changes in current intensity lead to changes in magnetic field intensity, which in turn affects the resonant frequency of the NV color center. In order to measure currents of different intensities, the frequency of the microwave source needs to be adjusted accordingly to match the resonant frequency of the diamond NV color center under different magnetic field intensities. The magnetic field intensity value can be calculated by measuring the fluorescence signal intensity, and the current intensity can be calculated according to the magnetic field distribution formula around the current-carrying long straight conductor shown in formula (2).

[0064] Assuming the microwave source can output frequencies ranging from f1 to f2, when the distance from the top color center of the diamond NV color center fiber optic probe to the center of the straight conductor is r, the measurable magnetic field strength range is: to The measurable current amplitude variation range is I1-I2 amperes. Within this range, resonance peaks can be observed in the photodetector magnetic resonance spectrum. The current measurement unit calculates the magnetic field strength by analyzing the resonance peak spacing (i.e., the energy level resonance frequency) in the resonance spectrum, thereby deducing the current amplitude.

[0065] When the current amplitude exceeds I², the resonant frequency of the diamond NV color center energy level exceeds the output range of the microwave source, making it impossible to observe the fluorescence resonance peak. Therefore, the magnetic field strength can be reduced by increasing the distance between the NV color center and the conductor axis. When the distance increases from r to r+L... nBy scanning the microwave frequencies f1-f2, the resonance peak can be observed again, and the measurable current amplitude range increases to I3-I4 amperes. By setting the distance value Ln, the current measurement range can be made continuous. Based on this principle, by continuously increasing the distance value, the current amplitude measurement range can be expanded while keeping the microwave source output frequency range constant.

[0066] Compared with existing technologies, this application uses multiple diamond NV color centers spaced at specific intervals from the conductor under test to simultaneously detect the magnetic field generated by a large current conductor using a lower frequency microwave signal. This not only reduces the frequency output range of the microwave source but also significantly reduces the manufacturing cost of the microwave source, while ensuring the frequency stability and resolution of the frequency source.

[0067] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A current measuring device based on diamond NV color centers, characterized in that, include: A microwave source circuit unit configured to output microwave signals; The diamond NV color center fiber optic probe unit includes multiple optical fibers, each of which is equipped with a diamond NV color center fiber optic probe at its tip. The tips of the multiple optical fibers are at different distances from the conductor to be tested. The diamond NV color center fiber optic probe unit is configured to use the microwave signal to sense the magnetic field strength at the location of the diamond NV color center fiber optic probe and emit an optical signal. The current measurement unit is configured to receive the optical signal and use the optical signal to calculate the current amplitude.

2. The current measuring device according to claim 1, characterized in that, Also includes: The laser source is configured to output laser light to the diamond NV color center fiber optic probe unit to excite the diamond NV color center to undergo energy level transition and emit the optical signal.

3. The current measuring device according to claim 2, characterized in that, It also includes a dichroic mirror and a photodetector group. The dichroic mirror is configured to sieve the light signal transmitted from the diamond NV color center probe to the photodetector through the optical fiber, so that the light signal can be detected by the photodetector group.

4. The current measuring device according to claim 3, characterized in that, The optical signal includes fluorescence, and the photodetector group is configured to detect the fluorescence, obtain the fluorescence intensity, and convert the fluorescence intensity into a voltage signal.

5. The current measuring device according to claim 4, characterized in that, The current measurement unit includes a fluorescence data processing module configured to receive the voltage signal and use the voltage signal to calculate the magnetic field strength.

6. The current measuring device according to claim 5, characterized in that, The fluorescence data processing module is further configured to identify the spectrum formed by the voltage signal to determine the energy level resonance frequency, and calculate the magnetic field strength based on the energy level resonance frequency, so as to calculate the current amplitude using the magnetic field strength.

7. The current measuring device according to claim 2, characterized in that, Also includes: An optical fiber coupler is configured to couple the laser emitted by the laser so that the coupled laser is input into each optical fiber in the diamond NV color center optical fiber probe unit.

8. The current measuring device according to claim 1, characterized in that, The current measurement unit is further configured to perform current measurement using the following formula: Where: B is the magnetic field strength in T, μ0 is the free permeability in 4π×10⁻⁷T·m / A, I is the current through the conductor under test in A, and r is the distance from the center of the conductor under test to the magnetic field measurement point in m.

9. The current measuring device according to claim 8, characterized in that, The fluorescence data processing unit is further configured to use the energy level resonant frequency to regulate the microwave frequency of the microwave source circuit unit, so as to stabilize it at the energy level resonant frequency.

10. The current measuring device according to claim 2, characterized in that, The diamond NV center fiber optic probe unit is further configured to generate an energy level transition and emit the optical signal when the microwave frequency of the microwave signal matches the energy level difference of the ground state of the diamond NV center.

Images