Quantum current sensor and method for measuring current

Abstract

The application provides a quantum current sensor and a current measurement method, which comprise a diamond NV sensing chip, a magnetic concentrating ring, a laser source, a photoelectric conversion module, a microwave modulation and demodulation module and a magnetic flux regulation module; the magnetic concentrating ring is provided with an opening for sensing the magnetic flux of a measured wire; the diamond NV sensing chip is used for detecting the magnetic flux at the opening; the laser source is used for generating a laser signal of a preset wavelength and outputting the laser signal to the diamond NV sensing chip; the photoelectric conversion module receives a reflected fluorescent signal, converts the fluorescent signal into an electric signal and transmits the electric signal to the microwave modulation and demodulation module to finally obtain a demodulation voltage; and the magnetic flux regulation module obtains a reverse magnetic flux loaded to the magnetic flux detection module based on the demodulation voltage, so as to maintain the magnetic flux at the opening. The application provides the reverse magnetic flux, so that the magnetic field sensed at the NV color center is always in a small range, the problem that the diamond NV color center is difficult to detect under a large current magnetic field is avoided, and the dynamic range of the diamond NV color center for measuring the current is effectively widened.

Description

Technical Field

[0001] This invention relates to the field of quantum applications, and in particular to a quantum current sensor and a current measurement method. Background Technology

[0002] The arrival of the second quantum revolution is giving rise to a new round of technological revolution and industrial transformation. Among these advancements, electromagnetic measurement based on quantum sensing technology has already found important applications in national defense, healthcare, and mineral exploration. For current sensing using quantum technology, the magnetic effect of current can be utilized to directly detect the magnetic field generated by the current, achieving non-contact sensing and effectively improving sensing accuracy.

[0003] Among the electromagnetic signal quantum detection methods developed in recent years, the superconducting quantum interference device (SQUID) is currently the most sensitive electromagnetic detection method and also has a significant advantage in measurement bandwidth. However, it requires operation in a low-temperature environment, and its large size and expensive cooling equipment greatly limit its application. An atomic magnetometer is an optical instrument used to detect the polarization changes of alkali metal vapor under the influence of an external magnetic field. It can operate in a relatively small magnetically shielded room, but requires high-temperature metal vapor, and its dynamic range is limited.

[0004] With the continuous development of quantum technology, a magnetometer based on diamond NV centers has attracted widespread attention. NV centers are a novel solid-state electron spin platform that can operate well in room temperature and atmospheric environments, exhibiting extremely high stability. Their excellent spin coherence, spin-state manipulation, and sensitivity to various physical fields make them one of the most promising quantum devices of our time. However, electromagnetic measurement techniques based on diamond NV centers are often based on confocal systems, involving bulky and complex experimental equipment. Furthermore, the magnetic measurement range is often limited by antenna bandwidth, making widespread adoption difficult.

[0005] Based on this, the present invention provides a non-contact quantum current sensor and measurement method based on magnetic flux signal modulation technology to solve the above problems.

[0006] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a quantum current sensor and a current measurement method to solve the problems of the existing quantum current sensor and current measurement method.

[0008] To achieve the above and other related objectives, the present invention provides a quantum current sensor.

[0009] Diamond NV sensor chip, magnetic ring, laser source, photoelectric conversion module, microwave modulation and demodulation module, and magnetic flux control module;

[0010] The magnetic ring has an opening; the magnetic ring is disposed around the conductor being tested to sense the magnetic flux of the conductor being tested.

[0011] The diamond NV sensor chip is disposed at the opening to detect the magnetic flux at the opening; the magnetic flux at the opening includes the magnetic flux of the wire being tested and the reverse magnetic flux generated by the magnetic flux control module.

[0012] The laser source is used to generate a laser signal of a preset wavelength and output it to the diamond NV sensor chip.

[0013] The photoelectric conversion module receives the fluorescence signal reflected by the diamond NV sensor chip, and then converts the fluorescence signal into an electrical signal and transmits it to the microwave modulation and demodulation module.

[0014] The microwave modulation and demodulation module is used to generate a microwave modulation signal and output it to the diamond NV sensor chip, and to obtain the demodulation voltage based on the same frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module.

[0015] The magnetic flux control module is connected to the demodulation voltage, obtains the reverse magnetic flux of the conductor under test based on the demodulation voltage, and loads the reverse magnetic flux onto the magnetic ring to control the magnetic flux at the opening.

[0016] Optionally, the optical interface of the diamond NV sensor chip receives the laser signal and reflects the fluorescence signal; the first microwave interface of the diamond NV sensor chip is connected to the microwave modulation signal, and the second microwave interface is connected to the load; a microstrip antenna is disposed between the first microwave interface and the second microwave interface; the microstrip antenna is disposed between the optical interface and the diamond structure in the diamond NV sensor chip, and the microstrip antenna partially or completely covers the diamond structure in the diamond NV sensor chip.

[0017] Optionally, the quantum current sensor further includes an optical fiber circulator, a first optical signal channel, and a second optical signal channel; the optical fiber circulator is disposed between the laser source and the diamond NV sensor chip; the first interface of the optical fiber circulator is connected to the laser source, the second interface is connected to the optical interface through the first optical signal channel, and the third interface is connected to the photoelectric conversion module through the second optical signal channel.

[0018] Optionally, the quantum current sensor further includes a filter; the filter is disposed on the second optical signal channel.

[0019] Optionally, the quantum current sensor further includes a beam splitter; the beam splitter is disposed between the laser source and the fiber optic circulator and the output end of the beam splitter is connected to the photoelectric conversion module, splitting the laser signal into a reference optical signal and outputting it to the photoelectric conversion module.

[0020] Optionally, the microwave modulation and demodulation module includes a microwave signal generation unit and a demodulation unit; the microwave modulation signal generation unit generates a microwave modulation signal and outputs it to the diamond NV sensor chip; the frequency of the microwave modulation signal is set to the first resonant frequency or the second resonant frequency of the electron spin resonance in the NV color center; the first input terminal of the demodulation unit is connected to the microwave modulation signal generation unit, the second input terminal is connected to the photoelectric conversion module, and the output terminal is connected to the magnetic flux control module, and the demodulation voltage is obtained based on the same frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module.

[0021] Optionally, the microwave modulation and demodulation module includes two microwave signal generation units and two demodulation units; each microwave signal generation unit and each demodulation unit are configured in a one-to-one correspondence; each microwave signal generation unit generates a first microwave modulation signal and a second microwave modulation signal, and the first microwave modulation signal and the second microwave modulation signal are superimposed and output to the diamond NV sensor chip; wherein, the frequency of the first microwave modulation signal is set to the first resonance frequency of the electron spin resonance in the NV color center, and the frequency of the second microwave modulation signal is set to the second resonance frequency of the electron spin resonance in the NV color center; the first input terminal of each demodulation unit is connected to the corresponding microwave signal generation unit, the second input terminal is connected to the output terminal of the photoelectric conversion module, and the output terminal is connected to the magnetic flux control module; a first demodulated signal is obtained based on the same frequency signal of the first microwave modulation signal and the output signal of the photoelectric conversion module, and a second demodulated signal is obtained based on the same frequency signal of the second microwave modulation signal and the output signal of the photoelectric conversion module; the first demodulated signal and the second demodulated signal are output as a differential demodulation voltage.

[0022] Optionally, the microwave modulation signal generation unit includes a microwave source, a mixer, and an adder; the first input terminal of the mixer is connected to the microwave source, and the second input terminal is connected to the intrinsic signal; the first input terminal of the adder is connected to the output terminal of the mixer, and the second input terminal is connected to the intrinsic signal, and outputs a corresponding microwave modulation signal.

[0023] Optionally, the demodulation unit is configured as a lock-in amplifier.

[0024] Optionally, the magnetic flux control module includes a reverse current control unit and a coil winding; the coil winding is wound on the magnetic ring and has N turns; N is an integer greater than or equal to 1; the input terminal of the reverse current control unit is connected to the demodulation voltage to generate and output a reverse current; the first end of the coil winding is connected to the output terminal of the reverse current control unit, and the second end is grounded.

[0025] Optionally, the reverse current control unit includes an analog-to-digital converter, a proportional-integral calculation circuit, a digital-to-analog converter, and a power amplifier; the demodulated voltage is output to the first end of the coil winding after being connected in series with the analog-to-digital converter, the proportional-integral calculation circuit, the digital-to-analog converter, and the power amplifier.

[0026] To achieve the above and other related objectives, the present invention provides a current measurement method based on the aforementioned quantum current sensor, comprising:

[0027] S1. Output the microwave modulation signal and the laser signal of the preset wavelength to the diamond NV sensing chip to obtain the magnetic flux at the opening of the magnetic ring; the magnetic flux at the opening includes the magnetic flux of the wire under test and the reverse magnetic flux generated by the magnetic flux control module.

[0028] S2. Using the same frequency signal of the microwave modulation signal as a reference signal, the output signal of the photoelectric conversion module is demodulated to obtain the demodulated voltage;

[0029] S3. Based on the linear relationship between the demodulation voltage and the reverse magnetic flux of the conductor under test, the reverse magnetic flux of the conductor under test is obtained, and the reverse magnetic flux is applied to the magnetic ring to balance the magnetic flux at the opening.

[0030] S4. Based on the linear relationship between the reverse magnetic flux and the current of the conductor under test, the current value of the conductor under test is calculated.

[0031] Optionally, in step S3, the reverse magnetic flux of the conductor under test is calculated by the demodulated voltage using a proportional-integral algorithm.

[0032] Optionally, when the reverse magnetic flux is applied to the magnetic ring through the coil winding, the current value of the conductor under test satisfies:

[0033] Ip = N × Is;

[0034] Where Ip is the current value of the conductor being measured; N is the number of turns of the coil winding; and Is is the current value of the coil winding.

[0035] As described above, the quantum current sensor and current measurement method of the present invention have the following beneficial effects:

[0036] 1. The quantum current sensor and current measurement method of the present invention, by providing a winding coil, ensures that the magnetic field induced at the NV color center is always within a small range, thus avoiding the problem of reduced fluorescence intensity and accuracy caused by directly inducing the magnetic field under large current through the diamond NV color center.

[0037] 2. The quantum current sensor and current measurement method of the present invention maintain dynamic balance by controlling the magnetic flux through reverse winding, effectively avoiding the hysteresis problem of the magnetic ring, thereby improving the linearity error of the quantum current sensor. At the same time, since the magnetic flux of the quantum current sensor and current measurement method of the present invention hardly changes, the diamond NV sensing chip can always operate in its optimal state and is unaffected by the bandwidth of the microwave antenna.

[0038] 3. The quantum current sensor and current measurement method of the present invention break through the range limitation of the sensor based on NV color center, avoid the error problem that may be introduced by the need for optical methods or ODMR spectrum to read the specific magnetic field value, so that the final range is only limited by the output current of the power amplifier and the number of winding turns, thereby enabling real-time and fast detection.

[0039] 4. The quantum current sensor and current measurement method of the present invention realize non-contact measurement, have wide applicability, and are more conducive to promotion and use. Attached Figure Description

[0040] Figure 1 The diagram shows the structure of a small-current quantum current sensor.

[0041] Figure 2 The diagram shown is a structural schematic of a quantum current sensor according to the present invention.

[0042] Figure 3 The diagram shown illustrates the principle of a quantum current sensor.

[0043] Figure 4 The diagram shows the structure of the Diamond NV sensor chip.

[0044] Figure 5 This is a schematic diagram of the energy level structure of the NV color center in diamond.

[0045] Figure 6 The diagram shows the structure of the microwave signal generation unit.

[0046] Figure 7 Displayed as Figure 2 Schematic diagram of the proportional-integral (PI) calculation circuit of a quantum current sensor.

[0047] Figure 8 The diagram shown is a structural schematic of another quantum current sensor according to the present invention.

[0048] Figure 9 Displayed as Figure 8 Optical detection magnetic resonance image.

[0049] Figure 10 Displayed as Figure 8 Schematic diagram of the proportional-integral (PI) calculation circuit of a quantum current sensor.

[0050] Figure 11 Displayed as Figure 8 The result of detecting step current by the quantum current sensor is shown in the figure.

[0051] Figure 12 Displayed as Figure 8 The result of detecting alternating current by the quantum current sensor is shown in the figure.

[0052] Component designation explanation

[0053] 1. Small Current Quantum Current Sensor

[0054] 10. The conductor under test

[0055] 11. Magnetic Ring

[0056] 12 Diamond NV sensor chips

[0057] 13 Microwave signal generation unit

[0058] 14 Optical emission units

[0059] 15 Photoelectric Conversion Units

[0060] 16 demodulation units

[0061] 17 Current Calculation Unit

[0062] 2. Quantum Current Sensor

[0063] 20. Test conductor

[0064] 21 Diamond NV sensor chip

[0065] 211 First Microwave Interface

[0066] 212 Second Microwave Interface

[0067] 213 Microstrip Antenna

[0068] 214 load

[0069] 215 Optical Interface

[0070] 216 Diamond Structure

[0071] 22 Magnetic Rings

[0072] 23 Laser sources

[0073] 231 Fiber Optic Circulator

[0074] 231a First Optical Channel

[0075] 231b Second Optical Channel

[0076] 232 filter

[0077] 233 Beam Spectroscope

[0078] 234 Coupler

[0079] 24 Photoelectric conversion module

[0080] 25 Microwave Modulation and Demodulation Module

[0081] 251 Microwave Signal Generation Unit

[0082] 2511 Microwave Source

[0083] 2512 Mixer

[0084] 2513 Adder

[0085] 252 demodulation units

[0086] 253 Microwave Signal Power Amplifier

[0087] 26. Magnetic Flux Control Module

[0088] 261 Reverse Current Control Unit

[0089] 2611 Analog-to-Digital Converter

[0090] 2612 Proportional-Integral Calculation Circuit

[0091] 2613 Digital-to-Analog Converter

[0092] 2614 Power Amplifier

[0093] 262 coil winding

[0094] 3. Quantum Current Sensor Detailed Implementation

[0095] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0096] Please see Figures 2 to 12 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0097] Comparative Example

[0098] like Figure 1 As shown in the comparative example, this provides a small current quantum current sensor 1, including: a magnetic ring 11 with an opening, a diamond NV sensing chip 12, a microwave signal generation unit 13, an optical emission unit 14, a photoelectric conversion unit 15, a demodulation unit 16, and a current calculation unit 17.

[0099] Specifically, the magnetic ring 11 is arranged around the conductor 10 under test. Based on the principle of electromagnetic induction, the current in the conductor 10 under test is converted into a magnetic signal, and the converted magnetic signal is collected by the magnetic ring 11.

[0100] Specifically, one end of the microwave signal generating unit 13 is connected to the diamond NV sensor chip 12, and the other end is connected to the demodulation unit 16. It is used to generate a modulated microwave signal and transmit a signal with the same frequency as the modulated microwave signal to the demodulation unit 16.

[0101] Specifically, the optical emitting unit 14 is used to emit a specific laser signal.

[0102] Specifically, the diamond NV sensor chip 12 is disposed at the opening of the magnetic ring, and further converts the magnetic signal collected and converted by the magnetic ring 11. In this comparative example, one end of the diamond NV sensor chip 12 is connected to the microwave signal generating unit 13, and the other end is connected to the optical emitting unit 14. Based on the modulated microwave signal output by the microwave signal generating unit 13 and the laser signal emitted by the optical emitting unit 14, the magnetic signal collected and converted by the magnetic ring 11 is converted into an optical signal. In this comparative example, the diamond NV sensor chip 12 converts the carried magnetic signal information into a fluorescent signal.

[0103] Specifically, the photoelectric conversion unit 15 is connected to the fluorescence signal and converts the fluorescence signal output by the diamond NV sensor chip 12 into an electrical signal, which is convenient for subsequent demodulation and analysis.

[0104] Specifically, one end of the demodulation unit 16 is connected to the microwave signal generation unit 13, and the other end is connected to the photoelectric conversion unit 15. The magnetic signal information carried by the fluorescence signal received by the photoelectric conversion unit 15 is demodulated to facilitate subsequent calculation and analysis.

[0105] Specifically, the current calculation unit 17 is connected to the demodulation unit 16, and calculates the information demodulated by the demodulation unit to obtain the current of the conductor 10 under test.

[0106] The small-current quantum current sensor 1 provided in this comparative example generates a corresponding magnetic field around the current in the measured wire 10 based on the principle of electromagnetic induction. Due to the magnetic sensitivity of the NV color centers in diamond, the magnetic signal can be effectively sensed and the acquired magnetic field information can be read out optically, thereby accurately determining the magnitude of the current.

[0107] However, the small-current quantum current sensor 1 in this comparative example is difficult to apply under high current conditions for four reasons: First, under the strong magnetic field generated by high current, the NV color centers in the diamond cannot effectively convert the magnetic signal into a fluorescent signal, resulting in a decrease in the magnetic sensitivity of the small-current quantum current sensor 1 and making it difficult to accurately read the current of the measured wire 10. Second, the transverse magnetic field deviating from the crystal axis of the NV color centers also reduces the sensitivity of the small-current quantum current sensor 1, which limits the sensor in high-current sensing. Third, in the process of measuring the magnetic field of the current, microwaves corresponding to the Zeeman shift frequency are needed to drive the electron spin state flip of the NV color centers, which requires a sufficiently high microwave frequency bandwidth. However, the microwave field strength generated by a large-bandwidth microwave antenna will decrease, thus failing to drive more NV color centers and reducing the sensor's sensitivity. Fourth, under high current conditions, a significant magnetic hysteresis phenomenon will appear in the magnetic ring, affecting the detection linearity of the small-current quantum current sensor 1.

[0108] Based on this, the small-current quantum current sensor 1 provided in this comparative example can only detect currents below A, while current detection under a large dynamic range (e.g., A to kA level) is difficult. Therefore, there is an urgent need for a new quantum current sensor 1 that can be applied not only to current detection in a small current range (below A) but also to current detection in a large dynamic range (A to kA level).

[0109] Example 1

[0110] This embodiment provides a quantum current sensor 2 to solve the problem in the comparative example that the small current quantum current sensor 1 can only detect small currents (below A) and cannot detect currents with a large dynamic range (A to kA level).

[0111] like Figure 2 As shown, the quantum current sensor 2 provided in this embodiment includes: a diamond NV sensing chip 21, a magnetic ring 22, a laser source 23, a photoelectric conversion module 24, a microwave modulation and demodulation module 25, and a magnetic flux control module 26.

[0112] like Figure 2As shown, the magnetic ring 22 has an opening; the magnetic ring 22 is disposed around the conductor 20 being tested to sense the magnetic flux of the conductor 20 being tested; in this embodiment, as... Figure 2 As shown, the opening is located on the left side of the magnetic ring 22.

[0113] like Figure 2 As shown, the diamond NV sensor chip 21 is disposed at the opening to detect the magnetic flux at the opening; the magnetic flux at the opening includes the magnetic flux of the measured wire 20 and the reverse magnetic flux generated by the magnetic flux control module 26. Figure 3 As shown, when the current Ip in the measured conductor 20 is directed to the left (that is, as shown in the figure), Figure 3 As shown in the -X direction), the magnetic flux B1 generated by the tested wire 20 based on electromagnetic induction is counterclockwise on the magnetic ring 22 (based on the X and Y planes). The direction of the magnetic flux B1 generated by the tested wire 20 at the opening of the diamond NV sensor chip 21 is to the left (-X direction). The reverse magnetic flux B2 generated by the magnetic flux control module 26 is opposite to the direction of the magnetic flux B1. The direction of the reverse magnetic flux B2 received at the opening of the diamond NV sensor chip 21 is to the right (X direction), and the direction on the magnetic ring 22 is clockwise.

[0114] Specifically, such as Figures 2-4 As shown, the optical interface 215 of the diamond NV sensor chip 21 receives the laser signal and reflects the fluorescence signal; the first microwave interface 211 of the diamond NV sensor chip 21 is connected to the microwave modulation signal, and the second microwave interface 212 is connected to the load 214; a microstrip antenna 213 is disposed between the first microwave interface 211 and the second microwave interface 212; the microstrip antenna 213 is disposed between the optical interface 215 and the diamond structure 216 in the diamond NV sensor chip, and the microstrip antenna 213 partially or completely covers the diamond structure 216 in the diamond NV sensor chip. A microwave field is generated on the diamond surface in the diamond NV color center sensor chip 101 by the microwave antenna 213, thereby driving the NV color centers in the diamond structure of the diamond NV sensor chip.

[0115] It should be noted that the diamond NV sensor chip 21 is a chip that integrates the optical interface 215, the first microwave interface 211, the second microwave interface 212, and the diamond structure with NV color centers into one unit. In this embodiment, the microwave interface and the optical interface are connected to the diamond structure with NV color centers by welding and adhesive bonding. The diamond structure with NV color centers, also known as diamond NV color centers, refers to a point defect in diamond where a nitrogen atom replaces a carbon atom and combines with a nearby hole to trap an electron. This is an artificial quantum defect state, and its special energy level structure is beneficial for magnetic field sensing. Its working principle is as follows... Figure 5 As shown, under normal conditions (without an external magnetic field), the ground state of the NV color center is a triple degenerate state, where there is a zero-field split D between the ms = 0 and ms = ±1 energy levels. gs ≈2.87 GHz. When the NV color center is excited using a 532 nm wavelength laser, electrons in the ms=0 state will directly transition back to the ground state and release red fluorescence with wavelengths of 637–800 nm. Electrons in the ms=±1 state, however, will undergo a non-relaxation process to transition to a metastable state before returning to the ground state. Therefore, when a portion of the electrons in the ms=0 state are modulated to the ms=±1 state using a microwave field, a decrease in fluorescence will be observed. When an external magnetic field is present, Zeeman splitting will occur between the ms=±1 energy levels. The size of the splitting is positively correlated with the projection of the magnetic field onto the NV color center axis. Therefore, by sweeping the frequency under continuous laser light, a decrease in fluorescence peak will be observed when electrons in the ms=0 state are modulated to the ms=±1 state. The frequency of this decrease peak matches the resonance frequency between the ms=0 and ms=±1 energy levels, allowing the magnitude of the magnetic field to be calculated from the resonance frequency. In other words, by adjusting the laser frequency, the resonance frequency between the ms=0 energy level and the ms=±1 energy level (the first or second resonance frequency of the electron spin resonance in the NV color center) can be obtained, thereby determining the magnitude of the external magnetic field. Macroscopically, this manifests as the input laser signal being output as a fluorescence signal, reflecting the magnitude of the external magnetic field sensed by the diamond's NV color center. Therefore, the diamond's NV color center can be considered to have achieved magneto-optical conversion.

[0116] like Figure 2 As shown, the laser source 23 is used to generate a laser signal of a preset wavelength and output it to the diamond NV sensor chip 21.

[0117] Specifically, the laser source 23 is connected to the optical interface 215 of the diamond NV sensor chip 21 to generate a laser signal of a preset wavelength. In use, the laser source generates a 532nm green laser signal, which is then irradiated onto the diamond surface of the diamond NV sensor chip 21 through the optical interface 215.

[0118] As an example, the quantum current sensor 2 further includes an optical fiber circulator 231, a first optical channel 231a, and a second optical channel 231b. The optical fiber circulator 231 is disposed between the laser source 23 and the diamond NV sensor chip 21. The first interface of the optical fiber circulator 231 is connected to the laser source 23, the second interface is connected to the optical interface 215 through the first optical channel 231a, and the third interface is connected to the photoelectric conversion module 24 through the second optical channel 231b. The optical fiber circulator 231 inputs the laser signal from the first interface and outputs it through the second interface, and then inputs the fluorescence signal through the second interface and outputs it through the third interface, thereby controlling the direction of light transmission.

[0119] It should be noted that a beam splitter can also be installed on the optical interface 215 to output the converted fluorescence signal to the photoelectric conversion module 24. The specific circuit structure is not limited to this embodiment, and any configuration that can input the laser signal and reflect the fluorescence signal to the photoelectric conversion module 24 is within the scope of protection of this embodiment. In addition, in actual use, the first optical channel 231a and the second optical channel 231b can use optical fibers, optical waveguides, and other devices as transmission channels for laser signals and fluorescence signals, and are not limited to this embodiment.

[0120] like Figure 2 As shown, the photoelectric conversion module 24 receives the fluorescence signal reflected by the diamond NV sensor chip 21, and then converts the fluorescence signal into an electrical signal and transmits it to the microwave modulation and demodulation module 25.

[0121] Specifically, the first end of the photoelectric conversion module 24 is connected to the optical interface of the diamond NV sensor chip 21, and the second end is connected to the microwave modulation and demodulation module 25, which converts the red fluorescence signal output by the diamond NV sensor chip 21 into an electrical signal for subsequent processing.

[0122] As an example, the quantum current sensor 2 further includes a filter 232; the filter 232 is disposed on the second optical channel 231b, that is, before the photoelectric conversion module 24 receives the fluorescence signal. The filter 232 is used to filter out the green laser signal in the red fluorescence signal. In this embodiment, it is set as a long-pass filter, which can completely filter out the laser signal in the green light band and only receive the fluorescence signal in the red band, making the analysis results more accurate.

[0123] As an example, the quantum current sensor also includes a beam splitter 233; the beam splitter 233 is disposed between the laser source 23 and the fiber optic circulator 231, and the output end of the beam splitter 233 is connected to the photoelectric conversion module 24, splitting the laser signal into a reference optical signal and outputting it to the photoelectric conversion module 24. A reference optical signal based on the laser signal can be obtained through the beam splitter 233, at which time the laser signal in the fluorescence signal received by the photoelectric conversion module 24 can be eliminated, thereby achieving the purpose of optical signal noise reduction and making the measurement conversion result more accurate.

[0124] In this embodiment, the quantum current sensor further includes a coupler 234; the coupler 234 is disposed between the beam splitter 233 and the laser source 23, and is used to couple the laser emitted by the laser source 23 to the optical interface 215. In practice, the coupler 234 may not be separately provided, and the laser may be directly input to the optical interface 215 through the fiber optic coupling interface.

[0125] like Figure 2 As shown, the microwave modulation and demodulation module 25 is used to generate a microwave modulation signal fmod and output it to the diamond NV sensor chip 21, and obtain the demodulation voltage ΔV based on the same frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module.

[0126] Specifically, the microwave modulation and demodulation module 25 includes a microwave signal generation unit 251 and a demodulation unit 252, that is, one microwave modulation signal corresponds to one demodulation unit 252 for demodulation.

[0127] As an example, the microwave modulation signal generation unit 251 generates a microwave modulation signal fmod and outputs it to the diamond NV sensor chip 21. The frequency of the microwave modulation signal fmod is set to either the first resonance frequency f1 or the second resonance frequency f2 of the electron spin resonance in the NV center (i.e., the resonance frequency between the electron spin ms=0 and ms=+1 energy levels or the resonance frequency between the electron spin ms=0 and ms=-1 energy levels). By applying a frequency modulation of fmod to the microwave signal, the microwave modulation signal fmod is obtained, thereby making the fluorescence signal also have the frequency characteristics. Combined with the subsequent demodulation step in the photoelectric conversion module 25, the signal-to-noise ratio of the quantum current sensor 2 is improved, and the detection sensitivity is enhanced.

[0128] In this embodiment, as Figure 6As shown, the microwave modulation signal generation unit 251 includes a microwave source 2511, a mixer 2512, and an adder 2513. The first input terminal of the mixer 2512 is connected to the microwave source 2511, and the second input terminal is connected to the intrinsic signal. The first input terminal of the adder 2513 is connected to the output terminal of the mixer 2512, and the second input terminal is connected to the intrinsic signal, outputting the corresponding microwave modulation signal fmod. The mixer 2512 can generate two sideband signals based on the microwave signal generated by the microwave source 2511 (in this embodiment, the set frequencies of the two sideband signals are 2.158MHz apart). Without the mixer 2512, a microwave modulation signal of one frequency corresponds to a falling peak in the NV color center. After passing through the mixer 2512, the output tri-frequency signal can correspond to three falling peaks in the NV color center, theoretically increasing the sensor signal-to-noise ratio by three times.

[0129] As an example, the first input terminal of the demodulation unit 252 is connected to the microwave modulation signal generation unit 251, the second input terminal is connected to the photoelectric conversion module 24, and the output terminal is connected to the magnetic flux control module 26. The demodulation voltage ΔV is obtained based on the same-frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module 24. In this embodiment, the same-frequency signal of the microwave modulation signal is used as a reference signal to demodulate the output signal of the photoelectric conversion module 25, thereby obtaining the demodulation voltage ΔV. By manipulating the NV color center using microwave modulation and demodulation, the resulting fluorescence signal carries the same frequency characteristics as the microwave modulation signal fmod. Then, phase-sensitive demodulation is performed using a lock-in amplifier to obtain a swept spectrum with characteristic zero-crossing points. At this time, the zero-crossing position in the frequency-fluorescence spectrum (i.e., the optically detected magnetic resonance (ODMR) spectrum) obtained by the frequency sweep is the resonance frequency position.

[0130] As an example, the microwave modulation and demodulation module 25 further includes a microwave signal power amplifier 253, which is disposed between the microwave modulation signal generation unit 251 and the diamond NV sensor chip 21. The microwave signal power amplifier is used to amplify the amplitude of the microwave modulation signal fmod to drive a larger number of NV color centers, thereby effectively improving the NV fluorescence contrast.

[0131] It should be noted that in this embodiment, the demodulation unit 252 is configured as a lock-in amplifier to perform phase-sensitive demodulation. In fact, other methods can also be used to demodulate the signal output by the photoelectric conversion module 24, and this embodiment is not the only one that can be used.

[0132] like Figure 2As shown, the magnetic flux control module 26 is connected to the demodulation voltage ΔV, obtains the reverse magnetic flux B2 of the conductor under test 20 based on the demodulation voltage ΔV, and loads the reverse magnetic flux B2 onto the magnetic flux detection module 21 to control the magnetic flux at the opening.

[0133] Specifically, the magnetic flux control module 26 includes a reverse current control unit 261 and a coil winding 262. The coil winding 262 is wound on the magnetic ring 22 and has N turns; N is an integer greater than or equal to 1. The input terminal of the reverse current control unit 261 is connected to the demodulation voltage ΔV, used to generate and output a reverse current Is; the first end of the coil winding 262 is connected to the output terminal of the reverse current control unit 261, and the second end is grounded. The reverse current control unit 261 is controlled by the microwave demodulation signal to generate the reverse current Is. S The output is connected to the coil winding 262 wound on the magnetic ring 22 to provide a reverse magnetic flux B2, thereby regulating the magnetic flux at the opening (i.e., at the opening, the magnetic flux B1 of the measured wire 20 and the reverse magnetic flux B2 are equal in magnitude and opposite in direction); when the magnetic flux at the opening is balanced, the reverse current I... S The current value is proportional to the current value Ip of the conductor 20 being measured.

[0134] As an example, the reverse current control unit 261 includes an analog-to-digital converter 2611, a proportional-integral calculation circuit 2612, a digital-to-analog converter 2613, and a power amplifier 2614; the demodulated voltage ΔV is output to the first end of the coil winding 262 through the analog-to-digital converter 2611, the proportional-integral calculation circuit 2612, the digital-to-analog converter 2613, and the power amplifier 2614 arranged in series.

[0135] The process of achieving magnetic flux signal modulation is as follows: Figure 7 As shown, in this embodiment, the current change Ip generated by the measured conductor 20 will be collected as ΔB(B1-B2) by the magnetic flux of the magnetic ring, and thus sensed by the diamond NV sensing chip 21, causing a change in the demodulation voltage ΔV. A proportional-integral (PI) calculation circuit 2612 is used to implement the proportional-integral algorithm, processing the demodulation voltage ΔV to form a reverse current Is. The PI calculation circuit 2612 consists of a proportional unit and an integral unit, and the output of the reverse current Is can be adjusted by adjusting the gains of these two units (Kp and Ki, respectively).

[0136] The demodulation voltage ΔV and the reverse current Is satisfy:

[0137] I S ·R s =kp ΔV+k i ∑ΔV (1)

[0138] Where ΔV is the detected demodulation voltage, Rs is the total resistance of the coil winding, and Is is the reverse current value output to the coil winding. By adjusting the gains of these two units (Kp and Ki, respectively), the output of the reverse current Is is adjusted to balance the change in magnetic flux. The final result of the balance is that the magnetic flux B1 generated by the change in the measured current Ip is canceled out by the coil winding 262, and the demodulation voltage ΔV returns to zero. At this time, measuring the output of the reverse current Is can restore the change in the measured current Ip. The current of the measured conductor 20 satisfies:

[0139] Ip=N×Is (2)

[0140] It should be noted that since the diamond NV sensing chip 21 can obtain the frequency-fluorescence spectrum (i.e., optically detected magnetic resonance (ODMR) spectrum) through frequency sweeping, the measured current Ip can still be obtained based on formula (2) by directly adjusting the reverse current Is until the frequency-fluorescence spectrum returns to the normal state (i.e., when no external magnetic field is sensed). Therefore, the structure of the reverse current control unit 261 is not limited to this embodiment, and any structure that can provide an adjustable reverse current Is to the coil winding 262 is within the protection scope of this embodiment.

[0141] This embodiment also provides a current measurement method, implemented based on the aforementioned quantum current sensor 2, including:

[0142] S1. The microwave modulation signal fmod and the laser signal of the preset wavelength are output to the diamond NV sensor chip 21 to obtain the magnetic flux at the opening of the magnetic ring 22; the magnetic flux at the opening includes the magnetic flux B1 of the wire under test 20 and the reverse magnetic flux B2 generated by the magnetic flux control module 26.

[0143] Specifically, the laser signal is set to a wavelength of 532nm. The diamond NV sensor chip 21 absorbs the green laser signal and emits a red fluorescent signal, thereby converting the magnetic flux information (ΔB = B1 - B2) at the opening of the magnetic ring 22 into optical information.

[0144] S2. The same frequency signal of the microwave modulation signal is used as a reference signal to demodulate the output signal of the photoelectric conversion module 24, thereby obtaining the demodulated voltage ΔV.

[0145] Specifically, in this embodiment, the same frequency signal of the microwave modulation signal is used as a reference signal and input into the lock-in amplifier. The other input terminal of the lock-in amplifier is connected to the voltage signal output by the photoelectric conversion module 24. The lock-in amplifier performs phase-sensitive demodulation to obtain the demodulated voltage ΔV.

[0146] S3. Based on the linear relationship between the demodulation voltage ΔV and the reverse magnetic flux B2 of the conductor under test 20, the reverse magnetic flux B2 of the conductor under test is obtained, and the reverse magnetic flux B2 is applied to the magnetic ring 22 to balance the magnetic flux at the opening (so that ΔB = 0).

[0147] Specifically, in this embodiment, based on the demodulation voltage ΔV, a reverse magnetic flux B2, equal in magnitude but opposite in direction to the magnetic flux generated by the conductor under test 20, is supplied to the magnetic focusing ring 22 until the magnetic flux at the opening is balanced. In this embodiment, in step S3, the reverse magnetic flux B2 of the conductor under test is calculated using a proportional-integral algorithm based on the demodulation voltage ΔV. The specific calculation method of the proportional calculation algorithm has been described above and will not be repeated here.

[0148] It should be noted that the reverse current Is can also be directly adjusted based on the optically detected magnetic resonance spectrum (ODMR) until the optically detected magnetic resonance spectrum returns to its normal state (the state where no external magnetic flux is detected), at which point the magnetic flux at the opening is balanced.

[0149] S4. The current value Ip of the conductor 20 under test is calculated based on the reverse magnetic flux B2.

[0150] Specifically, in a balanced state, the current Ip of the measured conductor 20 is proportional to the reverse current Is, and the current value Ip of the measured conductor 20 can be obtained. In this embodiment, the reverse current Is is converted into a reverse magnetic flux and applied to the magnetic ring 22 based on the winding coil 262, thus satisfying formula (2) (i.e., Ip = N × Is).

[0151] Under the strong magnetic field generated by a large current, the fluorescence intensity emitted by the NV color center is reduced due to the magnetic field, leading to a decrease in sensor sensitivity. At a fixed microwave frequency, the magnitude of the magnetic field signal generated by the large current exceeds the measurement range of the NV color center, resulting in unsuccessful readings when directly using the NV color center to sense the magnetic signal. While theoretically the magnetic signal can be brought within the detection range of the NV color center by proportionally reducing it or superimposing a reverse magnetic flux, several problems arise if the NV color center is still used to directly read the magnetic signal: First, since the magnetic flux of the measured conductor is unknown during measurement, it is impossible to directly preset the flux of the measured conductor. For example, if the magnetic field of the measured conductor is 1 mT and the detection range of the NV color center is 100 μT, if the measured conductor is attenuated proportionally, the attenuation ratio K is 0.1, and one attenuation is sufficient to enter the detection range of the NV color center. However, if the magnetic flux of the measured conductor is larger, more attenuations are required; or, when providing a preset magnitude of reverse magnetic flux, multiple superpositions of reverse magnetic flux may be necessary, still resulting in unsuccessful readings. Secondly, if the magnetic flux of the conductor under test is unknown during measurement, measuring the magnetic field of the conductor using methods such as frequency sweep ODMR spectrum analysis can be time-consuming and unstable. The spectrum sweeping process is laborious and time-consuming. Furthermore, since current is usually a real-time changing physical quantity in actual measurements, a long sweep time can easily introduce significant errors. For example, during the first and second scans of the NV color center spectrum, the current in the conductor under test may have changed during the measurement process, or there may have been changes due to error factors such as temperature, all of which can lead to inaccurate magnetic signal detection.

[0152] Based on this, the quantum current sensor 2 in this embodiment is composed of a magnetic sensing probe with a diamond NV color center and a magnetic ring 22 with a coil winding 262 to form a detection head, so as to realize non-contact current sensing. With the help of a proportional-integral circuit algorithm, the coil winding 262 ensures that the detection range of the quantum current sensor 2 is always in a magnetic balance state and the measured current value can be directly obtained through the coil winding 262. This realizes the dynamic adjustment of the magnetic field, avoids the measurement by directly adjusting the NV color center spectrum, and thus makes the detection real-time and accurate, achieving the purpose of rapid detection.

[0153] In addition, the quantum current sensor 2 in this embodiment can ignore the hysteresis caused by the material and shape of the magnetic ring itself, greatly improving the sensor's range and linearity, and realizing current detection with a large current dynamic range from mA to kA. At the same time, the transverse magnetic field deviating from the NV crystal axis will also reduce the sensor's sensitivity. Therefore, by using the principle of magnetic balance to ensure that the NV color center always maintains the optimal working state, the influence of the transverse field is ignored, which also makes the microwave bandwidth no longer limited.

[0154] Example 2

[0155] This embodiment provides a quantum current sensor 3, which is basically the same as that in Embodiment 1, except that the number of microwave signal generation units 251 and demodulation units 252 in the microwave modulation and demodulation module 25 of this embodiment is different.

[0156] Specifically, such as Figure 8 As shown, the microwave modulation and demodulation module 25 includes two microwave signal generation units 251 and two demodulation units 252. Each microwave signal generation unit 251 and each demodulation unit 252 are configured in a one-to-one correspondence.

[0157] As an example, each microwave signal generation unit 251 generates a first microwave modulation signal f1mod and a second microwave modulation signal f2mod, respectively. The first microwave modulation signal f1mod and the second microwave modulation signal f2mod are then superimposed and output to the diamond NV sensing chip 21. The frequency of the first microwave modulation signal f1mod is set to the first resonance frequency f1 of the electron spin resonance in the NV center, and the frequency of the second microwave modulation signal f2mod is set to the second resonance frequency f2 of the electron spin resonance in the NV center. During measurement, the frequencies of the two microwave sources are matched to the frequencies between a pair of on-axis electron spin ms=0 and ms=±1 energy levels in the NV center (i.e., the resonance frequency between the electron spin ms=0 energy level and the ms=+1 energy level, and the resonance frequency between the electron spin ms=0 energy level and the ms=-1 energy level), such as... Figure 9 As shown, the mixed microwave amplification output is sent to the microwave interface of the diamond NV sensor chip 21. The diamond NV color center probe is placed in the air gap of the magnetic ring 22. At the same time, two lock-in amplifiers are started. The same frequency signal of the first microwave modulation signal f1mod and the same frequency signal of the second microwave modulation signal f2mod are respectively sent to the corresponding lock-in amplifiers for frequency sweeping to obtain two demodulated signals. The first demodulated signal and the second demodulated signal are used as the differential demodulation voltage ΔV output to control the magnitude of the reverse current Is.

[0158] As an example, the first input terminal of each demodulation unit 252 is connected to the corresponding microwave signal generation unit 251, the second input terminal is connected to the photoelectric conversion module 24, and the output terminal is connected to the magnetic flux control module 26. A first demodulated signal ΔV1 is obtained based on the same frequency signal of the first microwave modulation signal f1mod and the output signal of the photoelectric conversion module 24, and a second demodulated signal ΔV2 is obtained based on the same frequency signal of the first microwave modulation signal f1mod and the output signal of the photoelectric conversion module 24. The first demodulated signal ΔV1 and the second demodulated signal ΔV2 are used as a differential demodulation voltage ΔV. Figure 10As shown, by directly performing differential analysis on the first demodulated signal and the second demodulated signal, which carry the same temperature information, the demodulated voltage ΔV can be obtained.

[0159] To further explain the measurement principle of the quantum current sensor 3 in this embodiment, considering the presence of an external magnetic field, the ground-state Hamiltonian of the NV color center is:

[0160]

[0161] Where Z is the NV color axis direction, the first term of the formula represents the zero-field splitting affected by temperature, which is usually expressed as D_gs≈2.87GHz at room temperature. The second term is the effect of the stress field on electron spin, which is usually neglected in single-crystal diamond (E=0). The third term is the effect of the external magnetic field on electron spin, where g is the Landé factor, μ B For Bohr magneton, It is the magnetic field vector. Let be the electron spin operator. Therefore, the resonance frequency between the spin ms=0 and ms=±1 energy levels can be expressed as:

[0162] f0≈D gs +βΔT±gμ B B NV (4)

[0163] Wherein, the temperature coefficient at room temperature β≈-74.2kHz / K, ΔT is the temperature offset from 300K, and B NV Let be the magnitude of the projection of the external magnetic field onto the NV axis. Therefore, for the NV color center of the spin ms = ±1 level, the effect of temperature drift is the same, while the direction of energy level change caused by the magnetic field is opposite. For example... Figure 9 As shown, in this embodiment, when the quantum current sensor 3 detects the wire 20 under test, it simultaneously uses two microwave sources to drive the NV color center. The frequencies of the two demodulated microwave signals correspond to the frequencies of the spin transition from ms=0 to ms=+1 and the spin transition from ms=0 to ms=-1, respectively. Since both energy levels are affected by temperature, the demodulated signals are differentially divided. The resulting signal eliminates the influence of temperature drift and is amplified by one time. Figure 10 As shown. The demodulated voltage ΔV in differential form is then processed by a proportional-integral (PI) circuit to form a reverse current Is, which is output to the winding coil 262 to regulate the change in magnetic flux. Ultimately, the magnetic flux B1 generated by the change in current Ip of the measured conductor 20 is canceled out by the reverse magnetic flux B2 generated by the winding coil 262. Simultaneously, since both demodulated signals contain the same temperature information and voltage information with opposite phases but the same amplitude, if the two demodulated signals are superimposed, the resulting temperature information is doubled. Since the voltage signals cancel each other out after addition, the quantum current sensor can be used as a temperature sensor, independent of changes in the magnetic field.

[0164] It should be noted that, compared to Embodiment 1, this embodiment includes two microwave signal generation units 251 and two demodulation units 252, making the demodulated voltage ΔV more accurate and effectively suppressing the influence of factors such as temperature on the demodulated voltage ΔV. Meanwhile, the specific configuration of the microwave signal generation unit 251 and the demodulation unit 252 is basically the same as in Embodiment 1, and will not be described in detail here.

[0165] This embodiment also provides a current measurement method based on the aforementioned quantum current sensor 3. The current measurement method in this embodiment is basically the same as in Embodiment 1, except that the calculation of the demodulation voltage ΔV is different. Embodiment 1 obtains the demodulation voltage ΔV for only one microwave modulation signal, while this embodiment obtains two demodulated signals for two microwave modulation signals, and the demodulation voltage ΔV is obtained by differentially dividing the two signals.

[0166] It should be noted that the current measurement method in this embodiment is basically the same as that in the previous embodiment, and will not be described in detail here. The current measurement method in this embodiment has better sensitivity and temperature drift suppression performance than that in the first embodiment.

[0167] The process diagram for step current measurement in this embodiment is shown below. Figure 11 As shown, the current to be measured in the test wire 20 increases continuously from 0A to 50A. At this time, the magnitude of the current generated by the detection coil winding 262 and the reverse current Is increase synchronously with the current Ip of the test wire 20. This can reflect the magnitude of the current Ip of the test wire 20 well and the detection accuracy is high.

[0168] The process diagram of AC current measurement in this embodiment is shown below. Figure 12 As shown, the test conductor 20 generates an AC current with a frequency of 500Hz and an amplitude of 30A. At this time, the magnitude of the current generated by the detection coil winding 262 and the reverse current Is quickly follow the current Ip of the test conductor 20 and rise synchronously. This can well reflect the magnitude of the current Ip of the test conductor 20 and the detection speed is fast.

[0169] In summary, this invention provides a quantum current sensor and current measurement method, comprising: a diamond NV sensing chip, a magnetic ring, a laser source, a photoelectric conversion module, a microwave modulation and demodulation module, and a magnetic flux control module. The magnetic ring has an opening for sensing the magnetic flux of the conductor under test. The diamond NV sensing chip detects the magnetic flux at the opening. The laser source generates a laser signal of a preset wavelength and outputs it to the diamond NV sensing chip. The photoelectric conversion module receives the reflected fluorescence signal and converts it into an electrical signal, which is then transmitted to the microwave modulation and demodulation module to obtain a demodulation voltage. The magnetic flux control module obtains a reverse magnetic flux based on the demodulation voltage and applies it to the magnetic flux detection module to balance the magnetic flux at the opening. This invention provides a reverse magnetic flux, ensuring that the magnetic field induced at the NV color center remains within a small range, avoiding the problem of difficulty in detecting the diamond NV color center under high-current magnetic fields, and effectively expanding the dynamic range of the current measured at the diamond NV color center. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0170] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A quantum current sensor, characterized in that, The quantum current sensor includes at least: a diamond NV sensing chip, a magnetic ring, a laser source, a photoelectric conversion module, a microwave modulation and demodulation module, and a magnetic flux control module; The magnetic ring has an opening; the magnetic ring is disposed around the conductor being tested to sense the magnetic flux of the conductor being tested. The diamond NV sensor chip is disposed at the opening to detect the magnetic flux at the opening; the magnetic flux at the opening includes the magnetic flux of the wire being tested and the reverse magnetic flux generated by the magnetic flux control module. The laser source is used to generate a laser signal of a preset wavelength and output it to the diamond NV sensor chip. The photoelectric conversion module receives the fluorescence signal reflected by the diamond NV sensor chip, and then converts the fluorescence signal into an electrical signal and transmits it to the microwave modulation and demodulation module. The microwave modulation and demodulation module is used to generate a microwave modulation signal and output it to the diamond NV sensor chip, and to obtain the demodulation voltage based on the same frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module. The magnetic flux control module is connected to the demodulation voltage, obtains the reverse magnetic flux of the conductor under test based on the demodulation voltage, and loads the reverse magnetic flux onto the magnetic ring to control the magnetic flux at the opening.

2. The quantum current sensor according to claim 1, characterized in that: The optical interface of the diamond NV sensor chip receives the laser signal and reflects the fluorescence signal; the first microwave interface of the diamond NV sensor chip is connected to the microwave modulation signal, and the second microwave interface is connected to the load; a microstrip antenna is provided between the first microwave interface and the second microwave interface; the microstrip antenna is provided between the optical interface and the diamond structure in the diamond NV sensor chip, and the microstrip antenna partially or completely covers the diamond structure in the diamond NV sensor chip.

3. The quantum current sensor according to claim 2, characterized in that: The quantum current sensor also includes an optical fiber circulator, a first optical signal channel, and a second optical signal channel; The fiber optic circulator is disposed between the laser source and the diamond NV sensor chip; the first interface of the fiber optic circulator is connected to the laser source, the second interface is connected to the optical interface through the first optical signal channel, and the third interface is connected to the photoelectric conversion module through the second optical signal channel.

4. The quantum current sensor according to claim 3, characterized in that: The quantum current sensor also includes a filter; the filter is disposed on the second optical signal channel.

5. The quantum current sensor according to claim 3 or 4, characterized in that: The quantum current sensor also includes a beam splitter; the beam splitter is disposed between the laser source and the fiber optic circulator and the output end of the beam splitter is connected to the photoelectric conversion module, which splits the laser signal into a reference optical signal and outputs it to the photoelectric conversion module.

6. The quantum current sensor according to claim 1, characterized in that: The microwave modulation and demodulation module includes a microwave signal generation unit and a demodulation unit. The microwave modulation signal generation unit is used to generate a microwave modulation signal and output it to the diamond NV sensing chip; the frequency of the microwave modulation signal is set to the first resonance frequency or the second resonance frequency of the electron spin resonance in the NV color center. The first input terminal of the demodulation unit is connected to the microwave modulation signal generation unit, the second input terminal is connected to the photoelectric conversion module, and the output terminal is connected to the magnetic flux control module. The demodulation voltage is obtained based on the same frequency signal of the microwave modulation signal and the output signal of the photoelectric conversion module.

7. The quantum current sensor according to claim 1, characterized in that: The microwave modulation and demodulation module includes two microwave signal generation units and two demodulation units; Each microwave signal generation unit is configured in a one-to-one correspondence with each demodulation unit; Each microwave signal generation unit generates a first microwave modulation signal and a second microwave modulation signal, and the first microwave modulation signal and the second microwave modulation signal are superimposed and output to the diamond NV sensor chip; wherein, the frequency of the first microwave modulation signal is set to the first resonance frequency of the electron spin resonance in the NV color center, and the frequency of the second microwave modulation signal is set to the second resonance frequency of the electron spin resonance in the NV color center. Each demodulation unit has its first input terminal connected to a corresponding microwave signal generation unit, its second input terminal connected to the output terminal of the photoelectric conversion module, and its output terminal connected to the magnetic flux control module. A first demodulated signal is obtained based on the same frequency signal of the first microwave modulation signal and the output signal of the photoelectric conversion module, and a second demodulated signal is obtained based on the same frequency signal of the second microwave modulation signal and the output signal of the photoelectric conversion module. The first demodulated signal and the second demodulated signal are used as differential demodulated voltage outputs.

8. The quantum current sensor according to claim 6 or 7, characterized in that: The microwave modulation signal generation unit includes a microwave source, a mixer, and an adder; the first input terminal of the mixer is connected to the microwave source, and the second input terminal is connected to the intrinsic signal; the first input terminal of the adder is connected to the output terminal of the mixer, and the second input terminal is connected to the intrinsic signal, and outputs a corresponding microwave modulation signal.

9. The quantum current sensor according to claim 6 or 7, characterized in that: The demodulation unit is configured as a lock-in amplifier.

10. The quantum current sensor according to claim 1, characterized in that: The magnetic flux control module includes a reverse current control unit and a coil winding; the coil winding is wound on the magnetic ring and the coil winding has N turns; N is an integer greater than or equal to 1; The input terminal of the reverse current control unit is connected to the demodulation voltage, which is used to generate and output reverse current; The first end of the coil winding is connected to the output terminal of the reverse current control unit, and the second end is grounded.

11. The quantum current sensor according to claim 10, characterized in that: The reverse current control unit includes an analog-to-digital converter, a proportional-integral calculation circuit, a digital-to-analog converter, and a power amplifier; The demodulated voltage is output to the first end of the coil winding after passing through the analog-to-digital converter, the proportional-integral calculation circuit, the digital-to-analog converter, and the power amplifier arranged in series.

12. A current measurement method, implemented based on a quantum current sensor as described in any one of claims 1 to 11, comprising: S1. Output the microwave modulation signal and the laser signal of the preset wavelength to the diamond NV sensing chip to obtain the magnetic flux at the opening of the magnetic ring. The magnetic flux at the opening includes the magnetic flux of the conductor under test and the reverse magnetic flux generated by the magnetic flux control module. S2. Using the same frequency signal of the microwave modulation signal as a reference signal, the output signal of the photoelectric conversion module is demodulated to obtain the demodulated voltage; S3. Based on the linear relationship between the demodulation voltage and the reverse magnetic flux of the conductor under test, the reverse magnetic flux of the conductor under test is obtained, and the reverse magnetic flux is applied to the magnetic ring to balance and regulate the magnetic flux at the opening. S4. Based on the linear relationship between the reverse magnetic flux and the current of the conductor under test, the current value of the conductor under test is calculated.

13. The current measurement method according to claim 12, characterized in that: In step S3, the reverse magnetic flux of the conductor under test is calculated by the demodulated voltage using a proportional-integral algorithm.

14. The current measurement method according to claim 12, characterized in that: When the reverse magnetic flux is applied to the magnetic ring through the coil winding, the current value of the measured conductor satisfies: Ip = N × Is; Where Ip is the current value of the conductor being measured; N is the number of turns of the coil winding; and Is is the current value of the coil winding.

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