A quantum sensing frequency tracking system based on a diamond NV center differential type

Abstract

The present invention discloses a quantum sensing frequency tracking system based on a diamond NV center differential type, comprising: a laser module for transmitting a laser into the diamond NV center to generate a fluorescence intensity signal; a photoelectric detection module for converting the fluorescence intensity signal generated by the diamond NV center into an electrical signal; an error correction module for processing the electrical signal to reduce environmental magnetic field noise, optical and electromagnetic interference errors; a microwave control module for generating an electrical signal capable of quickly tracking the resonance frequency of the diamond NV center according to the processed signal; and a microwave conversion module for converting the electrical signal into a microwave signal and transmitting it into the diamond NV center. The present invention can effectively eliminate noises such as environmental magnetic fields, isolate the temperature drift effect, make the change in the fluorescence intensity emitted by the diamond NV center consistent with the change in the magnitude of the magnetic field to be measured, and achieve precise tracking of the resonance frequency.

Description

Technical Field

[0001] The present invention relates to the field of quantum precision measurement technology, and specifically to a quantum sensing frequency tracking system based on a diamond NV center differential type. Background Art

[0002] Currently, we are in a period of transition from traditional metrology to quantum metrology. Quantum precision measurement technology has brought revolutionary breakthroughs using quantum control technology, overcome various limitations faced by traditional measurement technologies, and significantly improved measurement performance. This field has become a popular research area internationally. The diamond NV center is a structure containing nitrogen-vacancy defects in the diamond lattice, with unique properties and can be applied to magnetic field measurement. Through the excitation of a microwave source and optical detection, the diamond NV center can achieve high-sensitivity and high-resolution magnetic field measurement.

[0003] Currently, research on diamond NV center magnetic field measurement at home and abroad mainly focuses on improving the fluorescence contrast to improve the system sensitivity. Although the system sensitivity has been continuously improved with the development of optical methods, as the research continues to deepen, it has become increasingly difficult to improve the system performance through optical methods. The microwave circuit is an important part of the diamond NV center quantum detection system and is also one of the key factors to improve the system performance. Therefore, improving the microwave aspect and controlling the microwave source to enable it to quickly track the resonance frequency of the diamond NV center can also effectively improve the system performance.

[0004] In traditional designs, the magnetic measurement system does not consider the interference of environmental magnetic field noise, optical noise, and electromagnetic interference, etc. The microwave module directly transmits the electrical signal to the diamond NV center through the microwave antenna, thus generating measurement errors and affecting the sensitivity and accuracy of the entire system. For this reason, a quantum sensing frequency tracking system based on a diamond NV center differential type is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a quantum sensing frequency tracking system based on a diamond NV center differential type to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A quantum sensing frequency tracking system based on a diamond NV center differential type, comprising:

[0007] A laser module for transmitting laser into the diamond NV center to generate a fluorescence intensity signal;

[0008] A photoelectric detection module for converting the fluorescence intensity signal generated by the diamond NV center into an electrical signal;

[0009] An error correction module for processing electrical signals to reduce environmental magnetic field noise, optical and electromagnetic interference errors;

[0010] A microwave control module that generates an electrical signal capable of quickly tracking the resonance frequency of the diamond NV center based on the processed signal;

[0011] A microwave conversion module for converting the electrical signal into a microwave signal and transmitting it into the diamond NV center.

[0012] As a further aspect of the present invention: The diamond NV center includes a first diamond NV center and a second diamond NV center, and the first diamond NV center and the second diamond NV center are symmetrically placed on both sides of the magnetic field to be measured.

[0013] As a further aspect of the present invention: The laser module includes a laser source, an acousto-optic modulator, a beam splitter, and a dichroic mirror. The laser source is used to cause energy level transitions in the diamond NV center to generate a fluorescence intensity signal. The acousto-optic modulator is used to control the intensity of the laser source. The beam splitter is used to evenly divide the laser source into two beams of laser light and transmit them into the first diamond NV center and the second diamond NV center. The dichroic mirror is used to reflect the light intensity signal generated by the laser source and transmit the fluorescence intensity signal radiated by the diamond NV center.

[0014] As a further aspect of the present invention: The photoelectric detection module includes a photodetector and a filter. The photodetector is used to convert the fluorescence intensity signal generated by the diamond NV center into an electrical signal. The filter is used to select light of a specific wavelength or band while blocking light of other wavelengths or bands.

[0015] As a further aspect of the present invention: The error correction module includes a lock-in amplifier, an integration circuit, a PID circuit, and a differential amplifier circuit. The lock-in amplifier is used to demodulate the converted electrical signal. Under the action of the magnetic field to be measured, low and high resonance frequencies R L and R H , R L and R H will be demodulated by the lock-in amplifier to generate the first-order differential spectrum of the ODMR curve. The integration circuit is used to integrate the first-order differential spectrum. The PID circuit is used to perform noise reduction processing on the electrical signal. The differential amplifier circuit is used to perform differential calculation on the signal processed by the PID circuit. Since the times when the resonance frequencies R L and R H occur are different, the differential amplifier circuit calculates the differential results at the frequencies of R L and R H respectively according to the time difference.

[0016] As a further solution of the present invention: the microwave control module is composed of an FPGA control module and a microwave generator. The FPGA control module generates a corresponding control program according to the differentiated signal to control the microwave generator, and the microwave generator is used to generate an electrical signal capable of tracking the resonance frequency of the diamond NV center.

[0017] As a further solution of the present invention: the FPGA control module is composed of an analog-to-digital conversion module ADC, an FPGA board, and a digital-to-analog conversion module DAC. The analog-to-digital conversion module ADC converts the input analog signal into a digital signal and sends the digital signal to the FPGA board through serial communication. The FPGA board is used to process the data and generate corresponding control signals, and the digital-to-analog conversion module DAC is used to communicate with the FPGA board and transmit the control signals to the microwave generator.

[0018] As a further solution of the present invention: the microwave conversion module is composed of a microwave antenna and a power amplifier. The microwave antenna is used to convert the electrical signal into a microwave signal, and the power amplifier is used to amplify the microwave signal.

[0019] As a further solution of the present invention: the microwave antenna is placed close to the diamond, and the orientation and position of the microwave antenna relative to the diamond remain consistent.

[0020] As a further solution of the present invention: the number of diamonds is two, and the magnetic field component forces of the two diamonds in four axial directions are similar or the same.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] In the present invention, by placing two diamonds with NV centers on both sides of the magnetic field to be measured, and respectively performing differential processing on the signals at the high and low resonance frequencies measured by the NV centers of the diamonds on both sides, the influence of environmental magnetic field noise and temperature drift effects on the magnetic measurement system can be effectively reduced. In the signal processing process, the PID control circuit is used to effectively reduce the errors such as system optical noise and electromagnetic interference. The processed signal controls the center frequency of the microwave generator through the microwave control module, so that the change in the fluorescence intensity emitted by the diamond NV center is consistent with the change in the magnitude of the magnetic field to be measured, and the tracking accuracy of the resonance frequency of the entire system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a block diagram of the resonance frequency tracking system of the diamond NV center differential type of the present invention;

[0024] Figure 2 It is a schematic structural diagram of the error correction module;

[0025] Figure 3Schematic diagram of the microwave modulation module structure;

[0026] In the figure: 1. Laser module; 2. Diamond NV center; 2A. First diamond NV center; 2B. Second diamond NV center; 3. Photoelectric detection module; 4. Error correction module; 5. Microwave control module; 6. Microwave conversion module; 7. Magnetic field to be measured; 8. Lock-in amplifier; 8A. First lock-in amplifier; 8B. Second lock-in amplifier; 9. Integrating circuit; 9A. First integrating circuit; 9B. Second integrating circuit; 9C. Third integrating circuit; 9D. Fourth integrating circuit; 10. PID circuit; 10A. First PID circuit; 10B. Second PID circuit; 10C. Third PID circuit; 10D. Fourth PID circuit; 11. Differential amplifier circuit; 12. Analog-to-digital conversion module ADC; 13. FPGA board; 14. Digital-to-analog conversion module DAC; 14A. First digital-to-analog conversion module DAC; 14B. Second digital-to-analog conversion module DAC; 15. Microwave generator; 15A. First microwave generator; 15B. Second microwave generator. Specific implementation mode

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Please refer to Figures 1-3 , in the embodiments of the present invention, a quantum sensing frequency tracking system based on a diamond NV center differential type includes:

[0029] A laser module 1 for transmitting laser into the diamond NV center 2 to generate a fluorescence intensity signal;

[0030] A photoelectric detection module 3 for converting the fluorescence intensity signal generated by the diamond NV center 2 into an electrical signal;

[0031] An error correction module 4 for processing the electrical signal to reduce environmental magnetic field noise, optical and electromagnetic interference errors;

[0032] A microwave control module 5 for generating an electrical signal capable of quickly tracking the resonance frequency of the diamond NV center 2 according to the processed signal;

[0033] A microwave conversion module 6 for converting the electrical signal into a microwave signal and transmitting it into the diamond NV center 2.

[0034] Please refer to Figure 1, in one embodiment, preferably, the diamond NV color center 2 includes a first diamond NV color center 2A and a second diamond NV color center 2B, and the first diamond NV color center 2A and the second diamond NV color center 2B are symmetrically placed on both sides of the magnetic field 7 to be measured.

[0035] Specifically, for the magnetic field 7 to be measured, an energized wire is passed through two coils with opposite winding directions, and the current flows in opposite directions in the two coils, thereby generating two magnetic fields with opposite directions. The two magnetic fields with opposite directions act on the first diamond NV color center 2A and the second diamond NV color center 2B respectively. Before measuring the magnetic field 7 to be measured, a bias magnetic field needs to be placed at the position to be measured first, and the diamond NV color center 2 is irradiated with a laser source to polarize it and cause Zeeman splitting, completing the initialization work of the system.

[0036] Please refer to Figure 1 , in one embodiment, preferably, the laser module 1 includes a laser source, an acousto-optic modulator, a beam splitter, and a dichroic mirror. The laser source is used to cause energy level transitions in the diamond NV color center 2 to generate a fluorescence intensity signal. The acousto-optic modulator is used to control the intensity of the laser source. The beam splitter is used to evenly divide the laser source into two beams of laser and transmit them into the first diamond NV color center 2A and the second diamond NV color center 2B respectively. The dichroic mirror is used to reflect the light intensity signal generated by the laser source and transmit the fluorescence intensity signal radiated by the diamond NV color center 2.

[0037] Specifically, the laser source uses 532 nm green fluorescence to cause energy level transitions in the diamond NV color center 2 to generate a red fluorescence intensity signal. The acousto-optic modulator is used to control the intensity of the laser source. The beam splitter is used to evenly divide the laser source into two beams of laser and transmit them into the first diamond NV color center 2A and the second diamond NV color center 2B respectively. The dichroic mirror is used to reflect the 532 nm green fluorescence generated by the laser source and transmit the red fluorescence signal radiated by the diamond NV color center 2.

[0038] Please refer to Figure 2 , in one embodiment, preferably, the photoelectric detection module 3 includes a photodetector and a filter. The photodetector is used to convert the fluorescence intensity signal generated by the diamond NV color center 2 into an electrical signal. The filter is used to select light of a specific wavelength or band and simultaneously shield light of other wavelengths or bands.

[0039] Please refer to Figure 2 , in one embodiment, preferably, the error correction module 4 includes a lock-in amplifier 8, an integration circuit 9, a PID circuit 10, and a differential amplifier circuit 11. The lock-in amplifier 8 is used to demodulate the converted electrical signal. Under the action of the magnetic field to be measured, the diamond NV color center 2 exhibits low and high resonance frequencies R L and RH ,R L and R H will be demodulated by the lock-in amplifier 8 to generate the first-order differential spectrum of the ODMR curve. The integrating circuit 9 is used to integrate the first-order differential spectrum, and the PID circuit 10 is used to reduce the noise of the electrical signal. The differential amplifier circuit 11 is used to perform differential calculation on the signal processed by the PID circuit 10. Since the resonance frequencies R L and R H are generated at different times, the differential amplifier circuit 11 calculates the differential results at the frequencies of R L and R H respectively according to the time difference.

[0040] Specifically, the lock-in amplifier 8 includes a first lock-in amplifier 8A and a second lock-in amplifier 8B, and the integrating circuit 9 includes a first integrating circuit 9A, a second integrating circuit 9B, a third integrating circuit 9C, and a fourth integrating circuit 9D. The PID circuit 10 includes a first PID circuit 10A, a second PID circuit 10B, a third PID circuit 10C, and a fourth PID circuit 10D. The first lock-in amplifier 8A and the second lock-in amplifier 8B respectively demodulate the optically input electrical signal. Under the action of the measured magnetic field, the diamond NV color center 2 will exhibit low and high resonance frequencies R L and R H ,R L and R H will be demodulated by the lock-in amplifier 8 to generate the first-order differential spectrum of the ODMR curve. Then, the first integrating circuit 9A, the second integrating circuit 9B, the third integrating circuit 9C, and the fourth integrating circuit 9D integrate the first-order differential spectrum. The first PID circuit 10A, the second PID circuit 10B, the third PID circuit 10C, and the fourth PID circuit 10D are used to process the electrical signal. Among them, the first lock-in amplifier 8A, the second lock-in amplifier 8B, the first integrating circuit 9A, the second integrating circuit 9B, the third integrating circuit 9C, and the fourth integrating circuit 9D form one path of signal, and the first PID circuit 10A, the second PID circuit 10B, the third PID circuit 10C, and the fourth PID circuit 10D are another path of signal. The two paths of signals constitute a PID control circuit, which is used to reduce the noise generated by the scattering or absorption of the fluorescence signal by the optical system during transmission and the interference signal from the power supply and other electromagnetic sources to the fluorescence signal; the differential amplifier circuit 11 is used to perform differential calculation on the signal processed by the PID control circuit. Since the resonance frequencies R L and R H are generated at different times, the differential amplifier circuit 11 calculates the differential electrical signal results at the frequencies of R L and R H respectively according to the time difference, which is used to eliminate the influence of environmental magnetic field noise and temperature drift on the system.

[0041] Please refer to Figure 3 , in one embodiment, preferably, the microwave control module 5 is composed of an FPGA control module and a microwave generator 15. The FPGA control module generates a corresponding control program according to the differentiated signal to control the microwave generator 15. The microwave generator 15 is used to generate an electrical signal capable of tracking the resonance frequency of the diamond NV color center 2; the FPGA control module is composed of an analog-to-digital conversion module ADC12, an FPGA board 13, and a digital-to-analog conversion module DAC14. The analog-to-digital conversion module ADC12 converts the input analog signal into a digital signal and sends the digital signal to the FPGA board 13 through serial communication. The FPGA board 13 is used to process the data and generate a corresponding control signal. The digital-to-analog conversion module DAC14 is used to communicate with the FPGA board 13 and transmit the control signal to the microwave generator 15.

[0042] Specifically, the microwave generator 15 includes a first microwave generator 15A and a second microwave generator 15B. The digital-to-analog conversion module DAC14 includes a first digital-to-analog conversion module DAC14A and a second digital-to-analog conversion module DAC14B. Among them, the analog-to-digital conversion module ADC12 sequentially converts the differential analog signals at the resonance frequencies R L and R H into digital signals and sends the digital signals to the FPGA board 13 through serial communication. The FPGA board 13 is used to process the data and generate a corresponding control signal. The first digital-to-analog conversion module DAC14A and the second digital-to-analog conversion module DAC14B are used to communicate with the FPGA board 13 and transmit the control signals to the first microwave generator 15A and the second microwave generator 15B respectively. The first microwave generator 15A and the second microwave generator 15B are used to generate electrical signals capable of tracking the resonance frequency of the diamond NV color center 2. The FPGA control module processes the differentiated data and can generate corresponding control signals to control the first microwave generator 15A and the second microwave generator 15B, so that the first microwave generator 15A and the second microwave generator 15B respectively generate resonance frequency electrical signals A and resonance frequency electrical signals B capable of tracking the fluorescence intensity changes of the first diamond NV color center 2A and the second diamond NV color center 2B.

[0043] Please refer to Figure 1 , in one embodiment, preferably, the microwave conversion module 6 is composed of a microwave antenna and a power amplifier. The microwave antenna is used to convert an electrical signal into a microwave signal, and the power amplifier is used to amplify the microwave signal.

[0044] Specifically, the microwave antenna is used to convert the output signals, i.e., the resonance frequency electrical signals A and B, into microwave signals and respectively transmit them into the first diamond NV center 2A and the second diamond NV center 2B. The microwave antenna is placed close to the diamond, and the orientation of the microwave antenna remains consistent relative to the diamond. The power amplifier is used to amplify the microwave signals. The number of diamonds is two, and the magnetic field component forces of the two diamonds in the four axial directions are similar or the same.

[0045] Although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0046] Therefore, the above description is only the preferred embodiment of the present application and is not used to limit the scope of implementation of the present application; that is, all equivalent transformations made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A quantum sensing frequency tracking system based on diamond NV color center differential mode, characterized in that: include: A laser module (1) is used to transmit laser light into the diamond NV color center (2) to generate a fluorescence intensity signal; A photoelectric detection module (3) is used to convert the fluorescence intensity signal generated by the diamond NV color center (2) into an electrical signal; An error correction module (4) is used to process the electrical signal to reduce environmental magnetic field noise, optical and electromagnetic interference errors; A microwave control module (5) generates an electrical signal capable of quickly tracking the resonance frequency of the diamond NV color center (2) according to the processed signal; A microwave conversion module (6) for converting electrical signals into microwave signals and transmitting them into the diamond NV color center (2); The diamond NV color center (2) comprises a first diamond NV color center (2A) and a second diamond NV color center (2B), and the first diamond NV color center (2A) and the second diamond NV color center (2B) are symmetrically placed on both sides of the magnetic field (7) to be measured; The error correction module (4) comprises a lock-in amplifier (8), an integration circuit (9), a PID circuit (10) and a differential amplifier circuit (11). The lock-in amplifier (8) is used to demodulate the converted electrical signal. Under the action of the measured magnetic field, the diamond NV color center (2) has low and high resonance frequencies R L and R H , R L and R H The first-order differential spectrum of the ODMR curve is demodulated by the phase-locked amplifier (8), and the integration circuit (9) is used to integrate the first-order differential spectrum. The PID circuit (10) is used to perform noise reduction processing on the electrical signal. The differential amplifier circuit (11) is used to perform differential calculation on the signal processed by the PID circuit (10). The signals at the high and low resonance frequencies measured by the diamond NV color center (2) on both sides are respectively differentially processed. Due to the resonance frequency R L and R H The time difference is different, and the differential amplifier circuit (11) calculates R L and R H The difference result at frequency; The microwave control module (5) is composed of an FPGA control module and a microwave generator (15); the FPGA control module generates a corresponding control program according to the differential signal to control the microwave generator (15); the microwave generator (15) is used to generate an electrical signal capable of tracking the resonance frequency of the diamond NV color center (2).

2. The quantum sensing frequency tracking system based on the diamond NV color center differential mode according to claim 1 is characterized in that: The laser module (1) comprises a laser source, an acousto-optic modulator, a beam splitter and a dichroic mirror. The laser source is used to cause the diamond NV color center (2) to undergo energy level transition and generate a fluorescence intensity signal. The acousto-optic modulator is used to control the intensity of the laser source. The beam splitter is used to evenly split the laser source into two laser beams to be transmitted to a first diamond NV color center (2A) and a second diamond NV color center (2B). The dichroic mirror is used to reflect the light intensity signal generated by the laser source and transmit the fluorescence intensity signal radiated by the diamond NV color center (2).

3. The quantum sensing frequency tracking system based on the diamond NV color center differential mode according to claim 1 is characterized in that: The photoelectric detection module (3) comprises a photoelectric detector and a filter. The photoelectric detector is used to convert the fluorescence intensity signal generated by the diamond NV color center (2) into an electrical signal. The filter is used to select light of a specific wavelength or waveband and shield light of other wavelengths or wavebands.

4. The diamond NV color center differential quantum sensing frequency tracking system according to claim 1 is characterized in that: The FPGA control module is composed of an analog-to-digital conversion module ADC (12), an FPGA board (13) and a digital-to-analog conversion module DAC (14); the analog-to-digital conversion module ADC (12) converts an input analog signal into a digital signal and transmits the digital signal to the FPGA board (13) via serial port communication; the FPGA board (13) is used to process data and generate a corresponding control signal; and the digital-to-analog conversion module DAC (14) is used to communicate with the FPGA board (13) and transmit the control signal to the microwave generator (15).

5. The diamond NV color center differential quantum sensing frequency tracking system according to claim 1, characterized in that: The microwave conversion module (6) is composed of a microwave antenna and a power amplifier; the microwave antenna is used to convert electrical signals into microwave signals; and the power amplifier is used to amplify microwave signals.

6. The diamond NV color center differential quantum sensing frequency tracking system according to claim 5, characterized in that: The microwave antenna is placed close to the diamond, and the orientation and position of the microwave antenna relative to the diamond remain consistent.

7. The diamond NV color center differential quantum sensing frequency tracking system according to claim 6 is characterized in that: The number of the diamonds is two, and the magnetic field components of the two diamonds in four axial directions are similar or identical.

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