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CN-121454422-B - Diamond NV color center magnetic sensing method and system with wide dynamic range

CN121454422BCN 121454422 BCN121454422 BCN 121454422BCN-121454422-B

Abstract

The invention discloses a diamond NV color center magnetic sensing method and system with a wide dynamic range, wherein the method comprises the steps of (1) calibrating initial resonance frequency and magnetic sensing coefficient of a diamond NV color center in an initial magnetic field environment, (2) applying frequency modulated microwaves to the diamond NV color center by a microwave generator by taking the current resonance frequency as the center frequency in a magnetic field environment to be detected, demodulating a fluorescent signal in real time by using a phase-locking detection technology to obtain an error signal, calculating the harmonic loss of the center frequency in real time according to the error signal and the magnetic sensing coefficient, further calculating the magnetic field intensity variation, and simultaneously feeding the harmonic loss back to the microwave generator to track the resonance frequency of the diamond NV color center, and (3) continuously and repeatedly executing the step (2) to realize magnetic field measurement with a wide dynamic range. The invention has the advantages of wide dynamic range, strong detection capability for the mixed signals of strong and weak fields in complex application scenes and the like while considering the magnetic sensing sensitivity.

Inventors

  • YING QIANWEN
  • LI QIANG
  • PI XIAODONG
  • YANG DEREN

Assignees

  • 浙江大学杭州国际科创中心

Dates

Publication Date
20260508
Application Date
20260107

Claims (5)

  1. 1. The diamond NV color center magnetic sensing method with the wide dynamic range is characterized by comprising the following steps of: (1) In the initial magnetic field environment, the microwave generator radiates microwave modulated by frequency to the NV color center of the diamond based on the center frequency, and the initial resonance frequency and the magnetic sensing coefficient of the NV color center of the diamond are calibrated The specific process is as follows: The microwave generator radiates frequency modulated microwaves to the diamond NV color center on the basis of the center frequency, and scans the center frequency of the microwaves to enable the fluorescent signals of the diamond NV color center to change along with the center frequency of the microwaves, wherein the modulated microwave frequencies meet the following conditions: ; Wherein, the Expressed in the center frequency of the microwave On the basis of (1) microwave frequency is carried out along with time Is used for the sinusoidal modulation of (a), For the amplitude of the microwave modulation, Is the microwave modulation frequency; demodulating the fluorescent signal of the diamond NV color center by using a phase-locked detection technology, and matching the demodulated fluorescent signal with the microwave center frequency Zero point of the curve of the change and slope at zero crossing point, respectively, obtain resonance frequency Magnetic sensing coefficient (2) Applying frequency modulated microwave to the NV color center of the diamond by the microwave generator with the currently obtained resonance frequency as the center frequency in the magnetic field environment to be detected, and demodulating the collected fluorescent signal in real time by using the phase-locked detection technology to obtain an error signal Specifically, the time-frequency domain of the fluorescent signal is filtered by using a lock-in amplifier, and only the microwave modulation frequency is reserved To obtain an error signal ; According to the error signal And magnetic sensing coefficient Calculating the detuning amount of the center frequency in real time And further calculate the magnetic field strength variation After updating the magnetic field strength measurement result, and at the same time, the detuning amount Feedback to microwave generator to track resonance frequency of NV color center of diamond, single measured detuning amount Is limited to the error signal The relation curve between the microwave center frequency and the monotonic interval; (3) By continuously repeating the execution of step (2), a wide dynamic range magnetic field measurement is achieved.
  2. 2. The wide dynamic range diamond NV color center magnetic sensing method of claim 1, wherein the excitation and collection method of fluorescent signals is: Excitation light is generated by using a 532nm wavelength laser, and is incident on diamond NV color center particles, and fluorescence of the diamond NV color center is received by a photoelectric detector and converted into fluorescence signals after being separated from the excitation light by a filter.
  3. 3. The wide dynamic range diamond NV color center magnetic sensing method of claim 1, wherein in step (2), the amount of detuning The calculation formula of (2) is as follows: ; Variation of magnetic field strength The calculation formula of (2) is as follows: ; Wherein, the Is the electron gyromagnetic ratio.
  4. 4. The diamond NV color center magnetic sensing system with the wide dynamic range is characterized by being used for realizing the diamond NV color center magnetic sensing method with the wide dynamic range according to any one of claims 1-3, and comprising a fluorescence excitation collection subsystem, a magnetic field sensing subsystem and a dynamic tracking subsystem; The fluorescence excitation and collection subsystem comprises a 532nm wavelength laser, diamond NV color center particles and a photoelectric detector, wherein the 532nm wavelength laser is used for exciting fluorescence of the diamond NV color center particles and collecting fluorescence signals by the photoelectric detector; The magnetic field sensing subsystem comprises a microwave generator, a microwave antenna, a phase-locked amplifier and a sensing calculation module, wherein the microwave generator is used for generating a microwave field with adjustable frequency, the microwave antenna is connected with the microwave generator and used for radiating the microwave field to diamond NV color center particles to drive spin state transition of the diamond NV color center particles, the phase-locked amplifier is used for demodulating fluorescent signals collected by the photoelectric detector into error signals, and the sensing calculation module is used for converting the error signals into harmonic loss of the microwave center frequency and magnetic field intensity variation; the dynamic tracking subsystem is used for feeding back the detuning amount to the microwave generator so as to track the resonance frequency of the diamond NV color center.
  5. 5. The wide dynamic range diamond NV color center magnetic sensing system of claim 4, wherein in the magnetic field sensing subsystem, the lock-in amplifier sets a reference frequency and transmits the reference frequency to the microwave generator through a cable to ensure that the microwave modulation frequency, the lock-in amplifier reference frequency and the fluorescent power variation frequency are consistent.

Description

Diamond NV color center magnetic sensing method and system with wide dynamic range Technical Field The invention belongs to the technical field of quantum precision measurement, and particularly relates to a diamond NV color center magnetic sensing method and system with a wide dynamic range. Background The high-sensitivity magnetic sensing has important application value in the fields of material science, geological exploration, biomedicine and the like. The quantum magnetic sensing based on the diamond NV color center becomes a research hot spot by virtue of the advantages of room temperature work, nanoscale resolution, high sensitivity and the like. The NV colour centre is magnetically induced by Optical Detection Magnetic Resonance (ODMR) techniques. For example, chinese patent document CN105158709a discloses a magnetic field measuring device based on diamond with embedded NV color center, chinese patent document CN118642014A discloses a device and method for measuring magnetic field based on diamond NV color center, and all magnetic field measuring is performed by using quantum system of diamond NV color center. However, the traditional diamond NV magnetic sensing faces the bottleneck that the dynamic range is limited, because the ODMR resonance frequency and the magnetic field intensity are in a linear relation, the external magnetic field change can obviously deviate from the ODMR resonance frequency, so that the signal contrast is suddenly reduced and even leaves the resonance range, and the weak field high sensitivity and the strong field measurement capability are difficult to be combined. Although there are a number of techniques for improving single point measurement sensitivity, extending the dynamic range without sacrificing that sensitivity remains critical. Therefore, a new NV color center magnetic sensing method capable of realizing continuous tracking measurement of a wide dynamic range magnetic field is developed, and the method has important practical significance and application value. Disclosure of Invention Aiming at the defect that the dynamic range of the existing diamond NV color center magnetic sensing technology is limited, the invention provides the diamond NV color center magnetic sensing method and system with wide dynamic range, and the method and system have the advantages of wide dynamic range, high continuous automation degree, strong detection capability of mixed signals of strong and weak fields in complex application scenes and the like while considering the magnetic sensing sensitivity. A diamond NV color center magnetic sensing method with a wide dynamic range comprises the following steps: (1) In the initial magnetic field environment, the microwave generator radiates microwave modulated by frequency to the NV color center of the diamond based on the center frequency, and the initial resonance frequency and the magnetic sensing coefficient of the NV color center of the diamond are calibrated ; (2) In the magnetic field environment to be measured, the microwave generator applies frequency modulated microwave to the NV color center of diamond with the currently obtained resonant frequency as the central frequency, and the collected fluorescent signal is demodulated in real time by using the phase-locked detection technology to obtain an error signal; According to the error signalAnd magnetic sensing coefficientCalculating the detuning amount of the center frequency in real timeAnd further calculate the magnetic field strength variationAfter updating the magnetic field strength measurement result, and at the same time, the detuning amountFeedback to a microwave generator to track the resonance frequency of the diamond NV colour centre; (3) By continuously repeating the execution of step (2), a wide dynamic range magnetic field measurement is achieved. The method of the invention fundamentally breaks through the dynamic range limitation of the traditional NV magnetic sensor caused by resonance detuning by actively tracking the resonance frequency shift caused by the magnetic field with the microwave frequency. The specific process of the step (1) is as follows: radiating frequency-modulated microwaves to the diamond NV color center in an initial magnetic field environment, and scanning the center frequency of the microwaves to enable the fluorescent signals of the diamond NV color center to change along with the center frequency of the microwaves; demodulating the fluorescent signal of the diamond NV color center by using a phase-locked detection technology, and matching the demodulated fluorescent signal with the microwave center frequency Zero point of the curve of the change and slope at zero crossing point, respectively, obtain resonance frequencyMagnetic sensing coefficient。 The excitation and collection method of the fluorescent signal comprises the following steps: Excitation light is generated by using a 532nm wavelength laser, and is incident on diamond NV color