Magnetic field measurement system and method based on quantum coherent layout trapping principle

Abstract

The invention belongs to the technical field of quantum precision measurement, and particularly discloses a magnetic field measurement system and method based on a quantum coherent layout trapping principle, and the system comprises a laser device which is modulated by a microwave source and is used for generating linearly polarized light; the lambda / 4 wave plate is used for converting the linearly polarized light into circularly polarized light; the circularly polarized light passes through the alkali metal atom gas chamber influenced by an external measured magnetic field and then enters the photoelectric detector; the detector converts an optical signal into an electric signal and then takes the electric signal as an error signal after data acquisition; the error signal controls the center frequency of the microwave source through PID feedback; the whole system works in an atomic clock mode and a magnetometer mode in a time division multiplexing mode and is used for generating calibration reference frequency and magnetic field Larmor frequency respectively, and then a measured magnetic field value is obtained through calculation.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum precision measurement, and in particular relates to a magnetic field measurement system and method based on the quantum coherent layout trapping principle. Background Art

[0002] Atomic magnetometers using the Zeeman effect can achieve high-precision magnetic field measurements. Due to their advantages in size, power consumption, environmental adaptability, high accuracy and sensitivity, they are widely used in geological exploration, disaster relief, magnetic anomaly detection, geomagnetic navigation, etc. Among them, alkali metal atomic magnetometers can bring higher measurement sensitivity due to their longer relaxation time. However, due to the coupling of their nuclear spin and electron spin, a nonlinear Zeeman effect is generated, that is, the frequency correspondence between the magnetic field and the energy level splitting deviates from linearity, which affects the accuracy of magnetic field measurement.

[0003] CPT is the effect of using light to prepare atoms to a coherent dark state so that the atoms no longer absorb light. This effect can be used to develop CPT atomic magnetometers and CPT atomic clocks according to different transition energy level characteristics. Their common principle is to obtain coherent two-color light through microwave modulated lasers and the atoms in the atomic gas chamber to achieve CPT resonance, obtain the stable microwave frequency of the specific energy level radiation transition of the atom required by the atomic clock as a spectral line signal, and convert the microwave frequency into a standard frequency output that is convenient to use in practical applications through electronic devices. If the ground state energy level is selected to produce Zeeman effect movement under the action of a magnetic field, then the frequency of the microwave signal generated at this time corresponds to the size of the magnetic field, and the measurement of the magnetic field is achieved. In the prior art, since the CPT atomic magnetometer uses alkali metals as the working material, the nonlinear Zeeman effect still exists under a larger magnetic field. Since the frequency reference of the measurement system uses a crystal oscillator, the accuracy cannot be guaranteed. Therefore, it is urgent to propose a magnetic field measurement system and method based on the principle of quantum coherent layout trapping to solve the above technical problems. Summary of the invention

[0004] The present invention provides a magnetic field measurement system and method based on the quantum coherent layout trapping principle, which is used to solve the problem in the prior art that the magnetic field measurement has a large nonlinearity, resulting in inaccurate magnetic field measurement.

[0005] In a first aspect, a magnetic field measurement system based on the quantum coherent layout trapping principle is provided, the system comprising:

[0006] Microwave source, laser, λ / 4 wave plate, atomic gas chamber, photodetector, data acquisition module, clock-locked PID module, magnetic-locked PID module and magnetic field output module;

[0007] Wherein, the microwave source is used to modulate the laser;

[0008] The laser is used to receive the modulation of the microwave source and generate linearly polarized light;

[0009] The λ / 4 wave plate is used to convert the received linearly polarized light into circularly polarized light;

[0010] The atomic gas chamber is used to use the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize a coherent dark state;

[0011] The photoelectric detector is used to detect the light signal after interacting with the alkali metal atoms, and convert the light signal into an electrical signal and transmit it to the data acquisition module;

[0012] The data acquisition module is used to process the electrical signal to obtain an error signal, and feed the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively;

[0013] The clock locking PID module is used to output a clock locking output signal after subjecting the input error signal to PID control, and transmit the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode;

[0014] The magnetic locking PID module is used to output a magnetic locking output signal after subjecting the input error signal to PID control, and transmit the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode;

[0015] The magnetic field output module is used to obtain the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

[0016] In a second aspect, a magnetic field measurement method based on the quantum coherent layout trapping principle is provided, the method comprising:

[0017] A microwave source modulates the laser;

[0018] The laser receives the modulation of the microwave source and generates linearly polarized light;

[0019] The λ / 4 wave plate converts the received linearly polarized light into circularly polarized light;

[0020] The atomic gas chamber uses the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize the coherent dark state;

[0021] The photoelectric detector detects the light signal after interacting with the alkali metal atoms, and converts the light signal into an electrical signal and transmits it to the data acquisition module;

[0022] The data acquisition module processes the electrical signal to obtain an error signal, and feeds the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively;

[0023] The clock locking PID module outputs a clock locking output signal after the input error signal is subjected to PID control, and transmits the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode;

[0024] The magnetic locking PID module outputs a magnetic locking output signal after subjecting the input error signal to PID control, and transmits the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode;

[0025] The magnetic field output module obtains the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

[0026] The embodiments of the present invention provide a magnetic field measurement system and method based on the principle of quantum coherent population trapping. Based on the principle of quantum coherent population trapping (CPT), the system detects and locks multiple CPT signal resonant frequencies and obtains a measured magnetic field value with high accuracy based on these signal frequencies.

[0027] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 A schematic diagram of the structure of a magnetic field measurement system based on the quantum coherent layout trapping principle provided according to an embodiment of the present invention;

[0030] Figure 2 The present invention provides a schematic diagram of the implementation process of a magnetic field measurement method based on the quantum coherent layout trapping principle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0033] The technical solutions provided by the embodiments of this specification are described in detail below in conjunction with the accompanying drawings.

[0034] In order to improve the accuracy of magnetic field measurement of an alkali metal atomic magnetometer, an embodiment of the present invention provides a magnetic field measurement system and method based on the quantum coherent layout trapping principle.

[0035] Figure 1 A schematic diagram of a magnetic field measurement system based on the quantum coherent layout trapping principle provided according to an embodiment of the present invention is shown in FIG. Figure 1 , the system comprising:

[0036] Microwave source, laser, λ / 4 wave plate, atomic gas chamber, photodetector, data acquisition module, clock-locked PID module, magnetic-locked PID module and magnetic field output module;

[0037] Wherein, the microwave source is used to modulate the laser;

[0038] The laser is used to receive the modulation of the microwave source and generate linearly polarized light;

[0039] The λ / 4 wave plate is used to convert the received linearly polarized light into circularly polarized light;

[0040] The atomic gas chamber is used to use the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize a coherent dark state;

[0041] The photoelectric detector is used to detect the light signal after interacting with the alkali metal atoms, and convert the light signal into an electrical signal and transmit it to the data acquisition module;

[0042] The data acquisition module is used to process the electrical signal to obtain an error signal, and feed the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively;

[0043] The clock locking PID module is used to output a clock locking output signal after subjecting the input error signal to PID control, and transmit the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode;

[0044] The magnetic locking PID module is used to output a magnetic locking output signal after subjecting the input error signal to PID control, and transmit the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode;

[0045] The magnetic field output module is used to obtain the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

[0046] In a specific embodiment,

[0047] The laser is a vertical cavity surface emitting laser, capable of outputting linearly polarized light with a wavelength of 795nm and accepting frequency modulation from a microwave source;

[0048] The λ / 4 wave plate is specifically used for:

[0049] The phase difference of the received linearly polarized light is changed so that the linearly polarized light is delayed by Π / 2 phase along the slow axis to obtain circularly polarized light.

[0050] In a specific embodiment, the atomic gas chamber is used to provide gaseous 87 The Rb atom contains a heating module and a heat preservation module to heat the atomic system to 62 degrees Celsius and keep it warm;

[0051] In a specific implementation, the atomic clock mode is specifically:

[0052] Scan the microwave center frequency to obtain three resonant coherent layout trapped signal CPT peak absorption spectra corresponding to the energy level splitting caused by the Zeeman effect of the interaction between the measured magnetic field and the alkali metal atoms, and take the microwave frequencies f1, f2, f3 corresponding to the three maximum values ​​of the entire absorption spectrum;

[0053] The microwave frequency of the microwave source is reset to the first microwave frequency f2, and 156 Hz modulation and demodulation are applied to the microwave frequency to lock the microwave frequency on the second resonance peak of CPT. At this time, the microwave frequency is still marked as f2 and the system clock is calibrated according to the first microwave frequency f2. At this time, the system works in atomic clock mode.

[0054] In a specific implementation, the magnetometer mode is specifically:

[0055] Reset the microwave frequency of the microwave source to the second microwave frequency f1, apply 156 Hz modulation and demodulation to the microwave frequency, and lock the microwave frequency on the first resonance peak of CPT. The microwave frequency at this time is still marked as f1, and the system works in magnetometer mode.

[0056] In a specific embodiment,

[0057] The Breit-Rabi formula is as follows:

[0058]

[0059] In the formula, E is the energy level, x = (γ e -γ n )B / Δ,γ e ,γ n , Δ is the atomic correlation constant, B is the magnetic field, F is the total angular momentum, I is the nuclear spin angular momentum, m F is the angular momentum in the direction of the quantized axis;

[0060] The magnetic field output module is specifically used for:

[0061] According to the obtained first microwave frequency f2 and second microwave frequency f1, the measured magnetic field value is obtained according to the following Breit-Rabi formula:

[0062]

[0063] In the formula, h is Planck's constant, Δ is a constant related to atoms; δ is the first unknown, representing additive noise; x is the second unknown, that is, the measured magnetic field value;

[0064] The measured magnetic field value is obtained by solving the above two equations.

[0065] In a specific implementation, the measured magnetic field value may also be obtained according to f1 and f3 or f2 and f3 in the same calculation manner as above, which will not be described in detail here.

[0066] The present invention provides a magnetic field measurement system based on the principle of quantum coherent population trapping. Based on the principle of quantum coherent population trapping (CPT), the atomic magnetometer itself generates a reference frequency, detects and locks the measurement of multiple CPT signal resonance frequencies, and obtains a measured magnetic field value with high accuracy based on these signal frequencies, thereby reducing the nonlinearity of the magnetic field measurement of the alkali metal atomic magnetometer.

[0067] Based on the same inventive concept, the present invention also provides a magnetic field measurement method based on the quantum coherent layout trapping principle, see Figure 2 , the method comprising:

[0068] S200: a microwave source modulates the laser;

[0069] S202: The laser receives modulation from the microwave source and generates linearly polarized light;

[0070] S204: The λ / 4 wave plate converts the received linearly polarized light into circularly polarized light;

[0071] S206: the atomic gas chamber uses the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize a coherent dark state;

[0072] S208: The photoelectric detector detects the light signal after interacting with the alkali metal atoms, and converts the light signal into an electrical signal and transmits it to the data acquisition module;

[0073] S210: the data acquisition module processes the electrical signal to obtain an error signal, and feeds the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively;

[0074] S212: the clock locking PID module outputs a clock locking output signal after subjecting the input error signal to PID control, and transmits the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode;

[0075] S214: the magnetic locking PID module outputs a magnetic locking output signal after subjecting the input error signal to PID control, and transmits the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode;

[0076] S216: The magnetic field output module obtains the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

[0077] In a specific embodiment,

[0078] The laser is a vertical cavity surface emitting laser, capable of outputting linearly polarized light with a wavelength of 795nm and accepting frequency modulation from a microwave source;

[0079] The λ / 4 wave plate converts the received linearly polarized light into circularly polarized light, specifically comprising:

[0080] The phase difference of the received linearly polarized light is changed so that the linearly polarized light is delayed by Π / 2 phase along the slow axis to obtain circularly polarized light.

[0081] In a specific implementation, the atomic clock mode is specifically:

[0082] Scan the microwave center frequency to obtain three resonant coherent layout trapped signal CPT peak absorption spectra corresponding to the energy level splitting caused by the Zeeman effect of the interaction between the measured magnetic field and the alkali metal atoms, and take the microwave frequencies f1, f2, f3 corresponding to the three maximum values ​​of the entire absorption spectrum;

[0083] The microwave frequency of the microwave source is reset to the first microwave frequency f2, and 156 Hz modulation and demodulation are applied to the microwave frequency to lock the microwave frequency on the second resonance peak of CPT. At this time, the microwave frequency is still marked as f2 and the system clock is calibrated according to the first microwave frequency f2. At this time, the system works in atomic clock mode.

[0084] In a specific implementation, the magnetometer mode is specifically:

[0085] Reset the microwave frequency of the microwave source to the second microwave frequency f1, apply 156 Hz modulation and demodulation to the microwave frequency, and lock the microwave frequency on the first resonance peak of CPT. The microwave frequency at this time is still marked as f1, and the system works in magnetometer mode.

[0086] In a specific embodiment,

[0087] The Breit-Rabi formula is as follows:

[0088]

[0089] In the formula, E is the energy level, x = (γ e -γ n )B / Δ,γ e ,γ n , Δ is the atomic correlation constant, B is the magnetic field, F is the total angular momentum, I is the nuclear spin angular momentum, m F is the angular momentum in the direction of the quantized axis;

[0090] The magnetic field output module obtains the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency, specifically including:

[0091] According to the obtained first microwave frequency f2 and second microwave frequency f1, the measured magnetic field value is obtained according to the following Breit-Rabi formula:

[0092]

[0093] In the formula, h is Planck's constant, Δ is a constant related to atoms; δ is the first unknown, representing additive noise; x is the second unknown, that is, the measured magnetic field value;

[0094] The measured magnetic field value is obtained by solving the above two equations.

[0095] The present invention provides a magnetic field measurement method based on the principle of quantum coherent population trapping. Based on the principle of quantum coherent population trapping (CPT), the method detects and locks a plurality of CPT signal resonance frequencies and obtains a measured magnetic field value with high accuracy according to these signal frequencies, thereby reducing the nonlinearity of the magnetic field measurement of the alkali metal atomic magnetometer.

[0096] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0097] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A magnetic field measurement system based on the quantum coherent layout trapping principle, characterized in that: The system comprises: Microwave source, laser, λ / 4 wave plate, atomic gas chamber, photodetector, data acquisition module, clock-locked PID module, magnetic-locked PID module and magnetic field output module; Wherein, the microwave source is used to modulate the laser; The laser is used to receive the modulation of the microwave source and generate linearly polarized light; The λ / 4 wave plate is used to convert the received linearly polarized light into circularly polarized light; The atomic gas chamber is used to use the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize a coherent dark state; The photoelectric detector is used to detect the light signal after interacting with the alkali metal atoms, and convert the light signal into an electrical signal and transmit it to the data acquisition module; The data acquisition module is used to process the electrical signal to obtain an error signal, and feed the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively; The clock locking PID module is used to output a clock locking output signal after subjecting the input error signal to PID control, and transmit the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode; The magnetic locking PID module is used to output a magnetic locking output signal after subjecting the input error signal to PID control, and transmit the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode; The magnetic field output module is used to obtain the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

2. The system according to claim 1, characterized in that The laser is a vertical cavity surface emitting laser, capable of outputting linearly polarized light with a wavelength of 795nm and accepting frequency modulation from a microwave source; The λ / 4 wave plate is specifically used for: The phase difference of the received linearly polarized light is changed so that the linearly polarized light is delayed by Π / 2 phase along the slow axis to obtain circularly polarized light.

3. The system according to claim 2, characterized in that The atomic clock mode is specifically: Scan the microwave center frequency to obtain three resonant coherent layout trapped signal CPT peak absorption spectra corresponding to the energy level splitting caused by the Zeeman effect of the interaction between the measured magnetic field and the alkali metal atoms, and take the microwave frequencies f1, f2, f3 corresponding to the three maximum values ​​of the entire absorption spectrum; The microwave frequency of the microwave source is reset to the first microwave frequency f2, and 156 Hz modulation and demodulation are applied to the microwave frequency to lock the microwave frequency on the second resonance peak of CPT. At this time, the microwave frequency is still marked as f2 and the system clock is calibrated according to the first microwave frequency f2. At this time, the system works in atomic clock mode.

4. The system according to claim 3, characterized in that The magnetometer mode is specifically: Reset the microwave frequency of the microwave source to the second microwave frequency f1, apply 156 Hz modulation and demodulation to the microwave frequency, and lock the microwave frequency on the first resonance peak of CPT. The microwave frequency at this time is still marked as f1, and the system works in magnetometer mode.

5. The system according to claim 4, characterized in that The Breit-Rabi formula is as follows: In the formula, E is the energy level, x = (γ e -γ n )B / Δ,γ e ,γ n , Δ is the atomic correlation constant, B is the magnetic field, F is the total angular momentum, I is the nuclear spin angular momentum, m F is the angular momentum in the direction of the quantized axis; The magnetic field output module is specifically used for: According to the obtained first microwave frequency f2 and second microwave frequency f1, the measured magnetic field value is obtained according to the following Breit-Rabi formula: In the formula, h is Planck's constant, Δ is a constant related to atoms; δ is the first unknown, representing additive noise; x is the second unknown, that is, the measured magnetic field value; The measured magnetic field value is obtained by solving the above two equations.

6. A magnetic field measurement method based on the quantum coherent layout trapping principle, characterized in that: The method applied to the magnetic field measurement system based on the quantum coherent layout trapping principle as described in any one of claims 1 to 5 comprises: A microwave source modulates the laser; The laser receives the modulation of the microwave source and generates linearly polarized light; The λ / 4 wave plate converts the received linearly polarized light into circularly polarized light; The atomic gas chamber uses the received circularly polarized light to make the alkali metal atoms affected by the external measured magnetic field realize the coherent dark state; The photoelectric detector detects the light signal after interacting with the alkali metal atoms, and converts the light signal into an electrical signal and transmits it to the data acquisition module; The data acquisition module processes the electrical signal to obtain an error signal, and feeds the error signal back to the microwave source as input of the clock locking PID module and the magnetic locking PID module respectively; The clock locking PID module outputs a clock locking output signal after the input error signal is subjected to PID control, and transmits the clock locking output signal to the microwave source to obtain a first microwave frequency when the measurement system is locked in the atomic clock mode; The magnetic locking PID module outputs a magnetic locking output signal after subjecting the input error signal to PID control, and transmits the magnetic locking output signal to the microwave source to obtain a second microwave frequency when the measurement system is locked in the magnetometer mode; The magnetic field output module obtains the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency.

7. The method according to claim 6, characterized in that The laser is a vertical cavity surface emitting laser, capable of outputting linearly polarized light with a wavelength of 795nm and accepting frequency modulation from a microwave source; The λ / 4 wave plate converts the received linearly polarized light into circularly polarized light, specifically comprising: The phase difference of the received linearly polarized light is changed so that the linearly polarized light is delayed by Π / 2 phase along the slow axis to obtain circularly polarized light.

8. The method according to claim 7, characterized in that The atomic clock mode is specifically: Scan the microwave center frequency to obtain three resonant coherent layout trapped signal CPT peak absorption spectra corresponding to the energy level splitting caused by the Zeeman effect of the interaction between the measured magnetic field and the alkali metal atoms, and take the microwave frequencies f1, f2, f3 corresponding to the three maximum values ​​of the entire absorption spectrum; The microwave frequency of the microwave source is reset to the first microwave frequency f2, and 156 Hz modulation and demodulation are applied to the microwave frequency to lock the microwave frequency on the second resonance peak of CPT. At this time, the microwave frequency is still marked as f2 and the system clock is calibrated according to the first microwave frequency f2. At this time, the system works in atomic clock mode.

9. The method according to claim 8, characterized in that The magnetometer mode is specifically: Reset the microwave frequency of the microwave source to the second microwave frequency f1, apply 156 Hz modulation and demodulation to the microwave frequency, and lock the microwave frequency on the first resonance peak of CPT. The microwave frequency at this time is still marked as f1, and the system works in magnetometer mode.

10. The method according to claim 9, characterized in that The Breit-Rabi formula is as follows: In the formula, E is the energy level, x = (γ e -γ n )B / Δ,γ e ,γ n , Δ is the atomic correlation constant, B is the magnetic field, F is the total angular momentum, I is the nuclear spin angular momentum, m F is the angular momentum in the direction of the quantized axis; The magnetic field output module obtains the measured magnetic field value using the Breit-Rabi formula according to the first microwave frequency and the second microwave frequency, specifically including: According to the obtained first microwave frequency f2 and second microwave frequency f1, the measured magnetic field value is obtained according to the following Breit-Rabi formula: In the formula, h is Planck's constant, Δ is a constant related to atoms; δ is the first unknown, representing additive noise; x is the second unknown, that is, the measured magnetic field value; The measured magnetic field value is obtained by solving the above two equations.

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