Diamond Nitrogen-Vacancy Sensor Dual-Frequency Microwave Modulation
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Solution Overview
Problem
The accuracy of magnetic field measurement using diamond nitrogen-vacancy centers is degraded due to temperature variations, which affect the zero-field splitting, and vice versa, making it challenging to precisely measure magnetic fields and temperatures simultaneously.
Innovation Solution
A measurement apparatus and method utilizing a diamond nitrogen-vacancy center sensor with dual-frequency microwave modulation, where one frequency modulated signal causes a spin transition from spin state (ms=0) to (ms=+1) and the other from (ms=0) to (ms=-1, allowing for simultaneous measurement of magnetic fields and temperatures by eliminating the influence of temperature-induced zero-field splitting changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature varies due to external heat sources, then the zero-field splitting parameter D changes, but the accuracy of magnetic field measurement degrades
Solution Approach 1:
The system continuously monitors the fluorescence intensity at both resonance frequencies and uses this feedback to dynamically calculate and correct for temperature-induced shifts in the zero-field splitting parameter D, thereby maintaining accurate magnetic field measurements despite temperature variations
Solution Approach 2:
The invention measures changes in the zero-field splitting parameter D as a function of temperature and uses these parameter changes to compensate for temperature effects, transforming the temperature-dependent parameter variation into a corrective mechanism for accurate measurement
2Device complexity
If single-frequency microwave is applied to measure magnetic field, then the measurement process is simple, but temperature variations cannot be compensated
Solution Approach 1:
The single microwave frequency is segmented into two distinct resonance frequencies corresponding to different spin transitions. By applying microwaves at both frequencies and comparing the fluorescence responses, the system can separate and compensate for temperature effects from magnetic field effects, improving measurement accuracy without excessive complexity
Solution Approach 2:
The dual-frequency microwave system serves multiple functions: it measures the magnetic field strength through the Zeeman splitting while simultaneously monitoring temperature variations through the zero-field splitting changes. This multi-functionality allows one system to address both measurement needs without requiring separate apparatus
3Measurement precision
If dual-frequency microwaves are applied to compensate temperature effects, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The system uses the diamond nitrogen-vacancy center itself as the sensor for both temperature and magnetic field measurements. The intrinsic spin properties of the DNV center provide the necessary signals at both frequencies, eliminating the need for separate temperature sensors or additional complex measurement apparatus
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise measurement of magnetic fields and temperatures with minimal mutual interference, doubling the sensitivity and stability of the measurements by canceling out temperature and magnetic field-induced changes.
Implementation Method 1
in the presence of an external magnetic field along the axial direction of the nitrogen-vacancy center in diamond, due to the Zeeman effect, the overlap of the spin states of the nitrogen-vacancy center in the +1 and -1 spin states (ms) disappears and the spin states exist at different energy levels, so the spin of the nitrogen-vacancy center can have two resonance frequencies corresponding to the transition between the spin state (ms=0) and the spin state (ms=+1) or between the spin state (ms=0) and the spin state (ms=-1)
Implementation Method 2
When a laser of 532 nm wavelength is irradiated to the diamond nitrogen-vacancy center, the spin state (ms=0) is excited and then returns to the ground state by emitting red light over 630 nm
Implementation Method 3
by recording the change in fluorescence according to frequency while applying a microwave frequency to the diamond nitrogen-vacancy center, an optically detected magnetic resonance (ODMR) spectrum with reduced fluorescence intensity at the resonance frequency corresponding to each spin transition may be obtained
Data Source
AI summary
Disclosed is a method and apparatus for measuring magnetic field and/or temperature using a diamond nitrogen-vacancy center sensor, and a measuring apparatus based on a diamond nitrogen-vacancy center (DNV) sensor may include: a diamond nitrogen-vacancy center sensor; a frequency synthesizer for generating a first reference signal and a second reference signal; a first microwave generator for generating a first microwave that is frequency modulated according to the first reference signal and causes a first spin transition in the diamond nitrogen-vacancy center sensor; a second microwave generator for generating a second microwave that is frequency modulated according to the second reference signal and causes a second spin transition in the diamond nitrogen-vacancy center sensor; a laser irradiator for applying a laser to excite the spin state of the diamond nitrogen-vacancy center sensor; a power amplifier for combining and amplifying the first microwave and the second microwave to apply to the diamond nitrogen-vacancy center sensor; a detector for detecting a fluorescence signal output from the diamond nitrogen-vacancy center sensor; a reference detector for measuring power of the laser; a differential circuit for outputting the difference between an output signal of the detector and an output signal of the reference detector; a first lock-in amplifier for outputting a result of comparing an output of the differential circuit with the first reference signal, and a second lock-in amplifier for outputting a result of comparing an output of the differential circuit with the second reference signal. Using the apparatus, it is possible to remove an influence of the temperature when measuring the magnetic field, and remove an influence of a change in the magnetic field when measuring the temperature, thereby enabling more precise measurement.