Simultaneous Vector Magnetometry Using Modulated NV Centers
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Solution Overview
Problem
Current diamond-based vector magnetometry requires sequential interrogation of nitrogen vacancy (NV) centers along each axis, leading to increased photonic shot noise and reduced signal-to-noise ratio due to fluorescence from off-axis NVs, which degrades measurement sensitivity and efficiency.
Innovation Solution
Simultaneous vector magnetometry is achieved by illuminating a diamond sensor with modulated optical and microwave signals addressing multiple NV axes simultaneously, allowing for simultaneous detection of magnetic field projections along all axes using a single diamond sensor, thereby reducing measurement time and maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential interrogation of NV centers along each axis is performed, then measurement sensitivity is maintained, but measurement time increases and photonic shot noise increases
Solution Approach 1:
The patent combines multiple NV axis interrogations into a single simultaneous measurement process. By applying a broadband microwave pulse that excites all four NV axes at once and using a single optical detector to collect fluorescence from all axes simultaneously, the system merges what was previously four separate sequential measurements into one concurrent measurement, thereby reducing measurement time by a factor of four while maintaining sensitivity through proper signal demodulation
Solution Approach 2:
The patent employs periodic modulation of the microwave excitation signal at distinct frequencies for each NV axis. By modulating the microwave drive for each axis at a different frequency and then demodulating the detected fluorescence signal at these same frequencies, the system can separate and simultaneously measure all four axes using a single detector, resolving the contradiction between simultaneous measurement and signal separation
2Measurement precision
If sequential interrogation of NV centers along each axis is performed, then measurement sensitivity is maintained, but photonic shot noise increases
Solution Approach 1:
The patent combines the detection of fluorescence from all four NV axes into a single simultaneous detection process using one optical detector. By collecting photons from all axes at the same time and using frequency demodulation to separate the signals, the system reduces the total measurement time and associated photonic shot noise while maintaining the sensitivity required for accurate magnetic field measurements along each axis
3Productivity
If simultaneous multi-axis magnetometry is performed, then measurement time is reduced, but device complexity increases
Solution Approach 1:
The patent uses periodic modulation of microwave excitation signals at distinct frequencies for each NV axis, combined with synchronous demodulation of the fluorescence signal. This approach enables simultaneous measurement of all four axes using a single optical detector, reducing measurement time by a factor of four while managing complexity through well-established signal processing techniques
Solution Approach 2:
The patent makes a single optical detector perform the function of what would otherwise require four separate detectors, one for each NV axis. By using frequency-division multiplexing with modulated microwave excitation and corresponding demodulation, the single detector can simultaneously capture and distinguish signals from all four axes, reducing device complexity while achieving simultaneous multi-axis magnetometry
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 simultaneous multi-axis magnetometry with the same or better sensitivity as single-axis methods, reducing measurement time by a factor of four and minimizing noise, making it suitable for replacing fluxgate magnetometers in various applications.
Implementation Method 1
illuminating the solid-state spin sensor with a modulated microwave (MW) signal with multiple carrier frequencies, each of which addresses a resonance corresponding to a different color center defect crystallographic axis
Implementation Method 2
detecting, via an optical detector at a fixed position relative to the solid-state spin sensor, light emitted from the solid-state spin sensor in response to the optical signal
Data Source
AI summary
A system and method for performing vector magnetometry are described. A method can include illuminating diamond with a modulated optical signal and a modulated microwave (MW) signal. A first, bias magnetic field is also applied to the diamond. Light emitted from the diamond in response to the optical signal, the MW signal, and the first magnetic field is detected via a single detector at a fixed position relative to the diamond. A modulation of the detected light encodes information corresponding to a plurality of nitrogen vacancy (NV) axes of the diamond.