Diamond Magnetometer Sensor with NV Centers and Electrical Readout
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Solution Overview
Problem
Magnetometer sensors using negatively charged nitrogen-vacancy centers in diamond face limitations in spatial resolution, signal-to-noise ratio, and sensitivity due to complex optical setups and poor light collection efficiency, as well as lower contrast values in photocurrent detection methods.
Innovation Solution
A magnetometer sensor employing a diamond crystal with negatively charged nitrogen-vacancy centers, a light source, an electrode, and a microwave source with a modulator to generate a modulated microwave field, utilizing a lock-in amplifier with a microwave reference trigger signal to enhance the signal-to-noise ratio and sensitivity by suppressing parasitic photocurrent related to defects, and achieving high detection efficiency through photoelectrical read-out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optically read magnetometers using nitrogen-vacancy centers are used, then magnetic field detection capability is achieved, but spatial resolution is limited to about 300 nm and light collection efficiency is poor
Solution Approach 1:
The patent replaces the optical readout system with an electrical readout system using a field-effect transistor. Instead of using complex optical setups with single photon detectors to read the spin state of nitrogen-vacancy centers, the invention uses the NV center as a spin-dependent gate in a FET device, where the spin state modulates the drain current. This substitution of optical detection with electrical detection simplifies the overall system while improving spatial resolution beyond the optical diffraction limit.
2Measurement precision
If photocurrent measurement technique (PDMR) is used instead of optical measurement, then detection efficiency is improved, but signal-to-noise ratio is limited by shot noise and contrast values are lower
Solution Approach 1:
The patent introduces an intermediary mechanism - the field-effect transistor - that translates the微弱 photocurrent signal into a measurable electrical current modulation. The NV center spin state modulates the gate voltage of the FET, which in turn modulates the drain current. This intermediary amplification mechanism overcomes the shot noise limitation of direct photocurrent measurement while maintaining high detection efficiency.
Solution Approach 2:
The patent replaces the direct optical measurement system with an electrical field-effect system. Instead of measuring photocurrent directly and dealing with shot noise limitations, the invention uses the FET to convert spin-state information into electrical current modulation, achieving superior signal-to-noise ratio while maintaining productivity.
3Measurement precision
If complex optical setups with single photon detectors are used, then photoluminescence detection is achieved, but light collection efficiency is poor and sensitivity is limited
Solution Approach 1:
The patent replaces the entire optical detection system (light source, optical paths, single photon detectors) with a field-effect transistor-based electrical detection system. The NV center spin state is read out through its effect on the FET drain current, eliminating the need for complex optical components and achieving higher sensitivity without increasing device complexity.
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
The solution provides a magnetometer with improved spatial resolution, higher signal-to-noise ratio, and enhanced sensitivity for detecting low magnetic fields, with a significant increase in detected magnetic resonance contrast and sensitivity, reducing noise by up to 1×10^6 times and achieving a photoelectrical gain factor that enhances sensitivity by a factor of 1×10^3.
Implementation Method 1
a light source for exciting an electron of NV− to the diamond crystal conduction band
Implementation Method 2
an electrode for applying an electric field to the diamond crystal
Implementation Method 3
a microwave source for applying a microwave field to the negatively charged nitrogen vacancy centers
Implementation Method 4
By applying a microwave field at resonance frequency the ms=±1 ground state can be favorably populated
Implementation Method 5
a lock-in amplifier comprising a first input for receiving the photocurrent as an input signal, a second input for providing a lock-in reference signal operating at a reference frequency
Implementation Method 6
the microwave source comprises a microwave modulator configured to modulate the continuous wave CW microwaves at a modulation frequency fMOD so as to generate a modulated microwave field
Data Source
AI summary
The disclosure relates to a magnetometer sensor with negatively charged nitrogen-vacancy centers in diamond. One example embodiment is a magnetometer sensor. The magnetometer sensor includes a diamond crystal with one or more negatively charged nitrogen-vacancy centers. The magnetometer sensor also includes one or more light sources. Further, the magnetometer sensor includes an electrode. In addition, the magnetometer sensor includes a read-out module. The read-out module includes a read-out circuit configured to read-out a photocurrent from the electrode and a lock-in amplifier. The lock-in amplifier includes a first input, a second input, and an output. The magnetometer sensor additionally includes a microwave source configured to apply a microwave field to the negatively charged nitrogen-vacancy centers. The microwave source includes a microwave generator for generating continuous wave microwaves and a microwave modulator configured to modulate the continuous wave microwaves. Still further, the magnetometer sensor includes a processor.