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6CCVD Research

SNR enhancement of magnetic fields measurement with the diamond NV center using a compound filter system

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2023-01-01
JournalChinese Optics Letters
AuthorsAn Ye, Dingyuan Fu, Mingming Wu, Jiahao Guo, T. Y. Sheng
InstitutionsEast China University of Science and Technology
Citations3
AnalysisFull AI Review Included

Technical Documentation & Analysis: High-SNR NV Magnetometry

Section titled “Technical Documentation & Analysis: High-SNR NV Magnetometry”

Executive Summary

Section titled “Executive Summary”

This research successfully demonstrates a novel signal processing approach to significantly enhance the Signal-to-Noise Ratio (SNR) in Nitrogen-Vacancy (NV) center diamond magnetometry, a critical area for quantum sensing applications.

  • Core Achievement: Realization of efficient weak magnetic field measurement using a compound filter system combining wavelet denoising and an adaptive filter (NLMS algorithm).
  • Performance Metric: Achieved an average SNR enhancement of 17.80 dB at a weak magnetic field intensity of 50 nT across the 500 mHz to 100 Hz frequency range.
  • Low-Frequency Advantage: The system provided a 14.76 dB SNR improvement at 500 mHz, proving highly advantageous for low-frequency and weak magnetic field measurements (e.g., geological or biological sensing).
  • Signal Fidelity: The compound filter exhibited superior performance, retaining the desired signal with 97.77% fidelity, significantly surpassing conventional filters (Butterworth, Gaussian, Median).
  • Material Implication: The success of this Optically Detected Magnetic Resonance (ODMR) technique relies fundamentally on high-quality, low-strain Single Crystal Diamond (SCD) substrates, which 6CCVD specializes in manufacturing.
  • Value Proposition: This signal processing technique allows researchers to achieve high-resolution, real-time weak magnetic field measurements without requiring costly modifications to the existing NV diamond hardware setup.

Technical Specifications

Section titled “Technical Specifications”

The following hard data points were extracted from the research paper detailing the performance and parameters of the compound filter system applied to NV diamond ODMR signals.

ParameterValueUnitContext
Max SNR Enhancement (Average)17.80dBAt 50 nT, across 500 mHz to 100 Hz
Max SNR Enhancement (Low Freq)14.76dBAt 500 mHz, across 50 nT to 1100 nT
Weak Magnetic Field Tested50nTSinusoidal wave test field
High Magnetic Field Tested1100nTUsed for comparison of enhancement
Desired Signal Fidelity (Compound Filter)97.77%Highest fidelity achieved at 10 Hz, 100 nT
Optimal NLMS Step Size (”)0.69a.u.Adaptive Filter parameter
Optimal NLMS Constant (ÎŽ)0.012a.u.Adaptive Filter parameter
Excitation Laser Wavelength532nmUsed for NV center illumination
Bias Magnetic Field (B0)~70GProvided by aligned magnets
Sampling Rate100kSa/sUsed for square and sinusoidal wave tests
Filter Order (Wavelet Denoising)Sym6N/ASelected for optimal signal preservation
Filter Order (Adaptive Filter Reference)Sym2, Level 8N/ASelected for reference noise extraction

Key Methodologies

Section titled “Key Methodologies”

The experiment utilized a combination of differential measurement and a two-stage digital filtering system to optimize the ODMR signal.

  1. Experimental Setup: Continuous Wave (CW) ODMR was performed using a 532 nm excitation laser focused on the diamond. Microwave (MW) fields were delivered via a printed circuit board (PCB) antenna.
  2. Bias Field Application: A static bias magnetic field of approximately 70 G was applied along the NV axis using aligned magnets to enable magnetic resonance.
  3. Differential Measurement: Laser power ripple noise was mitigated by subtracting the signal recorded by an auxiliary photodiode (monitoring laser power) from the main fluorescent signal. This significantly improved low-frequency sensitivity.
  4. Wavelet Threshold Denoising (Stage 1): The differential signal was processed using a wavelet threshold denoising method (specifically, the Symlet ‘Sym6’ function) to obtain an initial wavelet filtered signal, effectively removing high-frequency noise components.
  5. Adaptive Filtering (Stage 2): A Normalized Least Mean Square (NLMS) adaptive filter was applied to the pre-filtered signal.
    • The original wavelet filtered signal served as the main input.
    • A second wavelet transform (using ‘Sym2’ at decomposition level 8) was applied to the pre-filtered signal to generate an artificial reference noise signal.
  6. Optimization: The adaptive filter parameters (step size ” and constant Ύ) were dynamically adjusted based on maximizing the resulting SNR, achieving optimal values of ” = 0.69 and Ύ = 0.012.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

The successful implementation of high-sensitivity NV magnetometry, particularly for weak field measurements, is critically dependent on the quality and customization of the diamond substrate. 6CCVD provides the necessary MPCVD diamond materials and engineering services to replicate, optimize, and extend this research.

Applicable Materials

Section titled “Applicable Materials”

To achieve the high spin coherence and low-strain environment required for sensitive ODMR, researchers need premium Single Crystal Diamond (SCD) substrates.

  • Optical Grade Single Crystal Diamond (SCD): 6CCVD offers high-purity, low-birefringence SCD wafers (Type IIa). These are the ideal starting material for creating high-quality NV centers, either through native incorporation or precise ion implantation and annealing, ensuring maximum spin coherence time (T2).
  • Custom NV Density: While the paper focuses on signal processing, 6CCVD’s engineering team can consult on material specifications (e.g., initial nitrogen concentration) to optimize the density of NV centers for specific sensing applications (ensemble vs. single NV).

Customization Potential

Section titled “Customization Potential”

The experimental setup utilized a diamond integrated with a lightguide and a microwave PCB antenna, requiring precise geometry and integration capabilities.

Research Requirement6CCVD Customization CapabilitySpecification Range
Custom Dimensions & IntegrationPrecision Laser Cutting & ShapingPlates/wafers up to 125mm (PCD); custom geometries for SCD wafers to fit lightguides or specialized ODMR setups.
Optimized ThicknessThickness Control (SCD/PCD)SCD wafers available from 0.1 ”m (for surface sensing) up to 500 ”m. Substrates up to 10 mm thick are available for bulk applications.
Surface Quality for OpticsUltra-Smooth PolishingSCD surfaces polished to Ra < 1 nm, minimizing optical scattering losses for both the 532 nm excitation and fluorescence collection.
Microwave Circuit IntegrationIn-House Metalization ServicesWe offer custom deposition of thin films (Au, Pt, Pd, Ti, W, Cu) for creating integrated microwave transmission lines (e.g., coplanar waveguides) directly on the diamond surface, enhancing MW field delivery efficiency.

Engineering Support

Section titled “Engineering Support”

6CCVD understands that optimizing quantum sensing experiments involves both material science and system integration.

  • Expert Consultation: 6CCVD’s in-house PhD team specializes in MPCVD diamond growth and characterization. We can assist researchers in selecting the optimal material specifications (purity, orientation, and surface termination) required for high-sensitivity NV-based ODMR Magnetometry projects.
  • Global Logistics: We ensure reliable global shipping (DDU default, DDP available) to deliver sensitive diamond materials securely and efficiently to research facilities worldwide.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Nitrogen-vacancy (NV) centers in diamond are progressively favored for room-temperature magnetic field measurement. The signal to noise ratio (SNR) optimization for NV diamond magnetometry generally concentrates on signal amplitude enhancement rather than efficient noise processing. Here, we report a compound filter system combining a wavelet denoising method and an adaptive filter for the realization of an efficient weak magnetic measurement with a high SNR. It allows enhanced magnetic field measurement with an average SNR enhancement of 17.80 dB at 50 nT within 500 mHz to 100 Hz and 14.76 dB at 500 mHz within 50 nT to 1100 nT. The introduction of this system in NV diamond magnetometry is aimed to improve signal quality by effectively eliminating the noise and retaining ideal signals.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2010 - Quantum register based on coupled electron spins in a room-temperature solid [Crossref]
  2. 2016 - Correction of the second-order degree of coherence measurement [Crossref]
  3. 2021 - Chiral single-photon switch-assisted quantum logic gate with a nitrogen-vacancy center in a hybrid system [Crossref]
  4. 2008 - High-sensitivity diamond magnetometer with nanoscale resolution [Crossref]
  5. 2015 - Subpicotesla diamond magnetometry [Crossref]
  6. 2013 - Nanometre-scale thermometry in a living cell [Crossref]
  7. 2011 - Electric-field sensing using single diamond spins [Crossref]
  8. 2014 - Electronic properties and metrology applications of the diamond NV-center under pressure [Crossref]
  9. 2020 - Sensitivity optimization for NV-diamond magnetometry [Crossref]
  10. 2016 - Optical magnetic detection of single-neuron action potentials using quantum defects in diamond [Crossref]

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