Research on Micro-Displacement Measurement Accuracy Enhancement Method Based on Ensemble NV Color Center

At a Glance

Metadata	Details
Publication Date	2023-04-26
Journal	Micromachines
Authors	Yuqi Liu, Zhonghao Li, Hao Zhang, Hao Guo, Ziyang Shi
Institutions	North University of China
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Precision Micro-Displacement Sensing via Ensemble NV Diamond

This document analyzes the research on enhancing micro-displacement measurement accuracy using ensemble Nitrogen-Vacancy (NV) color centers in diamond, providing technical specifications and aligning the requirements with 6CCVD’s advanced MPCVD diamond capabilities.

Executive Summary

This research successfully demonstrates a highly effective method for enhancing micro-displacement detection resolution using ensemble NV color centers in diamond, amplified by a Magnetic Flux Concentrator (MFC).

Core Achievement: Achieved a micro-displacement resolution of 25 nm using a diamond NV ensemble magnetometer.
Performance Enhancement: The use of the MFC resulted in a 24 times increase in resolution compared to measurements without flux concentration.
Methodology: The system relies on Continuous-Wave Optical Detection Magnetic Resonance (CW-ODMR) combined with a permanent magnet and a custom Permalloy MFC to amplify the magnetic field gradient.
Material Requirement: The experiment utilized a high-quality, 3 ppm concentration ensemble NV diamond sample (2 mm x 2 mm x 0.5 mm).
Mechanism: The MFC increases the magnetic field gradient (dB/dZ) by approximately 24 times, which directly translates to a higher sensitivity of the Zeeman splitting frequency (Δω) to small displacements (Δx).
Application: The results provide a robust, practical reference for developing high-precision, room-temperature micro-displacement sensors based on quantum diamond technology.

Technical Specifications

The following table summarizes the critical experimental parameters and performance metrics achieved in the research:

Parameter	Value	Unit	Context
Displacement Resolution (With MFC)	25	nm	Achieved accuracy enhancement
Resolution Improvement Factor	24	times	Ratio of resolution with MFC vs. without MFC
NV Center Concentration	3	ppm	Concentration of Nitrogen in the diamond sample
Diamond Sample Dimensions	2 x 2 x 0.5	mm	Size of the ensemble NV diamond plate
Excitation Laser Wavelength	532	nm	Green laser source (300 mW power)
Zero-Field Splitting Constant (D)	2.87	GHz	Ground state splitting of the NV center at room temperature
CW-ODMR Frequency (With MFC)	3.193	GHz	Fixed frequency point for noise analysis
CW-ODMR Frequency (Without MFC)	2.8896	GHz	Fixed frequency point for noise analysis
Magnetic Field Gradient (With MFC)	-9.89 ± 0.22	Gauss/mm	Slope dB/dZ, demonstrating high linearity (R²=0.998)
Magnetic Field Gradient (Without MFC)	-0.402 ± 0.009	Gauss/mm	Baseline slope dB/dZ
MFC Simulated Magnification (N)	~30	times	Amplification of the magnetic field intensity

Key Methodologies

The micro-displacement measurement accuracy enhancement was achieved through a systematic integration of quantum sensing and magnetic field engineering techniques:

Diamond Material Selection: An ensemble NV color center diamond sample (3 ppm concentration) was chosen for its stable optical readout and electronic polarization abilities at room temperature.
Magnetic Field Generation: A cylindrical N35-sintered permanent magnet (radius 5 mm, thickness 2 mm) was mounted on a precision displacement table (0.01 mm minimum step accuracy) to provide the static magnetic field gradient.
Magnetic Flux Concentration: A custom Permalloy MFC, combining conical and cylindrical geometries, was aligned coaxially with the magnet to amplify the magnetic field intensity and gradient near the diamond surface.
CW-ODMR Setup: The diamond was excited using a 532 nm laser, and the electron spin state was manipulated using a resonant microwave signal (N5183B MXGX source).
Signal Detection: Fluorescence was collected by a photodetector and demodulated using a lock-in amplifier to obtain the first-order differential signal, which correlates the Zeeman splitting frequency change (Δω) to the physical displacement (Δx).
Resolution Verification: Measurements were taken both with and without the MFC structure. The ratio of the system noise to the system sensitivity (dω/dZ) confirmed the 25 nm resolution achieved with the MFC.

6CCVD Solutions & Capabilities

6CCVD is the ideal partner for replicating and advancing this research. Our expertise in MPCVD diamond growth ensures the delivery of materials optimized for high-sensitivity quantum applications like NV magnetometry and micro-displacement sensing.

Applicable Materials

To replicate or extend the high-resolution micro-displacement sensing demonstrated in this paper, researchers require high-quality, low-strain diamond with precisely controlled nitrogen doping.

Optical Grade Single Crystal Diamond (SCD): We recommend our Optical Grade SCD with controlled nitrogen doping (e.g., 1-5 ppm) to maximize the density of the NV ensemble while maintaining the high crystal quality necessary for long coherence times and stable ODMR signals.
Substrate Quality: Our SCD features ultra-low surface roughness (Ra < 1 nm) polishing, minimizing optical scattering and maximizing the efficiency of the 532 nm laser excitation and fluorescence collection, which is critical for achieving high SNR and the 25 nm resolution.

Customization Potential

The success of this experiment relies on precise material dimensions and integration capabilities. 6CCVD offers full customization to meet the exact needs of quantum sensing engineers:

Requirement from Paper	6CCVD Capability	Benefit to Researcher
Sample Dimensions (2x2x0.5 mm)	Custom Plates/Wafers	We provide SCD plates with precise thickness control (0.1 µm to 500 µm) and custom lateral dimensions, ensuring optimal interaction volume for the magnetic field gradient.
High-Quality Surface	Polishing (Ra < 1 nm)	Essential for minimizing optical losses and maximizing fluorescence collection efficiency in the ODMR setup.
Future Integration (Antenna/Electrodes)	Custom Metalization	We offer in-house deposition of standard metals (Au, Pt, Pd, Ti, W, Cu) for integrating microwave antennas or electrodes directly onto the diamond surface, facilitating compact, high-frequency ODMR systems.
Scaling Potential	Large PCD Wafers	For large-area sensor arrays or commercial applications, 6CCVD can supply Polycrystalline Diamond (PCD) wafers up to 125 mm in diameter, also available with custom doping.

Engineering Support

6CCVD’s in-house PhD team provides authoritative support for complex quantum projects. We can assist researchers in optimizing material selection for similar NV Ensemble Micro-Displacement Detection projects by:

Doping Optimization: Consulting on the ideal nitrogen concentration (ppm) to balance NV density against coherence time (T₂) for maximum magnetic sensitivity (dω/dB).
Crystal Orientation: Supplying SCD plates cut and polished to specific crystal orientations to align the NV axis (Z’) optimally with the external magnetic field, maximizing Zeeman splitting sensitivity.
Thermal Management: Providing substrates up to 10 mm thick for applications requiring superior thermal dissipation, ensuring stable operation of the 300 mW laser and microwave components.

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

View Original Abstract

This paper builds a corresponding micro-displacement test system based on an ensemble nitrogen-vacancy (NV) color center magnetometer by combining the correlation between a magnetic flux concentrator, a permanent magnet, and micro-displacement. By comparing the measurement results obtained with and without the magnetic flux concentrator, it can be seen that the resolution of the system under the magnetic flux concentrator can reach 25 nm, which is 24 times higher than without the magnetic flux concentrator. The effectiveness of the method is proven. The above results provide a practical reference for high-precision micro-displacement detection based on the diamond ensemble.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi14050938

References

2016 - A digital measurement system based on laser displacement sensor for piezoelectric ceramic discs vibration characterization [Crossref]
2014 - Creep compliance mapping by atomic force microscopy [Crossref]
2015 - Investigation of micro-electrical properties of Cu2ZnSnSe4 thin films using scanning probe microscopy [Crossref]
2016 - A novel integrated fiber-optic interferometer model and its application in micro-displacement measurement [Crossref]
2021 - Three-dimensional micro-displacement measurement method based on capacitance-grating sensor [Crossref]
2016 - A 3-axis precision positioning device using PZT actuators with low interference motions [Crossref]
2014 - A Cr-N thin film displacement sensor for precision positioning of a micro-stage [Crossref]
2013 - The nitrogen-vacancy colour centre in diamond
2017 - Single-spin magnetic resonance in the nitrogen-vacancy center of diamond [Crossref]