Quantitative study of the response of a single NV defect in diamond to magnetic noise
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-06-15 |
| Journal | Physical review. B./Physical review. B |
| Authors | Maxime Rollo, Aurore Finco, Rana Tanos, Florentin Fabre, T. Devolder |
| Institutions | Centre National de la Recherche Scientifique, Université Paris-Saclay |
| Citations | 25 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Demonstrated a quantitative, all-optical method for detecting magnetic noise using the Nitrogen-Vacancy (NV) defect in diamond via continuous-wave (CW) Photoluminescence (PL) quenching.
- Mechanism: Magnetic noise accelerates the longitudinal spin relaxation rate (1/T1), which subsequently reduces the steady-state PL signal intensity (PL quenching).
- Modeling Validation: Experimental results align closely with predictions from a simplified closed three-level model of the NV defect, confirming the relationship between T1 reduction and PL drop.
- Sensitivity: The method achieves a calculated shot noise limited sensitivity (Ncw) of approximately 1 ”T2MHz-1/âHz.
- Practical Advantage: This PL quenching technique is conceptually and practically simple, offering optimal performance at low optical excitation power, which is beneficial for biological or charge-sensitive applications.
- Relaxation Dynamics: The intrinsic spin relaxation time (T10 = 5.5 ms) was reduced by three orders of magnitude (to 5.6 ”s) under maximum applied magnetic noise (SB ~ 3 ”T2MHz-1).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| NV Electron Spin Resonance (fNV) | 2.87 | GHz | Zero-field splitting between ms=0 and ms=±1 sublevels. |
| Intrinsic Longitudinal Relaxation (T10) | 5.5 ± 0.5 | ms | Measured in ultrapure bulk diamond, noise OFF. |
| Relaxation Time (T1) under Max Noise | 5.6 ± 0.2 | ”s | Achieved under maximum applied noise (three orders of magnitude reduction). |
| Maximum Applied Noise Density (SBmax) | ~3 | ”T2MHz-1 | Field spectral density at the NV center position. |
| Noise Frequency Window (Îf) | 50 | MHz | Fixed spectral width of the applied noise signal. |
| NV-Microwire Distance (d) | 28 ± 4 | ”m | Distance from the single NV defect to the copper microwire edge. |
| Electron Gyromagnetic Ratio (Îł) | 28 | GHz T-1 | Used in the calculation of the relaxation rate (1/T1). |
| Optical Saturation Power (Psat) | ~300 | ”W | Power required to saturate the optical transition. |
| Shot Noise Limited Sensitivity (Ncw) | ~1 | ”T2MHz-1/âHz | Calculated sensitivity using the optimized PL quenching method. |
| Three-Level Model Parameter (ÎČ) | 0.72 | Dimensionless | Phenomenological ratio R±1/R0 of PL rates for spin sublevels. |
Key Methodologies
Section titled âKey Methodologiesâ- NV Isolation and Illumination: Individual NV defects hosted in an ultrapure bulk diamond crystal were optically isolated at room temperature using a scanning confocal microscope under continuous green laser illumination.
- Magnetic Noise Generation: A tunable noise signal was synthesized by mixing a low-frequency white noise source with a microwave carrier frequency (fc = fNV = 2.87 GHz) and filtering the DC component.
- Field Application: The calibrated noise signal was transmitted through a copper microwire spanned directly on the diamond surface, generating a fluctuating Oersted field (SB) at the NV location.
- T1 Calibration (Relaxometry): The longitudinal spin relaxation time (T1) was measured using a standard sequence: optical initialization (ms=0), variable dark delay (Ï), and spin-dependent PL readout. This calibration established the linear relationship between 1/T1 and the applied field spectral density SB.
- PL Quenching Measurement (CW Method): The PL rate (Rcw) was measured under continuous optical illumination (CW) in the presence of magnetic noise and normalized against a reference rate (Ro) measured with noise OFF.
- Model Fitting and Optimization: The measured PL quenching ratio (Rcw/Ro) was fitted using a simplified three-level model to validate the mechanism and determine the optimal optical pumping power (Popt) required to maximize the Signal-to-Noise Ratio (SNR).
Commercial Applications
Section titled âCommercial Applicationsâ- Quantum Sensing and Magnetometry:
- Development of simple, all-optical, nanoscale sensors for detecting magnetic noise sources (relaxometry).
- Ideal for applications requiring low optical power to mitigate charge-state conversion or thermal effects.
- Materials Science and Spintronics:
- Imaging and characterization of complex magnetic textures, such as non-collinear spin textures in synthetic antiferromagnets.
- Studying spin wave dispersion and thermal magnons in magnetic materials, especially compensated materials where static stray fields are minimal.
- Solid-State Device Characterization:
- Characterization of electronic instabilities and noise sources in novel materials (e.g., observation of electronic instabilities in graphene).
- Measurement of Johnson noise in conductors at the nanoscale.
- Chemical and Biological Sensing:
- Measurement of pH and redox potential in microfluidic channels.
- Detection and characterization of paramagnetic molecules in biological or chemical environments.
View Original Abstract
The nitrogen-vacancy (NV) defect in diamond is an efficient quantum sensor of randomly fluctuating signalsvia relaxometry measurements. In particular, the longitudinal spin relaxation of the NV defect accelerates in thepresence of magnetic noise with a spectral component at its electron spin resonance frequency.We look into thiseffect quantitatively by applying a calibrated and tunable magnetic noise on a single NV defect.We show that anincrease of the longitudinal spin relaxation rate translates into a reduction of the photoluminescence (PL) signalemitted under continuous optical illumination, which can be explained using a simplified three-level model of theNV defect. This PL quenching mechanism offers a simple, all-optical method to detect magnetic noise sourcesat the nanoscale.