All-optical nuclear quantum sensing using nitrogen-vacancy centers in diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-06-10 |
| Journal | npj Quantum Information |
| Authors | Beat BĂŒrgler, Tobias F. Sjolander, Ovidiu Brinza, Alexandre Tallaire, Jocelyn Achard |
| Institutions | Sorbonne Université, Centre National de la Recherche Scientifique |
| Citations | 22 |
| Analysis | Full AI Review Included |
All-Optical Nuclear Quantum Sensing in Diamond: Technical Analysis and 6CCVD Solutions
Section titled âAll-Optical Nuclear Quantum Sensing in Diamond: Technical Analysis and 6CCVD SolutionsâThis document analyzes the research demonstrating all-optical coherent quantum sensing using 15N Nitrogen-Vacancy (NV) centers in diamond, focusing on the material requirements and connecting them directly to 6CCVDâs advanced MPCVD diamond capabilities.
Executive Summary
Section titled âExecutive SummaryâThis research presents a significant breakthrough in quantum sensing by eliminating the need for complex microwave (MW) or radio-frequency (RF) driving fields, paving the way for highly compact and energy-efficient sensors.
- Core Innovation: Demonstration of purely all-optical coherent quantum sensing using the 15N nuclear spin of the NV center in diamond.
- Mechanism: Exploits NV spin dynamics near the Excited State Level Anti-Crossing (ESLAC) under a small transverse magnetic field (Bâ„) to optically initialize the nuclear spin into a quantum superposition state.
- Key Protocol: Successful demonstration of all-optical nuclear Free Induction Decay (FID) measurements, the fundamental protocol for low-frequency quantum sensing.
- Coherence Achieved: Long nuclear spin coherence times (T2*) were measured, reaching 248.1 $\pm$ 12.4 ”s for single NV centers and 508.5 $\pm$ 17.4 ”s for NV ensembles.
- Projected Performance: Projected shot noise limited sensitivities for ensemble sensors are highly competitive: 1.22 nT Hz-1/2 for magnetometry and 135° hour-1/2 for gyroscopy.
- Material Requirement: Success relies critically on high-purity, isotopically controlled diamond (15N enrichment) to maximize coherence and enable the all-optical mechanism.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results and theoretical projections:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| NV Electron Spin Gyromagnetic Ratio ($\gamma_s$) | 2.8 | MHz G-1 | Fundamental Constant |
| 15N Nuclear Spin Gyromagnetic Ratio ($\gamma_I$) | 431.7 | Hz G-1 | Fundamental Constant |
| NV Ground State Zero-Field Splitting (Dgs) | 2.87 | GHz | Required for ESLAC calculation |
| Applied Magnetic Field (Bext) | 533 - 540 | G | Operating range near ESLAC |
| Optimal Transverse Magnetic Field (Bâ„) | $\approx$ 8.6 | G | Maximizes FID Contrast (Cmax) |
| Optimal Tilt Angle ($\Phi_{opt}$) | $\approx$ 0.86 | ° | Maximizes FID Contrast (Cmax) |
| Single NV Nuclear Coherence Time (T2*) | 248.1 $\pm$ 12.4 | ”s | Measured at Bext = 533 G |
| Ensemble NV Nuclear Coherence Time (T2*) | 508.5 $\pm$ 17.4 | ”s | Measured at Bext = 533 G |
| Ensemble Magnetometry Sensitivity ($\eta_{mag}$) | 1.22 | nT Hz-1/2 | Projected Shot Noise Limit |
| Ensemble Gyroscope Sensitivity ($\eta_{gyro}$) | 135 | ° hour-1/2 | Projected Shot Noise Limit |
| NV Ensemble Layer Thickness | 15 | ”m | CVD Grown Sample |
| Estimated NV Density (Ensemble) | $\approx$ 300 | ppb | 15N enriched CVD |
Key Methodologies
Section titled âKey MethodologiesâThe experimental success hinges on precise material engineering and controlled optical/magnetic manipulation:
- Single NV Creation: Electronic grade diamond was implanted with singly charged 15N ions (6 keV energy, 1011 cm-2 flux) followed by annealing.
- Ensemble NV Creation: A 15 ”m thick layer was grown via CVD on a (113) substrate using a 12C and 15N enriched gas mixture to achieve preferential NV orientation and high 15N concentration (300 ppb NV density).
- Optical Setup: A home-built confocal microscope utilizing a 515 nm green laser (Cobolt 06-MLD) was used for optical excitation and spin-dependent red photoluminescence (PL) collection.
- Magnetic Field Control: A static magnetic field (Bext $\approx$ 533 G) was applied using a permanent neodymium magnet mounted on a goniometric stage for precise alignment near the ESLAC.
- Pulse Sequence (FID): The all-optical protocol consisted of a 3 ”s green laser pulse separated by a variable free evolution delay ($\tau$). The first 350 ns of the pulse served as the optical nuclear spin readout, while the remainder reinitialized the spin system.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials required to replicate, scale, and extend this all-optical quantum sensing research. Our expertise in isotopic control and precise material engineering directly addresses the critical requirements for long coherence times and high NV density.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the high coherence and controlled NV density necessary for this all-optical sensing scheme, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Essential for minimizing background defects (P1 centers, strain) that limit electron and nuclear spin coherence (T2*). Our SCD offers Ra < 1nm polishing for optimal optical access and integration.
- Isotopically Controlled SCD: We specialize in CVD growth using 15N enriched gas mixtures to precisely control the concentration and isotopic purity of the NV centers, which is critical for maximizing the nuclear spin coherence (T2* $\approx$ 500 ”s demonstrated).
- Custom Orientation Substrates: We provide SCD substrates grown along specific crystal orientations (e.g., (113) or (100)) to ensure preferential alignment of the NV axis, maximizing ensemble contrast and sensitivity.
Customization Potential
Section titled âCustomization PotentialâThe research utilized specific dimensions, implantation techniques, and surface structures that 6CCVD can support or enhance:
| Research Requirement | 6CCVD Customization Potential |
|---|---|
| Thin Film Growth (15 ”m layer thickness) | Precision Thickness Control: We offer SCD and PCD layers from 0.1 ”m up to 500 ”m, allowing researchers to optimize the sensing volume for single NV or ensemble applications. |
| Custom Dimensions (Wafers/Plates) | Large Area Capability: We supply custom plates and wafers up to 125mm (PCD) and large-area SCD plates, enabling scaling from single-NV studies to integrated, wafer-level device fabrication. |
| Surface Structuring (Parabolic Pillars) | Advanced Laser Cutting & Etching: Our in-house capabilities include high-precision laser cutting and etching services to define micro-structures (e.g., pillars, waveguides, or trenches) necessary for enhanced PL collection efficiency. |
| Metalization for Integration (MW/RF components) | Custom Metal Stacks: Although the core protocol is all-optical, characterization and integration often require electrical contacts. We offer internal metalization services including Au, Pt, Pd, Ti, W, and Cu stacks. |
| Global Logistics | Reliable Global Shipping: We ship worldwide, offering DDU (default) and DDP services to ensure materials reach your lab efficiently. |
Engineering Support
Section titled âEngineering SupportâThe success of all-optical quantum sensing relies on complex material parameters, including precise NV depth, concentration, and isotopic purity. 6CCVDâs in-house PhD team offers expert consultation to optimize material selection for similar compact magnetometry and gyroscopy projects. We assist in defining the optimal CVD growth parameters to meet specific coherence time and NV density targets.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Solid state spins have demonstrated significant potential in quantum sensing with applications including fundamental science, medical diagnostics and navigation. The quantum sensing schemes showing best performance under ambient conditions all utilize microwave or radio-frequency driving, which poses a significant limitation for miniaturization, energy efficiency, and non-invasiveness of quantum sensors. We overcome this limitation by demonstrating a purely optical approach to coherent quantum sensing. Our scheme involves the 15 N nuclear spin of the Nitrogen-Vacancy (NV) center in diamond as a sensing resource, and exploits NV spin dynamics in oblique magnetic fields near the NVâs excited state level anti-crossing to optically pump the nuclear spin into a quantum superposition state. We demonstrate all-optical free-induction decay measurementsâthe key protocol for low-frequency quantum sensingâboth on single spins and spin ensembles. Our results pave the way for highly compact quantum sensors to be employed for magnetometry or gyroscopy applications in challenging environments.