Purcell effect of nitrogen-vacancy centers in nanodiamond coupled to propagating and localized surface plasmons revealed by photon-correlation cathodoluminescence
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-05-14 |
| Journal | Physical review. B./Physical review. B |
| Authors | Sotatsu Yanagimoto, Naoki Yamamoto, Takumi Sannomiya, K. Akiba |
| Institutions | National Institutes for Quantum Science and Technology, Tokyo Institute of Technology |
| Citations | 28 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Plasmon-Enhanced NV Centers in Nanodiamond
Section titled âTechnical Documentation & Analysis: Plasmon-Enhanced NV Centers in NanodiamondâThis document analyzes the research paper âPurcell effect of nitrogen-vacancy centers in nanodiamond coupled to propagating and localized surface plasmons revealed by photon-correlation cathodoluminescenceâ and outlines how 6CCVDâs advanced MPCVD diamond materials and customization services can accelerate and scale this critical quantum technology research.
Executive Summary
Section titled âExecutive SummaryâThe study successfully demonstrated the Purcell effect in nitrogen-vacancy (NV) centers within nanodiamonds (NDs) by coupling them to plasmonic structures, a key step toward high-speed quantum communication and optical computing.
- Core Achievement: Experimental verification of Purcell enhancement (lifetime shortening) of NV$^0$ centers coupled to both propagating Surface Plasmon Polaritons (SPPs) and Localized Surface Plasmons (LSPs).
- Measurement Innovation: Utilization of Hanbury Brown-Twiss (HBT) interferometry combined with STEM-Cathodoluminescence (CL) to achieve unprecedented nanometer and nanosecond resolution lifetime measurements.
- Material Performance: NV centers embedded in silver (Ag) nanoholes (Sample C) exhibited the strongest Purcell enhancement, achieving a mean lifetime of 9.4 ns and a Purcell Factor (F$_P$) of 1.73.
- Mechanism Confirmed: Finite Element Method (FEM) simulations confirmed that the strong enhancement in embedded structures is due to the LSP resonance peak overlapping with the NV emission spectrum, maximizing the electromagnetic local density of state (EMLDOS).
- Future Direction: The results provide a basis for manipulating quantum emitters (QEs) and enhancing the efficiency of light emitters by controlling dipole orientation and distance from the metal interface.
- 6CCVD Relevance: This research requires ultra-high purity diamond materials and precise integration with metallic nanostructures, capabilities that are core to 6CCVDâs custom MPCVD Single Crystal Diamond (SCD) and metalization services.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results and simulations:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Quantum Emitter Type | NV$^0$ center | - | Zero-Phonon Line (ZPL) at 575 nm |
| ND Particle Diameter | 100 | nm | Average size used in experiment |
| Graphitized Layer Thickness | 2.5 | nm | Layer surrounding ND particle (used in FEM) |
| Reference Lifetime (Sample A) | 16.3 | ns | Mean lifetime (NDs on 30 nm SiO$_{2}$) |
| SPP Coupled Lifetime (Sample B) | 14.2 | ns | Mean lifetime (NDs on flat 300 nm Ag film) |
| LSP Coupled Lifetime (Sample C) | 9.4 | ns | Mean lifetime (NDs embedded in Ag nanohole) |
| Purcell Factor (F$_P$) - Sample B | 1.15 | - | Calculated from mean lifetime (flat Ag) |
| Purcell Factor (F$_P$) - Sample C | 1.73 | - | Calculated from mean lifetime (embedded Ag) |
| Electron Acceleration Voltage | 80 | kV | Used for STEM-CL measurements |
| Electron Beam Current Range | 17 to 60 | pA | Used for lifetime measurement |
| Electron Probe Size | < 10 | nm | Required for nanoscale resolution |
| FEM Purcell Factor (Model C, Total) | 7.46 | - | Wavelength-averaged simulation result |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on precise sample fabrication and advanced photon-correlation cathodoluminescence techniques.
- Sample Fabrication (Three Types):
- Sample A (Reference): NDs (100 nm diameter, containing NV centers) dispersed on a 30 nm thick free-standing SiO$_{2}$ membrane.
- Sample B (Flat SPP): NDs dispersed on a 300 nm thick Ag film thermally deposited on an InP substrate.
- Sample C (Embedded LSP/SPP): NDs dispersed on a 30 nm SiO$_{2}$ membrane, followed by sputter-deposition of a 300 nm Ag film to embed the NDs, creating a nanohole structure.
- Excitation Source: Electron beam from a Scanning (Transmission) Electron Microscope (S(T)EM) operating at 80 kV acceleration voltage and 17-60 pA beam current.
- Detection System: Cathodoluminescence (CL) detection system installed in the STEM, utilizing a parabolic mirror to guide emitted light.
- Lifetime Measurement: Hanbury Brown-Twiss (HBT) interferometry was combined with the CL system to measure the second-order correlation function, g$^{(2)}(\tau)$, enabling lifetime determination with nanosecond resolution without requiring a pulsed electron source.
- Modeling and Analysis: Analytical calculations and Finite Element Method (FEM) simulations (using COMSOL Multiphysics) were performed to evaluate the Purcell factors, considering the dielectric effects, dipole orientation, and coupling to SPPs and LSPs.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research demonstrates the critical role of high-quality diamond and precise plasmonic integration for quantum applications. 6CCVD is uniquely positioned to supply the next generation of materials required to scale this technology from nanodiamond particles to integrated solid-state devices.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and advance this research into integrated quantum devices, researchers require high-purity, engineered diamond substrates, not just nanodiamond powder.
| Research Requirement | 6CCVD Material Solution | Technical Advantage |
|---|---|---|
| High-Purity NV Centers | Optical Grade Single Crystal Diamond (SCD) | Ultra-low nitrogen content (< 1 ppb) for superior coherence times, essential for high-fidelity quantum operations. |
| Integrated Plasmonics | High-Purity Polycrystalline Diamond (PCD) | Plates/wafers up to 125mm diameter, providing large-area platforms for scalable plasmonic circuit fabrication. |
| Emitter Control | Custom SCD Thicknesses (0.1”m - 500”m) | Allows precise control over the distance between the NV layer and the plasmonic metal surface, optimizing the Purcell factor and coupling efficiency. |
Customization Potential
Section titled âCustomization PotentialâThe paper emphasizes that the Purcell effect is highly sensitive to nanoscopic geometries (nanohole shape, dipole distance, and orientation). 6CCVD offers the necessary precision engineering services to transition from experimental nanodiamonds to robust, integrated diamond chips.
- Custom Dimensions: We provide SCD and PCD plates/wafers in custom sizes up to 125mm, enabling large-scale fabrication of plasmonic arrays and integrated circuits.
- Precision Structuring: 6CCVD offers advanced laser cutting and etching services to create precise geometries, such as the nanoholes or trenches required for LSP confinement and efficient SPP guiding.
- Integrated Metalization: The experiment relied on Ag films. 6CCVD offers in-house deposition of critical metals for plasmonic and electrical contacts, including Au, Pt, Pd, Ti, W, and Cu. This capability ensures seamless integration of QEs with plasmonic waveguides and resonators.
- Surface Quality: Plasmonic coupling efficiency is highly dependent on interface roughness. Our SCD polishing achieves surface roughness Ra < 1 nm, minimizing scattering losses at the diamond-metal interface.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in MPCVD growth and diamond material science for quantum applications. We can assist researchers with material selection and optimization for similar NV-center/Plasmonic Coupling projects, including:
- Optimizing nitrogen incorporation during growth for high-density NV creation.
- Designing custom SCD substrates with specific crystallographic orientations to control NV dipole alignment, maximizing coupling efficiency as suggested by the analytical models (vertical vs. horizontal dipoles).
- Consulting on metal stack design and deposition parameters for optimal plasmonic performance and adhesion.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We measured the second-order correlation function of the cathodoluminescence intensity and investigated the Purcell effect by comparing the lifetimes of quantum emitters with and without metal structure. The increase in the electromagnetic local density of state due to the coupling of a quantum emitter with a plasmonic structure causes a shortening of the emitter lifetime, which is called the Purcell effect. Since the plasmon-enhanced electric field is confined well below the wavelength of light, the quantum emitter lifetime is changed in the nanoscale range. In this study, we combined cathodoluminescence in scanning (transmission) electron microscopy with Hanbury Brown-Twiss interferometry to measure the Purcell effect with nanometer and nanosecond resolutions. We used nitrogen-vacancy centers contained in nanodiamonds as quantum emitters and compared their lifetime in different environments: on a thin SiO2 membrane, on a thick flat silver film, and embedded in a silver film. The lifetime reductions of nitrogen-vacancy centers were clearly observed in the samples with silver. We evaluated the lifetime by analytical calculation and numerical simulations and revealed the Purcell effects of emitters coupled to propagating and localized surface plasmons. This is the first experimental result showing the Purcell effect due to the coupling between nitrogen-vacancy centers in nanodiamonds and surface plasmon polaritons with nanometer resolution.