Probing Plasmon-NV0 Coupling at the Nanometer Scale with Photons and Fast Electrons

At a Glance

Metadata	Details
Publication Date	2017-11-13
Journal	ACS Photonics
Authors	Hugo Lourenço‐Martins, Mathieu Kociak, Sophie Meuret, François Treussart, Yih Hong Lee
Institutions	Université Paris-Sud, Centre National de la Recherche Scientifique
Citations	28
Analysis	Full AI Review Included

Probing Plasmon-NV$^0$ Coupling: Technical Documentation and 6CCVD Solutions

This document analyzes the research paper “Probing plasmon-NV$^0$ coupling at the nanometer scale with photons and fast electrons” to provide technical specifications and highlight how 6CCVD’s advanced MPCVD diamond materials and customization capabilities can support and extend this critical research in quantum optics and plasmonics.

Executive Summary

This research successfully quantified the Purcell effect resulting from the coupling between neutral nitrogen-vacancy (NV$^0$) centers in nanodiamonds and surface plasmons (SP) in silver nanocubes.

Core Achievement: Demonstrated a 40% reduction in the mean excited state lifetime of NV$^0$ centers when coupled to plasmonic structures.
Purcell Factor: Quantified the spontaneous decay rate enhancement factor ($\gamma$) to be 1.4, confirming significant coupling at the nanoscale.
Methodology: Utilized a powerful hybrid technique combining Scanning Transmission Electron Microscopy (STEM), Electron Energy Loss Spectroscopy (EELS), Cathodoluminescence (CL), and Hanbury Brown and Twiss (HBT) correlation spectroscopy.
Resolution: Achieved nanometer spatial resolution and nanosecond temporal resolution, essential for disentangling intrinsic material variability from coupling effects.
Statistical Approach: Overcame the intrinsic lifetime dispersion of NV$^0$ centers in nanodiamonds by measuring a large statistical ensemble (118 nano-objects).
Material Requirements: Requires ultra-high purity diamond material for reliable NV center formation and stable quantum properties, suitable for nanoscale integration.

Technical Specifications

The following table summarizes the key quantitative parameters and results extracted from the experimental data:

Parameter	Value	Unit	Context
Isolated NV$^0$ Lifetime (Most Probable)	22.5 ± 2.5	ns	Nanodiamonds alone
Coupled NV$^0$ Lifetime (Most Probable)	12.5 ± 2.5	ns	Nanodiamond-Ag nanocube dimers
Lifetime Reduction	40	%	Due to Purcell effect
Spontaneous Decay Rate Enhancement ($\gamma$)	1.4	N/A	Purcell Factor
Electron Beam Energy	60	kV	STEM operation
EELS ZLP Width Reduction	0.33 to 0.1	eV	Achieved via Richardson-Lucy algorithm
NV$^0$ Emission/Plasmon Resonance	1.8	eV	Energy matching for coupling
Cryogenic Temperature	150	K	Liquid Nitrogen cooling of microscope stage
HBT Sampling Time	512	ps	Photon correlation measurement resolution
Overall System Response Time	130	ps	HBT interferometer system limit

Key Methodologies

The experiment relied on a sophisticated combination of material preparation, advanced electron microscopy, and quantum optics techniques:

Sample Preparation: Sequential drop casting of Ag nanocubes (average size ~100 nm) and nanodiamonds (containing multiple NV centers) onto a 15 nm thick Si${3}$N${4}$ membrane.
Instrumentation: Experiments performed using a Vacuum Generator HB-501 STEM equipped with a cold field emission electron gun operating at 60 kV.
Spectroscopy Integration: An in-house Hanbury Brown and Twiss (HBT) interferometer was coupled to the nano-Cathodoluminescence (CL) system for photon correlation measurements.
Cryogenic Operation: The microscope stage was cooled with liquid nitrogen down to 150 K to stabilize measurements.
Imaging and Selection: Annular Dark Field (ADF) images and wavelength-filtered CL maps were acquired simultaneously to identify and select isolated nanodiamonds and nanodiamond-nanocube dimers with nanometer resolution.
Lifetime Measurement: The g⁽²⁾($\tau$) correlation function of emitted photons was measured using T-SPADs single photon avalanche photodiodes and a PicoHarp 300, allowing lifetime determination in a few tens of seconds.
Data Processing: EEL spectrum images were deconvolved using a Richardson-Lucy algorithm, reducing the Zero-Loss Peak (ZLP) width from 0.33 eV to 0.1 eV for enhanced spectral resolution.

6CCVD Solutions & Capabilities

This research demonstrates the critical role of high-quality diamond materials in advancing quantum technology. 6CCVD is uniquely positioned to supply the foundational MPCVD diamond required to replicate, scale, and extend these experiments into integrated quantum devices.

Applicable Materials

To ensure optimal NV center formation and stable quantum properties necessary for high-fidelity coupling experiments, researchers require high-purity Single Crystal Diamond (SCD) precursors.

Optical Grade SCD: Recommended for its low intrinsic nitrogen content, allowing precise, controlled creation of NV centers (e.g., via ion implantation and annealing). Our SCD offers superior structural quality, minimizing non-radiative decay channels observed in the paper.
- Thickness Range: Available from 0.1 µm up to 500 µm, ideal for thin-film quantum applications or robust substrates.
High-Purity Polycrystalline Diamond (PCD): For large-area plasmonic integration studies where wafer size is paramount, our PCD plates (up to 125 mm diameter) offer excellent thermal and optical properties.

Customization Potential

The paper highlights the need for precise nanoscale positioning and integration. 6CCVD’s in-house engineering capabilities directly address these requirements:

Research Requirement	6CCVD Capability	Technical Advantage
Substrate Quality	Ultra-low roughness polishing (Ra < 1 nm) for SCD.	Essential for subsequent lithography, precise nanodiamond placement, and minimizing scattering losses in plasmonic coupling.
Integrated Plasmonics	Custom metalization services (Au, Pt, Pd, Ti, W, Cu).	Allows researchers to move beyond drop-cast Ag nanocubes to integrated plasmonic circuits directly patterned onto the diamond surface.
Custom Dimensions	Plates/wafers up to 125 mm (PCD) and custom laser cutting.	Provides large-area substrates for high-throughput statistical analysis or custom geometries for specific optical setups.
Thin Film Applications	SCD thickness control from 0.1 µm to 500 µm.	Enables the fabrication of diamond membranes or thin films necessary for transmission electron microscopy (TEM/STEM) studies, similar to the Si${3}$N${4}$ membrane used in this work.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of quantum emitters and plasmonic integration. We offer consultation services to assist researchers in:

Material Selection: Choosing the optimal diamond grade (e.g., specific nitrogen concentration or isotopic purity) to maximize NV$^0$ yield and coherence time for similar quantum sensing and emitter coupling projects.
Integration Strategy: Advising on surface preparation and metalization schemes compatible with subsequent high-resolution lithography (EBL/FIB) required for integrated nanophotonics.
Global Logistics: Ensuring seamless global delivery (DDU default, DDP available) of sensitive, high-value diamond materials.

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

View Original Abstract

The local density of optical states governs an emitters lifetime and quantum\nyield through the Purcell effect. It can be modified by a surface plasmon\nelectromagnetic field, but such a field has a spatial extension limited to a\nfew hundreds of nanometers, which complicates the use of optical methods to\nspatially probe the emitter-plasmon coupling. Here we show that a combination\nof electron-based imaging, spectroscopies and photon-based correlation\nspectroscopy enables measurement of the Purcell effect with nanometer and\nnanosecond spatio-temporal resolutions. Due to the large variability of\nradiative lifetimes of emitters embedded in nanoparticles with inhomogeneous\nsizes we relied on a statistical approach to unambiguously probe the coupling\nbetween nitrogen-vacancy centers (NV^0) in nanodiamonds and surface plasmons in\nsilver nanocubes. We quantified the Purcell effect by measuring the NV^0\nexcited state lifetimes in a large number of either isolated nanodiamonds or\nnanodiamond-nanocube dimers and demonstrated a statistically significant\nlifetime reduction for dimers.\n

Tech Support

Original Source

DOI: https://doi.org/10.1021/acsphotonics.7b01093