Demonstration of a Coherent Electronic Spin Cluster in Diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-09-02 |
| Journal | Physical Review Letters |
| Authors | Helena S. Knowles, Dhiren M. Kara, Mete AtatĂŒre |
| Institutions | University of Cambridge |
| Citations | 37 |
| Analysis | Full AI Review Included |
Technical Analysis and Commercial Solutions for Coherent Spin Clusters in MPCVD Diamond
Section titled âTechnical Analysis and Commercial Solutions for Coherent Spin Clusters in MPCVD DiamondâThis document analyzes the research paper âDemonstration of a coherent electronic spin cluster in diamondâ (arXiv:1605.07552v2) and maps the experimental requirements to the advanced material and engineering capabilities offered by 6CCVD.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrates precise control and coherent spin exchange between a single Nitrogen-Vacancy (NV) center and a proximal cluster of three dark Nitrogen (N) electron spins in nanodiamond (ND). This breakthrough establishes the N spin cluster as a usable quantum resource rather than a source of decoherence.
Core achievements and value proposition:
- Coherent Resource Creation: Achieved full polarization and coherent coupling of a three-spin N cluster to an NV center, effectively converting magnetic noise into a quantum resource.
- Precision Sensing Equivalent: The achieved polarization degree for the N cluster is equivalent to applying an external magnetic field exceeding 300 T under ambient conditions.
- Sub-Nanometer Localization: Utilized Interferometric Directional Spin Echo (IDSE) and modeling to locate individual cluster spins relative to the NV center with sub-nanometer precision.
- Robust Ambient Operation: All techniques were executed at ambient temperatures, enabling practical applications in bio-sensing and integrated quantum devices.
- Quantum Simulation Platform: The observed robust coherent spin exchange ($T_{osc} \approx 2.3$ ”s) validates diamond as a platform for environment-assisted sensing schemes and scalable on-chip quantum simulations.
- Methodology: Polarization relies on matching the NV Excited State (ES) and N spin transition energies via applied magnetic field ($B_{app} = 24$ mT) and using the Hartmann-Hahn (HH) double resonance scheme for readout and coherent manipulation.
Technical Specifications
Section titled âTechnical SpecificationsâHard data points extracted from the experimental results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Host Material Geometry | 20 | nm | Mean diameter Nanodiamond (ND) |
| Nitrogen Concentration (Target Range) | 10 - 500 | ppm | Required for workable NV yield in ND host |
| Applied Magnetic Field ($B_{app}$) | 24 | mT | Field used to achieve resonance matching |
| NV ES Zero-Field Splitting ($D_{ES}$) | ~1.4 | GHz | Energy mismatch overcome by $B_{app}$ |
| Primary N Cluster Size | 3 | spins (N1, N2, N3) | Model used for high-likelihood fit (98%) |
| Maximum N1 Polarization (20 ”s init.) | 72 ± 2 | % | Polarization degree achieved for the closest spin |
| N1 Polarization Equivalence | >300 | T | External magnetic field equivalent under ambient operation |
| Coherent Spin Exchange Time ($T_{osc}$) | 2.3 | ”s | Coherence time of the combined NV-N cluster state (HH sequence) |
| NV-N1 Coupling Strength ($\Delta_1$) | 1.68 ± 0.01 | MHz | Extracted oscillation frequency |
| Cluster Spatial Resolution | Sub-1 | nm | Localization precision achieved |
| IDSE Measurement Phase Difference | 46 | degrees | Maximum phase difference observed (20 ”s initialization) |
| Net Magnetic Field from Cluster | -5 | ”T | Measured field along the NV axis from polarized cluster (20 ”s init.) |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relies on precise control of spin transitions and coupling via tailored magnetic fields, microwave (MW) pulses, radio frequency (RW) pulses, and continuous optical excitation.
- Material Preparation: Use of NDs (20 nm diameter) hosting naturally formed NV centers and high concentrations of dark substitutional N spins (~40 N impurities per NV).
- Spin Energy Matching: A constant magnetic field ($B_{app} = 24$ mT) is applied along the NV axis to match the NV excited state (ES) transitions with the N spin transitions, enabling efficient dipolar transfer.
- Optical Polarization (Pumping): Continuous optical excitation polarizes the NV spin, which then transfers polarization to the proximate N cluster via resonant dipolar interaction.
- Cluster Readout (DSE/IDSE): Directional Spin Echo (DSE) sequences, enhanced by the interferometric DSE (IDSE) method, are applied to the NV ground state (GS) to detect the precise magnitude and sign of the magnetic field ($B_{pol}$) generated by the polarized N cluster.
- Coherent Spin Exchange (HH Double Resonance): The Hartmann-Hahn (HH) double resonance scheme is used, driving both NV (GS) and N spins into dressed states with identical transition energies to allow observation of robust, coherent spin exchange dynamics.
- Localization: The spin couplings ($\Delta_i$) and polarization dynamics ($p_i$) are modeled to determine the precise lattice sites of the individual N spins (N1, N2, N3) relative to the NV center.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates diamond-based spin clusters as critical components for next-generation quantum technologies. 6CCVD provides the necessary material science and engineering customization to replicate this research on scalable platforms and extend its applicability.
Applicable Materials
Section titled âApplicable MaterialsâThe use of unstable nanodiamonds limits integration and scalability. 6CCVD offers superior, large-area MPCVD materials that enable direct lithographic integration and high-fidelity measurement:
| Material Grade | Application in Research | 6CCVD Advantage |
|---|---|---|
| Nitrogen-Doped SCD | Replication/Scaling of NV/N clusters. | Provides large, stable, high-purity single crystal wafers up to 125mm, eliminating ND handling challenges. We offer tight control over Nitrogen Doping concentrations (down to ppb level or up to 500 ppm+) necessary to tune the density of NV and dark N spins. |
| High Purity SCD | Advanced Quantum Sensing Applications. | For applications requiring extended coherence beyond the N cluster limit (e.g., $T_2$ improvement), 6CCVD supplies ultra-low N SCD ($< 5$ ppb) substrates, which can then be tailored with precise local implantation techniques for NV creation. |
| Polycrystalline Diamond (PCD) | High-Power/Large-Area Platforms. | Available up to 125mm diameter for scalable sensor arrays or integrated high-power RF/MW substrates. |
| Boron-Doped Diamond (BDD) | Custom RF/MW Components. | Can be used to fabricate integrated low-loss electrodes and contacts for MW transmission lines essential for the DSE/HH protocols. |
Customization Potential
Section titled âCustomization PotentialâThe success of the DSE/IDSE/HH methods relies heavily on external RF/MW components and precise optical alignment. 6CCVD provides in-house engineering services that match these requirements:
- Custom Dimensions and Substrates: 6CCVD provides SCD/PCD plates up to 125mm with custom thicknesses (0.1 ”m to 500 ”m) suitable for both transmission-mode and reflection-mode optical setups.
- Superior Surface Finish: Achieving stable, high-fidelity optical readout (ODMR) demands exceptional surface quality. We offer ultra-low roughness polishing (Ra < 1 nm for SCD, Ra < 5 nm for inch-size PCD), crucial for minimizing light scattering and improving optical throughput.
- Integrated Metalization: The experiment requires complex MW/RF pulsing (Fig. 4a). 6CCVD specializes in custom metal stack deposition (e.g., Ti/Pt/Au, Ti/W/Cu) for on-chip MW antenna integration and creation of robust ohmic contacts, streamlining the development cycle for quantum hardware engineers.
- Precision Cutting and Shaping: We provide advanced laser cutting services to shape substrates into specific geometries required for optimized RF/MW performance (e.g., microstrip lines for homogeneous $B_{1}$ field delivery) without damaging the SCD crystal structure.
Engineering Support
Section titled âEngineering SupportâThis research opens doors for applications in advanced metrology and quantum computation. 6CCVDâs in-house PhD team provides authoritative assistance in translating these findings to engineered products.
- Material Selection for Quantum Projects: Our experts assist clients in selecting the optimal MPCVD diamond gradeâtailoring N concentration and ensuring appropriate crystal orientationâfor specific quantum sensing (magnetometry) and quantum simulation projects involving coupled spin chains.
- Optimization for Integration: We support engineers integrating diamond material with complex RF/Optical systems, ensuring compatibility with demanding specifications such as high-power microwave coupling and cryogenic readiness (if required, though this paper demonstrates ambient operation).
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
An obstacle for spin-based quantum sensors is magnetic noise due to proximal spins. However, a cluster of such spins can become an asset, if it can be controlled. Here, we polarize and readout a cluster of three nitrogen electron spins coupled to a single nitrogen-vacancy spin in diamond. We further achieve sub-nm localization of the cluster spins. Finally, we demonstrate coherent spin exchange between the species by simultaneous dressing of the nitrogen-vacancy and the nitrogen states. These results establish the feasibility of environment-assisted sensing and quantum simulations with diamond spins.