Identification and Control of Electron-Nuclear Spin Defects in Diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-02-25 |
| Journal | Physical Review Letters |
| Authors | A. R. COOPER, Won Kyu Calvin Sun, Jean-Christophe Jaskula, Paola Cappellaro |
| Institutions | Massachusetts Institute of Technology, California Institute of Technology |
| Citations | 26 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Multi-Spin Quantum Registers in MPCVD Diamond
Section titled âTechnical Documentation & Analysis: Multi-Spin Quantum Registers in MPCVD DiamondâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a crucial step toward scalable quantum devices by successfully identifying, locating, and controlling two environmental electron-nuclear spin defects (X1, X2) interacting with a single Nitrogen-Vacancy (NV) center in diamond. This breakthrough relies fundamentally on high-quality, ultra-pure Single Crystal Diamond (SCD).
- Core Achievement: Creation and detection of quantum coherence among three electron spins (NV, X1, X2), paving the way for genuine tripartite entanglement and multi-spin quantum registers.
- Methodology: Utilized double electron-electron resonance spectroscopy (SEDOR) and Electron Spin-Echo Envelope Modulation (ESEEM) combined with magnetic field rotation to extract unknown hyperfine and dipolar tensor parameters.
- Material Requirement: The experiment necessitated isotopically-purified Single Crystal Diamond (99.999% 12C enrichment) to ensure long coherence times and minimize decoherence from background spins.
- Defect Engineering: Defects were created via precise 15N ion implantation (14 keV, 1013 cm-2 dose) through 30 nm nano-apertures, followed by 800 °C annealing.
- Localization: The environmental defects were precisely located at 9.23 nm (X1) and 6.58 nm (X2) from the NV center, demonstrating exceptional control over the solid-state quantum environment.
- Application: These results are directly applicable to advancing quantum sensing and quantum information processing (QIP) by converting typically detrimental environmental spins into useful quantum resources.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, highlighting the critical material and experimental parameters:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material Type | SCD | N/A | Single Crystal Chemical Vapor Deposition |
| Isotopic Purity | 99.999% 12C | Enrichment | Required for long coherence times |
| SCD Layer Thickness | 100 | ”m | Active layer thickness |
| Substrate Thickness | 300 | ”m | Electron grade single crystal diamond |
| NV Center Zero-Field Splitting (Î) | 2Ï * 2870 | MHz | Spin-triplet ground state |
| Ion Implantation Species | 15N | N/A | Used to create NV and X defects |
| Ion Implantation Energy | 14 | keV | Optimized for defect depth |
| Ion Implantation Dose | 1013 | cm-2 | Defect density control |
| Annealing Temperature | 800 | °C | 4 hours duration |
| X1 Defect Distance (r1) | 9.23 ± 0.03 | nm | Relative position to NV center |
| X2 Defect Distance (r2) | 6.58 ± 0.03 | nm | Relative position to NV center |
| Dipolar Constant (dc) | 2Ï * 52.041 | kHz | For two electronic spins at 1 nm |
Key Methodologies
Section titled âKey MethodologiesâThe experimental success hinged on precise material preparation, nanofabrication, and advanced spectroscopic techniques:
- Material Selection and Preparation: Utilized a 100 ”m layer of isotopically enriched (99.999% 12C) SCD grown on a 300 ”m substrate, cut with the edge directed along the (110) crystallographic axis.
- Surface Passivation: Deposited a 10 nm SiO2 layer to mitigate ion channeling during implantation.
- Nanofabrication: Employed electron-beam lithography (1400 ”C/cm2 dose) and PMMA resist to pattern 30 nm diameter nano-aperture arrays.
- Defect Creation: Implanted 15N ions at 14 keV and a dose of 1013 cm-2, followed by high-temperature annealing (800 °C for 4 h) to promote vacancy mobility and NV conversion.
- Magnetic Field Control: Mounted a 25.4 mm-edge cubic magnet on a translation stage with rotational degrees of freedom to systematically vary the static magnetic field orientation (polar angle $\theta$ and azimuthal angle $\phi$).
- Spectroscopic Characterization: Used continuous-wave Electron Spin Resonance (cw-ESR) and Electron Spin-Echo Envelope Modulation (ESEEM) to unambiguously determine the magnetic field strength (B0) and orientation ($\theta$, $\phi$) at the NV center location.
- Defect Identification: Performed Spin-Echo Double-Resonance (SEDOR) spectroscopy at various magnetic field orientations to extract the parameters of the hyperfine and dipolar interaction tensors for the unknown X spins.
- Quantum Control Protocol: Implemented coherent spin-exchange via Hartmann-Hahn cross-polarization and generated entangling CNOT gates using a recoupled spin-echo sequence to create and detect three-spin coherence.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials and customization services required to replicate and extend this critical quantum research.
Applicable Materials for Quantum Registers
Section titled âApplicable Materials for Quantum RegistersâTo achieve the long coherence times and controlled defect environments demonstrated in this paper, researchers require the highest quality SCD.
| Research Requirement | 6CCVD Solution | Technical Specification |
|---|---|---|
| Ultra-High Purity | Optical Grade Single Crystal Diamond (SCD) | Low nitrogen and substitutional defect density, essential for long T2 coherence times. |
| Isotopic Enrichment | Custom 12C Enriched SCD | We supply isotopically enriched substrates (e.g., 99.999% 12C) necessary to minimize decoherence caused by host nuclear spins. |
| Defect Engineering Base | SCD Plates/Wafers | Ideal platform for subsequent ion implantation (15N, SiV, GeV) and annealing processes. |
Customization Potential & Fabrication Support
Section titled âCustomization Potential & Fabrication SupportâThe experiment involved precise dimensional control, specific crystallographic alignment, and advanced nanofabrication steps (e-beam lithography, metalization). 6CCVD provides the necessary material customization:
- Custom Dimensions and Thickness: The paper used 100 ”m thick SCD layers. 6CCVD offers SCD plates/wafers with custom thicknesses ranging from 0.1 ”m up to 500 ”m, and substrates up to 10 mm thick, tailored to specific implantation depths and optical requirements.
- Crystallographic Orientation: The experiment relied on precise alignment along the (110) and (111) axes. 6CCVD provides custom orientation cuts to ensure optimal alignment of the NV molecular axis relative to the experimental magnetic field.
- Surface Quality for Nanofabrication: Nanofabrication (e-beam lithography for 30 nm apertures) requires an ultra-smooth surface. 6CCVD guarantees SCD polishing to Ra < 1 nm and PCD polishing to Ra < 5 nm (for inch-size wafers), ensuring compatibility with high-resolution lithography and low-loss optical integration.
- Integrated Metalization: The experiment involved Au evaporation. 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu) for integrating microwave control lines and electrodes directly onto the diamond surface, streamlining device fabrication.
Engineering Support
Section titled âEngineering SupportâThis research involves complex system identification and Hamiltonian fitting. 6CCVDâs technical expertise supports advanced quantum projects:
- Consultation: Our in-house PhD team specializes in material science for quantum applications. We assist clients in optimizing material selection, crystallographic orientation, and surface preparation strategies for similar multi-spin quantum register projects.
- Global Logistics: We ensure reliable, global delivery of sensitive materials, with DDU default shipping and DDP options available.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We experimentally demonstrate an approach to scale up quantum devices by harnessing spin defects in the environment of a quantum probe. We follow this approach to identify, locate, and control two electron-nuclear spin defects in the environment of a single nitrogen-vacancy center in diamond. By performing spectroscopy at various orientations of the magnetic field, we extract the unknown parameters of the hyperfine and dipolar interaction tensors, which we use to locate the two spin defects and design control sequences to initialize, manipulate, and readout their quantum state. Finally, we create quantum coherence among the three electron spins, paving the way for the creation of genuine tripartite entanglement. This approach will be useful in assembling multispin quantum registers for applications in quantum sensing and quantum information processing.