Long-Term Spin State Storage Using Ancilla Charge Memories
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-12-01 |
| Journal | Physical Review Letters |
| Authors | Harishankar Jayakumar, Artur Lozovoi, Damon Daw, Carlos A. Meriles |
| Institutions | City College of New York, The Graduate Center, CUNY |
| Citations | 13 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Ancilla-Aided Spin State Storage in MPCVD Diamond
Section titled âTechnical Documentation & Analysis: Ancilla-Aided Spin State Storage in MPCVD DiamondâThis document analyzes the research paper âLong-term spin state storage using ancilla charge memoriesâ to provide technical specifications and align the material requirements with 6CCVDâs advanced MPCVD diamond capabilities, driving sales to researchers and engineers in quantum technology.
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Demonstration of Ancilla-Aided Integrated Detection (AID) for long-term storage and readout of Nitrogen-Vacancy (NV) center spin states in bulk CVD diamond.
- Mechanism: NV spin information is converted into stable charge states (electrons/holes) via Spin-to-Charge Conversion (SCC), which are subsequently captured by neighboring defects (Silicon-Vacancy, SiV, or ancilla NV centers) acting as charge memories.
- Material Requirements: The protocol necessitates high-purity <100> CVD diamond with precise, controlled concentrations of both NV (qubit) and SiV (ancilla) defects, typically in the 10-2 to 10-1 ppm range.
- Readout Enhancement: AID offers a pathway to potentially boost sensitivity beyond standard optical sensing (SOS) by integrating the signal over long time intervals (up to 2 s demonstrated) due to the unlimited lifetime of trapped charge states.
- Integrated Platform: The methodology combines magnetic resonance (MW pulses) and multi-color confocal microscopy (520 nm/632 nm lasers) with integrated charge traps, establishing a robust platform for color-center-based quantum metrology and information processing.
- 6CCVD Value Proposition: 6CCVD specializes in providing the necessary Optical Grade Single Crystal Diamond (SCD) with custom, controlled doping (N and Si) and integrated metalization required to replicate and scale this advanced quantum sensing technique.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental section and supplementary notes, detailing the material and operational parameters.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Crystal Orientation | <100> | N/A | CVD grown bulk diamond |
| NV Concentration (Qubit/Ancilla) | 10-2 | ppm | Used in Sample 1 (Fig 1-2) |
| SiV Concentration (Ancilla Traps) | 10-1 | ppm | Used in Sample 1 (Fig 1-2) |
| Substitutional N Concentration | 1 | ppm | Background defects in both samples |
| MW Frequency (Resonant) | 2.87 | GHz | NV crystal-field resonance |
| MW/SCC Pulse Duration | 100 | ns | Spin manipulation and conversion |
| Green Laser Wavelength (L1) | 520 | nm | Used for Initialization and SCC |
| Red Laser Wavelength (L2) | 632 | nm | Used for Initialization, SCC, and Readout |
| Green Laser Power (L1) | 3 | mW | Typical power during initialization/SCC |
| Red Laser Power (L2) | Up to 21 | mW | Maximum power during SCC |
| Electron Diffusion Coefficient (Dn) | 6.1 * 109 | ”m2/s | Ambient conditions (T=293 K) |
| Hole Diffusion Coefficient (Dp) | 5.3 * 109 | ”m2/s | Ambient conditions (T=293 K) |
| Signal Integration Time | Up to 2 | s | Demonstrated long-term charge storage |
| Optical Illumination Spot Size | ~1 | ”m | Diameter of laser illumination |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relies on precise control over defect charge states, spin manipulation, and carrier dynamics in the diamond lattice.
- Material Preparation: Utilization of high-p-urity <100> CVD diamond with specific, low concentrations of NV, SiV, and substitutional Nitrogen impurities, purchased from commercial suppliers.
- Microwave (MW) Delivery: MW pulses are applied via an omega-shaped stripline (0.5 mm diameter) imprinted directly onto the diamond substrate, enabling resonant spin manipulation (2.87 GHz).
- Optical Setup: A home-built confocal microscope with an air objective (NA=0.7) is used, employing 520 nm (Green) and 632 nm (Red) diode lasers for excitation and a single photon counting module (SPCM) for photoluminescence (PL) detection (filtered 650 nm to 800 nm).
- Charge Initialization: Raster scanning using red laser pulses (632 nm) to prepare NVs and SiVs within a 40x40 ”m2 area into a non-fluorescent (dark) charge state.
- Spin-to-Charge Conversion (SCC): The qubit NV spin state is converted to a charge state via simultaneous 520 nm and 632 nm pulses (100 ns), generating free electrons and holes conditional on the initial spin state (|ms = 0> vs. |ms = ±1>).
- Ancilla Trapping: Generated carriers diffuse away from the illumination spot and are captured by neighboring, carrier-type-selective ancilla traps (SiV or NV centers), which convert to a fluorescent (bright) charge state, storing the spin information.
- Integrated Readout (AID): The stored spin state is detected by measuring the integrated fluorescence of the activated ancilla ensemble over extended periods (up to 2 seconds).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the critical need for highly controlled, customized diamond materials for advanced quantum applications. 6CCVD is uniquely positioned to supply the necessary SCD substrates, defect engineering, and integrated fabrication services.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this research, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Essential for minimizing background noise and maximizing the coherence time (T2) of the NV qubit. Our SCD material is grown via MPCVD, ensuring the highest purity and lowest intrinsic defect density.
- Custom Doped SCD Wafers: Required for precise control over the concentration and ratio of active defects. We offer custom doping recipes to achieve the specific concentrations cited in the paper (e.g., 10-2 ppm NV, 10-1 ppm SiV, and controlled substitutional N) necessary for optimal SCC and AID performance.
- Polycrystalline Diamond (PCD) Substrates: For scaling up integrated devices or creating large-area sensing arrays, 6CCVD offers PCD wafers up to 125 mm in diameter, polished to Ra < 5 nm.
Customization Potential
Section titled âCustomization PotentialâThe experimental setup requires integrated components and specific material geometries, all of which are standard offerings at 6CCVD:
| Research Requirement | 6CCVD Customization Service | Specification Match |
|---|---|---|
| Integrated MW Delivery | Custom Metalization | In-house deposition of Au, Pt, Pd, Ti, W, or Cu electrodes for fabricating omega-shaped striplines or complex electrode arrays for electrical readout. |
| High Optical Quality | Precision Polishing | SCD surfaces polished to Ra < 1 nm, ensuring minimal scattering and optimal coupling for 520 nm/632 nm confocal excitation. |
| Specific Thicknesses | Custom Thickness Control | SCD layers available from 0.1 ”m to 500 ”m, and robust substrates up to 10 mm thick for mechanical and thermal stability. |
| Custom Geometry | Laser Cutting & Shaping | Precise laser cutting services to achieve custom plate dimensions or specific geometries required for mounting and integration into cryogenic or high-power setups. |
Engineering Support
Section titled âEngineering SupportâThe success of Ancilla-Aided Detection (AID) hinges on optimizing the balance between qubit coherence, ancilla trap concentration, and carrier collection efficiency. 6CCVDâs in-house PhD team can assist with material selection and defect engineering protocols for similar Spin Qubit Readout and Quantum Metrology projects, ensuring optimal charge trap activation and minimizing the impact of background impurities (like substitutional Nitrogen).
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We articulate confocal microscopy and electron spin resonance to implement spin-to-charge conversion in a small ensemble of nitrogen-vacancy (NV) centers in bulk diamond and demonstrate charge conversion of neighboring defects conditional on the NV spin state. We build on this observation to show time-resolved NV spin manipulation and ancilla-charge-aided NV spin state detection via integrated measurements. Our results hint at intriguing opportunities in the development of novel measurement strategies in fundamental science and quantum spintronics as well as in the search for enhanced forms of color-center-based metrology down to the limit of individual point defects.