System for the remote control and imaging of MW fields for spin manipulation in NV centers in diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-03-16 |
| Journal | Scientific Reports |
| Authors | Giacomo Mariani, Shuhei Nomoto, Satoshi Kashiwaya, Shintaro Nomura |
| Institutions | University of Tsukuba, Nagoya University |
| Citations | 34 |
| Analysis | Full AI Review Included |
Technical Documentation: MW Field Imaging via NV Centers in Diamond
Section titled âTechnical Documentation: MW Field Imaging via NV Centers in DiamondâThis document analyzes the research paper âSystem for the remote control and imaging of MW fields for spin manipulation in NV centers in diamondâ to highlight key technical achievements and demonstrate how 6CCVDâs advanced MPCVD diamond materials and fabrication services can support and extend this critical quantum research.
Executive Summary
Section titled âExecutive Summaryâ- Core Value Proposition: Demonstration of a robust, remotely coupled system for the precise control and high-resolution imaging of microwave (MW) magnetic fields using ensembles of Nitrogen-Vacancy (NV) centers in ultra-pure diamond.
- Key Achievement: Achieved significant MW field enhancement (up to 22 times) compared to bulk measurements by employing inductively coupled gold lumped resonators (straight, tapered, and crossed wires).
- Measurement Technique: Quantitative MW field mapping is performed using Optically Detected Magnetic Resonance (ODMR) combined with Fast Fourier Transform (FFT) imaging of Rabi oscillations.
- Spatial Resolution: The system successfully maps MW field distribution localized to a micrometer-scale area (~2 ”m width) with a minimum imaging pixel size of 66 nm.
- Material Requirements: The experiment relies on high-quality, ultra-pure CVD Type IIa diamond substrates with near-surface NV ensembles (implanted at ~10 nm depth).
- Application Potential: The system is highly advantageous for quantum information processing, high-resolution magnetometry, and the characterization of complex MW devices, especially in cryogenic environments due to simplified wiring.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical hard data extracted from the experimental setup and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Substrate Material | CVD Type IIa Ultra-Pure | N/A | (100) orientation, 2.0 x 2.0 x 0.5 mmÂł |
| NV Center Implantation Depth | ~10 | nm | Near-surface ensemble |
| Nitrogen Ion (N+) Implantation Dose | 2 x 1012 - 2 x 1013 | cm-2 | Used for NV creation |
| Post-Implantation Annealing | 800 | °C | Required for NV activation |
| Excitation Laser Wavelength | 520 | nm | Green pulsed laser diode (70 mW peak power) |
| Static Magnetic Field (Bâ) | 4.6 | mT | Aligned along the [111] direction |
| MW Frequency Range | 2.7 - 3.1 | GHz | Used for spin manipulation |
| Maximum Rabi Frequency (Tapered Wire) | 165 | MHz | Measured in the narrowest part of the wire |
| MW Field Enhancement Factor | 22 | times | Compared to bulk Rabi frequency (tapered wire) |
| Resonator Standoff Distance (NV layer to Au) | 1.25 - 1.50 | ”m | Estimated distance for optimal coupling |
| Gold Film Thickness (Resonator) | 110 | nm | Fabricated on Si substrate |
| Titanium Adhesion Layer Thickness | 10 | nm | Used for Au adhesion to Si |
| MW Planar Ring Antenna Radius | 0.5 | mm | Provides uniform MW field |
| Minimum Imaging Pixel Size (N=1) | 66 | nm | Limited by objective Numerical Aperture (NA 0.73) |
Key Methodologies
Section titled âKey MethodologiesâThe experimental success hinges on precise material preparation and advanced quantum measurement techniques:
- Diamond Substrate Preparation: An ultra-pure (100) CVD Type IIa diamond substrate (2.0 x 2.0 x 0.5 mmÂł) was used. The substrate was cut along the [110] direction for alignment in the laboratory frame.
- NV Ensemble Formation: Nitrogen ions (N+) were implanted at 10 keV, followed by annealing at 800 °C and acid treatment to create a dense ensemble of near-surface NV centers (~10 nm depth).
- Lumped Resonator Fabrication: Gold structures (straight, tapered, split-ring, H-shaped) were fabricated on a separate silicon substrate using electron beam evaporation (10 nm Ti / 110 nm Au).
- Remote MW Coupling: The gold lumped resonator was coupled inductively to a large MW planar ring antenna (0.5 mm radius) positioned approximately 0.5 mm away from the diamond surface.
- Pulsed ODMR Measurement: The NV electron spin was initialized using a 520 nm green laser pulse (1 ”s duration) and manipulated using resonant MW pulses. The spin state was read out via photoluminescence (PL) detection (630-800 nm) using a cooled scientific CMOS camera.
- Quantitative MW Field Imaging: The MW field intensity was quantified by measuring the frequency of Rabi oscillations (Ω/2Ï) at various spatial points. The Rabi frequency was calculated by performing an FFT on the time-domain Rabi oscillations acquired across the CMOS camera pixels.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD specializes in providing the foundational MPCVD diamond materials and integrated fabrication services necessary to replicate and advance high-performance quantum sensing and spin manipulation experiments like the one described.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Required for the ultra-low defect density and high optical transparency essential for ODMR. Our SCD material is grown with high purity, ensuring minimal background noise and optimal performance for near-surface NV creation via implantation.
- Custom (100) or (111) Orientation: We supply SCD substrates cut to specific crystallographic orientations, crucial for aligning the NV symmetry axis with the static magnetic field (Bâ) and optimizing spin manipulation protocols.
Customization Potential
Section titled âCustomization PotentialâThe research utilized a separate Si substrate for the gold resonator, which complicates alignment and thermal management, especially in cryogenic setups. 6CCVD offers integrated solutions to overcome these challenges:
| Research Requirement | 6CCVD Integrated Solution |
|---|---|
| Separate Si Substrate for Resonator | Direct-on-Diamond Metalization: 6CCVD offers in-house metalization services (e.g., Ti/Au, Pt/Pd) directly onto the SCD surface. This eliminates the need for a separate substrate, minimizes the standoff distance, and significantly improves thermal contact for cryogenic applications. |
| Small Sample Dimensions (2.0 x 2.0 mm) | Scalable Substrates: While small samples were used, 6CCVD can provide SCD plates up to 500 ”m thick and PCD wafers up to 125 mm diameter, allowing researchers to scale up device integration or fabricate large-area arrays of resonators. |
| Ultra-Smooth Surface Finish (Crucial for 1.25 ”m Standoff) | Precision Polishing: Achieving high Rabi frequencies requires the closest possible proximity between the NV layer and the metal resonator. 6CCVD guarantees SCD polishing to Ra < 1 nm, ensuring the necessary surface quality for optimal near-field coupling. |
| Custom Resonator Geometries | Advanced Fabrication: We offer laser cutting and micro-machining services to define complex geometries (e.g., straight, tapered, split-ring, or crossed-wire patterns) directly into the metal layer on the diamond surface. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists and engineers can assist researchers in optimizing material selection for similar Quantum Sensing and MW Field Imaging projects. We provide consultation on:
- Material Specification: Selecting the optimal SCD grade, thickness (0.1 ”m to 500 ”m), and orientation for specific implantation and annealing recipes.
- Surface Preparation: Ensuring the surface quality meets the stringent requirements for high-fidelity near-field coupling and subsequent lithography steps.
- Integrated Device Design: Advising on the best metal stack and deposition method (Au, Pt, Ti, W, Cu) for integrated MW circuits on diamond.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Nitrogen-vacancy (NV) centers in diamond have been used as platforms for quantum information, magnetometry and imaging of microwave (MW) fields. The spatial distribution of the MW fields used to drive the electron spin of NV centers plays a key role for these applications. Here, we report a system for the control and characterization of MW magnetic fields used for the NV spin manipulation. The control of the MW field in the vicinity of a diamond surface is mediated by an exchangeable lumped resonator, coupled inductively to a MW planar ring antenna. The characterization of the MW fields in the near-field is performed by an FFT imaging of Rabi oscillations, by using an ensemble of NV centers. We have found that the Rabi frequency over a lumped resonator is enhanced 22 times compared to the Rabi frequency without the presence of the lumped resonator. Our system may find applications in quantum information and magnetometry where a precise and controlled spin manipulation is required, showing NV centers as good candidates for imaging MW fields and characterization of MW devices.