Nuclear quantum-assisted magnetometer
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-01-01 |
| Journal | Review of Scientific Instruments |
| Authors | Thomas HĂ€berle, Thomas Oeckinghaus, Dominik Schmid-Lorch, Matthias Pfender, Felipe FĂĄvaro de Oliveira |
| Institutions | University of Stuttgart, Max Planck Institute for Solid State Research |
| Citations | 19 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Nuclear Quantum-Assisted Magnetometer
Section titled âTechnical Documentation & Analysis: Nuclear Quantum-Assisted MagnetometerâThis document analyzes the requirements and achievements detailed in the research paper âNuclear Quantum-Assisted Magnetometerâ and maps them directly to the advanced material solutions and customization capabilities offered by 6CCVD.
Executive Summary
Section titled âExecutive SummaryâThis research demonstrates a significant breakthrough in quantum sensing, achieving near-ambient, high-sensitivity magnetometry using Nitrogen-Vacancy (NV) centers in MPCVD diamond.
- Record SNR Enhancement: A total Signal-to-Noise Ratio (SNR) improvement factor of 19.3x was achieved compared to standard readout on unstructured diamond.
- Acquisition Time Reduction: This enhancement translates to a 373x reduction in the required acquisition time, making high-resolution scanning probe applications practical.
- Dual Enhancement Mechanism: The gain is derived from two synergistic techniques:
- Quantum-Assisted Readout (SSR): Single Shot Readout (SSR) provided an 8.6x SNR gain, achieving a maximum fidelity of 92%.
- Photon Collection Engineering: Nano-engineered tapered nanopillars boosted photon collection efficiency by 5x (2.3x SNR gain).
- Material Requirements: The experiment relied on high-purity, electronic-grade Single Crystal Diamond (SCD) membranes, implanted with 15N+ ions, and annealed at 950 °C.
- Key Performance Metrics: The SCD material exhibited excellent spin coherence, demonstrating an electron spin T1 relaxation time of 3.5 ms and a T2* (Hahn) time of 108 ”s.
- Application Potential: The system is now optimized for cutting-edge quantum metrology, including high-sensitivity Nuclear Magnetic Resonance (NMR) and scanning probe microscopy (SPM).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results and material preparation sections of the paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Total SNR Improvement Factor | 19.3 | Factor | Compared to standard readout on unstructured diamond |
| Acquisition Time Reduction | 373 | Factor | To reach equivalent SNR |
| SSR Readout SNR Enhancement | 8.6 | Factor | Compared to standard readout |
| Nanopillar Photon Flux Improvement | 5 | Factor | Compared to unstructured diamond |
| Nanopillar Count Rate (Saturated) | 760 | kHz | Single NV center in nanopillar |
| Maximum SSR Fidelity (F) | 92 | % | Achieved with N = 400 repetitions |
| Electron Spin T1 Time | 3.5 ± 0.1 | ms | Measured via relaxometry |
| Electron Spin T2* (Hahn) Time | 108.1 ± 1.4 | ”s | Measured via Hahn echo sequence |
| Magnetic Bias Field (B0) | 398 | mT | Field used for primary measurements |
| Diamond Membrane Thickness | ~30 | ”m | Electronic-grade SCD substrate |
| 15N+ Implantation Energy | 5 | keV | Used for shallow NV creation |
| Annealing Temperature | 950 | °C | Post-implantation thermal treatment |
Key Methodologies
Section titled âKey MethodologiesâThe successful implementation of the quantum-assisted magnetometer relied on precise material engineering and complex spin manipulation sequences.
- Substrate Preparation: Electronic-grade CVD diamond was sourced and processed into thin membranes (~30 ”m thickness).
- NV Center Creation: The membranes were implanted with 15N+ ions at 5 keV to create shallow NV centers, followed by high-temperature annealing (950 °C) for defect activation and lattice repair.
- Photon Collection Optimization: Tapered nanopillars were fabricated on the diamond surface using nano-engineering techniques to enhance the collection efficiency of NV fluorescence by acting as waveguides.
- Magnetic Field Alignment: A custom-designed NdFeB permanent magnet assembly was used to generate a strong, highly stable bias field (398 mT), precisely aligned along the NV centerâs axis (54.75° relative to the (100) surface) using xyz slip stick positioners.
- Thermal Stabilization: A double-layer temperature stabilization system (PI loops) was implemented to maintain temperature stability of 0.04 K peak-to-peak, ensuring the NV center transition frequency drift remained below 0.5 MHz over 10 hours.
- Spin Manipulation: The electron spin was controlled via GHz Microwave (MW) radiation, and the 15N nuclear spin was controlled via MHz Radiofrequency (RF) fields, delivered via a coplanar waveguide stripline on the diamond surface.
- SSR Implementation: The measurement sequence utilized a controlled NOT (CeNOTn) gate (RF pulse) to transfer electron spin information to the nuclear spin, followed by repetitive CnNOTe gates (MW pulses and laser readout) to achieve high-fidelity, non-destructive readout.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-specification diamond materials and custom processing required to replicate and advance this quantum metrology research. Our MPCVD expertise ensures the highest quality substrates necessary for long coherence times and high-fidelity quantum operations.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the long T1 and T2* coherence times critical for high-fidelity SSR, researchers require the lowest defect density diamond available.
- Optical Grade Single Crystal Diamond (SCD): We recommend our electronic/optical grade SCD wafers. These materials offer ultra-low nitrogen concentration (< 1 ppb), minimizing paramagnetic defects that limit T1 and T2* times, essential for achieving the reported 3.5 ms T1.
- Thin Membranes: The experiment utilized a ~30 ”m membrane. 6CCVD routinely supplies custom-thickness SCD plates ranging from 0.1 ”m up to 500 ”m, perfectly matching the requirements for membrane fabrication and subsequent nanopillar etching.
- Isotopically Pure Substrates: For advanced nuclear spin applications (like the 15N system used here, or 13C decoupling), 6CCVD can supply isotopically enriched SCD substrates, providing a clean quantum environment for enhanced memory and sensing.
Customization Potential
Section titled âCustomization PotentialâThe complexity of this setupâinvolving thin membranes, nanopillars, and integrated microwave deliveryâdemands specialized fabrication capabilities.
| Research Requirement | 6CCVD Custom Solution | Technical Specification Match |
|---|---|---|
| Thin Substrate | Custom wafer thinning and cutting services. | SCD thickness range: 0.1 ”m to 500 ”m. |
| Microwave Delivery | Custom metalization for coplanar waveguide striplines. | Internal capability for Au, Pt, Pd, Ti, W, Cu deposition. |
| Surface Quality | Ultra-low roughness polishing for lithography and nanopillar etching. | Polishing to Ra < 1 nm (SCD) for optimal lithographic patterning. |
| Custom Dimensions | Supply of large-area SCD or PCD plates for scaling up. | Plates/wafers up to 125 mm (PCD) or custom SCD dimensions. |
| Post-Processing Support | Consultation on implantation and annealing protocols. | Support for achieving specific NV center densities and depths (e.g., 5 keV implantation depth). |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of the Nuclear Quantum-Assisted Magnetometer relies heavily on optimizing the NV creation process (implantation and annealing) and integrating the diamond with complex microwave circuitry.
- NV Center Optimization: 6CCVDâs in-house PhD team specializes in material science for quantum applications. We offer consultation on selecting the optimal SCD grade and surface termination necessary to maximize NV yield and maintain long coherence times for similar Quantum Sensing and Scanning Probe Microscopy projects.
- Integration Assistance: We provide expert advice on integrating diamond substrates with custom metalization patterns (e.g., Ti/Pt/Au) for efficient MW/RF delivery, crucial for implementing the CNOT gates used in the SSR scheme.
- Global Logistics: We ensure reliable, secure global shipping (DDU default, DDP available) for sensitive, high-value diamond substrates, minimizing delays in critical research timelines.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Magnetic sensing and imaging instruments are important tools in biological and material sciences. There is an increasing demand for attaining higher sensitivity and spatial resolution, with implementations using a single qubit offering potential improvements in both directions. In this article we describe a scanning magnetometer based on the nitrogen-vacancy center in diamond as the sensor. By means of a quantum-assisted readout scheme together with advances in photon collection efficiency, our device exhibits an enhancement in signal to noise ratio of close to an order of magnitude compared to the standard fluorescence readout of the nitrogen-vacancy center. This is demonstrated by comparing non-assisted and assisted methods in a T1 relaxation time measurement.