Noninvasive Imaging Method of Microwave Near Field Based on Solid-State Quantum Sensing
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-04-05 |
| Journal | IEEE Transactions on Microwave Theory and Techniques |
| Authors | Bo Yang, Yue Dong, Zhen-Zhong Hu, Guo Quan Liu, Yong-Jin Wang |
| Institutions | Peking University, Nanjing University of Posts and Telecommunications |
| Citations | 53 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Non-Invasive MW Near-Field Imaging via NV Diamond
Section titled âTechnical Documentation & Analysis: Non-Invasive MW Near-Field Imaging via NV DiamondâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates a novel, non-invasive method for quantitative microwave (MW) near-field imaging using ensemble Nitrogen-Vacancy (NV) centers in diamond, a critical advancement for integrated circuit diagnostics.
- Core Achievement: Developed a quantum sensing approach utilizing synchronous pulsed sequences (Laser, MW, CCD) and ODMR/Rabi frequency analysis to achieve high-resolution, non-invasive MW near-field imaging.
- Resolution & Application: Achieved spatial resolution approaching the optical diffraction limit, making the technique highly promising for Monolithic Microwave Integrated Circuit (MMIC) chip local diagnosis, failure analysis, and antenna characterization.
- Quantitative Measurement: The methodology allows for the full reconstruction of the local MW field vector (amplitude and phase) by measuring both left-hand and right-hand circular polarizations across the four crystalline NV axes.
- Material Requirement: The study confirms the necessity of using ultrathin diamond films (micrometer thickness) placed in close proximity to the circuit surface to minimize invasiveness and maximize resolution.
- Material Limitation Identified: The short Rabi oscillation decay time (TR = 71 ns) and electron spin decay time (T2 = 52 ns) observed in the tested Ib-type diamond particles highlight the critical need for high-purity, low-defect Single Crystal Diamond (SCD) materials to enhance sensitivity.
- 6CCVD Value Proposition: 6CCVD specializes in providing the high-purity, custom-thickness SCD wafers required to optimize NV center coherence times (T2) and enable the next generation of chip-scale quantum sensing devices.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental setup and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Sensing Element | Ensemble NV Centers | N/A | Solid State Quantum Sensor |
| Required Diamond Thickness | Micrometer Thinness | ”m | For high-resolution proximity imaging |
| Laser Excitation Wavelength | 532 | nm | Green Laser Pumping |
| Laser Output Power | 300 | mW | Used for NV center excitation |
| MW Source Maximum RF Power | +14 | dBm | Input to power amplifier |
| MW Pulse Minimum Length | 12 | ns | Limited by pulse generator resolution |
| Zero-Field Splitting (ZFS) Frequency | 2.87 | GHz | NV center resonance at room temperature |
| Antenna Working Frequency | 2951 | MHz | Frequency tuned for testing |
| Rabi Oscillation Decay Time (TR) | 71 | ns | Limits detection sensitivity |
| Electron Spin Decay Time (T2) | 52 | ns | Measured via Ramsey oscillation |
| Fluorescence Collection NA | 0.54 | N/A | Numerical Aperture of Objective Lens |
| Polishing Requirement (SCD) | Rougher Surface | N/A | Strived for rougher surface (compared to single crystal) for easier FL detection |
Key Methodologies
Section titled âKey MethodologiesâThe experimental system relies on precise synchronization and advanced quantum measurement techniques:
- System Construction and Synchronization: A non-confocal optical experimental system based on Kohler illumination was constructed. A TTL synchronous system was implemented to coordinate the 532 nm pulsed laser, the MW signal source, the Acousto-Optical Modulator (AOM), the MW switch, and the CCD camera triggers.
- Optical Excitation and Collection: A 532 nm green laser excites the NV centers. Kohler illumination ensures a homogeneous and uniformly enlarged illuminated area on the diamond film, maximizing the field of view (FOV). Fluorescence (FL) is collected by a high-NA (0.54) objective lens and filtered (600 nm high pass filter) before reaching the CCD camera.
- Frequency Tuning (Zeeman Splitting): A uniform external static magnetic field is imposed on the diamond probe, parallel to the NV center axial direction. This Zeeman splitting tunes the NV resonance frequency to match the working frequency of the Antenna Under Test (AUT).
- Differential Measurement: A differential measurement method is used, comparing a capture frame (FL integration with MW resonance) against a reference frame (FL integration without MW resonance) to isolate the pure MW field information and reduce measurement noise.
- MW Field Strength Calculation: MW strength is calculated either by fitting the Rabi oscillation frequency (for absolute accuracy) or by analyzing the area of the resonance peak in the ODMR spectrum (for higher Signal-to-Noise Ratio, SNR, in ensemble measurements).
- Full Vector Reconstruction: A complex algorithm is utilized to derive the full 3D MW vector (Bx, By, Bz, amplitude, and phase) by measuring the left-hand and right-hand circular polarizations across the four possible NV axes in the diamond crystal lattice.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research confirms the critical role of high-quality, custom-engineered diamond material for advancing solid-state quantum sensing. 6CCVD is uniquely positioned to supply the next-generation materials required to move this technology from particle-based demonstration to chip-scale integration.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this research, specifically addressing the need for improved coherence times (TR and T2) and ultrathin films, 6CCVD recommends:
- Optical Grade Single Crystal Diamond (SCD): Required for maximizing T2 coherence times. Our SCD material features extremely low native defect concentrations (P1 centers and broad spin), which are cited as the primary cause for the short TR (71 ns) observed in the paperâs Ib-type diamond.
- Custom Thickness SCD Wafers: The paper explicitly calls for âdiamond thin film with micrometer thinness.â 6CCVD offers SCD plates with precise thickness control from 0.1 ”m up to 500 ”m, allowing researchers to select the optimal thickness (e.g., 10 ”m to 50 ”m) for minimal invasiveness and maximum proximity to the MMIC surface.
Customization Potential
Section titled âCustomization PotentialâThe integration of this sensing method onto MMIC chips requires highly customized material preparation and integration services, all available in-house at 6CCVD:
| Research Requirement | 6CCVD Customization Capability | Benefit to Researcher |
|---|---|---|
| Ultrathin Film Dimensions | Custom Plates/Wafers up to 125mm (PCD) or custom SCD plates. | Enables large-area imaging or integration onto standard chip carriers. |
| Precise Thickness Control | SCD thickness control from 0.1 ”m to 500 ”m. | Allows precise tuning of the sensing volume and proximity to the AUT. |
| Surface Quality | SCD Polishing to Ra < 1 nm. | Provides an atomically flat surface necessary for subsequent NV creation (e.g., implantation) and high-quality optical coupling. |
| Integrated Contacts | Internal Metalization Capabilities (Au, Pt, Pd, Ti, W, Cu). | Essential for integrating on-chip MW waveguides or contact pads directly onto the diamond sensor surface. |
| Substrate Options | Substrates up to 10 mm thick available for robust handling and thermal management. | Provides mechanical stability for thin films during complex experimental setups. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in optimizing MPCVD growth parameters to meet stringent quantum sensing requirements. We can assist researchers with:
- Material Selection for Enhanced Coherence: Consulting on the optimal SCD grade and post-processing (e.g., high-pressure, high-temperature annealing) to minimize P1 centers and maximize T2 coherence times for similar MW Near-Field Quantum Sensing projects.
- Integration Strategy: Advising on the best methods for thin film handling, bonding, and integration onto custom MMIC substrates.
- Global Logistics: Ensuring reliable, fast global shipping (DDU default, DDP available) of sensitive, high-value diamond materials.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In this paper, we propose a non-invasive imaging method of microwave near\nfield using a diamond containing nitrogen-vacancy centers. We applied\nsynchronous pulsed sequence combined with charge coupled device camera to\nmeasure the amplitude of the microwave magnetic field. A full reconstruction\nformulation of the local field vector, including the amplitude and phase, is\ndeveloped by measuring both left and right circular polarizations along the\nfour nitrogen-vacancy axes. Compared to the raster scanning approach, the two\ndimensional imaging method is promising for application to circuit failure\nanalysis. A diamond film with micrometer thinness enables high-resolution near\nfield imaging. The proposed method is expected to have applications in\nmonolithic-microwave-integrated circuit chip local diagnosis, antenna\ncharacterization, and field mode imaging of microwave cavities and waveguides.\n
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2006 - Köhler illumination for high-resolution optical metrology
- 2006 - Pulsed magnetic resonance on single defect centers in diamond