Optically detected flip-flops between different spin ensembles in diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-04-30 |
| Journal | Physical review. B./Physical review. B |
| Authors | Sergei Masis, Sergey Hazanov, Nir Alfasi, Oleg Shtempluck, Eyal Buks |
| Institutions | Technion â Israel Institute of Technology |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research employs Optically Detected Magnetic Resonance (ODMR) to investigate dipolar interactions in diamond, focusing on optimizing spin cross-polarization for enhanced sensor sensitivity.
- Core Achievement: Direct and unambiguous detection of stimulated spin flip-flops between different NV- crystallographic orientations and between NV- centers and Substitutional Nitrogen (P1) defects.
- Sensitivity Enhancement: The high sensitivity achieved is attributed to a combination of high NV- density (3.25 x 1017 cm-3), cryogenic temperature (3.5 K), and lock-in amplification.
- Cross-Polarization Optimization: The findings provide critical data for optimizing cross-polarization protocols (like DNP), which is essential for improving the sensitivity of diamond-based magnetometers and detectors.
- Dipolar Interaction Study: Observation of resonant spin flip-flips (second Larmor line) within a single NV- ensemble, confirming strong dipolar spin-spin interaction at double the Larmor frequency.
- Acoustic Coupling: Strain coupling between NV- centers and bulk acoustic standing waves in the 0.5 mm thick diamond wafer was detected, characterized by a beating frequency of 20.4 MHz.
- P1 Role: The P1 ensemble, which is three times more concentrated than the NV- centers, is proposed as a potential low-noise spin bath for NV- or as a target ensemble for applications such as P1 masers.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material | Type Ib HPHT | N/A | Single crystal, (110) orientation. |
| Measurement Temperature | 3.5 | K | All ODMR measurements performed. |
| Excitation Wavelength | 637 | nm | Red laser used to excite NV centers at the ZPL. |
| NV Zero Field Splitting (DNV) | 2.87 | GHz | Standard parameter. |
| Electron Gyromagnetic Ratio (Îłe) | 28.03 | GHz/T | Standard parameter. |
| Initial Nitrogen Concentration | < 200 | ppm | Before irradiation. |
| Electron Irradiation Dose | 8 x 1018 | e/cm2 | Using 2.8 MeV electrons. |
| Annealing Temperature | 900 | °C | Annealed for 2 hours. |
| NV- Concentration (nNV) | 3.25 x 1017 | cm-3 | Measured fluorescent count. |
| NV-:P1 Concentration Ratio | 1:3 | N/A | Estimated from ESR data. |
| Diamond Wafer Thickness (t) | 0.5 | mm | Used for acoustic mode analysis. |
| Acoustic Beating Frequency (fa) | 20.4 | MHz | Characteristic frequency of strain coupling to bulk acoustic waves. |
| MW Modulation Frequency | 151 | Hz | Sine wave used for amplitude modulation and lock-in detection. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized Optically Detected Magnetic Resonance (ODMR) on a specially prepared diamond sample under cryogenic conditions.
- Sample Preparation: A Type Ib HPHT single crystal diamond, grown along the (110) face, was selected.
- NV Center Creation: The diamond was irradiated with 2.8 MeV electrons at a high dose (8 x 1018 e/cm2) to create vacancies.
- Defect Activation: The sample was annealed at 900 °C for 2 hours and subsequently boiled in a mixture of Perchloric, Sulfuric, and Fuming Nitric acids.
- Cryogenic Setup: The diamond wafer was mounted on a sapphire substrate and cooled to 3.5 K for all measurements.
- Magnetic Field Application: A strong longitudinal magnetic field (B) was generated by a main superconducting solenoid, aligned with the α([111]) axis of the diamond. Smaller side coils were used to compensate for sample misalignment.
- MW Excitation: Microwave (MW) radiation was delivered via a loop antenna pressed against the diamond face. The MW signal was 100% amplitude modulated at 151 Hz.
- Optical Excitation: A 637 nm red laser was used to excite the NV centers at the Zero-Phonon Line (ZPL), minimizing sample heating.
- Photoluminescence (PL) Detection: PL was collected via a multi-mode optical fiber, filtered (700 nm long pass), and measured by a photo-diode (PD).
- Signal Acquisition: The PD signal was demodulated using a lock-in amplifier synchronized to the 151 Hz MW modulation frequency to record the ODMR amplitude.
Commercial Applications
Section titled âCommercial ApplicationsâThe demonstrated control over spin ensembles and dipolar interactions is highly relevant for advanced quantum technologies and sensing applications.
- Quantum Sensing and Metrology: Optimizing cross-polarization (DNP) efficiency to maximize NV- spin polarization, leading directly to improved signal-to-noise ratio and sensitivity in diamond-based magnetometers and thermometers.
- Solid-State Quantum Information Processing: Utilizing controlled NV-NV and NV-P1 flip-flop interactions as a mechanism for robust quantum state transfer and entanglement generation in solid-state quantum registers.
- Dynamic Nuclear Polarization (DNP): Improving DNP protocols for hyperpolarization applications (e.g., enhancing signals in Nuclear Magnetic Resonance/Magnetic Resonance Imaging), using the P1 defects as efficient polarization sources.
- Cryogenic Microwave Amplification (Masers): Leveraging the P1 ensemble as a potential active medium for developing P1 masers, where the NV- centers could be used for optical initialization or readout.
- Hybrid Quantum Systems: The study of strain coupling to bulk acoustic modes (20.4 MHz) is crucial for engineering high-fidelity NV-based optomechanical and acoustic quantum transducers.
View Original Abstract
We employ the technique of optical detection of magnetic resonance to study\ndipolar interaction in diamond between nitrogen-vacancy color centers of\ndifferent crystallographic orientations and substitutional nitrogen defects. We\ndemonstrate optical measurements of resonant spin flips-flips (second Larmor\nline), and flip-flops between different spin ensembles in diamond. In addition,\nthe strain coupling between the nitrogen-vacancy color centers and bulk\nacoustic modes is studied using optical detection. Our findings may help\noptimizing cross polarization protocols, which, in turn, may allow improving\nthe sensitivity of diamond-based detectors.\n