| Metadata | Details |
|---|
| Publication Date | 2023-10-19 |
| Journal | Proceedings of International Exchange and Innovation Conference on Engineering & Sciences (IEICES) |
| Authors | Ali Abdelrahman, Abdelrahman Zkria, Tsuyoshi Yoshitake |
| Institutions | Ain Shams University, Kyushu University |
| Citations | 2 |
| Analysis | Full AI Review Included |
- Core Value Proposition: Negatively charged Nitrogen-Vacancy (NV-) color centers in diamond serve as robust, stable quantum sensors, enabling high-accuracy AC/DC magnetometry and quantum sensing applications at room temperature.
- Sensitivity Drivers: Magnetometry sensitivity (NDC, NAC) is critically dependent on maximizing NV- concentration (N) and optimizing the coherence time (T2), where sensitivity scales inversely with the square root of N * T2.
- Fabrication Methods: NV centers are formed either natively during CVD, via N ion implantation into pure diamond, or by electron/ion irradiation of N-rich diamond to create vacancies (V).
- Post-Treatment Requirement: Subsequent high-temperature thermal annealing (T > 800 °C, often 1800 °C) is mandatory to mobilize vacancies, allowing them to pair with substitutional Nitrogen (P1 centers) to form NV centers.
- Conversion Limitation: The conversion efficiency from precursor P1 centers to functional NV- centers remains low (maximum reported 16%), limiting achievable NV- concentration.
- Primary Challenge: Residual P1 centers and complex nonradiative defects severely degrade the coherence time (T2) by contributing to the electronic spin bath, thus reducing overall sensor sensitivity.
- Spatial Resolution: For enhanced sensing and imaging, NV centers must be fabricated near the diamond surface (hundreds of nm depth), which is typically achieved via N ion implantation.
| Parameter | Value | Unit | Context |
|---|
| NV Center Zero-Field Splitting (D) | 2.87 | GHz | Separation between ms=0 and ms=±1 ground states. |
| Single NV Coherence Time (T2) | Up to 2 | ”s | High sensitivity operation at ambient conditions. |
| Optimal Annealing Temperature | 1800 | °C | Used to minimize post-treatment damage and enhance diamond lattice recovery. |
| Minimum Activation Temperature | > 800 | °C | Required to activate vacancy mobility for NV formation. |
| Maximum P1-to-NV Conversion Efficiency | 16 | % | Achieved using 3 MeV electron irradiation on high [N] diamond. |
| 13C Isotope Natural Concentration | ~1.1 | % | Equivalent to 10700 ± 800 ppm; primary source of nuclear spin bath dephasing in low [N] diamond. |
| Electron Irradiation Energy (Example) | 1, 2, 5 | MeV | Used for homogeneous vacancy creation in N-rich diamond. |
| NV Center Orientation Limit | 4 | Orientations | Limits spatial resolution and can create âdead pointsâ in sensing. |
- Native Formation (CVD): NV centers are constructed directly within the diamond lattice during Chemical Vapor Deposition (CVD). This method typically yields very low NV concentrations (a few parts per billion).
- Nitrogen Ion Implantation: Used for diamond plates with low native nitrogen concentration ([N]). N ions (tens of KeV energy) are implanted to introduce both N atoms and vacancies, creating NV centers near the surface (hundreds of nm depth).
- Ion/Electron Irradiation: Used for nitrogen-rich diamond (Type Ib). High-energy irradiation (electrons, protons, or gamma-rays) is used to create a homogeneous distribution of vacancies (V) within the crystal structure.
- Thermal Annealing: A crucial post-treatment step where the diamond is heated (T > 800 °C, often up to 1800 °C). This mobilizes the created vacancies (V) to trap existing substitutional nitrogen atoms (P1 centers), forming the neutral NV° center (P1 + V â NV°).
- Charge State Conversion: The neutral NV° center is converted to the desired negatively charged NV- state by capturing an electron from other nearby defects, such as P1 centers (P1 + NV° â NV- + N+).
- Quantum Sensing and Metrology:
- High-sensitivity AC/DC magnetometry (measuring magnetic field magnitude and direction).
- Quantum thermometry, electric field sensing, pressure, and strain sensing.
- Biomedical and Nanoscale Imaging:
- Nanoscale magnetometry and tracking inside living cells (requires nanocrystalline diamond hosts for biocompatibility).
- High-accuracy sensing in chemically inert environments suitable for biological systems.
- Quantum Information Technology:
- Development of quantum bits (qubits) based on stable spin states.
- Single photon emitters for quantum communications.
View Original Abstract
Color centers in diamonds have promising and unique properties that can be optimized and engineered for several quantum-sensing applications. The negatively charged Nitrogen-vacancy (NV) center is one of the outstanding candidates due to its stable luminescence and spin features. It has a long coherence time that can be initialized and manipulated with high accuracy at room temperature. Nonetheless, many parameters, namely; nonradiative centers, complex defects, and nitrogen-based defect centers can severely affect the desirable properties of these NV centers. In this review, we highlight the recent advances of color center fabrication, parameters optimization, and current challenges to enhance these properties, with main focus on magnetometry applications.