Optical Spin Initialization of Nitrogen Vacancy Centers in a 28Si-Enriched 6H-SiC Crystal for Quantum Technologies
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-04-01 |
| Journal | Journal of Experimental and Theoretical Physics Letters |
| Authors | Fadis F. Murzakhanov, Margarita A. Sadovnikova, G. V. Mamin, D. V. Shurtakova, E. N. Mokhov |
| Institutions | Ioffe Institute, Kazan Federal University |
| Citations | 5 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: High-Coherence Spin Centers for Quantum Technologies
Section titled âTechnical Analysis and Documentation: High-Coherence Spin Centers for Quantum TechnologiesâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the optical spin initialization and long-coherence properties of Nitrogen-Vacancy (NV-) centers in isotopically enriched 6H-Silicon Carbide (SiC), a critical step toward scalable quantum technologies.
- Core Achievement: Optical spin initialization and readout of three distinct axial NV- centers in 28Si-enriched 6H-SiC using high-frequency (94 GHz) pulsed Electron Paramagnetic Resonance (EPR).
- Coherence Performance: Achieved long ensemble relaxation times at 150 K: Spin-Lattice ($T_1$) of 1.3 ms and Spin-Spin ($T_2$) of 59 ”s, demonstrating robust spin coherence in the SiC matrix.
- Material Purity Impact: The use of nonmagnetic 28Si (nuclear spin $I=0$) resulted in extremely narrow EPR absorption lines (450 kHz FWHM), enabling highly selective excitation and quantum manipulation.
- Methodology: The study utilized nonresonant optical excitation ($\lambda = 980$ nm) combined with high-field EPR (3.4 T) to achieve effective spin alignment and suppress spin mixing.
- Quantum Relevance: The results confirm the viability of high-spin photoactive centers in broadband semiconductors for developing quantum spintronics elements, directly competing with traditional diamond NV systems.
- 6CCVD Value Proposition: While SiC is presented as an alternative, 6CCVD provides superior, scalable, isotopically pure Single Crystal Diamond (SCD) solutions that offer inherently longer coherence times and higher thermal stability than SiC defects.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the photoinduced EPR spectroscopy of NV- centers in 6H-28SiC.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Crystal Matrix | 6H-28SiC | N/A | Isotopically enriched (approx. 99% 28Si, $I=0$) |
| EPR Frequency | 94 | GHz | W band, pulsed EPR method |
| Magnetic Field ($B_0$) | 3.4 | T | High-field regime, Zeeman interaction dominates |
| Measurement Temperature | 150 | K | Optimal temperature for photoactive defect observation |
| Optical Excitation Wavelength ($\lambda$) | 980 | nm | CW solid state laser (Near-Infrared) |
| Spin-Lattice Relaxation Time ($T_1$) | 1.3 | ms | Longitudinal relaxation (c |
| Spin-Spin Relaxation Time ($T_2$) | 59 | ”s | Transverse relaxation (c |
| EPR Linewidth (FWHM) | 450 | kHz | Extremely narrow, indicating high crystal quality |
| Zero-Field Splitting ($D$) - NVk1k2 | 1358 | MHz | Axial NV- center parameter |
| Zero-Field Splitting ($D$) - NVhh | 1331 | MHz | Axial NV- center parameter |
| Electron Irradiation Fluence | $4 \times 10^{18}$ | cm-2 | Used to form vacancy defects |
| Annealing Temperature | 900 | °C | Optimal for stable NV- center formation |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on high-purity material synthesis and advanced pulsed EPR techniques to characterize the NV- centers.
- Material Synthesis: Bulk 6H-28SiC crystals were grown using the high-temperature physical vapor deposition (HT-PVD) method, utilizing a precursor enriched with the nonmagnetic 28Si isotope (up to $\approx$99%).
- Defect Creation: Crystals were irradiated with 2-MeV electrons (fluence of $4 \times 10^{18}$ cm-2) to induce silicon and carbon vacancy defects.
- Defect Stabilization: Irradiated crystals were annealed in an argon atmosphere for 2 hours at $T = 900$ °C to promote the formation of stable NV- centers.
- EPR Setup: Pulsed EPR spectra were detected at $T = 150$ K using a commercial Bruker Elexsys E680 spectrometer equipped with a helium flow cryostat and a superconducting magnet (up to 6 T).
- Optical Initialization: Photoinduced EPR was performed using a continuous wave (CW) solid state laser ($\lambda = 980$ nm) with an output power up to 500 mW to achieve nonresonant excitation ($^3A \rightarrow ^3E$).
- Relaxation Time Measurement:
- Transverse relaxation ($T_2$) was determined using the Hahn pulse sequence ($\pi/2 - \tau - \pi$).
- Longitudinal relaxation ($T_1$) was determined using the âinversion-recoveryâ sequence ($\pi - T_1 - \pi/2 - \tau - \pi$).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the critical need for high-purity, isotopically controlled materials to achieve long spin coherence in solid-state quantum systems. While SiC is presented as an alternative, 6CCVDâs expertise in MPCVD diamond provides superior performance and scalability for quantum applications.
The paper notes that the âexpensive production and low technological efficiency of a diamond matrix complicate extensive integration.â 6CCVD directly addresses this challenge by offering high-quality, cost-effective, and scalable MPCVD diamond solutions.
| Research Requirement/Challenge | 6CCVD Material Solution | 6CCVD Capability & Advantage |
|---|---|---|
| Need for High Coherence ($T_1$, $T_2$) | Optical Grade Single Crystal Diamond (SCD) | SCD offers inherently superior coherence properties. 6CCVDâs low-strain, high-purity SCD typically achieves $T_2$ times significantly longer than the 59 ”s reported for SiC, especially at room temperature, which is essential for practical quantum devices. |
| Isotopic Purity (Minimizing Spin Noise) | Isotopically Purified 12C SCD | The SiC study used 28Si ($I=0$) to achieve narrow lines. 6CCVD provides SCD with controlled isotopic purity (e.g., < 1% 13C), minimizing the nuclear spin bath and maximizing the coherence time for NV centers. |
| Scalability and Integration | Large-Area Polycrystalline Diamond (PCD) & SCD | The SiC samples were small (450 x 450 ”m). 6CCVD offers custom plates/wafers up to 125 mm (PCD) and large SCD substrates (up to 10 mm thick), enabling integration into standard semiconductor processing lines. |
| High-Frequency Microwave/RF Delivery | Custom Metalization Services | The experiment required high-frequency (94 GHz) pulsed EPR. 6CCVD offers in-house metalization (Au, Pt, Pd, Ti, W, Cu) for fabricating integrated microwave structures (e.g., coplanar waveguides) directly onto the diamond surface for efficient spin manipulation. |
| Optical Readout Quality ($\lambda=980$ nm) | Precision Polishing (Ra < 1 nm) | High-quality optical interfaces are crucial for efficient spin initialization and readout. 6CCVD guarantees ultra-low surface roughness ($R_a < 1$ nm for SCD, $R_a < 5$ nm for inch-size PCD) to minimize scattering losses. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in defect engineering and material optimization for quantum applications. We can assist researchers in transitioning from SiC-based studies to high-performance diamond, including:
- Material Selection: Advising on the optimal SCD grade (e.g., low-nitrogen, high-purity) and thickness (0.1 ”m to 500 ”m) for specific NV center creation methods (e.g., ion implantation or in-situ doping).
- Custom Dimensions: Providing laser cutting and shaping services to meet unique device geometries required for high-field EPR or integrated quantum circuits.
- Global Logistics: Ensuring reliable, global shipping (DDU default, DDP available) for sensitive quantum materials.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
High-spin defect centers in crystal matrices are used in quantum computing technologies, highly sensitive sensors, and single-photon sources. In this work, optically active nitrogen-vacancy color centers NV - in a 28 Si-enriched (nuclear spin $$I = 0$$ ) 6H- 28 SiC crystal have been studied using the photoinduced ( $$\lambda $$ = 980 nm) high-frequency (94 GHz, 3.4 T) pulsed electron paramagnetic resonance method at a temperature of $$T = 150{\kern 1pt} $$ K. Three structurally nonequivalent types of NV - centers with axial symmetry have been identified and their spectroscopic parameters have been determined. Long spin-lattice, $${{T}{1}} = 1.3{\kern 1pt} $$ ms, and spin-spin, $${{T}{2}} = 59{\kern 1pt} $$ ÎŒs, ensemble relaxation times of NV - centers with extremely narrow (450 kHz) absorption lines allow highly selective excitation of resonant transitions between sublevels $$({{m}_{I}})$$ caused by the weak hyperfine interaction $$(A \approx 1{\kern 1pt} $$ MHz) with 14 N $$(I = 1)$$ nuclei for the quantum manipulation of the electron spin magnetization.