Optical driving, spin initialization and readout of single SiV− centers in a Fabry-Perot resonator
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2023-10-16 |
| Journal | Communications Physics |
| Authors | Gregor Bayer, Robert Berghaus, Selene Sachero, Andrea B. Filipovski, Lukas Antoniuk |
| Institutions | Université de Tours, Centre National de la Recherche Scientifique |
| Citations | 17 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Optical Driving of Single SiV- Centers in a Fabry-Perot Resonator
Section titled “Technical Documentation & Analysis: Optical Driving of Single SiV- Centers in a Fabry-Perot Resonator”Executive Summary
Section titled “Executive Summary”This research demonstrates a critical step toward scalable quantum communication networks by realizing a highly stable spin-photon interface using Silicon Vacancy (SiV-) centers in nanodiamonds (NDs) coupled to a Fabry-Perot (FP) microcavity.
- Quantum Repeater Platform: The system establishes a promising, passively stable platform for quantum repeater nodes, utilizing the SiV- center’s favorable optical properties.
- Coherent Optical Driving: Achieved high-speed coherent optical driving between the ground and excited states, yielding a Rabi-frequency of 330 MHz.
- Purcell Enhancement: Significant lifetime shortening was demonstrated, with an extrapolated Purcell factor (Fp) of 1.61 ± 0.06, essential for efficient spin-photon coupling.
- Rapid Spin Initialization: Demonstrated all-optical electron spin initialization within 67 ns, achieving a high fidelity of 80% under strong magnetic fields (up to 3.2 T).
- Cryogenic Stability: The open FP microcavity operates stably at 4 K (liquid Helium bath), providing high cooling power and mechanical stability without active length stabilization.
- Material Requirement: The use of small nanodiamonds (200-300 nm) minimizes scattering losses, highlighting the need for ultra-pure, high-quality diamond material precursors.
Technical Specifications
Section titled “Technical Specifications”The following hard data points were extracted from the experimental results, demonstrating key performance metrics for the SiV- center quantum node.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Operating Temperature | 4 | K | Liquid Helium bath cryostat |
| Maximum Magnetic Field (B) | 3.2 | T | Used for spin initialization and readout |
| Rabi-Frequency (ΩR/2π) | 330 ± 50 | MHz | Coherent optical driving speed |
| Spin Initialization Time (Tinit) | 67 ± 6 | ns | Time constant for spin-up state pumping |
| Spin Initialization Fidelity | 80 ± 4 | % | Achieved via all-optical pumping |
| Electron Spin Lifetime (Tspin) | 350 ± 40 | ns | Measured recovery time |
| Nanodiamond Size (Lateral) | 200 - 300 | nm | Used for SiV- incorporation |
| Excitation Wavelength (λlas) | 736.7 | nm | Resonant excitation |
| Cavity Quality Factor (Q) | 22,000 (m=8) to 30,000 (m=11) | Dimensionless | Depending on effective cavity length |
| Loaded Cavity Finesse (F) | 2700 ± 500 | Dimensionless | Experimentally achieved |
| Extrapolated Purcell Factor (Fp) | 1.61 ± 0.06 | Dimensionless | Lower bound estimate |
| Zero-Power Linewidth | 107 - 168 | MHz | Depending on cavity length |
Key Methodologies
Section titled “Key Methodologies”The experiment relied on precise material preparation and advanced nanomanipulation techniques to integrate the color centers into the optical resonator.
- Nanodiamond Synthesis: Nanodiamonds (NDs) containing ingrown SiV- centers were synthesized, likely using Chemical Vapor Deposition (CVD) precursors followed by High-Pressure/High-Temperature (HPHT) treatment with silicon and nitrogen sources.
- Pre-Characterization: NDs were pre-characterized using confocal spectroscopy to ensure the presence of spectrally stable SiV- centers.
- Precision Placement: An Atomic Force Microscope (AFM)-based pick-and-place technique was employed to transfer and position candidate NDs (200-300 nm size) onto the curved mirror (Radius of Curvature RoC ≈ 8 µm) of the FP microcavity.
- Microcavity Fabrication: The hemispherical FP microcavity mirrors were coated with Distributed Bragg Reflectors (DBRs). The curved mirror was fabricated using focused ion beam milling.
- Cryogenic Operation: The open cavity system was operated in direct contact with a liquid Helium bath at 4 K, ensuring high passive mechanical stability and superior cooling power.
- Spin Manipulation: All-optical initialization and readout were performed by applying 400 ns laser pulses resonant to the spin-cycling transition (C3) while applying a strong external magnetic field (up to 3.2 T) along the cavity axis.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The successful replication and scaling of this quantum repeater platform require ultra-high-purity diamond materials and precision engineering capabilities, which are core competencies of 6CCVD.
Applicable Materials for Quantum Repeaters
Section titled “Applicable Materials for Quantum Repeaters”While the paper utilized nanodiamonds, next-generation integrated quantum devices require bulk, low-strain diamond for superior coherence and scalability.
- Optical Grade Single Crystal Diamond (SCD):
- Requirement Match: Essential for minimizing strain broadening and maximizing the electron spin coherence time (T2), which is critical for long-lived quantum memories.
- 6CCVD Offering: Ultra-high purity SCD substrates, ideal for controlled SiV- creation via implantation or delta-doping during growth, ensuring precise placement and spectral stability superior to NDs.
- Custom SCD Membranes:
- Requirement Match: The integration of FP cavities or photonic crystal structures requires thin, high-quality diamond membranes.
- 6CCVD Offering: SCD plates available in thicknesses from 0.1 µm up to 500 µm, enabling the fabrication of integrated photonic devices and membranes for enhanced Purcell coupling.
Customization Potential for Integrated Photonics
Section titled “Customization Potential for Integrated Photonics”6CCVD provides the necessary precision engineering services to transition this research from a bulk cryostat setup to a scalable, integrated chip platform.
| Service | Research Requirement | 6CCVD Capability |
|---|---|---|
| Substrate Dimensions | Requires small, high-quality material for cavity integration. | Custom plates/wafers up to 125 mm (PCD) and large-area SCD for scalability. |
| Surface Quality | High-finesse cavities require extremely low scattering loss. | SCD polishing achieving Ra < 1 nm; Inch-size PCD polishing Ra < 5 nm. |
| Metalization & DBRs | DBRs are required for the FP cavity mirrors. | In-house metalization services including Au, Pt, Pd, Ti, W, and Cu for custom DBR coatings or microwave control structures (e.g., for NV- or SiV- spin control). |
| Precision Fabrication | Need for precise geometry control (e.g., for microcavity integration). | Custom laser cutting and shaping services for complex geometries required in integrated photonics. |
Engineering Support
Section titled “Engineering Support”The successful implementation of SiV- centers requires expertise in defect engineering and material science.
- Defect Creation Consultation: 6CCVD’s in-house PhD team can assist researchers in optimizing material selection and post-processing protocols (e.g., implantation energy, annealing temperature) to maximize the yield and spectral quality of SiV- centers for similar quantum repeater projects.
- Strain Engineering: We offer materials and consultation for strain engineering, a key technique mentioned in the paper (Ref. 24-26) for extending SiV- coherence times and controlling spectral properties.
- Global Logistics: Global shipping (DDU default, DDP available) ensures rapid and secure delivery of custom diamond materials worldwide, supporting international research collaborations.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Large-scale quantum communication networks require quantum repeaters due to the signal attenuation in optical fibers. Ideal quantum repeater nodes efficiently link a quantum memory with photons serving as flying qubits. Color centers in diamond, particularly the negatively charged silicon vacancy center, are promising candidates to establish such nodes. Inefficient connection between the color center’s spin to the optical fiber networks is a major obstacle, that could be resolved by utilizing optical resonators. Here, we couple individual silicon vacancy centers incorporated in a nanodiamond to a hemispherical, stable Fabry-Perot microcavity, achieving Purcell-factors larger than 1. We demonstrate coherent optical driving between ground and excited state with a Rabi-frequency of 330 MHz, all-optical initialization and readout of the electron spin in magnetic fields of up to 3.2 T. Spin initialization within 67 ns with a 80 % fidelity and a lifetime of 350 ns are reached. Our demonstration opens the way to realize quantum repeater applications.