Efficient Extraction of Zero-Phonon-Line Photons from Single Nitrogen-Vacancy Centers in an Integrated GaP-on-Diamond Platform
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-07-29 |
| Journal | Physical Review Applied |
| Authors | Michael Gould, Emma R. Schmidgall, Shabnam Dadgostar, Fariba Hatami, KaiâMei C. Fu |
| Institutions | University of Washington, Humboldt-UniversitÀt zu Berlin |
| Citations | 71 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Integrated GaP-on-Diamond Quantum Photonics
Section titled âTechnical Documentation & Analysis: Integrated GaP-on-Diamond Quantum PhotonicsâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a critical advancement in solid-state quantum networks by achieving highly efficient photon extraction from single Nitrogen-Vacancy (NV) centers utilizing a novel GaP-on-diamond integrated platform.
- High Quantum Efficiency: The platform achieved a total quantum efficiency ($\eta$) of up to 9% for ZPL photon emission into a guided waveguide mode, significantly exceeding the theoretical limit for non-resonant free-space collection.
- Purcell Enhancement: Resonant coupling via 1.3 ”m disk resonators yielded a substantial Purcell enhancement factor ($F_P$) of up to 26, close to the theoretical maximum for this geometry.
- Scalability Demonstrated: The hybrid GaP-on-diamond structure is compatible with large-area, uniform fabrication, addressing a major limitation of all-diamond integrated photonics platforms.
- Material Foundation: The devices rely on high-quality, electronic-grade Single Crystal Diamond (SCD) substrates for near-surface NV center creation via low-energy (10 keV) ion implantation.
- Application Potential: The high efficiency and integration capability enable a projected NV-NV entanglement generation rate of 400 Hz, paving the way for scalable Measurement-Based Quantum Information Processing (MBQIP) networks.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper detailing the performance and physical parameters of the GaP-on-diamond integrated photonic devices.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Total Quantum Efficiency ($\eta$) | 9 | % | Estimated for Disk 1 (Highest performing device) |
| Saturated On-Chip Collection Rate ($\gamma_{wg}$) | 2.48 x 106 | s-1 | Detected ZPL count rate into the bus waveguide (Disk 1) |
| Purcell Enhancement Factor ($F_P$) | 26 | - | Measured resonant enhancement (Disk 1) |
| Cavity Quality Factor ($Q$) | 8200 | - | Measured for 1.3 ”m diameter disk resonator |
| GaP Waveguiding Layer Thickness | 125 | nm | Transferred epitaxial membrane |
| Diamond Pedestal Thickness | 600 | nm | Etched Single Crystal Diamond support |
| NV Implantation Energy | 10 | keV | N+ ion implantation for near-surface NV centers |
| NV Implantation Dose | 1 x 1010 | cm-2 | Sparse layer density |
| Operating Temperature | 8 | K | Cryogenic measurement environment |
| Off-Resonance Lifetime ($\tau_{off}$) | 8.7 ± 0.8 | ns | Significantly shorter than bulk diamond (~12 ns) |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication process leverages advanced material transfer and nanoscale patterning techniques on high-purity diamond substrates.
- Substrate Preparation: Electronic-grade Single Crystal Diamond (SCD) chips were used as the base material.
- NV Center Creation: Near-surface NV centers were formed via N+ ion implantation (10 keV, 1 x 1010 cm-2 dose).
- Annealing Protocol: A two-step anneal was performed:
- 1 hour at 850° C (5%/95% H2/Ar forming gas) to mobilize vacancies.
- 24 hours at 450° C (Air) for surface oxygen termination, stabilizing the NV- charge state.
- Hybrid Integration: A 125 nm thick GaP membrane was transferred onto the implanted diamond chip using epitaxial lift-off and van der Waals bonding.
- Device Patterning: Electron-beam lithography (HSQ resist) defined the photonic structures (1.3 ”m disk resonators, 150 nm waveguides).
- Reactive Ion Etching (RIE): Two RIE steps were used:
- Etch 1 (Cl2/Ar/N2 chemistry) etched through the GaP layer.
- Etch 2 (O2 chemistry) etched 600 nm into the diamond to form the pedestal structure.
- Cryogenic Tuning: Devices were cooled to 8 K, and cavity modes were tuned onto the ZPL resonance using controlled Xenon gas deposition.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the critical need for high-quality, precisely engineered diamond substrates and advanced fabrication supportâcore competencies of 6CCVD. We are uniquely positioned to supply the foundational materials and processing services required to replicate and scale this GaP-on-diamond platform.
| Research Requirement | 6CCVD Solution & Capability | Value Proposition for Replication & Scaling |
|---|---|---|
| High-Purity Substrate | Electronic Grade Single Crystal Diamond (SCD). High-purity MPCVD diamond is essential for low background fluorescence and stable NV- charge states. | Guaranteed low defect density and high material uniformity, critical for achieving high $Q$ factors (Q=8200) and maximizing $\eta$. |
| Precise Thickness Control | Custom SCD Thicknesses (0.1 ”m to 500 ”m). We provide wafers tailored to specific RIE requirements, ensuring the 600 nm diamond pedestal is accurately formed. | Enables precise control over the hybrid stack geometry and minimizes material waste during deep etching processes. |
| Large-Scale Integration | Inch-Size Polycrystalline Diamond (PCD) Wafers (up to 125 mm). For scaling complex photonic circuits across a large area, PCD offers cost-effective, large-format substrates. | Supports the paperâs outlook for large-area, uniform GaP membrane transfer and fabrication of complex, cm-scale quantum networks. |
| Surface Quality | Ultra-Low Roughness Polishing (SCD: Ra < 1 nm; PCD: Ra < 5 nm). | Minimizes optical scattering losses in the waveguide and resonator, directly impacting the achievable $Q$ factor and Purcell enhancement ($F_P=26$). |
| Advanced Device Integration | Custom Metalization Services (Au, Pt, Pd, Ti, W, Cu). The paperâs outlook mentions integrating superconducting nanowire single-photon detectors (SNSPDs). | We provide in-house metal deposition capabilities necessary for creating contacts, wiring, and integrating active components onto the diamond surface. |
| Engineering Support | In-House PhD Team Consultation. Our experts specialize in material selection and processing for integrated quantum photonics projects, including NV center creation and hybrid material stacks. | Accelerate R&D timelines by leveraging 6CCVD expertise in diamond etching, annealing protocols, and surface termination. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Scaling beyond two-node quantum networks using nitrogen vacancy (NV) centers\nin diamond is limited by the low probability of collecting zero phonon line\n(ZPL) photons from single centers. Here, we demonstrate GaP-on-diamond disk\nresonators which resonantly couple ZPL photons from single NV centers to\nsingle-mode waveguides. In these devices, the probability of a single NV center\nemitting a ZPL photon into the guided waveguide mode after optical excitation\ncan reach 9%, due to a combination of resonant enhancement of the ZPL emission\nand efficient coupling between the resonator and waveguide. We verify the\nsingle-photon nature of the emission and experimentally demonstrate both high\nin-waveguide photon numbers and substantial Purcell enhancement for a set of\ndevices. These devices may enable scalable integrated quantum networks based on\nNV centers.\n