Quantum Frequency Conversion of Single Photons from a Nitrogen-Vacancy Center in Diamond to Telecommunication Wavelengths
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-06-19 |
| Journal | Physical Review Applied |
| Authors | Anaïs Dréau, Anna Tcheborateva, Aboubakr El Mahdaoui, Cristian Bonato, Ronald Hanson |
| Institutions | Centre National de la Recherche Scientifique, QuTech |
| Citations | 120 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Quantum Frequency Conversion in Diamond NV Centers
Section titled âTechnical Documentation & Analysis: Quantum Frequency Conversion in Diamond NV CentersâThis analysis addresses the critical material requirements and engineering solutions needed to replicate and advance the findings presented in âQuantum frequency conversion to telecom of single photons from a nitrogen-vacancy center in diamond.â
Executive Summary
Section titled âExecutive SummaryâThis paper successfully demonstrates the integration of diamond-based quantum emitters into existing fiber optic networks via Quantum Frequency Conversion (QFC). The core achievements and technological significance are summarized below:
- Quantum Interface Demonstrated: Successful frequency down-conversion of spin-selective single photons emitted by a Nitrogen-Vacancy (NV) center in diamond.
- Wavelength Transduction: Photons at 637 nm (Visible/Red, corresponding to the coherent NV ZPL) were converted to 1588 nm (Telecom L-band), drastically reducing fiber transmission loss (from â 8 dB/km to < 0.2 dB/km).
- High Efficiency & Fidelity: Achieved a total conversion efficiency of $\approx$ 17% and confirmed the preservation of the single-photon statistics via anti-bunching measurements (g(2)(0) = 0.32 after conversion).
- Signal Quality: Demonstrated a Signal-to-Noise Ratio (SNR) of $\approx$ 7, limited by pump-induced noise (Spontaneous Parametric Down-Conversion, SPDC) in the PPLN waveguide.
- Paving the Way for Networks: This result represents a key technological step toward developing long-range entanglement-based quantum networks using robust solid-state NV qubits housed in high-purity Single Crystal Diamond (SCD).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context / Function |
|---|---|---|---|
| Input Photon (Signal) | 637 | nm | NV Center Zero-Phonon-Line (ZPL) |
| Output Photon (Idler) | 1588 | nm | Telecom L-Band (Target Wavelength) |
| Pump Laser | 1064 | nm | Continuous-Wave (CW) DFG Source |
| Max Pump Power (Optimal) | $\approx$ 110 | mW | Input power maximizing detection probability $p_{c,tel}$ |
| Total Conversion Efficiency ($\eta_{c}$) | 17 | % | Overall system efficiency (diamond to detector) |
| Internal PPLN Conversion $\eta_{int}$ | $\approx$ 65 | % | Estimated efficiency inside the PPLN crystal |
| Signal-to-Noise Ratio (SNR) | $\approx$ 7 | - | Achieved at optimal conversion settings |
| Converted Photon Statistics (g(2)(0)) | 0.32 $\pm$ 0.08 | - | Shows preservation of anti-bunching, proving single-photon nature |
| NV Excited State Lifetime ($\tau$@637nm) | 12.9 $\pm$ 1.0 | ns | Baseline for spin-selective transition |
| Converted Photon Lifetime ($\tau$@1588nm) | 12.6 $\pm$ 1.2 | ns | Confirms conversion preserves temporal characteristics |
| PPLN Waveguide Dimensions | 8 x 8 x 48 | ”m x ”m x mm | Core element for Difference Frequency Generation (DFG) |
Key Methodologies
Section titled âKey MethodologiesâThe success of the QFC experiment relies on precise control over the NV photon source parameters and highly efficient nonlinear optical conversion techniques:
- High-Purity Diamond Source: Utilized a single NV center embedded in a diamond host. The NV center was addressed using a spin-selective optical transition.
- Pulsed Resonant Excitation: The NV center was resonantly driven by a 2-ns optical $\pi$-pulse, ensuring conditional single-photon emission (on the spin state).
- Photon Extraction & Coupling: NV photons were extracted from the diamond, coupled into a Polarization-Maintaining (PM) fiber, and directed to the down-conversion stage.
- Difference Frequency Generation (DFG): Implemented using a strong 1064 nm CW pump laser and the 637 nm NV photon, mixing them in a Zn-doped Type-0 Periodically-Poled Lithium Niobate (PPLN) waveguide.
- Quasi-Phase Matching (QPM): Achieved by careful thermal tuning of the PPLN crystal temperature to optimize the DFG process.
- Multi-Stage Spectral Noise Filtering: To overcome the low input photon rate and high pump noise (SPDC), a rigorous filtering chain was employed:
- Dispersive Prism
- Long-pass Filter (Semrock BLP01-1550R-25)
- Narrow-band Fiber Bragg Grating (FBG) filter (4 pm / 500 MHz bandwidth).
- Time-Correlated Detection: Used a Superconducting Single Photon Detector (SSPD) synchronized to the NV center excitation pulse, enabling temporal filtering to maximize the SNR.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the absolute necessity of high-quality, ultra-pure Single Crystal Diamond (SCD) for scaling quantum networks. 6CCVD provides the specialized MPCVD diamond material and engineering services required to replicate this work and advance subsequent generations of solid-state quantum emitters.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the long coherence times and minimal spectral diffusion required for high-fidelity NV center performance, researchers must start with optimal diamond material.
| Material Requirement (Paper Implied) | 6CCVD Recommended Solution | Key Benefit for Application |
|---|---|---|
| Ultra-high Purity Substrate | Optical Grade Single Crystal Diamond (SCD) | Minimal background nitrogen and defect density, crucial for long NV spin coherence ($\tau$ up to 1 second demonstrated elsewhere). |
| Custom Thickness Control | SCD Films: 0.1 ”m - 500 ”m | Allows precise integration of the NV layer relative to the surface for optimal coupling to external structures (e.g., PPLN waveguides or on-chip devices). |
| Controlled Doping | Nitrogen-Controlled SCD Growth | Targeted incorporation of nitrogen atoms to maximize the density and quality of isolated NV centers, enhancing ZPL count rates. |
Customization Potential & Post-Processing Services
Section titled âCustomization Potential & Post-Processing ServicesâThe paper noted that future SNR improvements rely on âincreased collection efficiencyâ and âPurcell enhancementâ via structures like microcavities or parabolic reflectors. 6CCVD specializes in the engineering required for these structures.
- Precision Fabrication: We offer Custom Laser Micromachining to etch precise patterns, trenches, or mesas onto the SCD substrate, enabling the fabrication of integrated optical components like solid-immersion lenses or parabolic reflectors used for enhancing NV photon collection efficiency (addressing a key bottleneck mentioned in the paper).
- Surface Preparation: The high coupling efficiency (estimated $\approx$ 90% into the PPLN waveguide) necessitates near-perfect optical interfaces. 6CCVD guarantees ultra-low surface roughness: SCD substrates are polished to Ra < 1 nm, significantly minimizing scattering losses.
- Metalization Services: While this study focused on DFG, other quantum components (e.g., microwave control structures, on-chip heaters) may require custom electrodes. 6CCVD provides in-house metalization services (Au, Pt, Pd, Ti, W, Cu) tailored for demanding cryogenic or high-power applications.
Engineering Support
Section titled âEngineering SupportâOur role as technical partners extends beyond material supply. The challenges highlighted in the paperâincluding low ZPL emission rate and noise filteringârequire specialized knowledge of MPCVD diamond processing.
- Application Expertise: 6CCVDâs in-house PhD team provides consultative support on material selection for Solid-State Quantum Emitter projects, including NV and SiV centers. We assist clients in optimizing diamond growth recipes specifically to maximize the ZPL extraction efficiency and minimize spectral diffusion.
- Global Supply Chain: We ensure reliable delivery of custom diamond plates and wafers (up to 125 mm PCD) globally, with flexible DDU (default) and DDP shipping terms.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We report on the conversion to telecom wavelength of single photons emitted\nby a nitrogen-vacancy (NV) defect in diamond. By means of difference frequency\ngeneration, we convert spin-selective photons at 637 nm, associated with the\ncoherent NV zero-phonon-line, to the target wavelength of 1588 nm in the\nL-telecom band. The successful conversion is evidenced by time-resolved\ndetection revealing a telecom photon lifetime identical to that of the original\n637 nm photon. Furthermore, we show by second-order correlation measurements\nthat the single-photon statistics are preserved. The overall efficiency of this\none-step conversion reaches 17\% in our current setup, along with a\nsignal-to-noise ratio of $\approx$7 despite the low probability $(< 10^{-3})$\nof an incident 637 nm photon. This result shows the potential for efficient\ntelecom photon - NV center interfaces and marks an important step towards\nfuture long-range entanglement-based quantum networks.\n