Extinction of light and coherent scattering by a single nitrogen-vacancy center in diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-05-10 |
| Journal | Physical review. A/Physical review, A |
| Authors | Thai Hien Tran, Petr Siyushev, Jörg Wrachtrup, Ilja Gerhardt |
| Institutions | University of Stuttgart, Center for Integrated Quantum Science and Technology |
| Citations | 5 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Coherent Scattering in NV-Diamond
Section titled âTechnical Documentation & Analysis: Coherent Scattering in NV-DiamondâThis document analyzes the research paper âExtinction of Light and Coherent Scattering by a Single Nitrogen-Vacancy Center in Diamondâ (arXiv:1608.05224v1) to highlight the critical role of high-quality MPCVD diamond and to position 6CCVDâs capabilities for supporting and advancing solid-state quantum research.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrates the fundamental quantum optical primitive of coherent scattering using a single Nitrogen-Vacancy (NV-) center embedded in diamond. This work relies heavily on the exceptional material properties of the diamond host.
- Core Achievement: Direct measurement of light extinction and coherent scattering from a single NV-center, enabling the estimation of the NVâs extinction cross-section.
- Material Requirement: The experiment necessitates ultra-high-purity, low-strain Single Crystal Diamond (SCD) to ensure stable, isolated NV-centers and minimize spectral diffusion effects at cryogenic temperatures (2 K).
- Key Quantification: The extinction cross-section was estimated to be approximately 30 nm2, confirming the NV-centerâs ability to influence an external laser field.
- Optimal Operation: The optimal point for generating coherent photons was determined to be at a saturation parameter $S = 0.45$, corresponding to an incident power of 1.5 nW.
- Interferometric Application: The NV-center was used as a nanoscopic probe to directly measure the Gouy phase shift ($\pi$ total shift) in a strongly focused laser beam.
- Quantum Potential: The demonstrated ability to influence a laser field (achievable effect of 0.42% in the forward direction) is crucial for realizing quantum non-demolition (QND) measurements and spin-dependent phase gates.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results, highlighting the stringent requirements for the diamond material and setup.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Operating Temperature | 2 | K | Cryogenic confocal microscope |
| Excitation Wavelength | 637 | nm | Tunable narrow-band laser |
| Optimal Excitation Power (Pin) | 1.5 | nW | Corresponds to Saturation Parameter $S = 0.45$ |
| Saturation Intensity (Isat) | 3.1 | nW | Deduced from Phonon Side Band (PSB) intensity |
| Extinction Cross-Section (dext) | ~30 | nm2 | Estimated for forward direction experiment |
| Maximum Measured Contrast (C) | 2.8 | % | Extinction signal contrast at low excitation limit |
| Achievable Forward Effect | 0.42 | % | Calculated influence on the laser beam |
| Zero-Phonon-Line (ZPL) Fraction | 3-4 | % | Light residing on the ZPL |
| Measured Linewidth (FWHM) | 34 | MHz | Ex transition (Fig. 1c) |
| Focus Waist (w0) | 0.23 ± 0.05 | ”m | Estimated via lateral scan |
| Rayleigh Length (zR) | 0.62 ± 0.30 | ”m | Derived from focus waist |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized a highly specialized cryogenic setup to isolate and probe a single NV-center, requiring precise control over optical alignment and excitation parameters.
- Cryogenic Confocal Microscopy: The experiment was conducted at 2 K to ensure the coherence of the photons to the internal spin state, a prerequisite for spin-photon entanglement.
- Efficient Laser Coupling: An external, narrow-band laser (637 nm) was tightly focused onto a single NV-center using a high-NA objective (NA=0.85).
- Dual Detection Scheme: Two avalanche photodetectors (APD1 and APD2) were used: APD1 monitored the red-shifted incoherent fluorescence (PSB), and APD2 monitored the coherent laser light (extinction signal).
- Saturation Parameter Determination: The saturation parameter ($S$) was determined indirectly by fitting the measured linewidth of the red-shifted fluorescence ($\Gamma_{eff}$) to the theoretical dependence $\Gamma_{eff} = \Gamma_{2} \sqrt{1+S}$.
- Gouy Phase Measurement: The NV-center was axially translated through the laser focus, and the resulting phase change of the interferometric signal (monitored on APD2) was used to directly measure the Gouy phase shift.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful replication and extension of this quantum optics research depend entirely on the quality and customization of the diamond host material. 6CCVD provides the necessary MPCVD diamond solutions to meet these exacting standards.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage for Quantum Applications |
|---|---|---|
| Ultra-Low Defect Density (Minimizing spectral diffusion and charge noise) | Optical Grade Single Crystal Diamond (SCD) | Our SCD material features extremely low nitrogen concentration (< 1 ppb) and minimal strain, ensuring stable, narrow-band Zero-Phonon-Line (ZPL) emission and long coherence times for NV-centers at 2 K. |
| Custom Sample Integration (Small, 0.6 mm thick samples for 2 K cryostats) | Custom Dimensions and Thickness Control | We offer SCD plates from 0.1 ”m up to 500 ”m thick, and substrates up to 10 mm. Custom laser cutting and shaping services ensure perfect integration into specialized cryogenic or vacuum systems. |
| High-Quality Optical Interface (Minimizing unwanted reflection/scattering) | Precision Polishing (Ra < 1 nm) | Our SCD surfaces are polished to an atomic level (Ra < 1 nm), which is essential for high-NA focusing systems and reducing background noise in sensitive extinction measurements (as monitored by APD2). |
| Advanced Device Integration (Future scaling into photonic circuits) | Custom Metalization Services | We provide in-house deposition of standard and custom metal stacks (Au, Pt, Pd, Ti, W, Cu) for creating robust electrical contacts, thermal sinks, or integrated optical elements directly onto the diamond surface. |
| Extending Research Scope (Implementing QND measurements, spin gates) | Expert Engineering Support | 6CCVDâs in-house PhD team can assist researchers with material selection, NV creation optimization (e.g., specific implantation recipes), and material preparation necessary for advanced solid-state quantum primitives. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Coherently scattered light from a single quantum system promises to get a\nvaluable quantum resource. In this letter an external laser field is\nefficiently coupled to a single nitrogen vacancy (NV-)center in diamond. By\nthis it is possible to detect a direct extinction signal and estimate the NVâs\nextinction cross-section. The exact amount of coherent and incoherent photons\nis determined against the saturation parameter, and reveals the optimal point\nof generating coherently scattered photons and an optimal point of excitation.\nA theoretical model of spectral diffusion allows to explain the deviation to an\natom in free-space. The introduced experimental techniques are used to\ndetermine the properties of the tight focusing in an interference experiment,\nand allow for a direct determination of the Gouy-phase in a strongly focused\nbeam.\n