Search for: All records

Integrating solid-state quantum emitters with photonic circuits is essential for realizing large-scale quantum photonic processors. Negatively charged tin-vacancy (SnV−) centers in diamond have emerged as promising candidates for quantum emitters because of their excellent optical and spin properties, including narrow-linewidth emission and long spin coherence times. SnV− centers need to be incorporated in optical waveguides for efficient onchip routing of the photons they generate. However, such integration has yet to be realized. In this Letter, we demonstrate the coupling of SnV− centers to a nanophotonic waveguide. We realize this device by leveraging our recently developed shallow ion implantation and growth method for the generation of high-quality SnV− centers and the advanced quasi-isotropic diamond fabrication technique. We confirm the compatibility and robustness of these techniques through successful coupling of narrow-linewidth SnV− centers (as narrow as 36 ± 2 MHz) to the diamond waveguide. Furthermore, we investigate the stability of waveguide-coupled SnV− centers under resonant excitation. Our results are an important step toward SnV−-based on-chip spin-photon interfaces, single-photon nonlinearity, and photon-mediated spin interactions. 

In thermionic energy converters, the absolute efficiency can be increased up to 40% if space-charge losses are eliminated by using a sub-10-µm gap between the electrodes. One practical way to achieve such small gaps over large device areas is to use a stiff and thermally insulating spacer between the two electrodes. We report on the design, fabrication and characterization of thin-film alumina-based spacers that provided robust 3–8 μm gaps between planar substrates and had effective thermal conductivities less than those of aerogels. The spacers were fabricated on silicon molds and, after release, could be manually transferred onto any substrate. In large-scale compression testing, they sustained compressive stresses of 0.4–4 MPa without fracture. Experimentally, the thermal conductance was 10–30 mWcm⁻²K⁻¹and, surprisingly, independent of film thickness (100–800 nm) and spacer height. To explain this independence, we developed a model that includes the pressure-dependent conductance of locally distributed asperities and sparse contact points throughout the spacer structure, indicating that only 0.1–0.5% of the spacer-electrode interface was conducting heat. Our spacers show remarkable functionality over multiple length scales, providing insulating micrometer gaps over centimeter areas using nanoscale films. These innovations can be applied to other technologies requiring high thermal resistance in small spaces, such as thermophotovoltaic converters, insulation for spacecraft and cryogenic devices.