Bright Single-Photon Emission from Individual Tin-Vacancy Centers in Multi-Cone Diamond Waveguides

TL;DR

This study addresses the challenge of efficiently extracting photons from tin-vacancy centers in diamond. By embedding a single SnV center in diamond multi-cone nanopillars, the authors achieve high-brightness, narrow-line emission with a ZPL near $619$ nm and a saturated count rate around $9$ Mcps, while demonstrating clear antibunching with $g^{(2)}(0) < 0.5$. Finite-difference time-domain simulations predict extraction efficiencies above $70\%$, consistent with the observed brightness. A broad survey across 126 cones reveals many emitters near the SnV line, though multiple emitters are common without spectral filtering; with targeted filtering around the ZPL, single-photon purity improves substantially. Overall, the diamond multi-cone platform shows strong potential for bright SnV-based quantum sources and sensing applications, with further optimization of implantation to ensure isolated single emitters per cone.

Abstract

Diamonds containing color centers have recently gathered significant attention for photonic quantum technologies, including quantum sensing, photonic quantum computers, and quantum networks. Among the various color centers, tin-vacancy (SnV) centers are particularly promising due to the high emission efficiency from the zero-phonon line and due to their long spin coherence times. However, the extraction of photons from diamond remains a key challenge. Here we demonstrate high photon extraction from a single SnV center incorporated in a diamond nanopillar with tapered sidewalls and a multi-cone structure. A sharp emission peak with a full width at half maximum (FWHM) of $6\,$nm was observed at a wavelength of $619\,$nm. Furthermore, the second-order correlation function exhibited an antibunching dip well below $g^{(2)}(0) = 0.5$, indicating single-photon emission. Remarkably, the emitter achieved a high saturation count rate of approximately $9\,$Mcps. These results establish our nanopillar platform as a promising candidate for bright and stable quantum sources and sensors based on SnV centers in diamond.

Figures (3)

• Figure 1: Overview of the sample properties and experimental setup. a) Schematic illustration of the cone morphology used for the calculation model. b) SEM image of the multi-cone structures. c) Backfocal image of a single SnV center inside a multi-cone. d) Schematic drawing of the fluorescence microscope setup.
• Figure 2: Properties of a single SnV center in a multi cone measured across different spectral ranges. a) shows the normalized emission spectra measured with three different sets of spectral filters. Pronounced emission at $619$ nm indicates the presence of the SnV^- center. b) and c) show the autocorrelation and saturation measurement for each filter configuration, respectively. The autocorrelation measurement is conducted under $532$ nm exciation at $120$ µW. This particular power is marked in c) by the dashed orange line. A lifetime measurement is shown in d) with a lifetime of $5.87$ ns retrieved from an exponential fit (yellow line). Only a single measurement is depicted as there were no differences in the data for the different used spectral filters.
• Figure 3: Overview of the measured properties across all cones for different spectal filter configurations. a) Distribution of ZPL positions. The majority of observed ZPLs are located around $620$ nm. b) Scatter plot of the measured $g^{(2)}(0)$ values over the count rates in saturation. The different filter settings are coded by different colors. c) and d) Boxplots of the $g^{(2)}(0)$ values and saturation count rates, respectively. The $g^{(2)}(0)$ values are improved, while the count rates in saturation are drastically reduced by the restriction of the measured spectral range.