arXiv subjects

Konosuke Shimazaki

Publications and source records attributed to Konosuke Shimazaki.

4 recordsLinked to original sources

arXiv2026

Engineering of Dual Wavelength, Polarization Selective Metalenses in Silicon Carbide

Spin defects in silicon carbide (SiC) are promising candidates for integrated quantum photonics, offering long-lived spin states and near-infrared emission suitable for low-loss photonic integration and fibre-based quantum communication. However, light extraction from these defects remains challenging due the relatively high refractive index of SiC. Metalenses offer a compact approach to enhance light collection by engineering the wavefront directly at the material interface. Here, we design and fabricate monolithic metalenses from SiC bulk material that simultaneously operate at 860 and 1240 nm, matching with emission from the nitrogen vacancy and silicon vacancy colour centers. By independently engineering the phase response at both wavelengths, the metalens enables collection and polarization manipulation of the emitted light. We further employ the metalenses to demonstrate optically detected magnetic resonance of both defects simultaneously. These multifunctional metalenses provide a compact optical interface for scalable integrated SiC photonic devices.

quant-ph↗

arXiv2026

On chip, multifunctional quantum sensing using single spins in a van der Waals crystal

Nanoscale thermometry and magnetometry are in high demand across a wide range of scientific and technological applications. In this context, optically addressable spins in solids have emerged at the forefront of on-chip quantum sensing. However, simultaneous quantum sensing of multiple parameters (e.g., temperature and magnetic field) using the same spin sensor remains challenging due to cross-sensitivity to multiple physical quantities. Here, we demonstrate independent dual sensing of temperature and magnetic field using single quantum emitters in hexagonal boron nitride (hBN). We experimentally verify the independent response of the zero-phonon line (ZPL) position to temperature and of optically detected magnetic resonance (ODMR) to magnetic fields. Furthermore, we demonstrate local temperature sensing of a microcircuit while simultaneously measuring an external magnetic field. Our results establish quantum emitters in hBN as a robust platform for multifunctional quantum sensing under realistic operating conditions.

quant-ph↗

arXiv2026

Coupling nitrogen vacancy centers in silicon carbide to nanophotonic resonators

Silicon carbide (SiC) is a promising platform for scalable quantum technologies owing to its well-established, wafer-scale industrial processing. SiC also hosts a variety of optically active color centres including the nitrogen vacancy defect that has a spin-triplet ground state. However, strong phonon coupling in the infrared range limits photon extraction from these defects. Here, we use nanophotonic structures, specifically micro-pillar and micro-disk resonators, to enhance optical collection and spin-readout. The micro-pillar geometry yields a 4-fold increase in photon collection, accompanied by a 2.4-fold reduction in spectral noise in optically detected magnetic resonance measurements. Consequently, the magnetic field sensitivity is improved by 24%. The large mode volume of the micro-disk supports resonances spanning 1150-1250 nm, enabling broadband coupling to nitrogen vacancy emission lines. Our results demonstrate that fabrication of scalable photonic structures efficiently improves performance of silicon carbide color centers for integrated quantum light generation and sensing.

physics.optics↗

arXiv2025

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

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.

quant-ph↗