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We developed a new technique that enables deterministic assembly of diamond color centers in a SiN photonic circuit. Using this technique, we observed Purcell enhancement of SiV centers coupled to a silicon nitride ring resonator. 

Nanophotonic structures have shown promising routes to controlling and enhancing nonlinear optical processes at the nanoscale. However, most nonlinear nanostructures require a handling substrate, reducing their application scope. Due to the underwhelming heat dissipation, it has been a challenge to evaluate the nonlinear optical properties of free-standing nanostructures. Here, we overcome this challenge by performing shot-controlled fifth harmonic generation (FHG) measurements on a SiC meta-membrane – a free-standing transmission metasurface with pronounced optical resonances in the mid-infrared (λres≈ 4,000 nm). Back focal plane imaging of the FHG diffraction orders and rigorous finite-difference time-domain simulations reveal at least two orders of magnitude enhancement of the FHG from the meta-membrane, compared to the unstructured SiC film of the same thickness. Single-shot measurements of the meta-membrane with varying resonance positions reveal an unusual spectral behavior that we explain with Kerr-driven intensity-dependent resonance dynamics. This work paves the way for novel substrate-less nanophotonic architectures. 

The negatively charged tin-vacancy center in diamond ( ${\mathrm{SnV}}^{-}$) is an emerging platform for building the next generation of long-distance quantum networks. This is due to the ${\mathrm{SnV}}^{-}$’s favorable optical and spin properties including bright emission, insensitivity to electronic noise, and long spin coherence times at temperatures above 1 K. Here, we demonstrate measurement of a single ${\mathrm{SnV}}^{-}$electronic spin with a single-shot readout fidelity of 87.4%, which can be further improved to 98.5% by conditioning on multiple readouts. In the process, we develop understanding of the relationship between strain, magnetic field, spin readout, and microwave spin control. We show that high-fidelity readout is compatible with rapid microwave spin control, demonstrating a favorable parameter regime for use of the ${\mathrm{SnV}}^{-}$center as a high-quality spin-photon interface. Finally, we use weak quantum measurement to study measurement-induced dephasing; this illuminates the fundamental interplay between measurement and decoherence in quantum mechanics, and provides a universal method to characterize the efficiency of color-center spin readout. Taken together, these results overcome an important hurdle in the development of the ${\mathrm{SnV}}^{-}$-based quantum technologies and, in the process, develop techniques and understanding broadly applicable to the study of solid-state quantum emitters. Published by the American Physical Society2024 

We developed a new technique that enables deterministic assembly of diamond color centers in a SiN photonic circuit. Using this technique, we observed Purcell enhancement of SiV centers coupled to a silicon nitride ring resonator.