We show diamond Tin-Vacancy centers, coherently-coupled to a tunable microcavity. The exceptional optical properties of this emitter in combination with a stable, high quality cavity enables a cavity transmission signal modulated by a single emitter.

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Efficient coupling of optically active qubits to optical cavities is a key challenge for solid-state-based quantum optics experiments and future quantum technologies. Here we present a quantum photonic interface based on a single tin-vacancy center in a micrometer-thin diamond membrane coupled to a tunable open microcavity. We use the full tunability of the microcavity to selectively address individual tin-vacancy centers within the cavity mode volume. Purcell enhancement of the tin-vacancy center optical transition is evidenced both by optical excited state lifetime reduction and by optical linewidth broadening. As the emitter selectively reflects the single-photon component of the incident light, the coupled emitter-cavity system exhibits strong quantum nonlinear behavior. On resonance, we observe a transmission dip of 50% for low incident photon number per Purcell-reduced excited state lifetime, while the dip disappears as the emitter is saturated with higher photon number. Moreover, we demonstrate that the emitter strongly modifies the photon statistics of the transmitted light by observing photon bunching. This work establishes a versatile and tunable platform for advanced quantum optics experiments and proof-of-principle demonstrations on quantum networking with solid-state qubits.@en

We demonstrate coherent coupling of a single diamond Tin-Vacancy center to a fiber-based microcavity, showing a cavity transmission dip of 50 % on resonance, and altered photon statistics in cavity transmission.

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We report on the realization of a fiber-based microcavity, exhibiting low cavity length fluctuations in combination with full spatial and spectral tunability. The microcavity is used to demonstrate Purcell-enhancement of diamond Tin-Vacancy centers.@en

For the next generation of very high throughput communication satellites, free-space optical (FSO) communication between ground stations and geostationary telecommunication satellites is a potential solution to overcome the limitations of RF links. To mitigate atmospheric turbulence effects, TNO proposes Adaptive Optics (AO) to apply uplink pre-correction. As a successor of Optics Feeder Link Adaptive Optics (OFELIA) breadboard [1], [2], the Terabit Optical Communication Adaptive Terminal (TOmCAT) project phase 2 aims to demonstrate the AO precorrection technology for a terabit Optical Ground Station (OGT) in a ground-to-ground link field test over 10 km. Within this demonstrator an upgraded version of the OFELIA breadboard is used as optical bench for the AO (pre-)correction, but moreover the demonstrator enables the (future) integration of equipment for the final OGT configuration including the Beam Multiplexer (BMUX) and communication equipment. Apart from the OGT demonstrator, the overall layout of the field test has been upgraded, including the test site and the Ground Support Equipment (GSE), with the goal to create a better understanding of the encountered link phenomena and the instant (turbulence) conditions at which it was measured. New additions to the GSE are several weather stations placed along the link path to quantify the local turbulence and to relate the measured link performance to the instant turbulence conditions. The test campaign is split in two successive field tests: First the AO Demonstrator evaluates the upgraded AO pre-correction performance with a single non-modulated link, followed by the OGT Demonstrator which will include the multiplexing of multiple uplink channels and RF end-to-end modems to prove the technical feasibility of supporting a terabit communication link. This paper covers the design of the AO demonstrator and GSE, the field test layout and the preliminary results for the AO demonstrator field test. For the downlink correction the residual Wave Front Error (WFE) is presented. The pre-correction performance is depicted in the uplink transmission loss and scintillation, all as function of the encountered turbulence conditions.

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