| Summary: | <p>Group-IV color centers in diamond are a promising light-matter interface for quantum networking devices. The negatively charged tin-vacancy center (<span tabindex="0">SnV</span>) is particularly interesting, as its large spin-orbit coupling offers strong protection against phonon dephasing and robust cyclicity of its optical transitions toward spin-photon-entanglement schemes. Here, we demonstrate multiaxis coherent control of the <span tabindex="0">SnV</span> spin qubit via an all-optical stimulated Raman drive between the ground and excited states. We use coherent population trapping and optically driven electronic spin resonance to confirm coherent access to the qubit at 1.7 K and obtain spin Rabi oscillations at a rate of <span tabindex="0">Ω/2π=19.0(1)  MHz</span>. All-optical Ramsey interferometry reveals a spin dephasing time of <span tabindex="0">T∗2=1.3(3)  μs</span>, and four-pulse dynamical decoupling already extends the spin-coherence time to <span tabindex="0">T2=0.30(8)  ms</span>. Combined with transform-limited photons and integration into photonic nanostructures, our results make the <span tabindex="0">SnV</span> a competitive spin-photon building block for quantum networks.</p>
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