The PL6 color center in silicon carbide has recently emerged as a promising platform for quantum information processing, yet its coherent spin--photon interface has remained largely unexplored. Here we present a comprehensive investigation of single PL6 centers, combining spectroscopy with theoretical analysis. The excited-state fine structure is fully resolved using group-theoretical modeling and strain-dependent measurements. Under resonant excitation, we achieve a spin initialization fidelity of $99.69 \pm 0.03\%$ and a readout contrast of $98.31 \pm 1.03\%$ . The spin--photon--entangled $A_2$ transition exhibits narrow optical linewidths ( $\sim 180$ ~MHz) and a polarization visibility of $\sim 82\%$ . Coherent optical driving enables Rabi frequencies up to $2.895$ ~GHz, while dynamical decoupling extends the spin coherence time from $0.5$ ~ms to $5.70$ ~ms. Our results establish PL6 as a competitive solid-state spin--photon interface hosted in a commercially available semiconductor platform.The PL6 color center in silicon carbide has recently emerged as a promising platform for quantum information processing, yet its coherent spin--photon interface has remained largely unexplored. Here we present a comprehensive investigation of single PL6 centers, combining spectroscopy with theoretical analysis. The excited-state fine structure is fully resolved using group-theoretical modeling and strain-dependent measurements. Under resonant excitation, we achieve a spin initialization fidelity of $99.69 \pm 0.03\%$ and a readout contrast of $98.31 \pm 1.03\%$. The spin--photon--entangled $A_2$ transition exhibits narrow optical linewidths ($\sim 180$~MHz) and a polarization visibility of $\sim 82\%$. Coherent optical driving enables Rabi frequencies up to $2.895$~GHz, while dynamical decoupling extends the spin coherence time from $0.5$~ms to $5.70$~ms. Our results establish PL6 as a competitive solid-state spin--photon interface hosted in a commercially available semiconductor platform.

quant-pharXiv:2602.06421Feb 9, 20260 citations

99.69 \pm 0.03\%

and a readout contrast of

98.31 \pm 1.03\%

. The spin--photon--entangled

A_2

transition exhibits narrow optical linewidths (

\sim 180

~MHz) and a polarization visibility of

\sim 82\%

. Coherent optical driving enables Rabi frequencies up to

2.895

~GHz, while dynamical decoupling extends the spin coherence time from

0.5

~ms to

5.70

~ms. Our results establish PL6 as a competitive solid-state spin--photon interface hosted in a commercially available semiconductor platform.