  Spins in semiconductor quantum dots constitute a promising platform for
scalable quantum information processing. Coupling them strongly to the photonic
modes of superconducting microwave resonators would enable fast non-demolition
readout and long-range, on-chip connectivity, well beyond nearest-neighbor
quantum interactions. Here we demonstrate strong coupling between a microwave
photon in a superconducting resonator and a hole spin in a silicon-based double
quantum dot issued from a foundry-compatible MOS fabrication process. By
leveraging the strong spin-orbit interaction intrinsically present in the
valence band of silicon, we achieve a spin-photon coupling rate as high as
330~MHz largely exceeding the combined spin-photon decoherence rate. This
result, together with the recently demonstrated long coherence of hole spins in
silicon, opens a new realistic pathway to the development of circuit quantum
electrodynamics with spins in semiconductor quantum dots.
