Inverted fine structure of a 6H-SiC qubit enabling robust spin-photon interface

Abstract Controllable solid-state spin qubits are currently becoming useful building blocks for applied quantum technologies. Here, we demonstrate that in a specific type of silicon-vacancy the 6H-SiC polytype excited-state fine structure is inverted, compared to 4H-SiC. From angular polarization dependencies emission, reconstruct spatial symmetry and determine optical selection rules depending on local deformation spin–orbit interaction. We show this system well suited implementation robust spin–photon entanglement schemes. Furthermore, inverted leads unexpected behavior readout contrast. It vanishes recovers with lattice cooling due two competing pumping mechanisms. Our experimental theoretical approaches provide deep insight into properties atomic-scale SiC required communication distributed information processing.