The silicon vacancy (V Si) in 3 C-SiC is studied as a center of interest in the field of quantum technologies, modeled as an electron spin (behaving as a two-state qubit in appropriate conditions) interacting through hyperfine coupling with the SiC nuclear spin bath containing Si 29 and C 13 nuclei in their natural isotopic concentration. We calculate the formation energies of the neutral and charged V Si with ab initio methods based on the density functional theory, identifying the stability of the neutral charge state for energies close to the valence band of 3 C-SiC. In addition, magnetic properties are calculated for the V Si− 1 in 3 C-SiC and for V Si 0 in both cubic and hexagonal SiC polytypes. We thereon evaluate, for the defect in the cubic polytype, the free induction decay and the Hahn-echo sequence on the electron spin interacting with the nuclear spin bath, shedding light on the electron spin-echo envelope …