Defects as qubits in 3C- and 4H-SiC

We employ hybrid density functional calculations to search for defects in different polytypes of SiC that may serve as qubits for quantum computing. We explore the divacancy in 4H- and 3C-SiC, consisting of a carbon vacancy adjacent to a silicon vacancy, and the nitrogen-vacancy (NV) center in 3C-SiC, in which the substitutional N sub(C) sits next to a Si vacancy (N sub(C) - V sub(Si)). The calculated excitation and emission energies of the divacancy in 4H-SiC are in excellent agreement with experimental data, and aid in identifying the four unique configurations of the divacancy with the four distinct zero-phonon lines observed experimentally. For 3C-SiC, we identify the paramagnetic defect that was recently shown to maintain a coherent quantum state up to room temperature as the spin-1 neutral divacancy. Finally, we show that the (N sub(C) - V sub(Si)) super(-) center in 3C-SiC is highly promising for quantum information science, and we provide guidance for identifying this defect.