First-principles studies of carbon-nitrogen complexes in Si for spin qubits and single-photon emitters

We present first-principles studies for a carbon-nitrogen impurity complex in silicon as a proposed isoelectronic alternative to the T center, (CCH)_Si, which has been pursued for applications in quantum information science. Questions have been raised about the T center's stability, particularly because of the involvement of hydrogen. Our proposed complex has no hydrogen, thereby eliminating this issue. Based on first-principles calculations using density functional theory and a hybrid functional, we show that the carbon-nitrogen complex has a similar electronic structure to the T center, and therefore could potentially be used in similar applications, as a spin qubit or as a single-photon emitter for quantum communication.