A first-principles investigation of halogen doped diamond and its application to quantum technologies

Defect centers in diamond have attracted considerable attention for the development of emerging quantum technologies, for example, quantum sensors and spin qubits. Nitrogen vacancy (NV) is the most well-studied and utilized defect; however, its relatively high zero phonon line (ZPL) is responsible for optical losses and limiting efficiency. Here, we focus on the halogen doping in diamond, employing the strongly constrained and appropriately normed meta-generalized gradient approximation functional to investigate the thermodynamic and electronic properties of these defects. We analyzed all stable charge states at their lowest energy spin state and identified qubit candidates with paramagnetic ground states and optically addressable transitions, suitable for quantum applications. We focus on the fluorine substitutional defect at negative charge (FC−1), which we found as a promising spin-defect that has not been extensively investigated before. We predict that it has a triplet ground state and a ZPL much lower compared to the NV center that falls into the desired telecommunication range. To describe its qubit operation protocol, we calculate the zero-field splitting and the hyperfine tensors. The present findings suggest that Fc has very promising properties and could be a viable alternative to traditional qubits in diamond.