An \emph{ab initio} study on split silicon-vacancy defect in diamond: electronic structure and related properties

The split silicon-vacancy defect (SiV) in diamond is an electrically and optically active color center. Recently, it has been shown that this color center is bright and can be detected at the single defect level. In addition, the SiV defect shows a non-zero electronic spin ground state that potentially makes this defect an alternative candidate for quantum optics and metrology applications beside the well-known nitrogen-vacancy color center in diamond. However, the electronic structure of the defect, the nature of optical excitations and other related properties are not well-understood. Here we present advanced \emph{ab initio} study on SiV defect in diamond. We determine the formation energies, charge transition levels and the nature of excitations of the defect. Our study unravel the origin of the dark or shelving state for the negatively charged SiV defect associated with the 1.68-eV photoluminescence center.Comment: 8 pages, 5 figures, 1 tabl

First principles study of charge diffusion between proximate solid state qubits and its implications on sensor applications

Solid state qubits from paramagnetic point defects in solids are promising platforms to realize quantum networks and novel nanoscale sensors. Recent advances in materials engineering make possible to create proximate qubits in solids that might interact with each other, leading to electron spin/charge fluctuation. Here we develop a method to calculate the tunneling-mediated charge diffusion between point defects from first principles, and apply it to nitrogen-vacancy (NV) qubits in diamond. The calculated tunneling rates are in quantitative agreement with previous experimental data. Our results suggest that proximate neutral and negatively charged NV defect pairs can form an NV--NV molecule. A tunneling-mediated model for the source of decoherence of the near-surface NV qubits is developed based on our findings on the interacting qubits in diamond.Comment: 4 figure

\emph{Ab initio} theory of N2V\text{N}_{2}\text{V} defect as quantum memory in diamond

$\text{N}_{2}\text{V}$ defect in diamond is characterized by means of \emph{ab initio} methods relying on density functional theory calculated parameters of a Hubbard model Hamiltonian. It is shown that this approach appropriately describes the energy levels of correlated excited states induced by this defect. By determining its critical magneto-optical parameters, we propose to realize a long-living quantum memory by $\text{N}_{2}\text{V}$ defect in diamond.Comment: 4 figures and 5 table