The electronic and magnetic properties of a neutral substitutional nickel (Nis0) impurity in diamond are studied using density functional theory in the generalized gradient approximation. The spin-one ground state consists of two electrons with parallel spins, one located on the nickel ion in the 3d9 configuration and the other distributed among the nearest-neighbor carbons. The exchange interaction between these spins is due to p−d hybridization and is controllable with compressive hydrostatic or uniaxial strain, and for sufficient strain the antiparallel spin configuration becomes the ground state. Hence, the Ni impurity forms a controllable two-electron exchange-coupled system that should be a robust qubit for solid-state quantum information processing.
@article{arxiv.1112.4436,
title = {Substitutional nickel impurities in diamond: decoherence-free subspaces for quantum information processing},
author = {Thomas Chanier and Craig Pryor and Michael E. Flatte'},
journal= {arXiv preprint arXiv:1112.4436},
year = {2015}
}