Donor spin in silicon have achieved record values of coherence times and single-qubit gate fidelities. The next stage of development involves demonstrating high-fidelity two-qubit logic gates, where the most natural coupling is the exchange interaction. To aid the efficient design of scalable donor-based quantum processors, we model the two-electron wave function using a full configuration interaction method within a multi-valley effective mass theory. We exploit the high computational efficiency of our code to investigate the exchange interaction, valley population, and electron densities for two phosphorus donors in a wide range of lattice positions, orientations, and as a function of applied electric fields. The outcomes are visualized with interactive images where donor positions can be swept while watching the valley and orbital components evolve accordingly. Our results provide a physically intuitive and quantitatively accurate understanding of the placement and tuning criteria necessary to achieve high-fidelity two-qubit gates with donors in silicon.
@article{arxiv.2012.06293,
title = {Full configuration interaction simulations of exchange-coupled donors in silicon using multi-valley effective mass theory},
author = {Benjamin Joecker and Andrew D. Baczewski and John K. Gamble and Jarryd J. Pla and André Saraiva and Andrea Morello},
journal= {arXiv preprint arXiv:2012.06293},
year = {2021}
}