First principles study of charge diffusion between proximate solid state qubits and its implications on sensor applications. (arXiv:1708.08626v3 [cond-mat.mes-hall] UPDATED)

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.

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