Dephasing of Si singlet-triplet qubits due to charge and spin defects

摘要

We study the effect of charge and spin noise on singlet-triplet qubits in Siquantum dots. We set up a theoretical framework aimed at enabling experiment toefficiently identify the most deleterious defects, and complement it with theknowledge of defects gained in decades of industrial and academic work. Werelate the dephasing rates $\Gamma_\phi$ due to various classes of defects toexperimentally measurable parameters such as charge dipole moment, spin dipolemoment and fluctuator switching times. We find that charge fluctuators are moreefficient in causing dephasing than spin fluctuators.