Exploring Bahaviors of Electrode-driven Si Quantum Dot Systems: From Charge Control to Qubit Operation

Abstract Charge stabilities and spin-based quantum bit (qubit) operations in Si double quantum dot (DQD) systems, whose confinement potentials are controlled with multiple gate electrodes, are theoretically studied with a multi-scale modeling approach that combines electronic structure simulations and a Thomas-Fermi method. Taking Si / SiGe heterostructures as the target of modeling, this work presents in-depth discussion on designs of electron reservoirs, electrostatic controls of quantum dot (QD) shapes and corresponding charge confinement, and spin qubit manipulations. Effects of unintentional inaccuracy in DC control biases and geometric symmetries on the Rabi cycle of spin qubits are investigated to examine the robustness of logic operations. Solid connections to the latest experimental result are also established to validate the simulation method. As a rare modeling study that explores a full-stack functionality of Si DQD structures as quantum logic gate devices, this work delivers the knowledge of engineering details that are not uncovered by the latest experimental work, and can serve as a basic but practical guideline for potential device designs.