Multiphysics Simulation & Design of Silicon Quantum Dot Qubit Devices

In this paper, we combine multiphysics simulation methods to assemble a comprehensive design methodology for silicon qubit devices. Key device parameters are summarized by modeling device electrostatics, stress, micro-magnetics, band-structure and spin dynamics. Based on the models, we infer that highly confined single electron qubits in quantum dots, with large orbital energy separations, can be induced in Si-MOS structures with thin (t(OX) < 20 nm) gate oxides. We further advocate that poly-silicon gate material, in conjunction with small barrier gate widths (b < 30 nm), will reduce the impact of strain on qubit readout and two-qubit gate-operations. We optimized a micromagnet design to provide fast single-qubit gate times (similar to 100 ns), with minimal dephasing field gradients. Finally, we estimate that the exchange coupling between qubits is tunable by over 4 orders of magnitude, for two-qubit operations.