Germanium-Based Gated Double Quantum Dot

In this section, we use QTCAD to model a realistic germanium-based gated double quantum dot system confining holes. In the first part, we use the Builder package to generate a mesh for the device based on a photomask layout of the double quantum dot’s gate electrodes. In the second part, we solve the nonlinear Poisson equation across the device to determine the confinement potential. We then solve the Schrödinger equation in the double-dot region to obtain its eigenenergies and corresponding eigenfunctions. In the third part, we compute how the double-dot energy levels depend on the voltages applied to the surrounding gates, allowing us to extract the lever-arm matrix. Finally, in the fourth part, we investigate transport through the double dot in the Coulomb blockade regime by computing the charge-stability diagram.

• 1. Builder workflow: Ge/SiGe double quantum dot
• 2. Simulating hole states in a Ge/SiGe quantum dot using Poisson and Schrödinger solvers
• 3. Calculating the lever-arm matrix of a quantum dot
• 4. Calculating Coulomb interactions and the charge stability diagram of a quantum dot