Tunnel Falls Detuning Spectrum

In this section, we demonstrate how QTCAD can be used to model the central region of a Tunnel Falls-style \(\mathrm{Si}/\mathrm{SiGe}\) double-dot device. The aim of the workflow is to simulate the energy spectra of a double-dot system as a function of gate detuning. The simulation accounts for correlated valley couplings consistent with experimentally measured valley splittings. These spectra are related to dipolar anticrossing spectroscopy (DAPS) measurements [MEB+25].

This practical application is organized into four files. First, QTCAD Builder is used to construct the Mesh over which the simulations are performed. Second, an importable helper function creates the QTCAD Device associated with that Mesh, representing a subsection of the full Tunnel Falls device containing two quantum dots and nearby confinement gates. Third, an importable \(\mathbf{k} \cdot \mathbf{p}\) helper defines the correlated valley-coupling model. Finally, the energy-versus-detuning script generates the energy spectrum under the influence of this correlated valley-coupling model.

• 1. Mesh generation using QTCAD Builder
• 2. Creating the Tunnel Falls Device
• 3. Position-Dependent Two-Valley \(\mathbf{k} \cdot \mathbf{p}\) Model
• 4. Calculating the Energy Spectrum as a Function of Detuning