Building and verifying a robust qubit model on Si/SiGe quantum dot arrays

The design and optimization of classical semiconductor devices rely on advanced computational tools to predict the device performance prior to fabrication, significantly reducing development cost and time. Inspired by these methods from the matured microelectronics industry, future generations of scalable and complex semiconducting qubit systems can similarly benefit from such predictive modeling.

We present our work on developing a robust qubit model based on Si/SiGe quantum dot arrays. Using the Quantum TCAD simulation tool, taking into account the 3D device geometry, along with high-level simulations, we estimate the electrostatic potential, as well as the eigenenergies and envelope functions of electrons confined in the quantum dot array. We then calculate the gate lever arms for each dot, followed by charge stability diagrams in the few-electron regime. Also, we compute the exchange interaction strength between adjacent dots, a critical parameter for understanding two-qubit gate operations.

To validate our model, we compare these theoretical predictions with experimental measurements from fabricated qubit devices, showing strong agreement. Spin qubits were measured through Pauli Spin Blockade at the (3,1) → (4,0) charge transition, followed by exchange oscillation measurements. Our long-term goal is to scale this technology to an industrial level and to co-integrate CMOS control and readout electronics on the same chip, enabling more efficient and scalable quantum computing systems.