Induced quantum dot probe for qubit and material characterization

We propose a non-destructive means of characterizing quantum dot parameters across a semiconductor wafer by inducing a quantum dot on the material system of interest with a separate probe chip that can also house the measurement circuitry. We show that a single wire can create the dot, determine if an electron is present, and be used to measure critical device parameters. Adding more wires enables more complicated setup and measurements. As one application for this concept we consider silicon metal-oxide-semiconductor and silicon/silicon-germanium quantum dot qubits relevant to quantum computing and show how to measure low-lying excited states (so-called `valley' states) in a novel way. The approach provides a simple and flexible method for characterization applicable to various quantum systems.