Multi-level, Multi-photon Landau-Zener-Stuckelberg Interferometry of Two-Electron States in Semiconductor Quantum Dots*

Gate-defined quantum dots enable defining few-level quantum systems with charge and spin degrees of freedom of one or many electrons. Such few-level systems are important and robust platforms for encoding and manipulating quantum information. The same few-level systems can also be used to study different aspects of natural and engineered quantum interactions between electrons. We present a study of multiple-photon and multiple-level Landau-Zener-Stuckelberg interference of both charge and spin states of two electrons in a semiconductor double quantum dot. By driving the electrons with a microwave electrical signal, we sweep them periodically through multiple avoided crossings that couple different spin and charge states. Our results agree with theoretical calculations and provide a new perspective on Landau-Zener-Stuckelberg interferometry in quantum systems.