2x2 quantum dot arrays in Si/SiGe*

Great progress has been made with silicon in scaling up the number of quantum dots in linear arrays, with realizations of up to nine quantum dots. However, a crucial requirement for quantum computation is the ability to engineer two-dimensional quantum dot arrays. This step will increase qubit interconnectivity and could enable to perform quantum error correction using the surface code. Here, we present the realization of two-dimensional silicon quantum dot arrays, defined in isotopically enriched Si/SiGe heterostructures using single layer and overlapping gate schemes. We show that quantum dots can be tuned to the single-electron regime, as confirmed by simultaneous charge sensing using two nearby quantum dot charge sensors. We concentrate on experimental results in gaining control over the quantum dot system focusing on quantum information processing with quantum dots realized in two-dimensional arrays.