Potential dependent intra-dot Coulomb interaction in quantum dots side-coupled to quantum wires

We present experiments on electronic states in few-electron lateral quantum dots side-coupled to quantum wires. The side-coupled structure enabled us to prepare the dots with various spatial sizes. The Coulomb energy and the quantum confinement energy depend on the dot size in different ways and thus the change in the size causes the change in the relative amplitude of the two energy scales. This results in non-monotonic occupation of single-electron energy levels. We have observed such non-trivial occupation through the collapse of the magic numbers and the response to magnetic field.