Charge States and Transition of Double Quantum Dot in the Few-Electron Regime

We present transport characterizations of a fully tunable double quantum dot over the few electron number down to zero, which is defined by means of surface gates on top of a GaAs/AlGaAs heterostructure. We also perform numerical simulations to map out the charge stability diagram, which is consistent with the measurements. The results demonstrate that the electric control in the double dot can be significantly enhanced by improving the design of the device structure, which provides potential advantages for quantum information processing.