Linear and non-linear transport through coupled quantum dots

We have measured linear and non-linear transport through a double quantum-dot system fabricated from the two-dimensional electron gas (2DEG) formed by a GaAs/AlGaAs heterostructure. At small source-drain bias, we observe Coulomb oscillations when the gate voltages of the two dots are tuned so that both dots conduct, in agreement with classical models of the two-dot system. At higher source-drain bias these Coulomb oscillations develop sharp overstructure, which arises from the alignment and de-alignment of quantized energy levels of the two dots.