The role of intersubband mixing in single-electron charging of open quantum dot

We compare the electrostatics and electron transmission through the quantum dots that have the inlet/outlet constrictions made by (i) split finger gates and (ii) overlaying finger gates. It has been found numerically that the intermode mixing is large in the former case while almost absent in the latter. We beleive this difference is responsible for single-electron charging of the open quantum dot of new type (ii) observed in C.-T. Liang et al. (Phys. Rev. Lett. 81 (1998) 3507). Our calculations show that the measured periods of conductance oscillations agree well with the change of the total charge of the dot by one elemental charge as the gate voltages change. Conventionally, single-electron charging does not show up in the transport through open quantum dots due to high transition probability from localized states to fully open channels.