CORRELATED ELECTRON-TRANSPORT IN COUPLED METAL DOUBLE DOTS

The electrostatic interaction between two capacitively coupled, series -connected metal double dots is studied at low temperatures. Experimen t shows that when the Coulomb blockade is lifted, by applying appropri ate gate biases, in both double dots simultaneously, the conductance t hrough each double dot becomes significantly lower than when only one double dot is conducting a current. The conductance lowering seen in i nteracting double dots is compared to that caused by an external ac mo dulation applied to the double-dot gates. The results suggest that the conductance lowering in each double dot is caused by a single-electro n tunneling in the other double dot. Here, each double dot responds to the instantaneous, rather than average, potentials on the other doubl e dot. This leads to correlated electron motion within the system, whe re the position of single electron in one double dot controls the tunn eling rate through the other double dot. (C) 1998 American Institute o f Physics. [S0003-6951(98)04445-3].