MEASURING INTERACTIONS BETWEEN TUNNEL-COUPLED QUANTUM DOTS

We report low-temperature tunneling measurements through double and tr iple quantum dots with adjustable interdot tunnel conductance, fabrica ted in a GaAs/AlxGa1-xAs heterostructure. As interdot tunnel conductan ce is increased, Coulomb blockade conductance peaks split into two pea ks for double dots and three for triple dots. The splitting approaches zero for weak tunneling and saturates as the dots merge for strong tu nneling. Coupled double and triple dots with different gate capacitanc e show quasiperiodic beating and peak suppression for weak interdot tu nneling. Analysis of the data in terms of tunneling and classical char ging theories shows that quantum charge fluctuations due to interdot t unneling dominate dot interactions when interdot tunnel conductance ap proaches 2e(2)/h.