Single-Electron Charging in Double and Triple Quantum Dots with Tunable Coupling

We report low-temperature tunneling measurements at zero magnetic field through double and triple quantum dots with adjustable interdot coupling, fabricated in a GaAs/AlGaAs heterostructure. As the coupling is increased, Coulomb blockade conductance peaks split into two (double dot) or three (triple dot) peaks each. The splitting tracks closely the measured tunnel conductance and experimentally determines the total interaction energy. Coupled double and triple dots with different gate capacitance show quasiperiodic beating.