Bouncing states in quantum dots

We observe sequences of asymmetric Coulomb blockade resonances in the conductance of a closed quantum dot. Around a symmetric peak at the center of such a sequence, several asymmetric resonances with a steep flank facing the central peak are found. This effect occurs for an average coupling of the quantum dot states to the leads which is of the order of both their average energy level spacing as well as of the thermal energy. These observations are interpreted in terms of a single state (“bouncing state”) that couples particularly well to the leads. Such a state can influence the line shapes of several neighboring Coulomb blockade resonances.