COULOMB-BLOCKADE IN A QUANTUM-DOT COUPLED STRONGLY TO A LEAD

We study theoretically a quantum dot in the quantum Hall regime that i s strongly coupled to a single lead via a point contact. We find that even when the transmission through the point contact is perfect, impor tant features of the Coulomb blockade persist. In particular, the tunn eling into the dot via a second weakly coupled lead is suppressed, and shows features that can be ascribed to elastic or inelastic cotunneli ng through the dot. When there is weak backscattering at the point con tact, both the tunneling conductance and the differential capacitance are predicted to oscillate as a function of gate voltage. We point out that the dimensionless ratio xi between the fractional oscillations i n G and C is an intrinsic property of the dot, which, in principle, ca n be measured. We compare xi within two models of electron-electron in teractions. In addition, we discuss the role of additional channels.