Mesoscopic capacitance oscillations due to quantum dynamic coherence in an interacting quantum capacitor

Abstract

We have measured the electrochemical capacitance in a quantum coherent capacitor consisting of a quantum dot connected to an electron reservoir by a gate tunable quantum point contact and Coulomb coupled to a gate. The results show that for a weak transparent channel, the capacitance exhibits sharp Coulomb blockade oscillations with gate voltage related to the oscillations of the dot density of states, which is almost independent of the applied magnetic field. As the transmitting channel becomes more transparent, the capacitance oscillations decrease in magnitude reflecting the broadening of the resonances. Remarkably, we find that the capacitance oscillation persists even for a fully transparent quantum channel. From the magnetic field and temperature dependence, we conclude that such a capacitance oscillation is a mesoscopic coherent effect that arises due to the interference of electrons in a nearly open dot.