The effects of the electrochemical capacitance on the ac admittance phase of a quantum point contact

Publication date: Available online 5 December 2018Source: Physics Letters AAuthor(s): Jianzhuang Yin, Shuwei Chen, Li SongAbstractWe investigate the ac admittance of a quantum point contact (QPC) in quantum hall regime. Experiment data shows that the phase of the QPC admittance is not transmission independent. With the increasing of the QPC transmission, the phase increases in large magnetic field, but stays constant in small field. The theoretical works indicated that the Coulomb interaction between the counter-propagate channels is the main reason for the non-constant phase in large field. Besides this, we also studied the other types of Coulomb interactions. Especially, the Coulomb interaction between the channels across the QPC could make the sample behave like a capacitance and thus a change from the capacitive behavior to inductive behavior is expected when the QPC is opening. Our investigation demonstrates that the Coulomb interaction can serve as a sensitive detection method for the internal properties of quantum devices, in particular, at gigahertz frequencies.

Source: Physics Letters A - December 6, 2018 Category: Physics Source Type: research