Series expansion of the quantum admittance in mesoscopic systems

TL;DR

This paper derives a series expansion for the quantum admittance in mesoscopic systems using refermionization, enabling analysis of its dependence on voltage, temperature, and frequency across different interaction regimes.

Contribution

It provides a non-perturbative series expansion of quantum admittance applicable to various interaction strengths in mesoscopic systems.

Findings

Explicit admittance expressions in weak and strong coupling limits

Identification of inductive or capacitive behavior based on parameters

Conditions for positive phase of current relative to ac voltage

Abstract

The quantum admittance of an interacting/coupled mesoscopic system and its series expansion are obtained by using the refermionization method. With the help of these non-perturbative results, it is possible to study the dependencies of the admittance according to the applied dc voltage, temperature, and frequency without any restriction on the relative values of these variables. Explicit expressions of the admittance are derived both in the limits of weak and strong interactions/coupling strength, giving clear indication of the inductive or capacitive nature of the mesoscopic system. They help to determine the conditions under which the phase of the current with respect to the ac voltage is positive.