Low-frequency excitation of double quantum dots

TL;DR

This paper theoretically investigates adiabatic charge transport in double quantum dots under low-frequency excitation, deriving formulas and comparing results with experimental data for pure pumping and bias-driven current.

Contribution

It introduces a detailed Green function formalism for adiabatic pumping in double quantum dots and derives the adiabatic limit of the Tien-Gordon formula, aligning theory with experiments.

Findings

Results agree with experimental data on quantum dot charge transport.

Derived the adiabatic limit of photon-assisted tunneling formula.

Provided a tutorial on Green function methods for adiabatic pumping.

Abstract

We address theoretically adiabatic regime of charge transport for a model of two tunnel-coupled quantum dots connected in series. The energy levels of the two dots are harmonically modulated by an external potential with a constant phase shift between the two. Motivated by recent experiments with surface-acoustic-wave excitation, we consider two situations: (a) pure pumping in the absence of external voltage (also at finite temperature), and (b) adiabatic modulation of the current driven by large external bias. In both cases we derive results consistent with published experimental data. For the case (b) we explicitly derive the adiabatic limit of Tien-Gordon formula for photon-assisted tunneling and compare it to the outcome of simple conductance modulation. A tutorial for adiabatic pumping current calculations with the Green function formalism is included.