Quantum interference and electron correlation in charge transport through triangular quantum dot molecules

Abstract

We study the charge transport properties of triangular quantum dot molecule (TQDM) connected to metallic electrodes, taking into account all correlation functions and relevant charging states. The quantum interference (QI) effect of TQDM resulting from electron coherent tunneling between quantum dots is revealed and well interpreted by the long distance coherent tunneling mechanism. The spectra of electrical conductance of TQDM with charge filling from one to six electrons clearly depict the many-body and topological effects. The calculated charge stability diagram for conductance and total occupation numbers match well with the recent experimental measurements. We also demonstrate that the destructive QI effect on the tunneling current of TQDM is robust with respect to temperature variation, making the single electron QI transistor feasible at higher temperatures.

A heat engine made of quantum dot molecules with high figure of merits

“…Noting that the interdot Coulomb interactions as well as intradot Coulomb interactions play a significant role on the charge transport in semiconductor QD arrays or molecular chains. [10][11][12][13] Because we are interested in the case that the thermal energy is much smaller than intradot Coulomb interactions, we consider QDs with only one energy level per dot.…”

“…Most theoretical studies of TE properties are limited in the linear response regime. [10][11][12][13] The many-body effect of QDMs also presents a big challenge to the development of theoretical studies for TE properties. In this article, we study the nonlinear behavior of EHE made of serially coupled triple QDs (SCTQDs) based on a previously developed numerically method, [12,13] which can suitably address the many body effect in the Coulomb blockade regime.…”

“…[10][11][12][13] The many-body effect of QDMs also presents a big challenge to the development of theoretical studies for TE properties. In this article, we study the nonlinear behavior of EHE made of serially coupled triple QDs (SCTQDs) based on a previously developed numerically method, [12,13] which can suitably address the many body effect in the Coulomb blockade regime. In addition, we investigate an engine with directiondependent electrical output driven by a temperature-bias for application as a novel nonlinear TE devices.…”

Quantum interference and structure-dependent orbital-filling effects on the thermoelectric properties of quantum dot molecules

“…Many theoretical studies have used the first-principles method (within mean-field approximation) to predict the TE coefficient of realistic molecules with orbital below the E F of electrodes. [22][23][24][25] Such a mean-field approach does not take full account of the electron correlation effects. Therefore, the predicted G e , S and PF can not reveal the realistic TE properties of molecule junction systems in the Coulomb blockade regime.…”

“…[1,2] Although many theoretical efforts have investigated the PF enhancement of QDs [10][11][12][13][14][15] and molecule junctions [22][23][24], quantum interference (QI) and orbital filling effects on the PF optimization are still puzzling due to the difficulty to treat many body effect reliably in either QDSLs or molecules. [25] For example, in the triangular QD molecule (TQDM), there are 923 electron correlation functions appeared in the 4752 Green's functions need to be solved, when electron Coulomb interactions are turned on, even though one just considers one energy level for each QD. As a consequence, a theoretical framework to treat adequately the many-body problem of a molecular junction remains elusive.…”