Correlated electron transport through parallel double-quantum-dot

TL;DR

This paper studies electron transport in a parallel double-quantum-dot system, analyzing spectral and conductance properties under various interactions and couplings using Green function techniques.

Contribution

It provides a detailed analysis of correlated electron transport in double quantum dots, including effects of interdot tunneling and Coulomb interactions, using both exact and approximate methods.

Findings

Correlated electron transport affects conductance spectra.

Interplay between Coulomb interaction and tunneling influences transport.

Spectral functions reveal the impact of interactions on electron flow.

Abstract

We investigate the spectral and transport properties of parallel double-quantum-dot (DQD) system with interdot tunneling coupling in both the equilibrium and nonequilibrium cases. The special geometry of DQD system is considered, in which each dot is connected to two leads by the tunneling barriers. With the help of Keldysh nonequilibrium Green function technique and the equation-of-motion approach, the spectral function and the conductance spectra of DQD system are calculated in two cases with and without the intradot Coulomb interaction, respectively. The exact calculation is performed in the absence of intradot Coulomb interaction. For the case with intradot Coulomb interaction, the Hartree-Fock approximation is applied to truncate the equation of motion for the high-order Green functions at high temperatures. The phenomenon of correlated electron transport is clearly shown in the linear conductance of each dot in the presence of interdot tunneling when setting one dot level and tuning another. The interplay between the intradot Coulomb interaction and the interdot tunneling coupling is displayed.