Anomalous Coulomb-Enhanced Charge Transport in Triangular Triple Quantum Dots Systems

TL;DR

This paper investigates how Coulomb interactions can unexpectedly enhance charge transport in a triangular triple quantum dot system, revealing complex interplay between electron correlations and quantum interference.

Contribution

It introduces a theoretical analysis of nonequilibrium transport in TTQD systems showing Coulomb interaction can increase current, contrasting with previous suppression in linear arrays.

Findings

Coulomb interaction U enhances stationary current in TTQD.

Spectral function analysis links enhancement to Coulomb shifts and interference.

Transport current depends on inter-dot tunneling t and Coulomb interaction U.

Abstract

Electron correlation and quantum interference are pivotal in mesoscopic transport. We theoretically study the nonequilibrium transport dynamics of a triangular triple quantum dot (TTQD) molecule connected to fermionic reservoirs using the exact hierarchical equations of motion (HEOM) formalism. We demonstrate a counter-intuitive transport signature where the stationary current is significantly enhanced by increasing the $U$, a behavior distinct from the suppression typically observed in linear quantum dot arrays. By analyzing the evolution of spectral functions, we attribute this enhancement to the interplay between Coulomb interaction-induced energy shifts and quantum interference effects unique to the triangular topology. We also explore how the circulation of chiral currents and electrode coupling strength modulates these interaction effects. Finally, we present a three-dimensional map of the transport current as a function of inter-dot tunneling ($t$) and Coulomb interaction ($U$), illustrating their combined effect on the current magnitude and its applications.