Electron transport through a coupled double dot molecule: role of inter-dot coupling, phononic and dissipative effects

TL;DR

This paper investigates how inter-dot coupling, phononic interactions, and dissipation influence electron transport in a double quantum dot molecule, revealing step-like current features and phononic sidebands that persist under various conditions.

Contribution

It provides new insights into the effects of inter-dot coupling and phononic interactions on electron transport in coupled quantum dots, highlighting the persistence of phononic features.

Findings

Current exhibits step-like features with increasing inter-dot coupling.

Step features vanish with higher lead tunneling rates, but two kinks remain.

Phononic sidebands persist even with strong lead-molecule coupling.

Abstract

In this work, we have investigated conduction through an artificial molecule comprising two coupled quantum dots. The question addressed is the role of inter-dot coupling on electronic transport. We find that the current through the molecule exhibits step-like features as a function of the voltage between the leads, where the step size increases as the inter-dot coupling is increased. These step-like features disappear with increasing tunneling rate from the leads, but we find that in the presence of coupling, this smooth behavior is not observed rather two kinks are seen in the current voltage curve. This shows that the resolution of the two levels persists if there is finite inter-dot coupling. Furthermore, we also consider the effects of electron-phonon interaction as well as dissipation on conduction in this system. Phononic side bands in the differential conductance survive for finite inter-dot coupling even for strong lead to molecule coupling.