Phonon-assisted tunneling regimes in diatomic molecules

TL;DR

This paper investigates how phonon interactions influence electron tunneling in diatomic molecules, revealing interference effects, resonance phenomena, and temperature-dependent Rabi-assisted tunneling, with implications for experimental control.

Contribution

It introduces a detailed analysis of phonon-assisted tunneling regimes considering electron-electron interactions, highlighting resonance effects and temperature dependence in diatomic molecules.

Findings

Phonon processes are significantly altered by Coulomb interactions.

Resonance conditions lead to interference effects in conductance.

Enhanced Rabi-assisted tunneling occurs at resonance, especially at higher temperatures.

Abstract

Electronic transport in diatomic molecules (two-level systems) connected to metallic contacts is analyzed in the presence of competing electron-electron and electron-phonon interactions. We show that phonon emission and absorption processes are strongly modified when a Coulomb energy $U$ is included, as the phonons open channels that can result in destructive or constructive interference effects. Resonance conditions for these processes produce dramatic effects both in the density of states at the molecular sites, as well as in the conductance through the system. We find in particular an enhanced {\it Rabi-assisted tunneling} due to phonons, as the resonance conditions are met, which is made more evident for increasing temperatures. These effects are controllable by voltage gating of the molecular sites, and should be accessible in current experiments.