Charge Transfer Through Molecules with Multiple Pathways: Quantum Interference and Dephasing

Quantum interference effects occurring in molecules through which a charge can travel via multiple pathways can be the basis for new unconventional design principles in molecular scale electronics. However, these quantum interference effects can be reduced by interaction between the charge and molecular vibrations. In this work dephasing (decoherence) effects have been studied using a model that combines a (classical) molecular mechanics description of molecular vibrations with a quantum mechanical propagation of the charge. It is found that despite the clear effect of dephasing on the charge propagation, interference effects are largely retained at room temperature if vibrations are accounted for. Additionally, it is shown that taking electronic interactions between non-nearest neighbor atoms into account also diminishes interference effects but not sufficiently to destroy them completely. It is concluded that interference effects are strong enough to use them in a functional manner in molecular electronics. This opens up new ways to design molecular electronic components that exploit quantum interference.