Strong noise suppression in non-Markovian transport through a vibrating molecular junction

Abstract

A deep understanding of the charge transport processes in molecular junctions is the central issue in the developing field of nanoscale molecular devices. Here, we present a non-Markovian full counting statistics formalism for a nanoelectromechanical system in terms of a generalized quantum master equation, which is valid at finite temperatures and bias. Based on this formalism, we investigate the electron transport through a vibrating molecule, which is tunnel-coupled to the source and drain, as well as an external heat bath. While the Markovian and non-Markovian currents are consistent with each other, we observe a substantial reduction of the non-Markovian noise, where the Fano factor is suppressed down to 10-3, implying well-organized electron tunneling events. In the finite-frequency noise, this is also indicated by the sharp peaks at the characteristic frequency of the oscillator, which broaden and eventually disappear as the temperature and/or tunneling length increase. These findings establish clear parameter boundaries for non-Markovian effects and may offer new insights into understanding charge transfer dynamics in molecular devices.