Charge transport through a molecule driven by a high-frequency field

We study the current and the associated noise for the transport through a two-site molecule driven by an external oscillating field. Within a high-frequency approximation, the time-dependent Hamiltonian is mapped to a static one with effective parameters that depend on the driving amplitude and frequency. This analysis allows an intuitive physical picture explaining the nontrivial structure found in the noise properties as a function of the driving amplitude. The presence of dips in the Fano factor permits a control of the noise level by means of an appropriate external driving. (C) 2003 Elsevier B.V. All rights reserved.