Beating in electronic transport through quantum dot based devices

Electronic transport through a two-level system driven by external electric field and coupled to (magnetic or non-magnetic) electron reservoirs is considered theoretically. The basic transport characteristics such as current and tunnel magnetoresistance (TMR) are calculated in the weak coupling approximation by the use of rate equation connected with Green function formalism and slave-boson approach. The time dependent phenomenon is considered in the gradient expansion approximation. The results show that coherent beats pattern can be observed both in current and TMR. The proposed system consisting of two quantum dots attached to external leads, in which the dots' levels can be tuned independently, can be realized experimentally to test this well known physical phenomenon. Finally, we also indicate possible practical applications of such device.Comment: 9 pages, 9 figure