Transition from the Kondo effect to a Coulomb blockade in an electron shuttle.

We investigate the effect of the mechanical motion of a quantum dot on the transport properties of a quantum dot shuttle. Employing the equation of motion method for the nonequilibrium Green's function, we show that the oscillation of the dot, i.e., the time-dependent coupling between the dot's electron and the reservoirs, can destroy the Kondo effect. With the increase in the oscillation frequency of the dot, the density of states of the quantum dot shuttle changes from the Kondo-like to a Coulomb-blockade pattern. Increasing the coupling between the dot and the electrodes may partly recover the Kondo peak in the spectrum of the density of states. Understanding of the effect of mechanical motion on the transport properties of an electron shuttle is important for the future application of nanoelectromechanical devices. [ABSTRACT FROM AUTHOR]