En las fronteras de la Materia Condensada

We study the transport through a quantum dot embedded in different environments. First we study the effect of finite wires. The quantization of states in the circuit that hosts the quantum dot gives rise to finite size effects. In the Kondo regime, these effects make the conductance sensitive to the ratio of the Kondo screening length to the wires length and provide a way of measuring the Kondo cloud. We also discuss the spin dependent transport when the contacts are ferromagnetic and analyze the cases of source and drain with parallel and antiparallel magnetization. We present results obtained with the numerical renormalization group for a wide range of physically accessible parameters.