En las fronteras de la Materia Condensada

Electron transport in atomic-size metallic contacts proceed through a reduced number of conduction channels. When the contact is in the superconducting state a quasi-particle current can be established at subgap bias voltages thanks to the mechanism of Multiple Andreev Reflections. This results in a highly non-linear current voltage characteristic which allows to extract information on the channel distribution. We shall discuss several theoretical predictions for electron transport properties that have been tested experimentally using atomic contacts including shot-noise, Josephson currents and the Coulomb blockade effect.