Resonant tunneling through a single-level quantum dot

We study resonant tunneling through a single-level quantum dot in the presence of strong Coulomb interaction. This system is described by the Anderson model, which at low temperatures for a low-lying level shows a peak in the.differential conductance at zero-bias voltage (zero-bias anomaly). This so-called Kondo resonance can be understood as a coherent coupling between the state on the dot and those in the reservoirs, which enhances transport. At higher temperatures and bias voltages, this coherence is destroyed. We obtain an approximate solution of the problem for arbitrary parameters by a diagrammatic expansion technique. Recently, Ralph and Buhrman interpreted their experiments as transport through one such impurity level. We compare our results with their experiment. (C) 1997 Elsevier Science B.V. All rights reserved.