Tunable pseudogap Kondo effect and quantum phase transitions in Aharonov-Bohm interferometers

Luis G. G. V. Dias da Silva, Nancy Sandler, Pascal Simon, Kevin Ingersent, Sergio E. Ulloa

Published 2009-01-16, updated 2009-04-27Version 2

We study two quantum dots embedded in the arms of an Aharonov-Bohm ring threaded by a magnetic flux. The system can be described by an effective one-impurity Anderson model with an energy- and flux-dependent density of states. For specific values of the flux, this density of states vanishes at the Fermi energy, yielding a controlled realization of the pseudogap Kondo effect. The conductance and transmission phase shifts reflect a nontrivial interplay between wave interference and interactions, providing clear signatures of quantum phase transitions between Kondo and non-Kondo ground states.