Conductance dip in the Kondo regime of linear arrays of quantum dots -: art. no. 035402

Using exact diagonalization of small clusters and Dyson equation embedding techniques, the conductance G of linear arrays of quantum dots is investigated. The Hubbard interaction induces Kondo peaks at low temperatures for an odd number of dots N and a filling of one particle per dot. Remarkably, for N=3,5,... the Kondo peak is split in half by a deep minimum, and the conductance vanishes at the gate voltage that induces particle-hole symmetry in the system. Tentative explanations for this unusual effect are proposed, including an interference process between two channels contributing to G, with one more and one less particle than the exactly solved cluster ground state. The Hubbard interaction and fermionic statistics of electrons also appear to be important to understand this phenomenon. Although most of the calculations used a particle-hole symmetric Hamiltonian and formalism, results also presented here show that the conductance dip exists even when this symmetry is broken. The conductance cancellation effect obtained using numerical techniques is potentially interesting, and other many-body techniques should be used to confirm its existence.