Transport through a double quantum dot with interdot repulsion

Abstract

We study transport through a double quantum dot with interdot hopping t, intradot repulsion U and interdot repulsion U', using the numerical renormalization group (NRG) method. At half-filling, the conductances in two-terminal series and four-terminal parallel configuration are calculated via two phase shifts for quasi-particles of double quantum dot connected to two noninteracting leads with hybridization strength G. For small values of t/Γ and U'/U, conductance in the two-terminal series configuration is suppressed to almost zero. In this region, plateau of conductance in the four-terminal parallel configuration appears and almost reaches a unitary limit value 4e2 /h of two conducting modes. For large values of t/Γ or U'/U, both conductances are suppressed to almost zero. The conductance in the two-terminal series configuration almost reaches a unitary limit value 2e2/h only around cross-over regions of electron-configuration in double quantum dot. Through the behavior of the local charge and some thermodynamic quantities, we discuss the relation between transport and electron-configuration.