Aharonov-Bohm interferometry with interacting quantum dots: Spin configurations, asymmetric interference patterns, bias-voltage-induced Aharonov-Bohm oscillations, and symmetries of transport coefficients

We study electron transport through multiply connected mesoscopic geometries containing interacting quantum dots. Our formulation covers both equilibrium and nonequilibrium physics. We discuss the relation of coherent transport channels through the quantum dot to flux-sensitive Aharonov-Bohm oscillations in the total conductance of the device. Contributions to transport in first and second order in the intrinsic linewidth of the dot levels are addressed in detail. We predict an interaction-induced asymmetry in the amplitude of the interference signal around resonance peaks as a consequence of incoherence associated with spin-flip processes. This asymmetry can be used to probe the total spin of the quantum dot. Such a probe requires less stringent experimental conditions than the Kondo effect, which provides the same information. We show that first-order contributions can be partially or even fully coherent. This contrasts with the sequential-tunneling picture, which describes first-order transport as a sequence of incoherent tunneling processes. We predict bias-voltage-induced Aharonov-Bohm oscillations of physical quantities which are independent of flux in the linear-response regime. Going beyond the Onsager relations we analyze the relations between the space-symmetry group of the setup and the flux-dependent nonlinear conductance.