Electron transport through a parallel double-dot system in the presence of Aharonov-Bohm flux and phonon scattering

We examine the transport and microwave properties of the tunnel-coupled double-dot structure with parallel arrangement between leads in the presence of Aharonov-Bohm magnetic flux. The nonequilibrium Green's function formalism is employed with account of electron-phonon coupling and interdot Coulomb repulsion. We obtain the energies, populations, and linewidths of the bonding and antibonding states in the double-dot structure as well as its current-voltage characteristics and the bias dependence of the electromagnetic energy absorbed by the system. For resonant magnetic fluxes when only one level is connected to the leads, the current-voltage characteristics have only one step, whereas for nonresonant fluxes there are either two steps or one sharp step depending on the common equilibrium chemical potential of the leads. In the case of two steps, the current value in the plateau region between the steps is the oscillatory function of applied magnetic flux. It is shown that the disconnection of one of the levels from the leads at the resonant phases gives rise to the residual absorption of the external electromagnetic field at high bias which vanishes otherwise.