Pumping and AC transport in a two-electron doublequantum dot molecule

摘要

We investigate the dynamics of interacting electrons in a double quantum dotsystem with an applied AC-field, using a Markov master equation approach for the timeevolution of the reduced density matrix. For the closed system with two electrons we study theevolution of the density matrix as a function of AC-field. We find that the addition of Zeemansplitting in one of the dots opens the possibility of pumping spin-selected electrons throughthis system. For the open system case, the behavior of the current through the double-dot isstudied, as a function of AC field, and coupling to the leads. We find that the formation of aspin triplet state blocks the pumping mechanism of the device, and analyze possible solutions.Finally we study the effects of applying a pulsed AC-field and the possibility of resolutionof Rabi oscillations. Our results demonstrate the possibility of using AC-fields to control theevolution of states in mesoscopic devices on extremely short timescales, which is an essentialcomponent of practical schemes for quantum information processing.