Time-dependent field-induced transport in a T-shaped triple quantum dot system

Abstract

We investigate electron transport through a T-shaped triple quantum dot system subjected to a time-dependent external field. Using the time-dependent Green’s function method, we calculate the average current. Under field irradiation, the three main current peaks exhibit reduced intensity, accompanied by the emergence of photon-assisted sideband peaks in the current spectrum. As the field amplitude increases, the main peaks evolve differently: notably, the central peak can transition into a current valley. By tuning the field frequency, reversible conversion between current peaks and valleys is achieved. Moreover, adjusting the interdot coupling strength gives rise to narrow Fano-type current resonances, which broaden with increasing coupling and eventually evolve into conventional current peaks. The applied field also enables controlled switching between zero and finite current states, suggesting the feasibility of an optically controlled quantum switch. This work provides insights for the design of future nanoscale devices and their applications in quantum information processing.