Dephasing effects on a driven triple quantum dot system

We analyze the effect of environmental dephasing on the electronic current in an ac-driven triple quantum dot system in a symmetric Λ-configuration characterized by an interdot energy. The electronic current is explored by solving the time evolution equation of the density matrix as a function of the frequency and amplitude of the driving field. Depending on the field amplitude, we observe two characteristic spectra, a Fano-type profile or a more symmetric structure. At resonance, the former shows a prominent peak, while the latter exhibits a strong suppression due to dynamic localization. In the first the case, we observe the maximum is reduced due to dephasing, while in the second it is shown that dephasing lifts the localization. In both cases, off resonance, we find that dephasing increases the current systematically at the current minima. This dephasing assisted tunneling phenomenon is found to persist for a large range of values of the coupling to the drain, in contrast to the known undriven case. The effect of dephasing is also discussed using Floquet theory, and by analytical expressions for the electronic current within the rotating wave approximation.