Optical phase control of electron transport in coupled quantum dots

The properties of electron transport through an effective closed three-level structure in an asymmetric double quantum dot system are studied. It is demonstrated that the relative phase between two laser fields can strongly modulate the current through the system, which is similar to the magnetic flux controlled coherent transport in an Aharnov-Bohm interferometer. Two different transport regimes are considered, one is the regime of the chemical potential μ_R of the right lead between the ground state ε₂ and the excited state ε₃ of the right dot, the other is the regime of μ_R<ε₂. In both regimes, the current can be tuned to zero by appropriately choosing the phases of the driving lasers, which can be used as an optically controlled current switch. In the regime of μ_R<ε₂, the current peak approaches zero because the electron is nearly trapped into the ground state of the left quantum dot. While in the regime of ε₂<μ_R<ε₃, I = 0 occurs when the electron is trapped in the dark state, a superposition of the two quantum dot ground states