Time-Dependent Behavior in Arrays of Two Coupled Quantum-Dot Cells

Time-dependent behavior of two kinds of arrays of two coupled quantum-dot cells is examined. Each square cell composed of four quantum dots in the corners contains two electrons and couples with the neighboring cells by Coulomb interactions. The electrons in one cell tend to occupy antipodal dots which results in a cell “polarization”. We have investigated the temporal evolution of the polarization of one cell under switch of the polarization of the other cell. Our results demonstrate that, with an adiabatic switch, if two cells are arranged in a line their polarizations will align each other, and if they are arranged in a diagonal way their polarizations will invert each other. However, with an abrupt switch, the above features for the polarizations of two cells can not hold. The reason is that the system does not stay in its ground state. It is pointed out that the energy dissipation should be considered in order to obtain the appropriate solutions.