Coupling Behavior Of The Exciton Dynamics In A Quantum Dot Molecule

Theoretical and experimental research about the reduced dimensional quantum structure such as quantum well and quantum dot attracts much attention because of the development of the growth technology of crystal. Semiconductor quantum dot is a kind of mesoscopic system which has been developed after super lattice, quantum well. Quantum device based on quantum dot has extensive application prospect in the field of nanoelectronics, optoelectronics because of unique electronic and optical performance and extremely low power consumption. In many literatures, the property of the carriers in confined quantum dot is discussed, the influence of the quantum dot's shape and the dielectric constant of the quantum dot and the surrounding substrate to the carriers is studied, however there is little research on the influence of the driving field to the carriers, so it is necessary to perform profound research on the influence of the driving field to the carriers.In this article, we have studied the dynamical behaviors of electron-hole system in coupled double quantum dot with DC and AC electric field. With a two-site Hubbard model and Floquet theory, the time-dependent Schrodinger equation is numerically solved. The minimum of probability P_min of the electron and the hole remain on the initial localized state within 20 periods of the external field is given. Three situations, the coulomb interaction between electron and hole is zero, only AC electric field exists, both DC and AC electric field exist are discussed. We have researched the effect of the coulomb interaction, DC and AC electric field to dynamical behaviors of electron-hole system in double coupled quantum dot; analyzed localization of exciton in this quantum system based on two-level approach theory and perturbation theory; pointed out the condition of dynamical localization. The obtained results show that for the weak field, the exciton mainly oscillates between two localized states, however, for the strong field, the electron and the hole can independently tunnel between two quantum dots. The driving field tends to drive the electron and the hole apart, under appropriate condition the electron and the hole can be localized in the initial state for a short of time. The DC field breaks the dynamical symmetry of the system and affects the dynamical localization.