Theoretical Study Of The Dynamic Properties Of Coupled Quantum Dot System. External Field

This thesis is devoted to study the quantum dynamics of coupled quantum dot system in the presence of external fields. Using the long-time averaged occupation probability method, we quantitatively study the dynamical localization of system.In chapter one, we introduce the current development in the field of coupled quantum dots and describe the main results of this thesis.In chapter two, we present a new method named long-time averaged occupation probability method, which can be used to study the dynamics of system. This new method overcomes the shortcoming of the traditional Floquet spectrum method in that the later one is only the necessary criterion of dynamical localization. As a necessary and sufficient evidence of dynamical localization, this method can be used to study the system quantitatively. We studied the dynamical localization of a double quantum dot system as a simple example of this method.In chapter three, we study the dynamical localization of a square quantum dot molecule. Besides the effect of electric field, we further considered the Aharonov-Bohm effect through introducing a vertical magnetic field. The results show that the dynamical localization can happen in such a system and the effect of the magnetic field increase with the increase of coupling.In chapter four, we study the property of a double quantum dot with two energy levels. The results show that the electrons which initially localized in a dot can still localize in this dot with appropriate parameters, while they still can transit between different energy levels.In chapter five, we study the possibility of dynamical localization in quantum dot array. Through increasing the quantum dot number in the array gradually, we find the dynamicallocalization effect has no change with some external parameters.In chapter six, we control the tunneling of electrons in the quantum dot array selectively rather than only localizing them in their initial state. We also find the Floquet spectrum can be further divided into two minibands, which describe different physical process respectively.