The Study Of Electronic Transport Properties Of Coupled Quantum Dot System

Since the eighties of the last century, with in-depth study of the physical problemscaused as a result of quantum coherence in small-scale configuration, a new branch ofphysics-Mesoscopic Physics was gradually formed. Related research is prompting thequantum device fabrication technology. Quantum devices also show a very broadapplication prospect of science and technology. Thus the study of mesoscopic systems areincreasins the interest of the majority of a large number of research groups in physics.Study of mesoscopic systems involves many aspects such as the optical properties ofmesoscopic systems, transport properties, the balance of nature, energy spectrum structureand so on. The vast majority of studies focused on the electron transport properties.Since the quantum dot shape, size, and the coupling between the quantum dot and thewire can be controlled, the research on it has a lot of value in use. As a popular, and it isattracted the enthusiastic attention of the physicists. People have studied a variety ofmodels.The middle region of the model in this artical is a six quantum dot constructing aquantum ring. We calculate the mesoscopic ring coupled the wire with one quantum dotand two quantum dots. Some meaningful results are given.The basic knowledge and application of the Green’s function are introduced in thesecond chapter. Especially, theoretical knowledge which is used in our artical is focused.The electronic transport properties of mesoscopic ring in the case of zero temperatureis studied in the third chapter, in which there is only one quantum dot coupled to the bothends of the wire. It is found that the system conductance depends on the coupled quantumdot level variously. With the number of the quantum dot levelε continuous reducing, thenumber of conductance decreases too. If quantum dots in mesoscopic rings have ndifferent energy levels, there is n1peaks, which is because the degeneracy of thequantum dot energy levels. The peak width is due to the coupling between quantum dotsand wires. With the the number of the value of ε decreasing, the peak is shifted to theright, i.e. The peak moves to a small energy direction, which indicates that theconductance peak tends to the direction of low energy electron. A mesoscopic ringcontacting the wire with two adjacent quantum dots is studied in chapter IV in the case ofzero temperature, when coupled electron transport properties of the two adjacent quantumdots with both ends of the wire. The conductance of the system is discussed in the different quantum dot levels. When the coupled quantum dot energy levels becomes thesame level with the first coupled quantum dot, the left peak of σ-ωchanges in additionto smaller and then become larger, which is the same as the single quantum dot coupled tothe wires, such as the number of peaks, the peak moveing and its width.However, when the second quantum dot levels has gradually change the left-mostpeak of conductance becomes larger, and moves to high-energy direction, while the rest ofthe peaks moves to the right, which indicates that the lowest level in the middle regionbecomes lower, while the rest of the discrete energy levels move to the higher-energydirection.