单量子点库仑作用有限值时散粒噪声研究.doc

摘  要：随着纳米制备技术的发展，纳米结构的量子输运性质成为当前凝聚态物理的一个研究热点。本文通过采用非平衡格林函数方法，通过研究单量子点体系的温度处于近藤温度区域时，散粒噪声随库仑相互作用以及量子点能级变化来揭示单量子点输运特性。本文的主要研究内容如下：

　　　首先，简单介绍了利用非平衡态格林函数研究库仑阻塞状态时，铁磁臂组成的双量子点/分子结构中的热电效应。

　　　然后，我们利用非平衡格林函数方法对在近藤温度TK时通过对量子点的态密度、电流以及散粒噪声等物理量的研究，揭示单量子点的输运特性。研究表明态密度与臂中的载流子双阶跃分布函数相关，而散粒噪声与投射率T以及库伦相互作用U紧密相关。

关键词：量子点系统；散粒噪声；近藤温度；格林函数

Abstract：With the development of nano technology, the quantum transport properties of nano-structure have become a hot topic in condensed matter physics. We study the shot noise in a quantum dot which coupled to metallic leads using the equation of motion of nonequilibrium Green’s function technique at Kondo temperature TK in this thesis. The primary works are summarized as follows:

　　　Firstly, With use of the nonequilibrium Green function formalism study the energy transport in the response regime, through a two-level quantum dot/molecule attached to ferromagnetic leads. 

　　　Secondly, We study the shot noise in a quantum dot which coupled to metallic leads using the equation of motion of nonequilibrium Green’s function technique at Kondo temperature TK. We compute the out of equilibrium density of states, the current and the shot noise. It shows that the density of states of on-site electronic is related to the double step distribution function of the carriers in the leads, the shot noise is interrelated with Coulomb interaction(T) and the transmission probability(U).

Keywords: quantum dot;shot noise; Kondo temperature;Green function.