Theoretical study for electron correlations in quantum transport phenomena

量子输运现象中电子相关性的理论研究

基本信息

批准号：
14540309
负责人：
OGURI Akira
金额：
$ 0.7万
依托单位：
Graduate School of Science, Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

[1]We have re-examined the microscopic formulation of the transport through small interacting systems connected to noninteracting leads based on the Kubo formalism, and have shown quite generally that the many body transmission coefficient Τ(ε), by which the dc conductance is expressed in a Landauer type form g=(2e^2/h) ∫ dε (-∂f/∂ε) Τ(ε) where f(ε) is the Fermi function, can be related to a three-point retarded function defined in the real time.[2]We have applied the linear-response formulation to the quantum-dot superlattice, which is modeled by a two-dimensional Hubbard cluster connected to two noninteracting leads. The results, which are obtained by using the second-order self-energy in the perturbation expansion with respect to the Coulomb interaction U, demonstrate how the structure of resonance peaks is affected by the interaction. Especially, the width and the position of the resonance are sensitive to the correlation effects.[3]We have also studied nonequilibrium properties of the Kondo effects in quantum dots based on the Anderson model under a finite bias voltage V. We have shown that for small but finite V the low-energy behaviors of the excitation spectrum and nonlinear response of the current can be described by the local Fermi-liquid theory. Furthermore, we have deduced the exact asymptotic behavior of the Green's function in the limit of the large bias voltage V.[4]We have also launched nonperturbative calculations of the transport properties using the numerical renormalization group method. With this approach, we have studied the Kondo effect of a quantum dot in a Josephson junction, and have clarified precise features of the quantum phase transition between the non-magnetic singlet and magnetic doublet ground states. We are now applying the method to a Mott-Hubbard insulator of a nanometer scale.

[1]我们重新审查了通过基于kubo的形式连接到非互动引线的小型相互作用系统的传输的显微镜公式，并且相当普遍地表明，许多车身传播系数τ（ε），DC电导在landauer类型G =（2e^2/H）中表达，其中f =（2e^2/h）f =（2e^2/h）fist/f（-h）（-h）∫ε（ - ε（-dis）ε（-dis）ε（-dis）ε（-dis）ε（-dis）。费米函数可以与实时定义的三点智障函数有关。[2]我们已将线性反应公式应用于量子点超级晶格，该公式由连接到两个非互动引线连接的二维Huberbard群集建模。结果是通过在摄动膨胀中使用二阶自能来获得的，相对于库仑相互作用u，结果证明了共振峰的结构如何受到相互作用的影响。尤其是，共振的宽度和位置对相关效应敏感。[3]我们还研究了基于Anderson模型在有限的偏置电压V中基于Anderson模型的近托效应的非平衡性能。我们已经表明，对于小而有限但有限的f interiqu for for for for for for for seppirum and Intorlim wose the the the Inlibiquy to the Inline of当今的兴奋性响应的范围是对当前的兴奋性响应的描述。此外，我们在较大的偏置电压V的极限下推导了绿色功能的确切不对称行为。[4]我们还使用数值重新分配组方法启动了对传输属性的非扰动计算。通过这种方法，我们研究了约瑟夫森交界处的量子点的昆多效应，并阐明了非磁性单元和磁双石基态之间量子相变的精确特征。现在，我们将该方法应用于纳米尺度的Mott-Hubbard绝缘子。