Dong B, Ding G H, Lei X L
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
J Phys Condens Matter. 2015 May 27;27(20):205303. doi: 10.1088/0953-8984/27/20/205303. Epub 2015 May 7.
A general theoretical formulation for the effect of a strong on-site Coulomb interaction on the time-dependent electron transport through a quantum dot under the influence of arbitrary time-varying bias voltages and/or external fields is presented, based on slave bosons and the Keldysh nonequilibrium Green's function (GF) techniques. To avoid the difficulties of computing double-time GFs, we generalize the propagation scheme recently developed by Croy and Saalmann to combine the auxiliary-mode expansion with the celebrated Lacroix's decoupling approximation in dealing with the second-order correlated GFs and then establish a closed set of coupled equations of motion, called second-order quantum rate equations (SOQREs), for an exact description of transient dynamics of electron correlated tunneling. We verify that the stationary solution of our SOQREs is able to correctly describe the Kondo effect on a qualitative level. Moreover, a comparison with other methods, such as the second-order von Neumann approach and Hubbard-I approximation, is performed. As illustrations, we investigate the transient current behaviors in response to a step voltage pulse and a harmonic driving voltage, and linear admittance as well, in the cotunneling regime.
基于从玻色子和凯尔迪什非平衡格林函数（GF）技术，提出了一种通用的理论公式，用于描述强在位库仑相互作用对在任意时变偏置电压和/或外部场影响下通过量子点的时间相关电子输运的作用。为避免计算双时格林函数的困难，我们推广了Croy和Saalmann最近开发的传播方案，将辅助模式展开与著名的拉克鲁瓦解耦近似相结合来处理二阶关联格林函数，然后建立了一组封闭的耦合运动方程，称为二阶量子速率方程（SOQREs），以精确描述电子关联隧穿的瞬态动力学。我们验证了我们的SOQREs的稳态解能够在定性水平上正确描述近藤效应。此外，还与其他方法进行了比较，如二阶冯·诺依曼方法和哈伯德-I近似。作为示例，我们研究了在共隧穿区域中响应阶跃电压脉冲和谐波驱动电压的瞬态电流行为以及线性导纳。
