自旋轨道耦合对串联双量子点电子全计数统计特性的影响  

Effect of Spin-orbit Coupling on Full Counting Statistics of Electron Transport Through Two Serially Coupled Quantum Dots

作　　者：王敏[1] 薛海斌[1] 

机构地区：[1]太原理工大学物理与光电工程学院,山西太原030024

出　　处：《山西大学学报（自然科学版）》2016年第1期61-67,共7页Journal of Shanxi University(Natural Science Edition)

基　　金：国家自然科学基金(11204203)

摘　　要：基于粒子数分辨的量子主方程,研究了具有自旋轨道耦合效应的串联双量子点体系的电子计数统计特性。通过分析电极的自旋极化率、量子点的点间隧穿耦合强度以及其能级失谐对前三阶累积矩的影响,发现当量子点的点间隧穿耦合强度与量子点电极耦合强度处于同一量级,且两个量子点的能级失谐大于其自旋轨道耦合强度数倍（约5~10）时,对于电极自旋极化率较大的情形,在仅有单占据态到空占据态参与电子输运的偏压区域内,自旋轨道耦合效应对电流的前三阶累积矩,尤其是高阶累积矩,有一个明显的影响。特别是,通过调节两个量子点的能级失谐,可以找到一个高阶电流累积矩基本上与自旋轨道耦合强度成正比的区域。因此,可以基于电流高阶累积矩定性获取串联双量子点的自旋轨道耦合参数,为其在固态量子计算中的应用提供理论基础。Abstract： The full counting statistics of electron transport through two serially coupled quantum dots with spin-orbit coupling is studied based on an efficient particle-number-resolved master equation. The effects of the spin polarization of two ferromagnetic leads, the strength of spin-orbit coupling and the energy-level detuning between the two quantum dots on the first three order cumulants are discussed. It is demonstrated that for a relatively large spin polarization and in the bias range,in which only the transition processes between the singly-occupied and empty eigenstates are involved in the quantum transport,the spin-orbit cou- pling has a significantly influence on the first three order cumulants,especially for higher-order cumulants when the strength of spin-orbit coupling and the quantum-dot-electrode coupling are of the same order of magnitude, and the energy-level detuning between two QDs is about 5~10 times larger than the strength of spin-orbit coupling. In particular, a range that the strength of spin-orbit coupling being substantially pro- portionate to the current higher-order cumulants can be observed by modulating the energy-level detuning between the two quantum dots. Consequently,the current high-order cumulants can be used to qualitatively extract information on the strength of spin-orbit coupling in serially coupled double quantum dots, which may provide some theoretical basis for its application in solid state quantum computing.

关 键 词：串联耦合双量子点 自旋轨道耦合效应 全计数统计 

分 类 号：O413[理学—理论物理]