随机核磁场调制的双量子点电子输运  

Random Nuclear Magnetic Field Modulated Electron Transport Through a Double Quantum Dot

作　　者：王文刚 焦虎军 

机构地区：[1]山西大学物理电子工程学院,山西太原030006

出　　处：《山西大学学报（自然科学版）》2018年第1期141-147,共7页Journal of Shanxi University(Natural Science Edition)

基　　金：国家自然科学基金(11004124;11574186)

摘　　要：采用Lindblad型粒子数分辨的量子主方程,研究了双量子点系统在自旋阻塞区受核随机场调制的电子输运。在弱和强核随机场下,发现双量子点输运系统的Fano因子在整个外磁场调制范围内都大于1,系统呈现了超泊松噪声;在弱核随机场情况下,随外磁场大小的变化,平均Fano因子和平均偏斜度呈现局部极大值;而在强核随机场情况下,平均Fano因子和平均偏斜度随外磁场大小的变化而近单调变化。这些特征都可以基于噪声和三阶矩对外磁场大小的依赖性加以解释。对于确定随机场情况下的噪声和偏斜度,Fano因子和偏斜度则可以给出丰富的输运信息。此外,随着非弹隧穿率的增加,在强核随机场情况下,平均电流增加而Fano因子和偏斜度减小。Electron transport in the spin blockade regime through a double quantum dot modulated by ran- dom nuclear magnetic field is investigated based on the Lindblad-type particle-resolved quantum master e- quation. The results show that the Fano factor of electron transport in the double quantum dot is larger than 1 in the whole transport regime studied for the weak and strong random nuclear magnetic field, i. e. , a super Poisson noise appears in the system. In the case of weak random nuclear magnetic field, the aver- age Fano factor and the average skewness show a local maximum with the change of the magnitude of the external magnetic field. In the case of strong random nuclear magnetic field, the average Fano factor and the average skewness present a nearly monotonic behavior with the magnitude of the external magnetic field. These characteristics can be interpreted from the dependence of the noise and third-order cumulant on the magnitude of the external magnetic field. For a given nuclear field realization, the Fano factor and the skewness can provide abundant transport information. In addition, the average current increases with in- creasing the inelastic transition while the average Fano factor and skewness decrease for the strong random nuclear magnetic field.

关 键 词：双量子点 核磁场 自旋阻塞 全计数统计 

分 类 号：O413[理学—理论物理]