Li Weijie, Mu Jingwei, Liu Zhi-Hai, Huang Shaoyun, Pan Dong, Chen Yuanjie, Wang Ji-Yin, Zhao Jianhua, Xu H Q
Beijing Key Laboratory of Quantum Devices and Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
Nanoscale. 2022 Oct 6;14(38):14029-14037. doi: 10.1039/d2nr03459j.
We report the realization of a coupled quantum dot (QD) system containing two single QDs made in two adjacent InAs nanowires. One QD (sensor QD) was used as a charge sensor to detect the charge state transitions in the other QD (target QD). We investigated the effect of the tunneling barrier asymmetry of the target QD on the detection visibility of the charge state transitions in the target QD. The charge stability diagrams of the target QD under different configurations of barrier-gate voltages were simultaneously measured the direct signals of electron transport through the target QD and the detection signals of the charge state transitions in the target QD revealed by the sensor QD. We find that the complete Coulomb diamond boundaries of the target QD and the transport processes involving the excited states in the target QD can be observed in the transconductance signals of the sensor QD only when the tunneling barriers of the target QD are nearly symmetric. These observations were explained by analyzing the effect of the ratio of the two tunneling rates on the electron transport processes through the target QD. Our results imply that it is important to consider the symmetry of the tunnel couplings when constructing a charge sensor integrated QD device.
我们报道了一种耦合量子点（QD）系统的实现，该系统包含两个在相邻的砷化铟纳米线中制成的单量子点。一个量子点（传感量子点）用作电荷传感器，以检测另一个量子点（目标量子点）中的电荷态跃迁。我们研究了目标量子点的隧穿势垒不对称性对目标量子点中电荷态跃迁检测可见度的影响。同时测量了在不同势垒栅极电压配置下目标量子点的电荷稳定性图、通过目标量子点的电子传输直接信号以及传感量子点揭示的目标量子点中电荷态跃迁的检测信号。我们发现，只有当目标量子点的隧穿势垒几乎对称时，才能在传感量子点的跨导信号中观察到目标量子点完整的库仑菱形边界以及涉及目标量子点中激发态的传输过程。通过分析两个隧穿速率之比对通过目标量子点的电子传输过程的影响，对这些观察结果进行了解释。我们的结果表明，在构建集成电荷传感器的量子点器件时，考虑隧道耦合的对称性很重要。
