Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University , Beijing 100871, China.
State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083, China.
Nano Lett. 2017 Jul 12;17(7):4158-4164. doi: 10.1021/acs.nanolett.7b00927. Epub 2017 Jun 16.
A highly tunable linear triple quantum dot (TQD) device is realized in a single-crystalline pure-phase InAs nanowire using a local finger gate technique. The electrical measurements show that the charge stability diagram of the TQD can be represented by three kinds of current lines of different slopes and a simulation performed based on a capacitance matrix model confirms the experiment. We show that each current line observable in the charge stability diagram is associated with a case where a QD is on resonance with the Fermi level of the source and drain reservoirs. At a triple point where two current lines of different slopes move together but show anticrossing, two QDs are on resonance with the Fermi level of the reservoirs. We demonstrate that an energetically degenerated quadruple point at which all three QDs are on resonance with the Fermi level of the reservoirs can be built by moving two separated triple points together via sophistically tuning of energy levels in the three QDs. We also demonstrate the achievement of direct coherent electron transfer between the two remote QDs in the TQD, realizing a long-distance coherent quantum bus operation. Such a long-distance coherent coupling could be used to investigate coherent spin teleportation and superexchange effects and to construct a spin qubit with an improved long coherent time and with spin state detection solely by sensing the charge states.
使用局部指栅技术，在单晶纯相 InAs 纳米线中实现了高度可调谐的线性三量子点（TQD）器件。电测量表明，TQD 的电荷稳定图可以由三种不同斜率的电流线表示，基于电容矩阵模型的模拟证实了实验结果。我们表明，在电荷稳定图中可观察到的每条电流线都与量子点与源极和漏极储层费米能级共振的情况有关。在两个斜率不同的电流线一起移动但显示交叉的三重点处，两个量子点与储层的费米能级共振。我们证明，通过巧妙地调整三个量子点中的能级，可以将两个分离的三重点一起移动，从而构建出能量简并的四重点，此时所有三个量子点都与储层的费米能级共振。我们还证明了可以在 TQD 中实现两个远程量子点之间的直接相干电子转移，从而实现远距离相干量子总线操作。这种远距离相干耦合可用于研究相干自旋传送和超交换效应，并构建具有改进的长相干时间和仅通过感测电荷状态即可进行自旋状态检测的自旋量子位。
