INFRARED LIGHT CONTROL OF SINGLE-ELECTRON SPIN IN THE NITRIDE QUANTUM DOTS AND ITS APPLICATION

提出了利用氮化镓及其相关材料实现量子逻辑门的新工作原理。利用MBE系统，采用选择性面积生长的方法获得了GaN量子点结构。6K时观察到明显的库仑阻塞现象。利用红外光脉冲制备了垂直单电子传输管，用于控制单电子自旋，研究了碳纳米管量子点的实现。在单壁碳纳米管（SWNT）量子点中已经清楚地证明了简单的双电子和四电子壳层结构，并且观察到它们依赖于能级间距Δ和能级失配Δ。在激发态光谱中，交换作用直接表现为源漏偏大的交换分裂。单粒子态在磁场中表现出简单的塞曼分裂，由于管直径比回旋加速器直径小得多，没有任何轨道效应。大的零维能级间距使得在含有多个电子的点中观察简单壳层结构成为可能，纳米管量子点是一个展示双电子系统的人工原子。本研究结果是实现量子信息处理中自旋量子比特和各种纠缠器件的重要一步。

The new operation principle to realize quantum logic gate using GaN and related materials was proposed. A GaN quantum dot structure was obtained by selective area growth method using MBE system. Clear Coulomb blockade phenomena were observed at 6K. The vertical single electron transisters were fabricated for manipulation of single electron spin using infrared light pulses carbon nanotube quantum dots were investigated for realizations of quantum elements. The simple two-electron and four-electron shell structures have been clearly demonstrated in the single-wall carbon nanotube (SWNT) quantum dot, and are observed to be dependent on the level spacing Δ and the level mismatch δ. The exchange interaction has been directly observed as an exchange splitting in the excitation spectroscopy with a large source-drain bias. The single particle state in magnetic fields has shown simple Zeeman splitting without any orbital effect due to a tube diameter that is much smaller than the cyclotron diameter. The large zero-dimensional level spacing has made it possible to observe the simple shell structures in a dot that contains many electrons, and the nanotube quantum dot is shown to be an artificial atom that demonstrates the two-electron system. The present results are an important step toward the realization of the spin-qubit and various entanglement devices in quantum information processing.