Kondo effect and spin manipulation in quantum dot complex systems

量子点是在半导体上制造的纳米尺度的盒子，通常被称为人造原子。自旋为1/2的人造原子作为金属中的磁性杂质表现出近藤效应。在这个项目中，Kondo效应已经在嵌入量子点的小环，耦合量子点或人工分子，存在强自旋轨道相互作用的量子点等中进行了理论研究。因此，在这个多体问题中揭示了新的物理学。人工原子等半导体纳米结构中的自旋操控是量子计算机和自旋电子学应用的重要课题。开展了自旋注入和隧道磁电阻效应的基础研究。

Quantum dots, boxes of nanometer scale fabricated on semiconductors, are often called artificial atoms. Artificial atoms with spin 1/2 show the Kondo effect as magnetic impurities in metals. In this project, the Kondo effect has been theoretically examined in a small ring with an embedded quantum dot, coupled quantum dots or artificial molecules, quantum dot in the presence of strong spin-orbit interaction, etc. In consequence, new physics has been revealed in this many-body problem. Spin manipulation in semiconductor nano-structures such as artificial atoms is an important issue for the application to quantum computers and spintronics. We have developed the fundamental researches for the spin injection and tunnel magnetoresistance.