准一维半导体量子点中电偶极自旋共振的物理机理

半导体量子点中的电子自旋具有较长相干时间以及可扩展性的特点, 在近十几年来引起了人们的广泛兴趣. 人们常常利用电子自旋共振技术来对单个自旋进行操纵. 这样不但需要一个静磁场来使电子产生赛曼劈裂, 同时还需要一个与之垂直的局域振荡磁场. 但是, 在实验上产生足够强且具有固定频率的局域磁场是比较困难的. 后来人们发现, 局域的振荡电场也可以操纵单个电子自旋, 也就是所谓的电偶极自旋共振. 众所周知, 自旋只有自旋磁矩, 不会与电场有任何直接的相互作用. 所以, 电偶极自旋共振的发生必须依赖于某些媒质. 这些媒质包括：量子点材料中的自旋轨道耦合作用, 量子点中的局域磁场梯度, 以及量子点中电子自旋与核自旋的超精细相互作用. 这些媒质能诱导出自旋与电场之间间接的相互作用, 从而外电场操纵单个电子自旋得以实现. 本文总结归纳了目前半导体量子点系统中发生电偶极自旋共振的三种主要物理机理.

The mechanisms of electric-dipole spin resonance in quasi-one-dimensional semiconductor quantum dot

Because of the long coherence time and the easy way to achieve the qubit scalability, quantum dot spin qubit has obtained considerable attentions recently. Single spin manipulation is usually achieved using the traditional electron spin resonance technique. This method not only needs a static Zeeman field, but also needs an ac magnetic field which is perpendicular to the static one. However, it is not easy to produce a local ac magnetic field experimentally. Recently, instead of an ac magnetic field, an ac electric field can also be used to manipulate an electron spin, an effect called electric-dipole spin resonance. As is well-known, there is no direct interaction between the spin and the electric field. Thus, the electric-dipole spin resonance must be mediated by some mechanisms. These mediums in the quantum dot can be: the slanting magnetic field, the spin-orbit coupling, and the electron-nucleus hyperfine interaction. This paper summarizes three main mechanisms of the electron-dipole spin resonance in semiconductor quantum dot.