Electron-Nuclear Spin Manipulation in Semiconductor Quantum Dots by Electrical Currents

在这个项目中，我们打算通过光和电驱动脉冲的组合来控制负电荷量子点中的电子-核自旋动力学。其中一个关键因素是使用准零维系统(自组装的CdSe/ZnSe量子点，在ZnO/ZnMgO量子阱中的局域化中心)，其中驻留电子看到的核自旋数量在100甚至更低的范围内。另一个关键因素是在半导体的顶部使用微米/纳米级线圈和导线，以施加频率超过1 GHz、幅度在10 mT以上的磁场脉冲，其长度为微米。在之前的供资期间，我们已经能够证明技术和实验的可行性，并进行了操纵电子-核自旋系统的第一次概念验证研究。现在，我们打算使用具有定制的横向和纵场和定义的时间形状(MHz和GHz、-脉冲、p/2脉冲等)的组合磁脉冲和光脉冲序列。(一)研究(相干)电子和核自旋动力学的基本机制；(二)研究电子和核自旋加热；(三)诱导拉比振荡；(四)发展电子-核自旋系统的相干控制方案。阐明这些新类型的动力学场景是实现基于量子点中的电子-核自旋系统的量子逻辑功能的一个起点。

In this project we intend to control of the electron-nuclear spin dynamics in negatively charged quantum dots by a combination of optical and electrical driving pulses. One key ingredient is the usage of quasi-zero-dimensional systems (self-assembled CdSe/ZnSe quantum dots, localization centers in ZnO/ZnMgO quantum wells), where the number of nuclear spins seen by the resident electron is in the range of 100 or even below. The other key ingredient is the usage of micro-/nanoscale coils and wires on top of the semiconductor for applying magnetic field pulses with frequencies above one GHz and amplitudes of 10 mT and beyond on a micrometer length scale. In the preceeding funding period we have been able to demonstrate the technological and experimental feasibility and first proof-of-concept studies have been performed to manipulate the electron-nuclear spin system. Now, we intend to use combined magnetic and optical pulse sequences with tailored transverse and longitudinal field and defined temporal shape (MHz and GHz, -pulses, p/2 pulses etc.) (i) to investigate the fundamental mechanism of (coherent) electron and nuclear spin dynamics, (ii) to study electron and nuclear spin heating, (iii) to induce Rabi oscillations and (iv) finally to develop schemes for a coherent control of the electron-nuclear spin system. Elucidation of these new types of dynamical scenarios represents a starting point for the implementation of quantum logical functions based on the electron-nuclear spin system in quantum dots.