Ultrafast manipulation and quantum kinetics of spin decoherence in magnetic quantum dots

该项目的主要目标是对磁量子点结构中自旋态的超快光学操纵进行微观理论分析，包括相关的弛豫和退相干过程。在第一期中，我们分析了掺杂单个Mn原子的未带电CdTe量子点的光致动力学。我们发现，通过使用特定的超短激光脉冲序列，可以将Mn原子的自旋驱动到它的六个可能的方向中。基于量子点中Mn自旋的光学控制的成功演示，在接下来的一段时间里，我们计划在三个方向上扩展我们的研究：(i)我们将扩展量子点结构的微观理论模型，以便分析更多可能影响自旋开关动力学效率的定量特征；（ii）将开发新的开关协议，以优化Mn自旋切换到特定方向或驱动Mn自旋进入定义良好的量子力学叠加态；（iii）计算将扩展到带电量子点结构以及由不同材料类别制成的量子点结构，这些材料再次掺杂单个（或可能几个）磁性原子。

The main objective of the project is a microscopic theoretical analysis of the ultrafast optical manipulation of spin states in magnetic quantum dot structures including the relevant relaxation and decoherence processes. In the first period we have analyzed the light-induced dynamics in an uncharged CdTe quantum dot doped with a single Mn atom. We have found that by using specific sequences of ultrashort laser pulses the spin of the Mn atom can be driven into each of its six possible orientations. Based on this successful demonstration of an optical control of the Mn spin in a quantum dot, in the following period we are planning to extend our investigations in three directions: (i) we will extend the microscopic theoretical model of the quantum dot structure in order to analyze more quantitatively features which might influence the efficiency of the spin switching dynamics; (ii) new switching protocols will be developed either to optimize the switching of the Mn spin into a specific orientation or to drive the Mn spin into well-defined quantum-mechanical superposition states; (iii) the calculations will be extended to charged quantum dot structures as well as to quantum dot structures made from different material classes, which are again doped with a single (or maybe a few) magnetic atoms.