Microscopic theory of quantum optical effects in semiconductor nanostructures

在过去的几年里，量子光学和半导体物理这两个领域都取得了很大的进展。现在，先进的量子电动力学理论在描述原子系统与量子化光场的相互作用方面非常成功，其中原子之间的相互作用只起到很小的作用。另一方面，半导体物理通常由载流子之间的库仑相互作用主导。因此，先进的半导体理论注重对费米子多体效应的正确描述，而电磁相互作用仅限于经典场。目前项目的主要目标是将量子光学和半导体物理的方法结合起来，发展一种包括强相互作用载流子之间的多体关联效应以及与量子化光场的耦合的理论。选择密度矩阵方法，我们推导了耦合载流子-光子-声子系统的运动方程，并将所得到的层级截断为相关的期望值。计算了可在实验测量中直接获得的光子关联。在此基础上，我们计划研究相干和非相干激发条件下半导体出射光的光子统计特性。更具体地说，应研究相干和非相干激子布居对光发射的影响，并应重点研究纠缠光子态的创建。这个研究小组与实验结果的密切比较对于检验我们理论的预测和激发详细的研究主题将是至关重要的。

In the two fields of quantum optics and semiconductor physics much progress has been made during the last years. Advanced quantum electrodynamics theories are now very successful in the description of the interaction of atomic systems with the quantized light field where the interaction between the atoms plays only a minor role. On the other hand, semiconductor physics is usually dominated by the Coulomb interaction between the carriers. Therefore, advanced semiconductor theories focus on the correct description of the Fermionic many-body effects while the electro-magnetic interaction is limited to classical fields. The main goal of the current project is to combine the methods of quantum optics and semiconductor physics and develop a theory that includes the many-body correlation effects between the strongly interacting carriers as well as the coupling to a quantized light field. Choosing a density matrix approach, we derive the equations of motion for the coupled carrier-photon-phonon system and truncate the resulting hierarchy to the relevant expectation values. Photonic correlations are computed which are directly accessible in experimental measurements. Based on those, we plan to investigate the photon statistics of light emitted from semiconductors under coherent and incoherent excitation conditions. More particularly, the effect of the presence of coherent and incoherent exciton populations on the light emission shall be investigated and the creation of entangled photon states shall be focused on. The close comparison to experimental results within this research group will be vital to check the predictions of our theory and to stimulate the detailed research topics.