Optical decoherence and coherent coupling of excitons in quantum dots embedded in photonic cavities

本理论物理项目旨在研究与光子腔强耦合的单个和多个半导体量子点（QDs）中的光激发（激子）的相干动力学。您的培训和研究将集中在量子点声子诱导光学退相干的多体理论、量子光学和量子空腔量子电动力学领域。本课题将研究光学电路中光学谐振器对远程量子点的相干耦合和相干控制。这些量子点扮演着孤立量子比特的角色，它们的受控耦合对于量子技术的应用至关重要。您将计算耦合于光腔和波导的量子点中的激子吸收和光致发光，以及它们发射的Purcell增强。您将学习声声子诱导的消相和电子解耦量子点中福斯特转移的理论基本机制，并考虑声声子环境。您将使用各种多体理论的方法，包括图技术，密度矩阵方法与林德布莱德耗散，特罗特的分解，矩阵累积展开等。该项目是EPSRC在卡迪夫物理与天文学院资助的一项更大的研究活动的一部分，并将受益于与一个实验研究团队的密切合作，该团队致力于通过腔体控制量子点的远程相干耦合。将理论与实测光学数据进行比较，将理解相干耦合的基本机制，并提取实验研究系统的重要参数，用于复杂量子电路中嵌入的量子点的预测建模。我们在该领域的卓越科学成就得到了自然集团期刊上关于该主题的研究论文的证实：Nature Mater. 9,304 -308（2010）和Nature commons . 4:1747(2013)，以及最近的理论工作，为长期存在的声子诱导的qd腔系统退相干的基本问题提供了精确的解决方案：arXiv:1807.10977（2018）。可行性：该项目的工作将是分析方法和数值方法的平衡结合，并将包括以下阶段：(i)研究文献和理论方法，解决入门培训问题（0-0.5年）；（ii）计算远程量子点的相干耦合和控制，撰写研究论文（0.5-2.5年）；撰写论文并在会议上做报告（2.5-3.5年级）。

This project in theoretical physics aims to study the coherent dynamics of optical excitations (excitons) in single and multiple semiconductor quantum dots (QDs) strongly coupled to photonic cavities. Your training and research will be in the areas of many-body theory of phonon-induced optical decoherence in QDs, quantum optics and QD-cavity quantum electrodynamics. In this project, coherent coupling and coherent control of remote QDs via optical resonators in optical circuits will be investigated. Such QDs play the role of isolated qubits, and their controlled coupling is of paramount importance for quantum technology applications. You will be calculating the excitonic absorption and photoluminescence in QDs coupled to optical cavities and waveguides, as well as the Purcell enhancement of their emission. You will be studying theoretically fundamental mechanisms of the acoustic-phonon induced dephasing and the Foerster transfer in electronically decoupled quantum dots with account for the acoustic-phonon environment. You will be using various methods of many-body theory including diagram techniques, density matrix approach with Lindblad dissipators, Trotter's decomposition, matrix cumulant expansion and so on. The project is embedded in a bigger EPSRC funded research activity at Cardiff School of Physics and Astronomy and will benefit from a close collaboration with an experimental research team working on the controlled long-range coherent coupling of quantum dots via cavities. Comparing theory with measured optical data, fundamental mechanisms of the coherent coupling will be understood and important parameters of the experimentally investigated systems will be extracted for predictive modelling of QDs embedded in complex quantum circuits. Our scientific excellence in this field is confirmed by research publications on this topic in Nature group journals: Nature Mater. 9, 304-308 (2010) and Nature Commun. 4:1747 (2013), as well as by the most recent theoretical work providing an exact solution of a long-standing fundamental problem of the phonon-induced decoherence of the QD-cavity system: arXiv:1807.10977 (2018).Feasibility: The work on the project will be a balanced combination of both analytical and numerical methods and will consist of the following stages: (i) Studying literature and theoretical methods, solving introductory training problems (yr 0-0.5); (ii) Calculating coherent coupling and control of remote QDs, drafting research papers (yr 0.5-2.5); Writing up thesis and presenting at conferences (yr 2.5-3.5).