SQAM_Spin Qubits in Artificial Molecules

量子信息技术的一个关键要求是实现量子比特，其中量子信息可以在比处理操作所需的时间长得多的时间尺度上存储和操作。光活性半导体量子点内的自旋由于其优越的光学特性，易于集成到光电器件中以及量子态初始化，控制和读出的光学技术的可用性而成为这项任务的极有希望的候选者。在这里，我们建议研究耦合量子点对中的自旋动力学，即所谓的量子点分子（qdm），一种支持高度鲁棒和可控的多自旋量子比特的结构。具体的项目任务包括开发基于光活性单自旋（电子或空穴）和双自旋量子比特的新型定制量子硬件，这些量子比特局限于可控的QDM设备。德国团队通过分子束外延、纳米制造和光谱学（光致发光、哈恩回声、光子相关、共振荧光）开发了最先进的纳米结构生长技术，而波兰团队在先进理论和建模（k.p方法、量子光学、开放系统动力学）方面拥有广泛的专业知识。这些互补的能力将结合起来，以发展对qdm的自旋动力学的全面理解，以及自旋与环境的相互作用，特别是与可用于控制量子态的外部磁场和电场的结合。了解自旋动力学对于控制量子信息在固态环境中的损失至关重要。因此，该项目的成功实现将使分布式量子相干网络的原型在信息处理和安全通信中得到应用。只有在理论-实验反馈循环中工作，包括制造、表征和建模，才能实现项目目标。因此，拟议的研究需要将两个贡献小组的高度互补的能力与世界领先的实验和理论固体物理专业知识和能力相结合。

A key requirement for quantum information technology is the realisation of quantum bits where quantum information can be stored and manipulated on timescales much longer than the time needed for processing operations. Spins confined within optically active semiconductor quantum dots are highly promising candidates for this task due to their superior optical properties, the ease with which they can be integrated into optoelectronic devices and the availability of optical techniques for quantum state initialisation, control and readout. Here, we propose to investigate the dynamics of spins in pairs of coupled quantum dots, so-called quantum dot molecules (QDMs), a structure that supports highly robust and controllable multi-spin qubits. Specific project tasks include the development of novel and tailored quantum hardware based on optically active single spin (electron or hole) and double spin qubits confined to electrically controllable QDM devices.The German group has developed state-of-the-art techniques in nanostructure growth by molecular beam epitaxy, nanofabrication and spectroscopy (photoluminescence, Hahn echo, photon correlations, resonance fluorescence), while the Polish group has extensive expertise in advanced theory and modelling (k.p methods, quantum optics, open system dynamics). These complementary capabilities will be combined to develop a comprehensive understanding of the spin dynamics of QDMs, as well as of the interaction of spins with their environment, in particular in combination with external magnetic and electric fields which can be used to control the quantum states.Understanding the spin dynamics is crucial for controlling the loss of quantum information to the solid-state environment. Thus, the successful realisation of this project will enable prototypes of distributed quantum coherent networks with applications in information processing and secure communication.Reaching the project goals is only possible by working in a theory-experiment feedback loop involving manufacturing, characterisation and modelling. Therefore, the proposed research requires combining the highly complementary capabilities of the two contributing groups with world-leading expertise and capabilities in experimental and theoretical solid-state physics.