Helium-free cryostat for resonance fluorescence measurements

本应用的主题是用于在低温（4K - 300K）下测量空间分辨共振荧光的光学装置。该仪器特别用于低维固体的光谱学，如量子点。量子点是纳米尺寸的半导体结构，它在空间上限制载流子（电子/空穴），这样量子现象就可以观察到。其中（除了能量和电荷量子化外）交换相互作用和磁现象使量子点成为类原子模型系统。不过，它们之间存在根本性的区别。例如，量子点可以被接触和电调谐。此外，外部磁势和电势可以与约束势竞争，从而允许广泛的量子可调性。有了这些特性，量子点不仅具有基本的科学兴趣。它们还构成了当今纳米级商用半导体结构的桥梁，并为未来（量子）信息技术的电子和光学构建块提供了前景。在这方面，电子光谱学和光学光谱学的结合具有特别的意义。申请人的团队可以参考大量相关的先前经验。在这里，空间分辨共振荧光光谱已被证明是一种特别有效的方法。由于它的高空间和能量分辨率，使得观察单个量子点中单个电子的动力学成为可能。这种动态过程的例子可以用光学和时间分辨率来跟踪：电子隧穿，俄歇复合，内部光效应和内部电子捕获。此外，还可以制备非平衡态，并观察到它们弛豫到平衡态。该仪器将用于量子点和其他低维结构的相关实验。特别是，该装置将大大加强1242合作研究中心A01项目“凝聚态非平衡动力学在时域”的科学工作。将受益于该仪器的进一步科学工作包括DFG项目“量子点中的俄歇效应”和优先计划2244“2d材料”中的一项提案。

The subject of this application is an optical setup for measuring spatially resolved resonance fluorescence at low temperatures (4K – 300K). The instrument is intended to be used in particular for the spectroscopy of low-dimensional solids, such as quantum dots. Quantum dots are nanometer-sized semiconductor structures, which spatially confine charge carriers (electrons/holes), such that quantum phenomena become observable. Among those are (besides energy and charge quantization) exchange interaction and magnetic phenomena, which make quantum dots atom-like model systems. There are fundamental differences, though. For example, quantum dots can be contacted and electrically tuned. Also, external magnetic and electric potentials can compete with the confinement potentials and thus allow for wide quantum tunability. With these properties, quantum dots are not only of fundamental scientific interest. They also form a bridge to present-day , nanometer-size commercial semiconductor structures and offer perspectives as electronic and optical building blocks in future (quantum) information technologies. In this regard, the combination of electronic and optical spectroscopy is of particular interest. The applicant’s group can refer to sizable and relevant previous experience. Here, spatially resolved resonance fluorescence spectroscopy has proven to be a particularly fruitful method. Because of its high spatial and energy resolution, it makes it possible to observe the dynamics of single electrons in a single quantum dot. Examples for such dynamical processes that can be followed optically and with time resolution are: Electron tunneling, Auger recombination, internal photoeffect, and internal electron capture. Furthermore, non-equilibrium states can be prepared and their relaxation into equilibrium can be observed. The proposed instrument will be employed for these and related experiments on quantum dots and other low-dimensional structures. In particular, the setup will significantly strengthen the scientific work in project A01 of the Collaborative Research Centre 1242 “Non-Equilibrium Dynamics of Condensed Matter in the Time Domain". Further scientific work that will benefit from this instrument include DFG project “Auger effects in quantum dots” and a proposal within the Priority Programme 2244 „2D-Materials”.