Helium-free cryostat for resonance fluorescence measurements

本申请的主题是一种用于在低温(4K-300K)下测量空间分辨共振荧光的光学装置。该仪器专门用于低维固体的光谱分析，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)，从而使量子现象变得可见。其中包括(除了能量和电荷量子化)交换相互作用和磁现象，它们使量子点成为类似原子的模型系统。不过，它们之间存在根本性的不同。例如，量子点可以接触和电调谐。此外，外部磁势和电势可以与限制势竞争，从而允许广泛的量子可调谐。具有这些性质的量子点不仅具有基本的科学价值。它们还构成了通向当今纳米商业半导体结构的桥梁，并为未来(量子)信息技术提供了电子和光学构建块的前景。在这方面，电子光谱学和光学光谱学的结合特别令人感兴趣。申请人的团队可以参考相当大的和相关的先前经验。在这里，空间分辨共振荧光光谱已被证明是一种特别富有成效的方法。由于它具有很高的空间和能量分辨率，使得观察单个量子点中单电子的动力学成为可能。可以用光学和时间分辨率跟踪的这种动力学过程的例子有：电子隧穿、俄歇复合、内部光效应和内部电子俘获。此外，可以制备非平衡态，并可以观察到它们的松弛到平衡。该仪器将用于这些和相关的量子点和其他低维结构的实验。特别是，这一设置将大大加强合作研究中心1242项目A01“凝聚态物质在时间域中的非平衡动力学”中的科学工作。将受益于该仪器的其他科学工作包括DFG项目“量子点中的俄歇效应”和优先方案2244“二维材料”中的一项提议。

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”.