Time-resolved optical charge sensing for transport measurements on single self-assembled quantum dots

在过去的20年里，固态物理学的驱动力之一是通过纳米尺度上形状和尺寸的变化来控制材料的电子和光学性质。这种可能性是一种范式转变，在所谓的和突出的纳米技术的定制功能材料。作为一个例子，自组装砷化铟纳米岛的行为就像晶体半导体基质中的人工原子，并已被建立为一个理想的模型系统，以研究在固态环境中的类原子性质。除了这些量子点的基本物理利益，他们已经进入市场（在量子点激光器），并在量子信息处理有远见的前景。在这个研究项目中，一个单一的InAs量子点将被用作一个非常敏感的光电荷探测器在纳米尺度上。这使得可以实时研究第二邻近量子点和导电层之间的电荷载流子动力学。因此，单电子的输运性质的研究使用的光学检测方案。不同电荷的纳米岛的量子力学隧穿过程的性质可以在近平衡的情况下进行研究。此外，在单点中制备了电子的非平衡量子态，从而可以首次检测到它们的多粒子自旋和电荷构型，而无需考虑电子-空穴相互作用。这种激发多粒子自旋态的全电制备及其光学检测构成了将量子点用于基于自旋的量子比特的决定性一步。

One of the driving forces in solid-state physics over the last 20 years has been the control over the electronic and optical properties of materials by the variation of shape and size on the nanometer scale. This possibility is a paradigm shift towards tailored functional materials in the so-called and prominent Nanotechnology. As an example, self-assembled indium arsenide Nano-islands behave like artificial atoms in a crystalline semiconductor matrix and have been established as an ideal model system to study atom-like properties in a solid-state environment. Besides the fundamental physical interest in these quantum dots, they have already entered the market (in quantum dot lasers) and have visionary perspectives in quantum information processing.Within this research project, a single InAs quantum dots will be used as a very sensitive optical charge detector on the nanoscale. This makes it possible to study the charge carrier dynamics between a second nearby quantum dot and a conducting layer in real-time. Thus, transport properties of single electrons are studied using an optical detection scheme. The nature of the quantum mechanical tunnelling process of differently charged nano-islands can be investigated in a near-equilibrium situation. Furthermore, non-equilibrium quantum states of the electrons are prepared in the single dot, so that their many-particle spin and charge configurations can be detected for the first time, without the need to take electron-hole interaction into account. This all-electric preparation of excited many-particle spin states and their optical detection constitutes a decisive step towards the use of quantum dots for spin-based quantum bits.