Lateral Quantum Dot molecule - towards electric field controlled quantum gate

该项目的目标是对横向紧密间隔的相互作用半导体量子点进行控制定位和光学表征，即横向量子点分子（qdm）。横向qdm的精确定位将通过在预图型GaAs（001）衬底上生长来实现，我们计划通过非原位光刻和反应离子蚀刻来生产。横向qdm由InAs/GaAs以及GaAs/AlGaAs量子点（QDs）组成。利用单量子点发光和隧穿光谱研究了相邻量子点中载流子之间的电子耦合。通过施加横向电场，系统地研究了耦合强度。为了调整组成QDM的量子点之间相互作用的强度，将栅极精确地放置在QDM的上方。然后将研究QDM特性作为栅极电压的函数。这是演示基本逻辑运算和制造半导体量子门的必要步骤。

The goal of this project is the controlled positioning and optical characterisation of interacting semiconductor quantum dots closely spaced in lateral direction, i.e. of lateral quantum dot molecules (QDMs). The exact positioning of the lateral QDMs will be achieved by growth on pre-patterned GaAs (001) substrates, which we plan to produce by ex-situ lithography and reactive ion etching. The lateral QDMs consist of InAs/GaAs as well as GaAs/AlGaAs quantum dots (QDs). By means of single QD luminescence and tunnelling spectroscopy the electronic coupling between charge carriers in neighbouring QDs will be investigated. The coupling strength will be systematically studied by applying an electric field in lateral direction. In order to tune the strength of the interaction between the QDs composing a QDM, a gate electrode will be accurately positioned above the QDM. The QDM properties will be then investigated as a function of gate voltage. This is a necessary step towards the demonstration of basic logic operations and the fabrication of a semiconductor quantum gate.