CAREER: Controllable Coupling of Quantum Dots in Scalable Architectures

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****NON-TECHNICAL ABSTRACT****Semiconductor nanostructures known as quantum dots (QDs) can be considered artificial atoms. Two QDs close to each other may become quantum mechanically coupled, resembling an artificial molecule, or quantum dot molecule (QDM). The ability to control the quantum mechanical behavior of assemblies of QDMs is important for future technologies. In order to be of use in future technologies it is necessary to be able to increase the number of QDMs assembled together, just as scientists today assemble many molecules into materials. This Faculty Early Career Development award supports a project that seeks to understand and investigate the signatures and mechanisms of quantum mechanical coupling in two types of QDMs. The geometric configuration of the QDMs under study is one that may be useful for increasing the size of the assembly of QDMs. Therefore the project may lead to a significant impact on technologies ranging from quantum information to photovoltaics. This project includes a comprehensive educational plan consisting of: 1) hands-on research and curriculum development for k-12 teachers; 2) hands-on exploratory science experiences for k-12 students; and 3) the development of interdisciplinary courses on nanoscale materials aimed at advanced undergraduate students. This award is supported by the Division of Materials Research and the Division of Physics.****TECHNICAL ABSTRACT****Quantum dots are at the forefront of research into quantum coupling because they can locally confine single charges in discrete energy states that are analogous to the orbital energy levels of natural atoms. Coupling between two quantum dots leads to delocalized ?molecular? electron and hole wave functions that are distributed over both dots and the barrier in between. Such quantum mechanically coupled quantum dots may be viewed as a quantum dot molecule (QDM). While vertically stacked QDs, forming a vertical QDM, have been an important configuration for studying spin interactions and effects, they are unlikely to be a practical architecture for future technology. This Faculty Early Career Development award supports a project that seeks to investigate and understand the signatures and mechanisms of quantum coupling in two types of potentially scalable architectures of QDMs. These are 1) lateral QDMs consisting of two laterally separated InAs QDs embedded in GaAs and 2) bio-molecular QDMs comprised of two colloidally grown QDs connected by active bio-molecular linkers. Time-resolved optical spectroscopy methods will be utilized to study the quantum mechanical coupling in these single QDMs. The understanding of the physics of this coupling may lead the ability to control the quantum mechanical coupling in ways that are scalable and thus relevant to future technologies such as quantum information technology and optoelectronic devices. This project includes a comprehensive educational plan involving k-12 teachers and students as well as undergraduate and graduate students. This award is supported by the Division of Materials Research and the Division of Physics.