Atomistic engineering of semiconductor nanostructures for quantum information

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The Government of Canada's Science and Technology Strategy identifies Information and Communications Technology and Advanced Manufacturing as two of the four research priority areas. Here, quantum computing and quantum communication are considered among key technologies which have a potential to transform societies in terms of their social and economic well-being. Quantum computing is disruptive, as it promises a new way of computing, enabling efficient solutions of problems such as optimization, coding and decoding, machine learning and simulation. The recent years witnessed an explosive increase of worldwide interest in this technology, with investments by IBM, Google, Microsoft, D-Wave Systems. Quantum communication offers the promise of absolutely secure communication, which is of vital interest in light of the need to protect sensitive data (financial, personal) from intrusion. However, in both areas, the development of new materials and prototype devices frequently involves fabrication of a large number of test devices with very low yield and little deliberate control over design details, with the lack of predictive theoretical design tools being a major stumbling block. The aim of this project is to provide tools for fast, predictive computer-aided design of prototype devices and to allow the optimization of their parameters. To this end, I will pursue two short-term objectives, and I request funding for two PhD students. The first objective will focus on the development of a simulation tool for gated quantum dots confining electrons or holes, in which the carrier spin plays the role of the quantum bit for quantum computing. This tool will account for microscopic details of the material, the structure of the sample, and the external fields (electric, magnetic) in a fully quantum-mechanical approach. The suite will also model the coherent control, enabling it to simulate quantum gates. In the fundamental part of the study, we plan to apply this tool to study dots confining holes and explore the coherent control of the carrier spin by phonons. In the second objective, we will develop another, fully atomistic tool to study the electronic properties of quantum dots and dot molecules embedded in quantum wires playing the role of an optical cavity. These systems hold promise as efficient and fast sources of single photons and entangled photon pairs for quantum communication, but their quality sensitively depends on atomistic details of their structure and geometry. The goal will be to demonstrate a time-dependent simulation of an emitter of non-classical light and to guide the experimental realization of such a device. The impact of this project consists in enabling computer-aided design and optimization of quantum devices, simplifying and guiding the experimental work. Due to the importance of these outcomes, we expect high-level publications and conference presentations as well as collaborations with experimental groups worldwide.