Development of theoretical approaches for post-silicon information processing
Viktor Ivády · Linköping studies in science and technology. Dissertations · 2016
Despite knowing the fundamental equations in most of the physics research areas, still there is an unceasing need for theoretical method development, thanks to the more and more challenging problems addressed by the research community.The investigation of post-silicon, non-classical information processing is one of the new and rapidly developing areas that requires tremendous amount of theoretical support, new understanding, and accurate theoretical predictions.My thesis focuses on theoretical method development for solid-state quantum information processing, mainly in the field of point defect quantum bits (qubits) in silicon carbide (SiC) and diamond.Due to recent experimental breakthroughs in this field, there are diverse theoretical problems, ranging from functional development for accurate first principles description of point defects, through complete theoretical characterization of qubits, to the modeling and simulation of actual quantum information protocols, that are needed to be addressed.The included articles of this thesis cover the development of (i) hybrid-DFT+V w approach for the first principles description of mixed correlated and uncorrelated systems, (ii) zero-field-splitting tensor calculation for solid-state quantum bit characterization, (iii) a comprehensive model for dynamic nuclear spin polarization of solid-state qubits in semiconductors, and (iv) group theoretical description of qubits and novel two-dimensional materials for topologically protected states.v vi First of all, I would like to thank my main supervisor, Prof. Igor Abrikosov, and my co-supervisors, Prof. Adam Gali and Prof. Erik Janzén, for their great guidance and helpfulness over the years.I appreciate and thank the numerous advice, the valuable discussions and the inspiring ideas.I am particularly grateful to all of them for providing and maintaining an unusual working agreement through which I can experience and learn much more than I could imagine before.Furthermore, I am thankful to Prof. Adam Gali for launching me on my career, helping from the beginning, and for involving me in several collaborations as well as to Prof. Igor Abrikosov for showing me numerous theoretical techniques, guiding me towards method development studies, and for supporting during my PhD studies.I would like to thank all of the members of our Swedish and Hungarian groups for creating a friendly and helpful atmosphere and for always being open for discussions.I am also very grateful to all of my collaborators, particularly from