A well isolated environment can be ideal for a quantum system to perform e ciently. Unlike this a PhD student needs to interact with many people during the course to complete a research project timely. Having said that, here is a list of people whom I would like to pay my deepest and profound gratitude. I would like to thank my rst principal supervisor Prof. David Kielpinski, who accepted me to work in his research group and guided me like a professional physicist. Later on, sudden news about his permanent departure to USA at the stage when I was really close to nish a project was quite challenging. Nevertheless, Dr. Erik Streed and Dr. Mirko Lobino took me under their wings as new advisers with their instrumental counselling to complete my PhD thesis. My special thanks goes to Dr. Tim Byrnes from New York University, with whom I did some theoretical work mentioned in the thesis. Beside these, my lab fellows including Matthew Petrasiunas, Valdis Blums, Paul Fisher, Dr. Ben Norton and Dr. Moji Ghadimi were very instructive and helping during my stay at Gri th University. Above all, I have no words to thank my parents and family for their selfess support over the years. An experimental research project is no more than a dream without money. Therefore, I would like to say a big thanks to all the funding agencies who were linked to this project, directly or indirectly from the beginning to end, including Gri th University for their international postgraduate research and postgraduate research scholarships, the US air force and the Australian research council.
A well isolated environment can be ideal for a quantum system to perform e ciently. Unlike this a PhD student needs to interact with many people during the course to complete a research project timely. Having said that, here is a list of people whom I would like to pay my deepest and profound gratitude. I would like to thank my rst principal supervisor Prof. David Kielpinski, who accepted me to work in his research group and guided me like a professional physicist. Later on, sudden news about his permanent departure to USA at the stage when I was really close to nish a project was quite challenging. Nevertheless, Dr. Erik Streed and Dr. Mirko Lobino took me under their wings as new advisers with their instrumental counselling to complete my PhD thesis. My special thanks goes to Dr. Tim Byrnes from New York University, with whom I did some theoretical work mentioned in the thesis. Beside these, my lab fellows including Matthew Petrasiunas, Valdis Blums, Paul Fisher, Dr. Ben Norton and Dr. Moji Ghadimi were very instructive and helping during my stay at Gri th University. Above all, I have no words to thank my parents and family for their selfess support over the years. An experimental research project is no more than a dream without money. Therefore, I would like to say a big thanks to all the funding agencies who were linked to this project, directly or indirectly from the beginning to end, including Gri th University for their international postgraduate research and postgraduate research scholarships, the US air force and the Australian research council.
No journey of scientific discovery is ever truly taken alone. Every step along the way, we encounter people who are a great source of encouragement, guidance, inspiration, joy, and support to us. The journey I have embarked upon during the course of this project is no exception. I would like to extend my gratitude to my project partner on many occasion during the past 5 years, Ng Tien Tjeun. His humorous take on various matters ensures that there is never a dull moment in any late night lab work. A resounding shout-out to the ‘elite ’ mem-bers of 0205 (our office), Tan Peng Kian, Shi Yicheng, and Victor Javier Huarcaya Azanon for their numerous discourses into everything under the sun, some which are possibly work related. Thank for tolerating my borderline hoarding behavior and the frequently malfunc-tioning door? I would like to thank Alessandro Ceré for his invaluable inputs on the many pesky problems that I had with data processing. Thanks for introducing me to world of Python programming. Now there is something better than Matlab? A big thanks also goes out to all of my other fellow researchers and colleagues both in the Quantum Optics group and in CQT. They are a source of great inspiration, support, and joy during my time in the
The development of quantum electrodynamics (QED), which studies the light-matter interaction in quantum level, has been accompanied by the enhancement of the coupling strength g between an atom (matter) and an electromagnetic (EM) field (light).With the introduction of a cavity, forming a cavity QED system, the coupling strength reached weak coupling (WC) and strong coupling (SC) regime.These regimes are defined by the system dissipations, the atom decay rate γ and the cavity decay rate κ, where g ≪ γ, κ for the WC regime and g ≫ γ, κ for the SC regime.Especially for the SC regime, the energy exchange between the atom and the EM field can happen repeatedly before the system losses the energy.This physical property enables quantum state manipulation in First and foremost, I would like to express my sincere appreciation to my principal supervisor, Takao Aoki, for his advice and support during my PhD studies.He is the first person who welcomed me to the field of cavity quantum electrodynamics at the end my third-year as an undergraduate student.Then, when I proposed to go to NICT and study about circuit QED and USC/DSC regimes, he agreed and quickly worked on the joined research contract, which yield the contents of this thesis.I still remember his words, "the Hamiltonian is the same anyway", which he said after agreeing my proposal.I also would like to thank him to allow me to the Leading Graduate Program in Science and Engineering and Power Energy Professional WISE Program.These programs require extra work for some unique curriculums, such as Lab.Rotations, internship and studying abroad.He has been supportive and flexible all the time and gave me full room to what I needed to do.All these works could not be done without support and guidance.Next, I would like to thank the members of Macroscopic Quantum Physics Project, National Institute of Information and Communication Technologies (NICT).I greatly appreciate Kouichi Semba, the leader of the project, letting me join the team and supported my PhD studies.He recommended me to Prof. William D. Oliver at MIT which made my visiting stay at EQuS at MIT become true.I also want to thank you him for applying for the fund by CREST which greatly helped me financially for a period of working at NICT.His advices and supports were not only very helpful for the works but also enriched my life.Fumiki Yoshihara was my mentor all the time during these works.He told me how to design and analyze the circuits, prepare the samples and operate the systems for experiments.He always answered me when I face problems and help me solve them, even they are easy ones.It has to be pointed out that he gave me the idea coupling the qubit to multiple modes in the resonator.This research topic has been tough due to its complicity, yet also been fun to mess around.I also appreciate he invited me to the soccer games during the lunch breaks.The cryostat which I used to cool the circuits was mostly prepared by Tomoko Fuse.She also told me how to prepare the cryostat and manage the cables inside it.Her advices and comments on my works were always greatly helpful.As a theorist Sahel Ashhab supported my works from the basic ideas.His advices helped me a lot to understand what is happening in the systems.He also helped me analyze the multimode circuit QED system by carefully deriving the expressions.I would like to thank the of the group, Sunmi Kim, with the discussions over chip designs and preparation of the Lab.At the end, I thank Akiko Hoshi for dealing all the paper works and Takashi Nakayama for helping me with the coding and equipment preparation.Thirdly, I would like to thank Shiro Saito and Kosuke Kakuyanagi from Superconducting Quantum Circuits Research Group at NTT Basic Research Laboratories.As the co-authors, they fabricated the samples with maximum care.I also appreciate the discussions about the experimental results where they always gave helpful advices and suggestions.I would like to thank all the members for the discussions during my iii internship at the same group.I especially thank Shiro Saito and Satoru Toida, the mentor during the internship, to let me join the group and conduct experiments.It was a great experience to work with the top-level researchers around the globe.I also would like to thank my two supervisors of the two Lab.Rotations, Kazuya Yuasa and Hiroshi Kawarada, for giving me the opportunity to join them.Although they were for a short period of time, the experiences broaden my interests towards science and engineering and will be surely valuable for me.I am deeply grateful to my supervisor of Engineering Quantum Systems group, William D. Oliver, for making me joining with he and the other Laboratory members and hosted my stay.I also appreciate the discussions and works with Roni Winik, who patiently explained his research and brought me in with his research topic.I spent a great time discussing and chatting with the group members and enjoyed working with them.I also want to thank William D. Oliver who applied a
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
Approved by Supervising Committee: For my parents. Thank you for your love and support. Acknowledgments First of all, I would like to thank my supervisor, Prof. Mark Raizen. Mark, you allowed me great freedom in my work and put a lot of trust in me. Nevertheless, you were always there with good advice and great ideas when I needed you. I am very proud that I was given the opportunity to work in your group. Thank you for supporting me during my time in Austin and beyond. I am equally thankful to my fellow group members and friends Adam Libson, Dr. Ed Narevicius and Christian Parthey. Everything we accomplished during the last one and a half years was a group effort and they are the main reason I am writing this thesis using the pronoun “we”. Adam, although you sometimes “unnerved ” us with your constant fear of leaks or fatal rotor destruction, I wouldn’t have wanted to work with anybody else than you on this project. You often foresaw problems we would have easily