Variational techniques for strongly correlated open quantum systems

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dc.contributor.advisor Weimer, Hendrik Kazemi, Seyedjavad eng 2021-11-23T15:04:56Z 2021-11-23T15:04:56Z 2021-09-30
dc.identifier.citation Kazemi, Seyedjavad: Variational techniques for strongly correlated open quantum systems. Hannover : Gottfried Wilhelm Leibniz Universität, Diss., 2021, ix, 155 S. DOI: eng
dc.description.abstract Quantum systems are subject to dissipation as perfect isolation from the surrounding environment is impractical. Though this might wash out the intriguing quantum features that are absent in classical systems, proper engineering of dissipation, by contrast, opens up the possibility to not only prepare resilient quantum states but also attain dynamical properties unreachable in closed systems. The former provides a robust source for universal quantum computation and the latter transcends the conventional equilibrium physics bringing on genuinely new many-body phenomena. This work utilizes novel variational techniques to explore many-body effects in strongly correlated and/or interacting open quantum systems. After introducing these techniques in Part I, innovative solutions to several challenging problems in the context of non-equilibrium steady states are presented in Part II. In this part, we first address the issue of having genuine bistability in the steady state of open quantum systems. To this end, we develop a powerful framework to analyze stability in the long-time limit of a generic dissipative process with or without the detailed balance condition. The study of Toom's majority voting model in the presence of quantum fluctuations paves the way for engineering bistability using chiral jump operators. In a second step, we extend our variational method to approach otherwise intractable problems in the context of strongly interacting dissipative spin systems. Our method enables the estimation of steady-state properties across phase transitions. We exemplify this by simulating long-range interacting Rydberg gases undergoing different kinds of dissipation. In Part III, we turn our attention to dynamical properties of open quantum systems. We mainly focus on the classification of dynamical behaviors in quantum systems building upon the notion of elementary cellular automata (ECA). A master equation embedding of ECA dynamical rule 110 being capable of universal computation reveals the existence of a phase transition between chaotic and unpredictable behavior. We then complement the dynamical system with a second process in such a way that unpredictability coexists with quantum entanglement even in the long time limit. Finally, we demonstrate an efficient realization of many-body interactions required for such systems relying on a variational quantum simulation scheme that employs available qubit technologies. eng
dc.language.iso eng eng
dc.publisher Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
dc.rights CC BY 3.0 DE eng
dc.rights.uri eng
dc.subject Open Quantum Many-Body Systems eng
dc.subject Variational Principles for Steady States eng
dc.subject Dissipative Phase Transitions eng
dc.subject Correlated Jump Operators eng
dc.subject Toom's Majority Voting Model eng
dc.subject Genuine Bistability eng
dc.subject Mesoscopic Langevin Equation eng
dc.subject Driven-Dissipative Rydberg Gases eng
dc.subject Unpredictable Dynamical Systems eng
dc.subject Probabilistic Cellular Automata eng
dc.subject Variational Quantum Simulation eng
dc.subject Offene Quanten-Vielteilchensysteme ger
dc.subject Dissipative Phasenübergänge ger
dc.subject Variationsprinzipien für stationäre Zustände unübersetzt ger
dc.subject.ddc 500 | Naturwissenschaften eng
dc.title Variational techniques for strongly correlated open quantum systems eng
dc.type DoctoralThesis eng
dc.type Text eng
dcterms.extent ix, 155 S.
dc.description.version publishedVersion eng
tib.accessRights frei zug�nglich eng

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