This thesis investigates the structure and behaviour of entanglement, the purely quantum mechanical part of correlations, in many-body systems, employing both numerical and analytical techniques at the interface of condensed matter theory and quantum information theory. Entanglement can be seen as a precious resource which, for example, enables the noiseless and instant transmission of quantum information, provided the communicating parties share a sufficient "amount" of it. Furthermore, measures of entanglement of a quantum mechanical state are perceived as useful probes of collective properties of many-body systems. For instance, certain measures are capable of detecting and classifying ground-state phases and, particularly, transition (or critical) points separating such phases. Chapters 2 and 3 focus on entanglement in many-body systems and its use as a potential resource for communication protocols. They address the questions of how a substantial amount of entanglement can be established between distant subsystems, and how efficiently this entanglement could be "harvested" by way of measurements. The subsequent chapters 4 and 5 are devoted to universality of entanglement between large collections of particles undergoing a quantum phase transition, where, despite the enormous complexity of these systems, collective properties including entanglement no longer depend crucially on the microscopic details.
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From the reviews:
"The theses brings new and very interesting knowledge on the quantum information field. ... this thesis gives a new insight of entanglement between noncomplementary regious of many-body systems, with interesting discussions and well carried out mathematical models." (Nicolae Constantinescu, Zentralblatt MATH, Vol. 1222, 2011)
"The theses brings new and very interesting knowledge on the quantum information field. ... this thesis gives a new insight of entanglement between noncomplementary regious of many-body systems, with interesting discussions and well carried out mathematical models." (Nicolae Constantinescu, Zentralblatt MATH, Vol. 1222, 2011)