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Quantum information theory combines classical information theory with quantum physics. This combination opens the door to many fascinating applications which either do not have a classical counterpart or outperform them. Prominent examples thereof are quantum communication and quantum computation and simulations. Many of the application are possible due to the subtle properties of quantum many-body systems. In particular entanglement, which is a strong correlation among several quantum systems, plays an essential role. In this talk, I will first present some recent results on multipartite entanglement theory. In particular, I will show that deterministic local transformations among pure n-partite d-level systems are almost never possible. The consequences of these findings in the context of entanglement theory will be discussed. Then I will talk about certain aspects of quantum computations, where entanglement plays an important role. I will consider quantum algorithms which are composed of so-called matchgates. I will show that such an algorithm can always be compressed into an exponentially smaller quantum computation. However, as will be explained, the usage of an additional resource, the so-called magic states, elevates such a computation to universal quantum computation, while maintaining the same gate set. I will present the characterization of these magic states and discuss the consequences of these results in the context of quantum computation.

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Barbara Kraus, Innsbruck
Seminar Room 0.03, ETP
Contact: Sebastian Diehl