Philipp Strasberg

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This talk has three parts. In the first part of the talk I give a pedagogical introduction to the framework of decoherent histories, which decides which processes in an isolated (unitarily evolving) quantum system can be modeled by a classical stochastic process whose events leave detectable records in the final quantum state. In the second part of the talk I review recent research results about the quantitative behavior of decoherence. While they reveal a robust form of decoherence for slow and coarse observables in chaotic quantum systems, they also show that decoherence is never exact but only approximate. The third part explores the consequences of approximate decoherence, which is ongoing research work, from the perspective of quantum information theory. In particular, we find that there are many more possible decoherent histories than observers inside a "Multiverse" can discriminate. From the perspective of the many worlds interpretation this would lead to a kind of "branch selection problem", at least if the (observable) Universe can be described by a finite dimensional quantum system.

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Instituto de Fisica de Cantabria (IFCA), Santander, Spain
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Contact: Andreas Winter