This was actually really interesting. See also the german article: http://www.nzz.ch/wissenschaft/physik/was-man-von-quantencomputern-erwarten-darf-und-was-nicht-1.18422829
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Quantum Computing and the Limits of the Efficiently Computable - 2011 Buhl Lecture Scott Aaronson, an expert in the realm of computational complexity theory and the founder of ComplexityZoo.