This is a site to present ideas about the theory of quantum computation considered from the standpoint of computational complexity (i.e. as a special topic in theoretical computer science), deliberately ignoring von Neumann’s advice about understanding mathematics.
We consider quantum computation from the standpoint of a computational theory, as a model which happens to be related to (and possibly efficiently simulatable by) physical processes. Regardless of whether quantum computers are ever realised physically, one may consider their computational power. A quantum computation is mathematically well-defined, and consists of a composition of simple parts: as such, its power is a proper subject in the theory of computation. That those simple parts may happen to correspond to simple quantum evolutions is not needed to justify this model, though this does motivate it as a subject of possible practical interest.
To this end we explore ideas which enhance our understanding of quantum computation and related branches of mathematics and computational complexity, without demanding immediate connections to application or implementation, but instead emphasizing that it be motivated from a computational perspective.