Necessity of an energy barrier for self-correction of Abelian quantum doubles

Abstract

We rigorously establish an Arrhenius law for the mixing time of quantum doubles based on any Abelian group Z_d. We have made the concept of the energy barrier therein mathematically well defined; it is related to the minimum energy cost the environment has to provide to the system in order to produce a generalized Pauli error, maximized for any generalized Pauli errors, not only logical operators. We evaluate this generalized energy barrier in Abelian quantum double models and find it to be a constant independent of system size. Thus, we rule out the possibility of entropic protection for this broad group of models.