Description
We explore the possibility of passive error correction in
the toric code model. We first show that even coherent
dynamics, stemming from spin interactions or the coupling to
an external magnetic field, lead to logical errors. We then
argue that Anderson localization of the defects, arising
from unavoidable fluctuations of the coupling constants,
provides a remedy. This protection is demonstrated using
general analytical arguments that are complemented with
numerical results which demonstrate that self-correcting
memory can in principle be achieved in the limit of a
nonzero density of identical defects. The talk is mainly
based on arXiv:1101.6028.
