  Anderson localization emerges in quantum systems when randomised parameters
cause the exponential suppression of motion. Here we consider this phenomenon
in topological models and establish its usefulness for protecting topologically
encoded quantum information. For concreteness we employ the toric code. It is
known that in the absence of a magnetic field this can tolerate a finite
initial density of anyonic errors, but in the presence of a field anyonic
quantum walks are induced and the tolerable density becomes zero. However, if
the disorder inherent in the code is taken into account, we demonstrate that
the induced localization allows the topological quantum memory to regain a
finite critical anyon density, and the memory to remain stable for arbitrarily
long times. We anticipate that disorder inherent in any physical realisation of
topological systems will help to strengthen the fault-tolerance of quantum
memories.
