Edge-induced qubit polarization in systems with Ising anyons

We investigate the proposed experimental setup for measuring the topological charge in an Ising anyon system by means of Fabry-Perot interferometry with a chiral edge state. We show that such an interferometer has the unintended but not necessarily unwelcome effect of stabilizing the state of the system being measured (i.e. a topological qubit). We show further that interactions between the edge mode and the localized bulk quasiparticles can have the effect of polarizing the qubit, again stabilizing its state. We discuss these results in the context of recent interferometer experiments in the 5/2 fractional quantum Hall state, where the first of these effects is small, but the second may be relevant to the observed phenomena.