  We examine interferometric measurements of the topological charge of
(non-Abelian) anyons. The target's topological charge is measured from its
effect on the interference of probe particles sent through the interferometer.
We find that superpositions of distinct anyonic charges a and a' in the target
decohere (exponentially in the number of probes particles used) when the probes
have nontrivial monodromy with the charges that may be fused with a to give a'.
