Fusion rules and vortices in px+ipy superconductors -: art. no. 014505

The "half-quantum" vortices (sigma) and quasiparticles (psi) in a two-dimensional p(x)+ip(y) superconductor obey the Ising-like fusion rules psi x psi=1, sigma x psi=sigma, and sigma x sigma=1+psi. We explain how the physical fusion of vortex-antivortex pairs allows us to use these rules to read out the information encoded in the topologically protected space of degenerate ground states. We comment on the potential applicability of this fact to quantum computation.