Quasiparticle Tunneling in the Fractional Quantum Hall State at v = 5/2

Theory predicts that quasiparticle tunneling between the counter- propagating edges in a fractional quantum Hall state can be used to measure the effective quasiparticle charge e and dimensionless interaction parameter g, and thereby characterize the many-body wavefunction describing the state. We report measurements of quasiparticle tunneling in a high mobility GaAs twodimensional electron system in the fractional quantum Hall state at v = 5/2 using a gate-defined constriction to bring the edges close together. We find the dc-bias peaks in the tunneling conductance at different temperatures collapse onto a single curve when scaled, in agreement with weak tunneling theory. Various models for the v = 5/2 state predict different values for g. Among these models, the non-abelian states with e = 1/4 and g = 1/2 are most consistent with the data.