Flux-period scaling in the Laughlin quasiparticle interferometer

We report experiments on electron interferometer devices in the quantum Hall regime, where edge channels circle a two-dimensional (2D) electron island. The main confinement is produced by etch trenches, into which front-gate metal is deposited. We find a linear dependence of the Aharonov-Bohm period on gate voltage for electrons (integer filling f=1) and for Laughlin quasiparticles (fractional 2/5 embedded in 1/3). The capacitance of a large 2D electron island with respect to the front gates is approximately proportional to the island radius. Comparing the experimental data for the integer and the fractional fillings and for two samples, we find the magnetic field period and its slope scale with the radius of the Aharonov-Bohm orbit. Analysis of the directly measured integer and fractional slope data allows us to determine the interferometer area in the fractional regime, and thus the Laughlin quasiparticle flux period of 5h/e, within the experimental accuracy.