Fabry-Perot interferometry with fractional charges

Resistance oscillations in electronic Fabry-Perot interferometers near fractional quantum Hall (FQH) filling factors 1/3, 2/3, 4/3, and 5/3 in the constrictions are compared to those near integer quantum Hall (IQH) filling factors in the same devices and at the same gate voltages. Two-dimensional plots of resistance versus gate voltage and magnetic field indicate that all oscillations are Coulomb dominated. A charging-model analysis of gate-voltage periods yields an effective tunneling charge e ^* e/3 for all FQH states and e ^* e for IQH states. Temperature decay of the oscillations appears exponential, qualitatively consistent with a recent prediction, and the surprising filling-factor dependence of the associated energy scale may shed light on edge structure.