Mach-Zehnder interferometer in the fractional quantum Hall regime

We consider tunneling between two edges of quantum Hall liquids of filling factors nu(0,1)=1/(2m(0,1)+1), with m(0)>or=m(1)>or=0, through two-point contacts forming a Mach-Zehnder interferometer. A quasiparticle description of the interferometer is derived explicitly through the instanton duality transformation. For m(0)+m(1)+1 identical withm>1, tunneling of quasiparticles of charge e/m leads to nontrivial m-state dynamics of effective flux through the interferometer, which restores the regular "electron" periodicity of the current in flux. The exact solution available for equal propagation times between the contacts shows that the interference pattern depends on voltage and temperature only through a common amplitude.