  We consider tunneling between two edges of Quantum Hall liquids (QHL) of
filling factors $\nu_{0,1}=1/(2 m_{0,1}+1)$, with $m_0 \geq m_1\geq 0$, through
two point contacts forming Mach-Zehnder interferometer. Quasi-particle
description of the interferometer is derived explicitly through the instanton
duality transformation of the initial electron model. For $m_{0}+m_{1}+1\equiv
m>1$, tunneling of quasiparticles of charge $e/m$ leads to non-trivial
$m$-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 along the two edges
demonstrates that the interference pattern in the tunneling current depends on
voltage and temperature only through a common amplitude.
