  We report experimental temperature dependence of the amplitude of
Aharonov-Bohm oscillations in the Laughlin quasiparticle interferometer. The
results fit very well the thermal dephasing dependence predicted for a g = 1/3
chiral Luttinger liquid interferometer, and are clearly distinct from the
activated behavior observed in single-particle resonant tunneling and Coulomb
blockade devices. The small deviation from the zero-bias theory seen below 20
mK indicates yet unrecognized source of experimental decoherence, not included
in theory.
