  The dephasing rate of an electron level in a quantum dot, placed next to a
fluctuating edge current in the fractional quantum Hall effect, is considered.
Using perturbation theory, we first show that this rate has an anomalous
dependence on the bias voltage applied to the neighboring quantum point
contact, because of the Luttinger liquid physics which describes the fractional
Hall fluid. Next, we describe exactly the weak to strong backscattering
crossover using the Bethe-Ansatz solution.

Mesoscale and Nanoscale Physics