Electronic dephasing in the quantum Hall regime

Summary form only given. We present the first investigation of electronic dephasing in the presence of two dimensional electron gas (2DEG) in the Quantum Hall regime using four wave mixing (FWM). We observe a transition from Markovian to non-Markovian behavior and abrupt variation of the decay time with filling factor, which we interpret in terms of photoexcited electrons scattering with collective excitations of the 2DE-liquid in the lowest Landau level.