Current noise in an irradiated point contact

We propose a new approach to calculate current and current correlations in a ballistic quantum point contact interacting with a classical field. The a pproach is based on the concept of scattering states for a time-dependent H amiltonian neglecting electron-electron interaction. Using this approach we calculate the spectra of the current noise in a biased point contact irrad iated by a weak random field. For typical radiation frequencies v less than the temperature T and the bias voltage V, we find a narrow peak of width v on top of a broad background of width max(T, eV).