Scattering of chiral currents by quantum point contacts

The conductive channels and the current distributions through a narrow quantum point contact (QPC) in a two-dimensional electron gas threaded by a uniform magnetic field are studied using the Keldysh nonequilibrium Green's function formalism and a site representation of the electron Hamiltonian. We show that when the conditions of chiral transport regime are met in the two regions separated by the QPC, exact quantization in integer multiples of 2e/sup 2//h is maintained both for the conductance of the incident current and the backscattered plus transmitted currents.