  A highly non-thermal electron distribution is generated when quantum Hall
edge states originating from sources at different potentials meet at a quantum
point contact. The relaxation of this distribution to a stationary form as a
function of distance downstream from the contact has been observed in recent
experiments [Phys. Rev. Lett. 105, 056803 (2010)]. Here we present an exact
treatment of a minimal model for the system at filling factor \nu=2, with
results that account well for the observations.
