We discuss the interplay between transport and intrinsic dissipation in
quantum Hall bilayers, within the framework of a simple thought experiment. We
compute, for the first time, quantum corrections to the semiclassical dynamics
of this system. This allows us to re-interpret tunnelling measurements on these
systems. We find a strong peak in the zero-temperature tunnelling current that
arises from the decay of Josephson-like oscillations into incoherent charge
fluctuations. In the presence of an in-plane field, resonances in the
tunnelling current develop an asymmetric lineshape.Comment: 4 pages, 3 figure
