  Kang et al. have recently observed a remarkable zero-bias anomaly in the
spectrum for electron tunneling between two 2D electron gases separated
laterally by a narrow but high barrier in the presence of a perpendicular
quantising magnetic field. We argue that this is a result of interedge phase
coherence analogous to the interlayer phase coherence in quantum Hall (QHE)
bilayer systems. The disruption of the QHE by the barrier is 'healed' by strong
coulomb exchange enhancement of the weak tunneling through the barrier.
