Interedge phase coherence in quantum Hall line junctions

Kang et al. have recently observed a remarkable zero-bias anomaly in the spectrum for electron tunneling between two two-dimensional electron gases separated laterally by a narrow but high barrier in the presence of a perpendicular quantizing magnetic field. We argue that this is a result of interedge phase coherence analogous to the interlayer phase coherence seen in quantum Hall effect (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.