Interedge coherent line junctions in Quantum Hall systems

In this paper we address some of the properties of quantum Hall line junctions (QHLJ) that occur near barriers separating electron gases on quantum Hall plateaus.In narrow barriers where electron tunneling can occur, the low energy physics of the QHLJ is described by the quantum sine-Gordon model. We propose procedures to study a sort of properties of these systems in relation with recent experimental studies of Kang {\it et al.}, Nature {\bf 403}, 59 (2000). We propose experimental ways of measuring the values of the dimensionless coupling constant characteristic for the Sine-Gordon model as well as its Fermi velocity. When the bulk filling of the 2DEG subsystems is $\nu \sim 2$, these systems can be good candidates for observation of spin-incoherent LL behavior.