LINE JUNCTIONS IN THE QUANTUM HALL-EFFECT

A long narrow gate across a fractional quantum Hall fluid at filling n u=1/m with odd integer m, creates a one-dimensional (1D) system that i s isomorphic to a disordered 1D electron gas with attractive interacti ons. By varying the gate potential along such a line junction, it shou ld be possible to tune through the ID localization transition, predict ed for an attractively interacting electron gas. The key signature of this 1D metal-insulator transition is the temperature dependence of th e conductivity, which diverges as a power of temperature in the metall ic phase, and vanishes rapidly in the insulator. We show that the 1D c onductivity can be extracted from a standard Hall transport measuremen t, in the regime where the Hall conductance is close to its quantized value. A line junction in a nu=2/3 quantized Hall fluid is predicted t o exhibit a similar localization transition.