Line junctions in the quantum Hall effect

A long narrow gate across a fractional quantum Hall fluid at filling n51/m with odd integer m , creates a one-dimensional ~1D! system that is isomorphic to a disordered 1D electron gas with attractive interactions. By varying the gate potential along such a line junction, it should be possible to tune through the 1D localization transition, predicted for an attractively interacting electron gas. The key signature of this 1D metal-insulator transition is the temperature dependence of the conductivity, which diverges as a power of temperature in the metallic phase, and vanishes rapidly in the insulator. We show that the 1D conductivity can be extracted from a standard Hall transport measurement, in the regime where the Hall conductance is close to its quantized value. A line junction in a n52/3 quantized Hall fluid is predicted to exhibit a similar localization transition. @S0163-1829~97!02544-7#