Magnetic-field-induced V-shaped quantized conductance staircase in a double-layer quantum point contact

We show that the low-temperature conductance (G) of a quantum point contact consisting of ballistic tunnel-coupled double-layer quantum-well wires is modulated by an in-layer magnetic field B due to the anticrossing. B create s a V-shaped quantum staircase for G, causing it to decrease in steps of 2e (2)/h to a minimum and then increase to a maximum, where G may saturate or decrease again at higher B's. Relevance of the result to recent data is dis cussed. [S0163-1829(99)14935-X].