Conductance quantization in V-groove quantum wires

We have observed and studied ballistic one-dimensional (1D) electron transport in V-grooved GaAs-AlxGa1-xAs heterostructures. In two different regimes of quantum wire confinement the conductance varies in a steplike manner, with the number of populated 1D subbands controlled by a gate voltage. For weak lateral confinement, the conductance steps nearly attain the 2e(2)/h value, whereas for stronger confinement the values of the conductance steps are suppressed. Our results suggest that a poor coupling between the 1D states of the wire and the 2D states of the reservoirs outside the gated region is responsible for the conductance suppression for strong lateral confinement. [S0163-1829(99)50516-X].