Conductance quantization in V-groove quantum wires

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