Bound states in waveguides and bent quantum wires .2. Electrons in quantum wires

Charged particles which move through bent quantum wires should possess one or more bound states. One way to observe these bound states is by measuring electron conductance in quantum wires. In the previous paper, we calculated the location and properties of bound states in quantum wires with two rectangular bends, and we found these confined states by measuring microwave transmission in bent rectangular waveguides. In this paper we calculate the conductance for electrons in quantum wires of the same geometry. Experimental measurements of such electrons observe conductance below the threshold for free propagation. It was conjectured that this effect resulted from quantum tunneling through an impurity state in the substrate. We compare the observed subthreshold conductance with theoretical calculations of electron tunneling through bound states in the bent quantum wire. We also compare our results with previous theoretical calculations of electron conductance in a system with this geometry.