Conductance of Rashba electron in a quantum waveguide with smooth boundary

By using the transfer matrix method, we theoretically investigated Rashba electron's spin transport in a straight waveguide with a stub which has a smooth boundary. It is proved that the two spin states propagate independently. The conductance of the waveguide has been calculated. Conductance quantization is common in this structure when we change the Fermi energy and the width of the stub. If the shape of the stub converges toward the limit-a quadrate stub, the conductance will reduce distinctly due to reflection.