Mode mixing in quantum waveguides: A gauge field approach
Sektion Physik, Ludwig-Maximilians-Universität München,
Theresienstraße 37, D-80333 München, Germany
Accepted: 1 December 1997
It is shown that the elimination of the discrete transverse motion in a waveguide of arbitrary shape may be described in terms of a non-Abelian gauge field for the longitudinal dynamics. This allows for an exact treatment of the scattering between different modes by eliminating the gauge field at the expense of a non-diagonal matrix of local subband energies. The method is applied to calculate the local density of states (LDOS) in a quantum point contact. Contrary to the total conductance which is well described by an adiabatic approximation, mode mixing turns out to play a crucial role for local properties like the LDOS.
PACS: 03.80.+r – General theory of scattering / 72.10.-d – Theory of electronic transport; scattering mechanisms
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