  A semiconductor nanowire based superconductor-normal-superconductor (SNS)
junction is modeled theoretically. A magnetic field is applied along the
nanowire axis, parallel to the current. The Bogoliubov-de Gennes equations for
Andreev bound states are solved while considering the electronic subbands due
to radial confinement in the N-section. The energy-versus-phase curves of the
Andreev bound states shift in phase as the N-section quasiparticles with
orbital angular momentum couple to the axial field. A similar phase shift is
observed in the continuum current of the junction. The quantum mechanical
result is shown to reduce to an intuitive, semi-classical model when the
Andreev approximation holds. Numerical calculations of the critical current
versus axial field reveal flux-aperiodic oscillations that we identify as a
novel form of Josephson interference due to this orbital subband effect. This
behavior is studied as a function of junction length and chemical potential.
Finally, we discuss extensions to the model that may be useful for describing
realistic devices.
