  We show that when an electron or photon propagates in a cylindrically
symmetric waveguide, it experiences both a zitterbewegung effect and a
spin-orbit interaction leading to identical propagation dynamics for both
particles. Applying a unified perturbative approach to both particles
simultaneously, we find that to first-order in perturbation theory their
Hamiltonians each contain identical Darwin (zitterbewegung) and spin-orbit
terms, resulting in the unification of their dynamics. The presence of the
zitterbewegung effect may be interpreted physically as the delocalization of
the electron on the scale of its Compton wavelength, or the delocalization of
the photon on the scale of its wavelength in the waveguide. The presence of the
spin-orbit interaction leads to the prediction of several rotational effects:
the spatial or time evolution of either particle's spin/polarization vector is
controlled by the sign of its orbital angular momentum quantum number, or
conversely, its spatial wave function is controlled by its spin angular
momentum.
