Effects of a transversely polarized electric field on the quantum transport in narrow channels

The quantum transport in a narrow channel (NC) is studied in the presence of a time-dependent delta-profile electric field. The electric field is taken to be transversely polarized, with frequency $\omega$, causing inter-subband and inter-sideband transitions. Suppression in the dc conductance $G$ is found, which escalates with the chemical potential. There are structures in $G$ which are related to the quasi-bound states (QBS) features. Major dip, and dip-and-peak, structures occur when an incident electron makes transition to a subband edge by absorbing or emitting one, and two, $\mathrm{\hslash }\omega$, respectively. Structures associated with three $\mathrm{\hslash }\omega$ processes are recognized. The QBS are closely associated with the singular density of states (DOS) at subband bottoms. Our results indicate that, due to this singular features of the DOS, the interaction of the electron with the electric field has to be treated beyond finite order perturbation.