Coherent quantum transport in the presence of a finite-range transversely polarized time-dependent field

TL;DR

This paper explores how a finite-range transversely polarized time-dependent electric field affects quantum transport in narrow constrictions, revealing inelastic scattering effects, conductance suppression, and quasi-bound states linked to subband transitions.

Contribution

It introduces a generalized scattering-matrix method with a time-dependent mode-matching scheme to analyze inelastic scattering in quantum transport under a finite-range transverse field.

Findings

Conductance G shows suppression features increasing with chemical potential.

Dip structures in G are identified as quasi-bound-state features from intersubband transitions.

Higher photon processes make QBS features more prominent, related to the density of states at subband bottoms.

Abstract

This work investigates the quantum transport in a narrow constriction acted upon by a finite-range transversely polarized time-dependent electric field. A generalized scattering-matrix method is developed that has incorporated a time-dependent mode-matching scheme. The transverse field induces coherent inelastic scatterings that include both intersubband and intersideband transitions. These scatterings give rise to the dc conductance $G$ a general suppressed feature that escalates with the chemical potential. In addition, particular suppressed features -- the dip structures -- are found in $G$. These features are recognized as the quasi-bound-state (QBS) features that arise from electrons making intersubband transitions to the vicinity of a subband bottom. For the case of larger field intensities, the QBS features that involve more photons are more evident. These QBS features are closely associated with the singular density of states at the subband bottoms. An experimental setup is proposed for the observation of these features.