Coherent quantum transport in narrow constrictions in the presence of a finite-range longitudinally polarized time-dependent field

TL;DR

This study investigates how a finite-range longitudinally polarized time-dependent electric field affects quantum transport in narrow constrictions, revealing unique quasi-bound-state features and field-dependent energy shifts.

Contribution

It introduces the analysis of coherent inelastic scattering and QBS features in quantum conductance under a finite-range time-dependent electric field, highlighting novel field-sensitive effects.

Findings

QBS features exhibit valley-like structures unlike dip-like in static cases.

Subband bottoms are shifted upward proportionally to the square of the electric field.

Field-sensitive QBS features are linked to an effective potential barrier from the vector potential.

Abstract

We have studied the quantum transport in a narrow constriction acted upon by a finite-range longitudinally polarized time-dependent electric field. The electric field induces coherent inelastic scatterings which involve both intra-subband and inter-sideband transitions. Subsequently, the dc conductance G is found to exhibit suppressed features. These features are recognized as the quasi-bound-state (QBS) features which are associated with electrons making transitions to the vicinity of a subband bottom, of which the density of states is singular. Having valley-like instead of dip-like structures, these QBS features are different from the G characteristics for constrictions acted upon by a finite-range time-modulated potential. In addition, the subband bottoms in the time-dependent electric field region are shifted upward by an energy proportional to the square of the electric field and inversely proportional to the square of the frequency. This effective potential barrier is originated from the square of the vector potential and it leads to the interesting field-sensitive QBS features. An experimental set-up is proposed for the observation of these features.