Floquet scattering in parametric electron pumps

TL;DR

This paper compares Floquet and adiabatic scattering approaches in parametric electron pumps, showing their agreement at weak potentials and deviations at strong potentials, and discusses the adiabatic theory's validity using Wigner delay time.

Contribution

It introduces a Floquet scattering method for parametric electron pumps and compares it with the traditional adiabatic approach, highlighting their range of validity.

Findings

Floquet and adiabatic approaches agree at small oscillation strengths.

Deviations occur between the two methods at large oscillation strengths.

Wigner delay time analysis assesses the adiabatic theory's validity.

Abstract

A Floquet scattering approach to parametric electron pumps is presented and compared with Brouwer's adiabatic scattering approach [Phys. Rev. B 58, R10135 (1998)] for a simple scattering model with two harmonically oscillating delta-function barriers. For small strength of oscillating potentials these two approaches give exactly equivalent results while for large strength, these clearly deviate from each other. The validity of the adiabatic theory is also discussed by using the Wigner delay time obtained from the Floquet scattering matrix.