A scattering matrix approach to quantum pumping: Beyond the small-ac-driving-amplitude limit

TL;DR

This paper develops a scattering matrix approach to quantum pumping that accounts for high-order effects and strong modulation, revealing non-sinusoidal behaviors and complex current-amplitude relations beyond the weak-driving limit.

Contribution

It introduces a method considering high-order time dependence of the scattering matrix, extending quantum pump analysis beyond the small-amplitude approximation.

Findings

Reveals non-sinusoidal behavior in strong pumping regimes

Shows the pumped current's dependence on amplitude varies from quadratic to fractional powers

Provides an interpretation framework for experimental observations involving multi-energy-quantum processes

Abstract

In the adiabatic and weak-modulation quantum pump, net electron flow is driven from one reservoir to the other by absorbing or emitting an energy quantum $\hbar \omega $ from or to the reservoirs. In our approach, high-order dependence of the scattering matrix on the time is considered. Non-sinusoidal behavior of strong pumping is revealed. The relation between the pumped current and the ac driving amplitude varies from power of 2, 1 to 1/2 when stronger modulation is exerted. Open experimental observation can be interpreted by multi-energy-quantum-related processes.