Quantum ratchet control - harvesting on Landau-Zener transitions

TL;DR

This paper demonstrates control over quantum ratchet currents by designing ramping schemes that exploit Landau-Zener transitions, enabling directed transport and current reversal through adiabatic and diabatic processes.

Contribution

It introduces a method to control quantum ratchet currents using tailored ramping schemes based on Landau-Zener transitions between Floquet states.

Findings

Strong current changes in the adiabatic regime

Current reversal achieved through control schemes

Desymmetrization increases critical ramping speed

Abstract

We control the current of a single particle quantum ratchet by designing ramping schemes for experimentally accessible control parameters. We harvest on Landau-Zener transitions between Floquet states. Adiabatic and diabatic ramping allow to control the resulting directed transport. We find strong changes of the current in the adiabatic regime. Simple loops in control parameter space with alternating adiabatic and diabatic ramping are proposed. We obtain also current reversal. Full desymmetrization of the quantum ratchet increases the critical ramping speed which separates the adiabatic from the diabatic regime.