Coherent Quantum Ratchets Driven by Tunnel Oscillations

TL;DR

This paper shows how tunnel oscillations in a double quantum dot can drive a quantum ratchet, revealing unexpected current steps due to two-electron states, using a master equation approach.

Contribution

It introduces a model where tunnel oscillations serve as a driving force for a quantum ratchet, highlighting novel current features from two-electron states.

Findings

Tunnel oscillations can drive a quantum ratchet.

Two-electron states cause unexpected current steps.

Master equation approach ensures proper equilibrium limit.

Abstract

We demonstrate that the tunnel oscillations of a biased double quantum dot can be employed as driving source for a quantum ratchet. As a model, we use two capacitively coupled double quantum dots. One double dot is voltage biased and provides the ac force, while the other experiences the ac force and acts as coherent quantum ratchet. The current is obtained from a Bloch-Redfield master equation which ensures a proper equilibrium limit. We find that the two-electron states of the coupled ratchet-drive Hamiltonian lead to unexpected steps in the ratchet current.