A double-dot quantum ratchet driven by an independently biased quantum point contact

TL;DR

This paper investigates a quantum ratchet mechanism where a double quantum dot system exhibits directed current flow driven by a strongly biased quantum point contact, revealing a novel energy transfer process in quantum nanostructures.

Contribution

It demonstrates a quantum ratchet effect in a double quantum dot system energized by an independently biased quantum point contact, a novel experimental realization of quantum energy transfer.

Findings

Finite current observed in Coulomb blockaded DQD due to QPC bias

Current direction depends on energy level detuning

Quantum ratchet behavior confirmed in the system

Abstract

We study a double quantum dot (DQD) coupled to a strongly biased quantum point contact (QPC), each embedded in independent electric circuits. For weak interdot tunnelling we observe a finite current flowing through the unbiased Coulomb blockaded DQD in response to a strong bias on the QPC. The direction of the current through the DQD is determined by the relative detuning of the energy levels of the two quantum dots. The results are interpreted in terms of a quantum ratchet phenomenon in a DQD energized by a nearby QPC.