Capacitively coupled nano conductors: Ratchet currents and exchange fluctuation relations

TL;DR

This paper studies electron transport in coupled quantum circuits, deriving transport coefficients for fluctuation relations and analyzing non-equilibrium effects like ratchet currents induced by noise.

Contribution

It introduces a formalism for testing exchange fluctuation relations in coupled quantum circuits and explores non-equilibrium phenomena such as ratchet currents.

Findings

Derived transport coefficients for fluctuation relation testing

Validated the consistency of the master equation approach

Identified ratchet currents induced by noise in the system

Abstract

We investigate electron transport in two quantum circuits with mutual Coulomb interaction. The first circuit is a double quantum dot connected to two electron reservoirs, while the second one is a quantum point contact in the weak tunneling limit. The coupling is such that an electron in the first circuit enhances the barrier of the point contact and, thus, reduces its conductivity. While such setups are frequently used as charge monitors, we focus on two different aspects. First, we derive transport coefficients which have recently been employed for testing generalized equilibrium conditions known as exchange fluctuation relations. These formally exact relations allows us to test the consistency of our master equation approach. Second, a biased point contact entails noise on the DQD and induces non-equilibrium phenomena such as a ratchet current.