Mono-parametric quantum charge pumping: interplay between spatial interference and photon-assisted tunneling

TL;DR

This paper investigates quantum charge pumping in an open ring with a quantum dot, revealing that a single-parameter cyclic drive combined with magnetic flux induces a current through interference and photon-assisted tunneling, with current direction controllable by magnetic field.

Contribution

It demonstrates that a single-parameter cyclic modulation can induce charge pumping in a ring with a quantum dot, highlighting the role of magnetic flux and photon-assisted processes.

Findings

Pumped current is proportional to the square of the driving frequency at low frequencies.

Magnetic flux can reverse the direction of the pumped current.

Interplay between spatial interference and photon-assisted tunneling enables charge pumping.

Abstract

We analyze quantum charge pumping in an open ring with a dot embedded in one of its arms. We show that cyclic driving of the dot levels by a \textit{single} parameter leads to a pumped current when a static magnetic flux is simultaneously applied to the ring. Based on the computation of the Floquet-Green's functions, we show that for low driving frequencies $\omega_0$, the interplay between the spatial interference through the ring plus photon-assisted tunneling gives an average direct current (dc) which is proportional to $\omega_0^{2}$. The direction of the pumped current can be reversed by changing the applied magnetic field.