Carbon nanotube quantum pumps

TL;DR

This paper investigates the potential of nanomechanical carbon nanotube devices to function as adiabatic quantum pumps, analyzing how chirality differences influence charge transfer efficiency.

Contribution

It introduces a Green's function approach to quantify pumped charge in nanotube-based quantum pumps driven by rotational motion.

Findings

No pumping occurs when chiral angles are identical.

Optimal chiralities yield significant pumped charge.

Pumped charge can reach a notable fraction of the theoretical maximum.

Abstract

Recently nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly-rotating outer tube have been fabricated. In this Letter, we study the possibility of using such devices as adiabatic quantum pumps. Using the Brouwer formula, we employ a Green's function technique to determine the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that there is virtually no pumping if the chiral angle of the two nanotubes is the same, but for optimal chiralities the pumped charge can be a significant fraction of a theoretical upper bound.