Large oscillating non-local voltage in multi-terminal single wall carbon nanotube devices

TL;DR

This paper reports the observation of a large, oscillating non-local voltage in a multi-terminal single-wall carbon nanotube device, driven by quantum interference effects in a ballistic one-dimensional conductor.

Contribution

It demonstrates that quantum interference causes large non-local voltages in carbon nanotube devices, which classical models cannot fully explain.

Findings

Large oscillating non-local voltage observed

Quantum interference explains the voltage magnitude

Classical resistor model insufficient for magnitude prediction

Abstract

We report on the observation of a non-local voltage in a ballistic one-dimensional conductor, realized by a single-wall carbon nanotube with four contacts. The contacts divide the tube into three quantum dots which we control by the back-gate voltage $V_g$. We measure a large \emph{oscillating} non-local voltage $V_{nl}$ as a function of $V_g$ with zero mean. Though a classical resistor model can account for a non-local voltage including change of sign, it fails to describe the magnitude properly. The large amplitude of $V_{nl}$ is due to quantum interference effects and can be understood within the scattering-approach of electron transport.