Strong and tunable mode coupling in carbon nanotube resonators

TL;DR

This paper investigates the non-linear interaction between mechanical resonances in carbon nanotube resonators, revealing tunable mode coupling dominated by single-electron tunneling, with significantly stronger effects than in traditional micromechanical systems.

Contribution

It demonstrates that in carbon nanotube resonators, mode coupling can be tuned via gate voltage and is primarily driven by single-electron tunneling, contrasting with tension-based coupling in strings.

Findings

Mode coupling can be tuned with gate voltage.

Coupling strength is six orders of magnitude larger than in micromechanical resonators.

Mode softening and stiffening behaviors are observed.

Abstract

The non-linear interaction between two mechanical resonances of the same freely suspended carbon nanotube resonator is studied. We find that in the Coulomb blockade regime, the non-linear modal interaction is dominated by single-electron-tunneling processes, and that the mode-coupling parameter can be tuned with the gate voltage, allowing both mode softening and mode stiffening behavior. This is in striking contrast to tension-induced mode coupling in strings, where the coupling parameter is positive and gives rise to a stiffening of the mode. The strength of the mode coupling in carbon nanotubes in the Coulomb blockade regime is observed to be six orders of magnitude larger than the mechanical mode coupling in micromechanical resonators.