Immersing carbon nano-tubes in cold atomic gases

TL;DR

This paper models the relaxation dynamics of a vibrating carbon nanotube immersed in ultra-cold atoms, providing insights into how atomic collisions induce phonon excitations and how this process can be controlled for cooling applications.

Contribution

It develops a dynamic theoretical framework for phonon relaxation in a nano-tube due to atomic collisions, extending understanding of nano-mechanical cooling techniques.

Findings

Relaxation rates depend on atom density and temperature.

Theoretical estimates align with experimental data.

Guidelines for sympathetic ground state cooling are provided.

Abstract

We investigate the sympathetic relaxation of a free-standing, vibrating carbon nano-tube that is mounted on an atom chip and is immersed in a cloud of ultra-cold atoms. Gas atoms colliding with the nano-tube excite phonons via a Casimir-Polder potential. We use Fermi's Golden Rule to estimate the relaxation rates for relevant experimental parameters and develop a fully dynamic theory of relaxation for the multi-mode phononic field embedded in a thermal atomic reservoir. Based on currently available experimental data, we identify the relaxation rates as a function of atom density and temperature that are required for sympathetic ground state cooling of carbon nano-tubes.