Scattering and absorption of ultracold atoms by nanotubes

TL;DR

This paper provides a theoretical analysis of how ultracold atoms interact with nanotubes, examining scattering, absorption, and the effects of various physical factors, with implications for experimental observations.

Contribution

It introduces a modified pairwise summation method for calculating scattering potentials and analyzes the roles of quantum reflection, atomic interactions, and nanotube vibrations.

Findings

Lifshitz theory predicts stronger scattering potentials than experiments.

Quantum reflection is significant at low temperatures for non-metallic tubes.

Atomic interactions increase atom loss rates and induce complex dynamics.

Abstract

We investigate theoretically how cold atoms, including Bose-Einstein condensates, are scattered from, or absorbed by nanotubes with a view to analysing recent experiments. In particular we consider the role of potential strength, quantum reflection, atomic interactions and tube vibrations on atom loss rates. Lifshitz theory calculations deliver a significantly stronger scattering potential than that found in experiment and we discuss possible reasons for this. We find that the scattering potential for dielectric tubes can be calculated to a good approximation using a modified pairwise summation approach, which is efficient and easily extendable to arbitrary geometries. Quantum reflection of atoms from a nanotube may become a significant factor at low temperatures, especially for non-metallic tubes. Interatomic interactions are shown to increase the rate at which atoms are lost to the nanotube and lead to non-trivial dynamics. Thermal nanotube vibrations do not significantly increase loss rates or reduce condensate fractions, but lower frequency oscillations can dramatically heat the cloud.