Ballistic atomic transport in narrow carbon nanotubes

TL;DR

This paper demonstrates that helium-4 can exhibit ballistic, frictionless wave transport through narrow carbon nanotubes due to quantum effects, even with realistic imperfections and finite temperatures.

Contribution

It extends quantum mechanical modeling of helium flow in CNTs, showing near-frictionless transport persists under realistic conditions and imperfections.

Findings

Helium waves can propagate with no friction below a critical velocity.

Large mean free paths exceeding micrometers are possible despite impurities.

Thermal phonons and plasmons cause minimal scattering, supporting ballistic transport.

Abstract

Friction forces are conventionally modeled via semiclassical theories that associate energy dissipation with newtonian motion on corrugated interface potentials. This consolidated approach is challenged at the nanoscale by observation of nearly unimpeded water flow in narrow carbon nanotubes (CNTs), in spite of nonvanishing energy corrugations. Here we go beyond the standard newtonian perspective, adopting a quantum mechanical description of 4 He flow through narrow CNTs. Building upon our Bloch-wave dynamics [Phys. Rev. Lett. 131, 206301 (2023)] we explore realistic flow conditions, including non-negligible interface interactions, finite temperatures, and imperfect CNTs. At T = 0 K we found that 4 He waves can propagate through ideally periodic, corrugated interface potentials with no friction: below a critical velocity regulated by interface corrugations, energy loss by emission of plasmon and phonon quanta is forbidden. Introducing realistic impurities/defects one still finds very large mean free paths that can exceed the micrometer scale, while thermal phonons and plasmons yield even lower scattering rates. This establishes the unexpected emergence of ballistic wavelike transport in narrow CNTs within realistic nanoscale devices, and demonstrates the intrinsic quantumness of nanoscale interfaces.