Towards frictionless molecular transport in narrow nanotubes

Abstract A large fraction of the worldwide energy production is dissipated each year by friction, causing self-evident economical and environmental impact. While search for non-dissipative motion is a long-standing and still ongoing strive, practical realizations remain essentially limited to low-temperatures, with superconductors (charge transport), or superfluids (mass transport). Here we examine a different quantum mechanism which enables frictionless motion (denoted as {\it superflow}) of small, weakly interacting particles through narrow nanotubes. At T=0 K complete {\it superflow} through ideal carbon nanotubes is possible even in the presence of corrugated interface potentials, below a critical velocity $v_{\rm c}$. This is shown by analysis of the {\it superflowing} density fraction. The critical velocity tends to decrease when energy corrugations becomes larger, providing a quantum analog of the semi-classical relation between friction and interface energy-landscape. Moreover, partial {\it superflow} (quantum superposition of {\it superflowing} and normal state) can persist for velocities exceeding $v_{c\rm}$ by two orders of magnitude, implying quantum-mechanical friction suppression, and gradual transition to the semi-classical regime. Viscous effects -possibly emerging at finite temperature are also examined from a kinematic perspective, confirming the possible persistence of ballistic transport in the low temperature limit.