Local Superfluidity at the Nanoscale

TL;DR

This study uses quantum Monte Carlo simulations to explore superfluidity in helium-4 within nanopores, revealing anisotropic superfluid responses, a superfluid core with Luttinger liquid behavior, and insights into one-dimensional quantum liquids.

Contribution

First detailed simulation of superfluid response in helium-4 nanopores showing anisotropy and Luttinger liquid characteristics.

Findings

Superfluid response depends on type of boundary motion.

Superfluid density saturates below unity at 0.5 K.

Superfluid core exhibits Luttinger liquid scaling.

Abstract

We have performed quantum Monte Carlo simulations measuring the finite size and temperature superfluid response of helium-4 to the linear and rotational motion of the walls of a nanopore. Within the two-fluid model, the portion of the normal liquid dragged along with the boundaries is dependent on the type of motion and the resulting anisotropic superfluid density saturates far below unity at T=0.5 K. The origin of the saturation is uncovered by computing the spatial distribution of superfluidity, with only the core of the nanopore exhibiting any evidence of phase coherence. The superfluid core displays scaling behavior consistent with Luttinger liquid theory, thereby providing an experimental test for the emergence of a one dimensional quantum liquid.