Superfluidity versus localization in bulk 4He at zero temperature

TL;DR

This study uses quantum Monte Carlo simulations to explore the transition from superfluid to localized phases in bulk helium-4 at zero temperature, revealing how superfluid density diminishes as the system approaches solid-like behavior.

Contribution

It introduces a model where external confining potentials induce a transition from liquid to solid-like phases in helium-4, providing new insights into superfluidity and localization at zero temperature.

Findings

Superfluid density decreases with increasing localization.

At the experimental Lindemann ratio, superfluid density is approximately 0.079.

The model mimics the transition from liquid to solid helium-4.

Abstract

We present a zero-temperature quantum Monte Carlo calculation of liquid $^4$He immersed in an array of confining potentials. These external potentials are centered in the lattice sites of a fcc solid geometry and, by modifying their well depth and range, the system evolves from a liquid phase towards a progressively localized system which mimics a solid phase. The superfluid density decreases with increasing order, reaching a value $ \rho_{\rm s}/\rho = 0.079(16)$ when the Lindemann's ratio of the model equals the experimental value for solid $^4$He.