Disorder and the elusive superfluid phase of para-hydrogen

TL;DR

This study uses Quantum Monte Carlo simulations to explore whether disorder can induce superfluidity in two-dimensional para-hydrogen, finding that disorder instead leads to glassy phases without superfluid properties.

Contribution

It provides a theoretical analysis showing that disorder does not stabilize superfluidity in 2D para-hydrogen, contrasting with previous hypotheses.

Findings

Disorder results in glassy phases lacking superfluidity.

Quantum exchanges are suppressed by disorder.

Regular scatterer arrangements also do not produce superfluidity.

Abstract

The possibility that disorder may stabilize a superfluid phase of para-hydrogen in two dimensions is investigated theoretically by means of Quantum Monte Carlo simulations. We model disorder using a random distribution of scatterers, and study the thermodynamic behavior of the system as a function of the scatterer density. Disorder gives rise to equilibrium glassy phases with no superfluid properties. Indeed, the propensity for quantum exchanges of hydrogen molecules is reduced even with respect to what is observed if the scatterers are arranged as a regular crystal, a physical setting that also yields no superfluidity.