Statistical model of a superfluid solid

TL;DR

This paper develops a microscopic statistical model for quantum solids with disordered regions that can exhibit superfluidity, particularly in Bose atom systems, by averaging over disordered configurations to predict superfluid behavior.

Contribution

It introduces a novel statistical model that accounts for disordered regions within a quantum solid, allowing for superfluidity to emerge in certain parameter regimes.

Findings

Disordered regions can exhibit Bose-Einstein condensation and superfluidity.

Averaging over disordered configurations leads to a renormalized Hamiltonian combining crystal and superfluid properties.

The model predicts conditions under which real quantum crystals can display superfluidity.

Abstract

A microscopic statistical model of a quantum solid is developed, where inside a crystalline lattice there can exist regions of disorder, such as dislocation networks or grain boundaries. The cores of these regions of disorder are allowed for exhibiting fluid-like properties. If the solid is composed of Bose atoms, then the fluid-like aggregations inside the regions of disorder can exhibit Bose-Einstein condensation and hence superfluidity. The regions of disorder are randomly distributed throughout the sample, so that for describing the overall properties of the solid requires to accomplish averaging over the disordered aggregation configurations. The averaging procedure results in a renormalized Hamiltonian of a solid that can combine the properties of a crystal and superfluidity. The possibility of such a combination depends on the system parameters. In general, there exists a range of the model parameters allowing for the occurrence of superfluidity inside the disordered aggregations. This microscopic statistical model gives the opportunity to answer which real quantum crystals can exhibit the property of superfluidity and which cannot.