Superfluid properties of a honeycomb dipolar supersolid

TL;DR

This paper investigates the properties of honeycomb supersolids in dipolar condensates, highlighting their enhanced superfluidity compared to droplet supersolids and proposing methods to probe their superfluid fraction.

Contribution

It introduces the honeycomb supersolid phase as a distinct density pattern with superior superfluid properties and analyzes its vortex creation limitations and experimental probing techniques.

Findings

Honeycomb supersolids have a higher superfluid fraction than droplet supersolids.

Quantized vortices cannot be created without transitioning to a labyrinthic phase.

Superfluid fraction can be probed via scissors-like perturbation dynamics.

Abstract

Recent breakthrough experiments on dipolar condensates have reported the creation of supersolids, including two-dimensional arrays of quantum droplets. Droplet arrays are, however, not the only possible non-trivial density arrangement resulting from the interplay of mean-field instability and quantum stabilization. Several other possible density patterns may occur in trapped condensates at higher densities, including the so-called honeycomb supersolid, a phase that exists, as it is also the case of a triangular droplet supersolid, in the thermodynamic limit. We show that compared to droplet supersolids, honeycomb supersolids have a much-enhanced superfluid fraction while keeping a large density contrast, and constitute in this sense a much better dipolar supersolid. However, in contrast to droplet supersolids, quantized vortices cannot be created in a honeycomb supersolid without driving a transition into a so-called labyrinthic phase. We show that the reduced moment of inertia, and with it the superfluid fraction, can be however reliably probed by studying the dynamics following a scissors-like perturbation.