Two-dimensional supersolidity in a dipolar quantum gas

TL;DR

This paper demonstrates the realization of two-dimensional supersolidity in a dipolar quantum gas, advancing the understanding of supersolid phases beyond one-dimensional systems and closer to bulk solid helium.

Contribution

It introduces the first observation of 2D supersolidity in a dipolar quantum gas, extending supersolid properties into two dimensions.

Findings

Supersolidity extended into two dimensions in a dipolar gas.

Observation of phase transition similar to ionic chains and dipolar particles.

Potential for studying vortex formation and varied ground-state geometries.

Abstract

Supersolidity -- a quantum-mechanical phenomenon characterized by the presence of both superfluidity and crystalline order -- was initially envisioned in the context of bulk solid helium, as a possible answer to the question of whether a solid could have superfluid properties. While supersolidity has not been observed in solid helium (despite much effort), ultracold atomic gases have provided a fundamentally new approach, recently enabling the observation and study of supersolids with dipolar atoms. However, unlike the proposed phenomena in helium, these gaseous systems have so far only shown supersolidity along a single direction. By crossing a structural phase transition similar to those occurring in ionic chains, quantum wires, and theoretically in chains of individual dipolar particles, we demonstrate the extension of supersolid properties into two dimensions, providing an important step closer to the bulk situation envisioned in helium. This opens the possibility of studying rich excitation properties, including vortex formation, as well as ground-state phases with varied geometrical structure in a highly flexible and controllable system.