Quantum crystals in a trapped Rydberg-dressed Bose-Einstein condensate

TL;DR

This paper investigates the formation of quantum crystals in a trapped Rydberg-dressed Bose-Einstein condensate, revealing crystalline superfluid states, droplet lattices, and phase transitions influenced by interaction strength and anisotropy.

Contribution

It introduces the numerical study of quantum crystal states with superfluid properties in Rydberg-dressed BECs, including lattice structures and phase transitions under various conditions.

Findings

Hexagonal droplet lattice observed in quasi-2D systems

Transition from hexagonal to square lattice induced by anisotropic interactions

Significant drop in non-classical rotational inertia indicating crystalline order

Abstract

Spontaneously crystalline ground states, called quantum crystals, of a trapped Rydberg-dressed Bose-Einstein condensate are numerically investigated. As a result described by a mean-field order parameter, such states simultaneously possess crystalline and superfluid properties. A hexagonal droplet lattice is observed in a quasi-two-dimensional system when dressing interaction is sufficiently strong. Onset of these states is characterized by a drastic drop of the non-classical rotational inertia proposed by Leggett [Phys. Rev. Lett. 25, 1543 (1970)]. In addition, an AB stacking bilayer lattice can also be attained. Due to an anisotropic interaction possibly induced by an external electric field, transition from a hexagonal to a nearly square droplet lattice is also observed.