Supersolid behavior of a dipolar Bose-Einstein condensate confined in a tube

Year: 2019

Authors: Roccuzzo S. M., Ancilotto F.

Autors Affiliation: Univ Trento, INO CNR BEC Ctr, I-238123 Povo, Italy; Univ Trento, Dipartitnento Fis, I-238123 Povo, Italy; Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35122 Padua, Italy; Univ Padua, CNISM, Via Marzolo 8, I-35122 Padua, Italy; CNR IOM Dernocritos, Via Bonotnea 265, I-34136 Trieste, Italy

Abstract: Motivated by a recent experiment [L. Chomaz et al., Nat. Phys. 14, 442 (2018)], we perform numerical simulations of a dipolar Bose-Einstein condensate (BEC) in a tubular, periodic confinement at T = 0 within density functional theory, where the beyond-mean-field correction to the ground-state energy is included in the local density approximation. We study the excitation spectrum of the system by solving the corresponding Bogoliubov-de Gennes equations. The calculated spectrum shows a roton minimum, and the roton gap decreases by reducing the effective scattering length. As the roton gap disappears, the system spontaneously develops a periodic linear structure formed by denser clusters of atomic dipoles immersed in a dilute superfluid background. This structure shows the hallmarks of a supersolid system, i.e., (i) a finite nonclassical translational inertia along the tube axis and (ii) the appearance of two gapless modes, i.e., a phonon mode associated with density fluctuations and resulting from the translational discrete symmetry of the system, and a Nambu-Goldstone gapless mode corresponding to phase fluctuations, resulting from the spontaneous breaking of the gauge symmetry. A further decrease in the scattering length eventually leads to the formation of a periodic linear array of self-bound droplets

Journal/Review: PHYSICAL REVIEW A

Volume: 99 (4)      Pages from: 041601-1  to: 041601-6

KeyWords: QUANTUM GAS; VORTEX
DOI: 10.1103/PhysRevA.99.041601

Citations: 47
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