Motivated by a recent experiment [L. Chomaz et al., Nat. Phys. 14, 442 (2018)1745-247310.1038/s41567-018-0054-7], 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.

Supersolid behavior of a dipolar Bose-Einstein condensate confined in a tube / Roccuzzo, S. M.; Ancilotto, F.. - In: PHYSICAL REVIEW A. - ISSN 2469-9926. - 99:4(2019). [10.1103/PhysRevA.99.041601]

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

Roccuzzo S. M.;
2019-01-01

Abstract

Motivated by a recent experiment [L. Chomaz et al., Nat. Phys. 14, 442 (2018)1745-247310.1038/s41567-018-0054-7], 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.
2019
4
Roccuzzo, S. M.; Ancilotto, F.
Supersolid behavior of a dipolar Bose-Einstein condensate confined in a tube / Roccuzzo, S. M.; Ancilotto, F.. - In: PHYSICAL REVIEW A. - ISSN 2469-9926. - 99:4(2019). [10.1103/PhysRevA.99.041601]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/255724
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