Two bosonic dipoles under elongated confinement

Jochen Arlt, Kishan Dholakia, Josh Soneson +1 more

We theoretically investigate the use of Bessel light beams generated using axicons for creating optical dipole traps for cold atoms and atomic waveguiding. Zeroth-order Bessel beams can be used to produce highly elongated dipole traps, allowing for the study of one-dimensional trapped gases and realization of a Tonks gas of impenetrable bosons. First-order Bessel beams are shown to be able to produce tight confined atomic waveguides over centimeter distances.

G. Mazzarella, Luca Dell’Anna

Debopriya Das

Mamta Ale, Harsimranjit Kaur, Kuldeep Suthar

We investigate the vortex lattices of harmonically confined quasi-two-dimensional tilted rotational dipolar Bose-Einstein condensates. By employing an extended Gross-Pitaevskii equation for a rotating condensate, we reveal the structural transformation of vortices from square to triangular lattices as the tilt of dipolar bosons relative to the polarization axis approaches a critical angle. When the tilt of the magnetic dipoles surpasses the magic angle, the condensate elongates diagonally and becomes devoid of vortices. Moreover, we include the Lee-Huang-Yang correction, which enables the formation of vortices in the elongated condensate. Additionally, when dipoles are oriented perpendicular to the polarization axis, the Lee-Huang-Yang correction results in the fragmentation of condensates under strong rotation. The quench dynamics of the rotational frequency demonstrate the development of vortex lattices; however, with a strong rotational quench, the condensate remains free of vortices. Our numerical analysis highlights the beyond mean-field effects of the rotational properties of anisotropic dipolar bosons, which can be observed in current dipolar quantum gas experiments.

A. Macia, F. Mazzanti, J. Boronat

Sukla Pal, D. Baillie, P. B. Blakie

We study the properties of a magnetic dipolar Bose-Einstein condensate in an elongated (cigar shaped) confining potential in the beyond quasi-one-dimensional regime. In this system the dipole-dipole interactions develop a momentum dependence related to the transverse confinement and the polarization direction of the dipoles. This leads to density fluctuations being enhanced or suppressed at a length scale related to the transverse confinement length, with local atom number measurements being a practical method to observe these effects in experiments. We use mean-field theory to describe the ground state, excitations, and the local number fluctuations. Quantitative predictions are presented based on full numerical solutions and a simplified variational approach that we develop. In addition to the well-known roton excitation, occurring when the dipoles are polarized along a tightly confined direction, we find an ``antiroton'' effect for the case of dipoles polarized along the long axis: A nearly noninteracting ground state that experiences strongly repulsive interactions with excitations of sufficiently short wavelength.