Comunicazione
Dipolar physics in low dimensions: From the gas, to the liquid and droplet formation.
Citro R., De Palo S., Orignac E., Salasnich L.
We theoretically investigate the ground-states properties, the radial collective oscillations and the droplets formation in a quasi-one-dimensional dipolar gas of bosonic atoms. We model the dipolar gas with an effective quasi-one-dimensional Hamiltonian and derive the equation of state using a variational approximation based on the Lieb-Liniger gas Bethe ansatz wave function or perturbation theory. We calculate the density profile and show that when the strength of the dipolar interaction becomes sufficiently attractive compared to the contact one, a solitonic-like density profile evolves into a liquid-like droplet. The incipient gas-liquid transition is also signaled by a steep increase of the breathing mode and a change in sign of the chemical potential. Upon a sudden release of the trap the numerical solution of a time-dependent generalized Gross-Pitaevskii equation shows that the droplet either evaporates or forms a single self-bound droplet or fragments in multiple droplets, depending on the number of trapped atoms and the scattering length. These results can help in characterizing the effect of the dipolar interaction in a quasi-one-dimensional geometry $vs.$ the 3D geometry.