Dipolar Bose-Einstein condensate soliton on a two-dimensional optical lattice

TL;DR

This paper investigates the stability and arrangement of dipolar Bose-Einstein condensate solitons on 2D optical lattices using a 3D mean-field model, revealing conditions for stable arrays and their relation to Mott insulator states.

Contribution

It introduces a detailed analysis of 1D dipolar BEC solitons on 2D optical lattices, identifying stability regimes and the formation of stable 2D arrays of droplets, linking to Mott insulator states.

Findings

Stable solitons exist within specific interaction limits.

Stable 2D arrays of droplets form at certain filling factors.

Arrays become unstable when more than half the sites are filled.

Abstract

Using a three-dimensional mean-field model we study one-dimensional dipolar Bose-Einstein condensate (BEC) solitons on a weak two-dimensional (2D) square and triangular optical lattice (OL) potentials placed perpendicular to the polarization direction. The stabilization against collapse and expansion of these solitons for a fixed dipolar interaction and a fixed number of atoms is possible for short-range atomic interaction lying between two critical limits. The solitons collapse below the lower limit and escapes to infinity above the upper limit. One can also stabilize identical tiny BEC solitons arranged on the 2D square OL sites forming a stable 2D array of interacting droplets when the OL sites are filled with a filling factor of 1/2 or less. Such an array is unstable when the filling factor is made more than 1/2 by occupying two adjacent sites of OL. These stable 2D arrays of dipolar superfluid BEC solitons are quite similar to the recently studied dipolar Mott insulator states on 2D lattice in the Bose-Hubbard model by Capogrosso-Sansone et al. [B. Capogrosso-Sansone, C. Trefzger, M. Lewenstein, P. Zoller, G. Pupillo, Phys. Rev. Lett. 104 (2010) 125301].