Effective field theory for spinor dipolar Bose Einstein condensates

TL;DR

This paper develops an effective field theory using an extended Non-linear sigma model to describe the low-energy behavior of dipolar Bose-Einstein condensates with large dipole moments, revealing complex spin-mass interactions and topological features.

Contribution

It introduces a novel effective energy functional incorporating non-local dipole-dipole interactions for spinor dipolar BECs, enabling analysis of their density, spin profiles, and excitations.

Findings

Strong spin-mass density intertwining

Transfer of angular momentum via Einstein-de Haas effect

Emergence of topological properties in condensate configurations

Abstract

We show that the effective theory of long wavelength low energy behavior of a dipolar Bose-Einstein condensate(BEC) with large dipole moments (treated as a classical spin) can be modeled using an extended Non-linear sigma model (NLSM) like energy functional with an additional non-local term that represents long ranged anisotropic dipole-dipole interaction. Minimizing this effective energy functional we calculate the density and spin-profile of the dipolar Bose-Einstein condensate in the mean-field regime for various trapping geometries. The resulting configurations show strong intertwining between the spin and mass density of the condensate, transfer between spin and orbital angular momentum in the form of Einstein-de Hass effect, and novel topological properties. We have also described the theoretical framework in which the collective excitations around these mean field solutions can be studied and discuss some examples qualitatively.