Bose-Einstein condensation of trapped atoms with dipole interactions

TL;DR

This study uses path integral Monte Carlo simulations to explore how long-range dipole-dipole interactions affect the properties of trapped Bose gases at finite temperatures, revealing geometry-dependent attractive or repulsive effects.

Contribution

It introduces a detailed simulation approach combining anisotropic pseudopotentials and hard-sphere potentials to analyze dipolar Bose gases in different trapping geometries.

Findings

Dipolar interactions cause density profile shrinking in cigar-shaped traps.

Dipolar interactions lead to density expansion in disk-shaped traps.

The net effect of dipole-dipole forces depends on trap geometry.

Abstract

The path integral Monte Carlo method is used to simulate dilute trapped Bose gases and to investigate the equilibrium properties at finite temperatures. The quantum particles have a long-range dipole-dipole interaction and a short-range s-wave interaction. Using an anisotropic pseudopotential for the long-range dipolar interaction and a hard-sphere potential for the short-range s-wave interaction, we calculate the energetics and structural properties as a function of temperature and the number of particles. Also, in order to determine the effects of dipole-dipole forces and the influence of the trapping field on the dipolar condensate, we use two cylindrically symmetric harmonic confinements (a cigar-shaped trap and a disk-shaped trap). We find that the net effect of dipole-dipole interactions is governed by the trapping geometry. For a cigar-shaped trap, the net contribution of dipolar interactions is attractive and the shrinking of the density profiles is observed. For a disk-shaped trap, the net effect of long-range dipolar forces is repulsive and the density profiles expand.