Bose-Einstein condensation with magnetic dipole-dipole forces

TL;DR

This paper investigates Bose-Einstein condensates with magnetic dipole-dipole interactions, revealing stability conditions, internal structures near instability, and providing an analytic estimate for characteristic lengths.

Contribution

It presents the first study of Bose-Einstein condensation considering realistic long-range magnetic dipole-dipole forces.

Findings

All solutions are stable for typical magnetic moments and scattering lengths.

Lowering the scattering length leads to unstable solutions.

Near instability, ground states exhibit novel internal structures.

Abstract

Ground-state solutions in a dilute gas interacting via contact and magnetic dipole-dipole forces are investigated. To the best of our knowledge, it is the first example of studies of the Bose-Einstein condensation in a system with realistic long-range interactions. We find that for the magnetic moment of e.g. chromium and a typical value of the scattering length all solutions are stable and only differ in size from condensates without long-range interactions. By lowering the value of the scattering length we find a region of unstable solutions. In the neighborhood of this region the ground state wavefunctions show internal structures not seen before in condensates. Finally, we find an analytic estimate for the characteristic length appearing in these solutions.