Bose-Einstein condensation with magnetic dipole-dipole forces

TLDR

This is the first study of Bose‑Einstein condensation in a system with realistic long‑range magnetic dipole‑dipole interactions. The study investigates ground‑state solutions of a dilute gas interacting via contact and magnetic dipole‑dipole forces. The authors analyze these solutions by solving the mean‑field equations for a dilute gas with contact and magnetic dipole‑dipole interactions. For chromium (6 μ_B) and a typical scattering length, all solutions are stable and differ only in size from condensates without long‑range interactions, while reducing the scattering length produces an unstable region with previously unseen internal structures, and the authors provide an analytic estimate of the characteristic length.

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 Bose-Einstein condensation in a system with realistic long-range interactions. We find that for the magnetic moment of, e.g., chromium $(6{\ensuremath{\mu}}_{B}),$ 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 wave functions show internal structures that we believe have not been seen before in condensates. Finally, we find an analytic estimate for the characteristic length appearing in these solutions.