Line of Dirac monopoles embedded in a Bose-Einstein condensate

The gauge field of a uniform line of magnetic monopoles is created using a single Laguerre-Gauss laser mode and a gradient in the physical magnetic field. We study the effect of these monopoles on a Bose condensed atomic gas, whose vortex structure transforms when more than six monopoles are trapped within the cloud. Finally, we study this transition with the collective modes

A repulsive atomic gas in a harmonic trap on the border of itinerant ferromagnetism

Alongside superfluidity, itinerant (Stoner) ferromagnetism remains one of the most well-characterized phases of correlated Fermi systems. A recent experiment has reported the first evidence for novel phase behavior on the repulsive side of the Feshbach resonance in a two-component ultracold Fermi gas. By adapting recent theoretical studies to the atomic trap geometry, we show that an adiabatic ferromagnetic transition would take place at a weaker interaction strength than is observed in experiment. This discrepancy motivates a simple non-equilibrium theory that takes account of the dynamics of magnetic defects and three-body losses. The formalism developed displays good quantitative agreement with experiment.Comment: 4 pages, 2 figure