Resonant demagnetization of a dipolar Bose-Einstein condensate in a three-dimensional optical lattice

We study dipolar relaxation of a chromium Bose-Einstein condensate loaded into a three-dimensional (3D) optical lattice.
arXiv:1212.5469 (2012) / Phys. Rev. A 87, 051609(R) (2013)

We observe dipolar relaxation resonances when the magnetic energy released during the inelastic collision matches an excitation towards higher-energy bands. Spectroscopy of these resonances for two orientations of the magnetic field provides a 3D band spectroscopy of the lattice.

The narrowest resonance is registered for the lowest excitation energy. Its line shape is sensitive to the on-site interaction energy.

We use such sensitivity to probe number squeezing in a Mott insulator.

Dipolar relaxation only occurs provided the loss of Zeeman energy ∆EZeeman matches a gain in orbital energy (band excitation).