Resonant control of spin dynamics in ultracold quantum gases by   microwave dressing
  We study experimentally interaction-driven spin oscillations in optical lattices in the presence of an off-resonant microwave field. We show that the energy shift induced by this microwave field can be used to control the spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations. Finally, we propose a scheme based on this technique to create a flat sample with either singly- or doubly-occupied sites, starting from an inhomogeneous Mott insulator, where singly- and doubly-occupied sites coexist. 
Fabrice Gerbier, Artur Widera, Simon Foelling, Olaf Mandel, Immanuel   Bloch