Exploring correlated 1D Bose gases from the superfluid to the   Mott-insulator state by inelastic light scattering
  We report the Bragg spectroscopy of interacting one-dimensional Bose gases loaded in optical lattices across the superfluid to Mott-insulator phase transition. Elementary excitations are created with a non-zero momentum and the response of the correlated 1D gases is in the linear regime. The complexity of the strongly correlated quantum phases is directly displayed in the spectra which exhibit novel features. This work paves the way for a precise characterization of the state of correlated atomic phases in optical lattices. 
D. Cl\'ement, N. Fabbri, L. Fallani, C. Fort and M. Inguscio