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We report the Bragg spectroscopy of interacting one-dimensional Bose gases loaded in an optical lattice across the superfluid to the Mott-insulator phase transition. Elementary excitations are created with a nonzero 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 gases in optical lattices. D. Clément et al., See also the Physics Viewpoint by D. Jaksch: D. Jaksch |
In June 10th 1999, the Rubidium BEC1 apparatus produced the first italian Bose-Einstein condensate. We soon focused our activity on the study of a quantum gas of 87Rb bosons in optical lattices, investigating static and dynamic properties and enlightening the role of different kinds of instabilities. The last part of the activity was concentrated on the study of the superfluid to Mott insulator transition (also adding disorder and “quasi-disorder”) and on the physics of low-dimensional bosonic gases, characterized by measuring the excitation spectrum of these systems through inelastic light scattering. The BEC1 experiment retired in 2014 after 15 years of activity. We would like to thank all the people – students, technicians, and researchers – who have contributed to these exciting fifteen years of activity.