title: Probing number squeezing of ultracold atoms across the superfluid-Mott insulator transition.
abstract: The evolution of on-site number fluctuations of ultracold atoms in optical lattices is experimentally investigated by monitoring the suppression of spin-changing collisions across the superfluid-Mott insulator transition. For low atom numbers, corresponding to an average filling factor close to unity, large on-site number fluctuations are necessary for spin-changing collisions to occur. The continuous suppression of spin-changing collisions is thus direct evidence for the emergence of number-squeezed states. In the Mott insulator regime, we find that spin-changing collisions are suppressed until a threshold atom number, consistent with the number where a Mott plateau with doubly occupied sites is expected to form.
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany. fabrice.gerbier@lkb.ens.fr
authors.forename: Fabrice
authors.initials: F
authors.lastname: Gerbier
authors.forename: Simon
authors.initials: S
authors.lastname: Fölling
authors.forename: Artur
authors.initials: A
authors.lastname: Widera
authors.forename: Olaf
authors.initials: O
authors.lastname: Mandel
authors.forename: Immanuel
authors.initials: I
authors.lastname: Bloch