title: Ultracold atoms in a disordered crystal of light: towards a bose glass.
abstract: We use a bichromatic optical lattice to experimentally realize a disordered system of ultracold strongly interacting 87Rb bosons. In the absence of disorder, the atoms are pinned by repulsive interactions in the sites of an ideal optical crystal, forming one-dimensional Mott-insulator states. We measure the excitation spectrum of the system as a function of disorder strength and characterize its phase-coherence properties with a time-of-flight technique. Increasing disorder, we observe a broadening of the Mott-insulator resonances and the transition to a state with vanishing long-range phase coherence and a flat density of excitations, which suggest the formation of a Bose-glass phase.
authors.affiliation: LENS European Laboratory for Nonlinear Spectroscopy and Dipartimento di Fisica, Università di Firenze, via Nello Carrara 1, I-50019 Sesto Fiorentino (FI), Italy. fallani@lens.unifi.it
authors.forename: L
authors.initials: L
authors.lastname: Fallani
authors.forename: J E
authors.initials: JE
authors.lastname: Lye
authors.forename: V
authors.initials: V
authors.lastname: Guarrera
authors.forename: C
authors.initials: C
authors.lastname: Fort
authors.forename: M
authors.initials: M
authors.lastname: Inguscio