title: Controlling coherence via tuning of the population imbalance in a bipartite optical lattice.
abstract: The control of transport properties is a key tool at the basis of many technologically relevant effects in condensed matter. The clean and precisely controlled environment of ultracold atoms in optical lattices allows one to prepare simplified but instructive models, which can help to better understand the underlying physical mechanisms. Here we show that by tuning a structural deformation of the unit cell in a bipartite optical lattice, one can induce a phase transition from a superfluid into various Mott insulating phases forming a shell structure in the superimposed harmonic trap. The Mott shells are identified via characteristic features in the visibility of Bragg maxima in momentum spectra. The experimental findings are explained by Gutzwiller mean-field and quantum Monte Carlo calculations. Our system bears similarities with the loss of coherence in cuprate superconductors, known to be associated with the doping-induced buckling of the oxygen octahedra surrounding the copper sites.
authors.affiliation: Institute for Theoretical Physics, Centre for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Di Liberto
authors.affiliation: 1] Institute for Theoretical Physics, Centre for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands [2] Laboratoire de Physique Statistique, École Normale Supérieure, UPMC, Université Paris Diderot, CNRS, 24 rue Lhomond, 75005 Paris, France.
authors.forename: T
authors.initials: T
authors.lastname: Comparin
authors.affiliation: Institut für Laser-Physik, Fachbereich Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kock
authors.affiliation: Institut für Laser-Physik, Fachbereich Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ölschläger
authors.affiliation: Institut für Laser-Physik, Fachbereich Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hemmerich
authors.affiliation: Institute for Theoretical Physics, Centre for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands.
authors.forename: C Morais
authors.initials: CM
authors.lastname: Smith