Scientific Results

Correlation function of weakly interacting bosons in a disordered lattice

Year: 2011

Authors: Deissler B., Lucioni E., Modugno M., Roati G., Tanzi L., Zaccanti M., Inguscio M., Modugno G.

Autors Affiliation: Univ Firenze, LENS, I-50019 Sesto Fiorentino, Italy; INO CNR, I-50019 Sesto Fiorentino, Italy; Ist Nazl Fis Nucl, Sez Firenze, I-50019 Sesto Fiorentino, Italy; Univ Basque Country, Dept Theoret Phys & Hist Sci, Bilbao 48080, Spain; Basque Fdn Sci, IKERBASQUE, Bilbao 48011, Spain; Austrian Acad Sci, Inst Quantenopt & Quanteninformat, A-6020 Innsbruck, Austria; Univ Innsbruck, Inst Expt Phys, A-6020 Innsbruck, Austria

Abstract: One of the most important issues in disordered systems is the interplay of the disorder and repulsive interactions. Several recent experimental advances on this topic have been made with ultracold atoms, in particular the observation of Anderson localization and the realization of the disordered Bose-Hubbard model. There are, however, still questions as to how to differentiate the complex insulating phases resulting from this interplay, and how to measure the size of the superfluid fragments that these phases entail. It has been suggested that the correlation function of such a system can give new insights, but so far very little experimental investigation has been performed. Here, we show the first experimental analysis of the correlation function for a weakly interacting, bosonic system in a quasiperiodic lattice. We observe an increase in the correlation length as well as a change in the shape of the correlation function in the delocalization crossover from Anderson glass to coherent, extended state. In between, the experiment indicates the formation of progressively larger coherent fragments, consistent with a fragmented BEC, or Bose glass.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 13      Pages from: 023020  to: 023020

More Information: We acknowledge stimulating discussions with L Fontanesi and A Cetoli. We thank C D\’Errico and M Fattori for experimental contributions during the early stage of the experiment and discussions, J Seman for experimental assistance and all of the members of the Quantum Gases group at LENS. This work was supported by the EC (MEIF-CT-2004-009939 and Integrated Project AQUTE), by the ERC through the Starting Grant QUPOL and Advanced Grant DISQUA and by the ESF and INO-CNR through the EuroQUASAR and DQS EuroQUAM programmes.
KeyWords: Anderson localization; Andersons; Bose glass; Bose Hubbard model; Bosonic systems; Correlation function; Correlation lengths; Delocalizations; Disordered lattices; Disordered system; Experimental analysis; Experimental investigations; Insulating phasis; Interacting bosons; Quasi-periodic lattices; Repulsive interactions; Ultracold atoms, Glass; Hubbard model, Correlation methods
DOI: 10.1088/1367-2630/13/2/023020

Citations: 23
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English