title: Excitations of one-dimensional Bose-Einstein condensates in a random potential.
abstract: We examine bosons hopping on a one-dimensional lattice in the presence of a random potential at zero temperature. Bogoliubov excitations of the Bose-Einstein condensate formed under such conditions are localized, with the localization length diverging at low frequency as l(omega) approximately 1/omega(alpha). We show that the well-known result alpha=2 applies only for sufficiently weak random potential. As the random potential is increased beyond a certain strength, alpha starts decreasing. At a critical strength of the potential, when the system of bosons is at the transition from a superfluid to an insulator, alpha=1. This result is relevant for understanding the behavior of the atomic Bose-Einstein condensates in the presence of random potential, and of the disordered Josephson junction arrays.
authors.affiliation: Department of Physics, University of Colorado, Boulder, CO 80309, USA.
authors.forename: V
authors.initials: V
authors.lastname: Gurarie
authors.forename: G
authors.initials: G
authors.lastname: Refael
authors.forename: J T
authors.initials: JT
authors.lastname: Chalker