Localization versus incommemsurability for finite boson system in one-dimensional disordered lattice

Abstract

We explore the effect of disorder on a few-boson system in a finite one-dimensional quasiperiodic potential covering the full interaction ranging from uncorrelated to strongly correlated particles. We apply numerically exact multiconfigurational time-dependent Hartree for bosons to obtain the few-body emergent states in a finite lattice for both commensurate and incommensurate filling factors. The detailed characterization is done by the measures of one- and two-body correlations, fragmentation, order parameter. For commensurate filling, we trace the conventional fingerprints of disorder induced localization in the weakly interacting limit, however we observe robustness of fragmented and strongly correlated Mott in the disordered lattice. For filling factor smaller than one, we observe existing delocalization fraction of particles interplay in a complex way. For strongly interacting limit, the introduced disorder drags the fragmented superfluid of primary lattice to Mott localization. For filling factor larger than one in the primary lattice, the extra delocalization always resides on commensurate background of Mott-insulator. We observe beyond Bose-Hubbard physics in the fermionization limit when the pairing bosons fragment into two orbitals -- Mott dimerization happens. The introduced disorder first relocates the dimers, then strong disorder starts to interfere with the background Mott correlation. These findings unlock a rich landscape of unexplored localization process in the quasiperiodic potentials and pave the way for engineering exotic quantum many-body states with ultracold atoms.