Emergence of a superglass phase in the random hopping Bose-Hubbard model

Abstract

We study an experimentally feasible system of strongly correlated bosons with random hoppings, described by the infinite-range Bose-Hubbard model on a lattice with hopping integrals given by independent random variables of Gaussian distribution with non-zero mean. We solve this quantum model in the thermodynamic limit, employing the replica method and the Trotter-Suzuki formula. We find and describe a superglass phase that emerges at the interface between glass and superfluid phases. Both glassy and long-range orderings are present in the superglass and compete with each other, as revealed by the anticorrelation of their order parameters. We present phase diagrams in various cross-sections of the multidimensional space of system parameters. In selected parameter subspaces, we compare the results to those of non-disordered, diagonally-disordered, and once celebrated spin-glass systems.