Glassy properties of the Bose-glass phase of a one-dimensional disordered Bose fluid

We study a one-dimensional disordered Bose fluid using bosonization, the replica method and a nonperturbative functional renormalization-group approach. The Bose-glass phase is described by a fully attractive strong-disorder fixed point characterized by a singular disorder correlator whose functional dependence assumes a cuspy form that is related to the existence of metastable states. At nonzero momentum scale, quantum tunneling between these metastable states leads to a rounding of the nonanalyticity in a quantum boundary layer that encodes the existence of rare superfluid regions responsible for the $omega^2$ behavior of the (dissipative) conductivity in the low-frequency limit. These results can be understood within the droplet picture put forward for the description of glassy (classical) systems.