EXOTIC PHASES IN A SPIN-1 BOSONIC FLUX SYSTEM

Abstract

We study, using the optimisation of matrix product states, the ground state properties of an interacting spin-1 hardcore boson model on a ladder in a transverse magnetic field at zero temperature. At unit filling in the strong-interacting regime, we observe a Mott insulator phase characterised by a charge gap and a periodic exponential decay of the Green’s functions. However, surprisingly, the connected density-density correlation functions decay with a power law and neutral excitations are gapless. When the hopping strength is sufficiently large or at non-commensurate filling, the system transitions to a superfluid phase characterised by the absence of a charge gap and a power-law decay of the Green’s functions. Due to the magnetic field, bond currents, which quantify the rate of change of the average number of particles on a given site, are observed and can characterise the phases. Notably, bond current loops form in the superfluid phase.