Percolation analysis of a disordered spinor Bose gas

Abstract: We study the effects of an on-site disorder potential in a gas of spinor (spin-1) ultracold atoms loaded in an optical lattice corresponding to both ferromagnetic and antiferromagnetic spin dependent interactions. Starting with a disordered spinor Bose-Hubbard model (SBHM) on a two dimensional square lattice, we observe the appearance of a Bose glass phase using the fraction of the lattice sites having finite superfluid order parameter and non integer local densities as an indicator. A precise distinction between three different types of phases namely, superfluid (SF), Mott insulator (MI) and Bose glass (BG) is done via a percolation analysis thereby demonstrating that a reliable enumeration of phases is possible at particular values of the parameters of the SBHM. Finally we present the phase diagram based on the above information for both antiferromagnetic and ferromagnetic interactions.