Figure 2

Phase diagram. Ground-state phase diagram for a 1D system of coupled cavities described by Hamiltonian (1) in the \(g_{2}-t\) parameter space. Here and in the subsequent figures we choose \(g_{1} / \Omega= 0.8\), \(\Delta/ \Omega= -2\). The various symbols correspond to points belonging to different phases (triangles = MI, circles = DW, squares = SF). Filled points lie close to a phase transition, and are used to draw the interpolating curves (dashed lines). The DW-to-MI/SF boundary (filled circles) has been obtained by analyzing the density-wave order parameter, while the MI-SF boundary (filled squares) through the charge gap. The two vertical dotted lines denoted two cuts in the phase diagram which will be analyzed in details below. The error bars in the points characterizing the DW-to-MI/SF boundary take into account the discretization of the \(g_{2}\) values that we adopted in our numerical simulations (see the text).