Figure 4
From: Su-Schrieffer-Heeger chain with one pair of \(\mathcal{P}\mathcal{T}\)-symmetric defects
The numerically calculated γ c as a function of location m. (a) γ c minimum in region θ ∈ [−π, π] is depicted, which indicates the \(\mathcal{P}\mathcal{T}\)-symmetric SSH chain spectrum is entirely real for γ < γ c at arbitrary θ. The blue bars are for odd m, which approaches zero for m < 30; the green bars are for even m. (b) γ c depicted for full θ ∈ [−π, π], the dark blue from left to dark red on the right represent θ from −π to π, the green area in the center corresponds to θ = 0, indicated by arrows in the upper right corner. Other parameters are N = 100, Δ = 1/2.
