Variance bound for energy differences between incongruent states
Let HΛ,JH_{\Lambda,J}HΛ,J be the finite-volume Hamiltonian in a box Λ\LambdaΛ with ∣Λ∣=Ld|\Lambda|=L^d∣Λ∣=Ld, and let σ1\sigma^1σ1 and σ2\sigma^2σ2 be chosen as in Theorem. Write Var\operatorname{Var}Var…