Abstract:
We initiate an approach to simultaneously treat numerators and denominators of Green's functions arising from quasi-periodic Schrödinger operators, which in particular allows us to study completely resonant phases of the almost Mathieu operator.
Let (Hλ,α,θu)(n)=u(n+1)+u(n−1)+2λcos2π(θ+nα)u(n) be
the almost Mathieu operator on ℓ2(Z), where λ,α,θ∈R.
Let β(α)=lim supk→∞−ln||kα||R/Z|k|.
We prove that for any θ with 2θ∈αZ+Z,
Hλ,α,θ
satisfies Anderson localization if |λ|>e2β(α).
This confirms a conjecture of Avila and Jitomirskaya [The Ten Martini Problem. Ann. of Math. (2) 170 (2009), no. 1, 303–342] and a particular case of a conjecure of Jitomirskaya [Almost everything about the almost Mathieu operator. II. XIth International Congress of Mathematical Physics (Paris, 1994), 373–382, Int. Press, Cambridge, MA, 1995].