“…The solution of the eigenvalue problem for the corresponding Floquet operator U (t,t 0 ), |ψ(t + t 0 ) = U (t,t 0 )|ψ(t 0 ) provides the set of eigenfunctions {|ψ α (t) }. The eigenfunctions satisfy the Floquet theorem |ψ α,κ (t) = e −iε α [κ]t/h |φ α,κ (t) , |φ α,κ (t) = |φ α,κ (t + T ) , and the Bloch theorem [18]. The Hilbert space of the system is sliced into invariant subspaces, each one of which is spanned by the states bearing the same quasimomentum value κ ∈ [−1/2,1/2].…”