MOURRE THEORY FOR TIME-PERIODIC SYSTEMS

Studies for A.C. Stark Hamiltonian are closely related to that for the self-adjoint operator K = -i d/dt + H(t) on torus. In this paper we u se Mourre's commutator method, which makes great progress for the stud y of time-independent Hamiltonian. By use of it we show the asymptotic behavior of the unitary propagator e(-i sigma K) as sigma --> +/- inf inity.