On the Mourre estimates for Floquet Hamiltonians.

In the spectral and scattering theory for a Schrödinger operator with a time-periodic potential H (t) = p 2 / 2 + V (t , x) , the Floquet Hamiltonian K = - i ∂ t + H (t) associated with H(t) plays an important role frequently, by virtue of the Howland–Yajima method. In this paper, we introduce a new conjugate operator for K in the standard Mourre theory, that is different from the one due to Yokoyama, in order to relax a certain smoothness condition on V. [ABSTRACT FROM AUTHOR]