@article {2003,
title = {Parameter differentiation and quantum state decomposition for time varying Schr{\"o}dinger equations},
journal = {Rep. Math. Phys. 52 (2003) 381-400},
number = {arXiv.org;quant-ph/0201034v2},
year = {2003},
publisher = {Elsevier},
abstract = {For the unitary operator, solution of the Schroedinger equation corresponding to a time-varying Hamiltonian, the relation between the Magnus and the product of exponentials expansions can be expressed in terms of a system of first order differential equations in the parameters of the two expansions. A method is proposed to compute such differential equations explicitly and in a closed form.},
doi = {10.1016/S0034-4877(03)80037-X},
url = {http://hdl.handle.net/1963/3017},
author = {Claudio Altafini}
}