On the Hamiltonian of a Class of Quantum Stochastic Processes

Following the approach proposed by A. M. Chebotarev, we study the generator of a strongly continuous unitary group associated with solutions of the Hudson-Parthasarathy quantum stochastic differential equation (QSDE) in the case when the operators of the system of arbitrary multiplicity (or operator-valued coefficients characterizing the quantum system) are unbounded and noncommuting. We apply our results to the two-photon absorption and emission process.