A MICROSCOPIC DERIVATION OF STOCHASTIC DIFFERENTIAL-EQUATIONS

With the help of the formulation of Non-Equilibrium Thermo Field Dynam ics, constructed is a unified canonical operator formalism for the qua ntum stochastic differential equations. In the course of its construct ion, it is found that there are at least two formulations, i.e. one is non-hermitian and the other is hermitian. Having been settled the fra mework which should be satisfied by the quantum stochastic differentia l equations, performed is a microscopic derivation of these stochastic differential equations by extending the projector methods. This inves tigation may open a new field for quantum systems in order to understa nd the deeper meaning of dissipation.