  Dynamics of quantum systems which are perturbed by linear coupling to the
reservoir stochastically can be studied in terms of quantum stochastic
differential equations (for example, quantum stochastic Liouville equation and
quantum Langevin equation). To work it out one needs definition of quantum
Brownian motion. Since till very recent times only its boson version has been
known, in present paper we demonstrate definition which makes possible
consideration also for fermion Brownian motion.
