The quantum master equation revisited

M.O. CÁCERES; A.A. BUDINI; A.K. CHATTAH

REVISTA MEXICANA DE FISICA

Sociedad Mexicana de Física (CONACYT)

Año: 1999 vol. 45 p. 217 - 217

p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; tab-stops: 172.0pt">We have proved that tracing-out the bath variables a generator of the Kossakowski-Lindblad form is always obtained. This fact does not guarantee the completely positivite condition. Nevertheless, in terms of the interaction Hamiltonian we have stressed the relevance of the invariance under Davies´s average procedure in order to arrive to a completely positive semigroup. The alternative approach called the Schrödinger-Langevin picture has been introduced. Then a non-Markovian evolution equation for a stochastic state vector has been presented. In the context of a perturbation theory in the Kubo number, the average over the noises leads to a dissipative generator which has formally a Kossakowski-Lindblab form. In this context it is possible to find noise correlation funtions to guarantee the completely positive condition. The equivalence of this picture with the trace-out techniq