The mutual influence of a system with few degrees if freedom, and a "heat bath" with many degrees of freedom, on each other is the central concept in the physics of noise, both quantum and classical. In classical version, the typical example is the Langevin equation for the Brownian particle.
In quantum domain, we write a Shrödinger Langevin for a system in contact with a thermal bath. This equation contains the hamiltonean term, and are included a damping and another fluctuating terms, taking in account the finite quantum correlation time of the thermal bath. The goal of this work is to introduce the quantum correlation function of the noise coming from an harmonic oscillators bath; this gives correct temperature dependent coefficients in the Master Equation for the density matrix. A Fluctuation - Dissipation like theorem arises, when we ask for the conservation of the averaged norm of the wave function.
The Master Equation for the density matrix is worked out for two particular examples: the two level atom and the harmonic oscillator. In this examples we obtain the thermodynamic equilibrium limit, and the correct classical limit, the Brownian particle equation.
TRABAJO PRESENTADO COMO POSTER POR AK CHATTAH
