RESUMO
In the study of open quantum systems, one of the most common ways to describe environmental effects on the reduced dynamics is through the spectral density. However, in many models this object cannot be computed from first principles and needs to be inferred on phenomenological grounds or fitted to experimental data. Consequently, some uncertainty regarding its form and parameters is unavoidable; this in turn calls into question the accuracy of any theoretical predictions based on a given spectral density. Here, we focus on the spin-boson model as a prototypical open quantum system, find two error bounds on predicted expectation values in terms of the spectral density variation considered, and state a sufficient condition for the strongest one to apply. We further demonstrate an application of our result, by bounding the error brought about by the approximations involved in the hierarchical equations of motion resolution method for spin-boson dynamics.
RESUMO
PIP: Contraception always interferes into the sexual life of the couple, modifying it in an emotional or psychological sense. In many cases sexual communication is improved because of contraception; in many cases it has a negative influence, caused mainly by the mental immaturity of the partners, by their emotional instability, or by their sociocultural background. Negative sexual side effects of contraception are usually caused, in the woman, by a conflict with the traditional image of the woman as mother, and by an unconscious desire of fertility; in the man they are usually caused by the long-accepted identification of sexual potency with reproductive ability, and by fears for the newly acquired freedom of the female partner. Positive or negative psychological effects of contraception vary, but not greatly, according to the method used. A sympathetic and experienced doctor can furnish good advice on the matter.^ieng