Quantum Brownian motion represents a paradigmatic model of open quantum
system, namely a system inextricably coupled to the surrounding
environment. Such a model is largely used in physics, for instance in
quantum foundations to approach in a quantitative manner the
quantum-to-classical transition, but also for more practical purposes as
the estimation of decoherence in quantum optics experiments.
This book presents the main techniques aimed to treat the dynamics of
the quantum Brownian particle: Born-Markov master equation, Lindblad
equation and Heisenberg equations formalism. Particular attention is
given to the interaction between the particle and the bath depends
non-linearly on the position of the former. This generalization
corresponds to the case in which the bath is not homogeneous. An
immediate application is the Bose polaron, specifically an impurity
embedded in an ultracold gas.