  Analyzing the dynamics of open quantum systems has a long history in
mathematics and physics. Depending on the system at hand, basic physical
phenomena that one would like to explain are, for example, convergence to
equilibrium, the dynamics of quantum coherences (decoherence) and quantum
correlations (entanglement), or the emergence of heat and particle fluxes in
non-equilibrium situations. From the mathematical physics perspective, one of
the main challenges is to derive the irreversible dynamics of the open system,
starting from a unitary dynamics of the system and its environment.
  The repeated interactions systems considered in these notes are models of
non-equilibrium quantum statistical mechanics. They are relevant in quantum
optics, and more generally, serve as a relatively well treatable approximation
of a more difficult quantum dynamics. In particular, the repeated interaction
models allow to determine the large time (stationary) asymptotics of quantum
systems out of equilibrium.
