  We discuss a qubit weakly coupled to a finite-size heat bath (calorimeter)
from the point of view of quantum thermodynamics. The energy deposited to this
environment together with the state of the qubit provides a basis to analyze
the heat and work statistics of this closed combined system. We present results
on two representative models, where the bath is composed of two-level systems
or harmonic oscillators, respectively. Finally, we derive results for an open
quantum system composed of the above qubit plus finite-size bath, but now the
latter is coupled to a practically infinite bath of the same nature of
oscillators or two-level systems.
