  Motivated by proposed thermometry measurement on an open quantum system, we
present a simple model of an externally driven qubit interacting with a finite
sized, fermion environment acting as calorimeter. The derived dynamics is
governed by a stochastic Schr\"odinger equation coupled to the temperature
change of the calorimeter. We prove a fluctuation relation and deduce from it a
notion of entropy production. Finally, we discuss the first and second law
associated to the dynamics.
