  Micro-to-nano scale thermal devices that operate under large thermal
fluctuations, are an active field of research where instead the average values,
the full distributions of thermodynamic quantities are important. Here we study
a model of stochastic heat engine consisting of a harmonically trapped Brownian
particle driven by the time-periodic strength of the confinement, within two
thermal baths of different temperatures. The particle follows two isotherms
correspond to two baths and connected by two micro-adiabates. The
microadiabaticity is implemented by conserving the phase space volume of the
particle along the adiabatic paths. Here we show that it can operate as an
engine or as a heater under microadiabaticity, depending on the parameter
space. We also compute the distribution of stochastic efficiency and its
averages for different cycle times of the engine.
