  The possibility of efficiently converting heat into work at the microscale
has triggered an intense research effort to understand quantum heat engines,
driven by the hope of quantum superiority over classical counterparts. In this
work, we introduce a model featuring an atom-doped optical quantum cavity
propelling a classical piston through radiation pressure. The model, based on
the Jaynes-Cummings Hamiltonian of quantum electrodynamics, demonstrates the
generation of mechanical work through thermal energy injection. We establish
the equivalence of the piston expansion work with Alicki's work definition,
analytically for quasistatic transformations and numerically for finite time
protocols. We further employ the model to construct quantum Otto and Carnot
engines, comparing their performance in terms of energetics, work output,
efficiency, and power under various conditions. This model thus provides a
platform to extract useful work from an open quantum system to generate net
motion, and sheds light on the quantum concepts of work and heat.
