  Entangled states are an important resource for quantum information processing
and for the fundamental understanding of quantum physics. An intriguing open
question would be whether entanglement can improve the performance of quantum
heat engines in particular. One of the promising platforms to address this
question is to use entangled atoms as a non-thermal bath for cavity photons,
where the cavity mirror serves as a piston of the engine. Here we theoretically
investigate a photonic quantum engine operating under an effective reservoir
consisting of quantum-correlated pairs of atoms. We find that maximally
entangled Bell states alone do not help extract useful work from the reservoir
unless some extra populations in the excited states or ground states are taken
into account. Furthermore, high efficiency and work output are shown for the
non-maximally entangled superradiant state, while negligible for the subradiant
state due to lack of emitted photons inside the cavity. Our results provide
insights in the role of quantum-correlated atoms in a photonic engine and
present new opportunities in designing a better quantum heat engine.
