Quantum Otto and Carnot thermal machines powered by two two-level atoms enveloped by QED-cavity

This paper presents a conceptual model for quantum Otto and Carnot machines that utilizes two-level atoms interacting with a cavity field, initially prepared in a number state, as working substance. We focus on fundamental thermodynamic quantities, including work done, heat absorption from, release to heat baths, efficiency, and performance in both machines. According to our results, photon numbers significantly affect the upper and lower boundaries of the work that both machines can achieve. More specifically, the Carnot machine's maximal bound of work is higher than the Otto machine's. Furthermore, it is found that generating specific operation modes depends on ratios between system parameters. Importantly, similarities observed between behaviour patterns of thermodynamic quantities exhibited by both Carnot and Otto machines under different conditions.