Concepts of work in autonomous quantum heat engines

摘要: One of the fundamental questions in quantum thermodynamics concerns decomposition energetic changes into heat and work. Contrary to classical engines, entropy change piston cannot be neglected domain. As a consequence, different concepts work arise, depending on desired task implied capabilities agent using generated by engine. Each quantifier---from ergotropy non-equilibrium free energy---has well defined operational interpretations. We analyse these quantifiers for heat-pumped three-level maser derive respective engine efficiencies. In limit strong intensities efficiency converges towards Scovil--Schulz-DuBois efficiency, irrespective quantifier.