Two-level quantum Otto heat engine operating with unit efficiency far from the quasi-static limit under a squeezed reservoir

Recent theoretical and experimental studies in quantum thermodynamics show that, in the quasistatic limit, it is possible to have higher efficiency than the limit imposed by Carnot, provided that engineered reservoirs are used. The quasi-static regime, however, is a strong limitation to the operation of thermal machines, since infinitely long time is required to complete a cycle. In this paper we propose a two-level model as the working substance to perform a quantum Otto heat engine surrounded by a squeezed reservoir. Taking advantage of this model we show a striking achievement, that is to attain unity efficiency even at non-null power.