Two-stroke thermal machine using spin squeezing operation

Abstract

Quantum thermal machines are powerful platforms to investigate how quantum effects impact the energy flow between different systems. We here investigate a two-stroke cycle in which spin squeezing effects are intrinsically switched on during all the operation time. By using Kitagawa and Ueda’s parameter and the ${\ell }_1$-norm to compute the degree of spin squeezing and the quantum coherence, we first show that the greater the spin squeezing effect, the greater the amount of coherence in the energy basis. Then, we investigate the engine performance given the amount of spin squeezing into the system. Our results show that even assuming an always-on spin squeezing, which is directly associated with the amount of entropy production in the cycle, it is possible to find a better set of efficiency and extracted power for the engine provided a high level of control over the relevant parameters, i.e., the operation time and the squeezing intensity.